HK1021110A1

HK1021110A1 - Method for disinfecting of air by iodine/resin based disinfectant and systems for disinfection of air borne microorganisms

Info

Publication number: HK1021110A1
Application number: HK99106101A
Authority: HK
Inventors: Pierre Jean Messier
Original assignee: Triosyn Holding, Inc.
Priority date: 1992-09-16
Filing date: 1998-11-26
Publication date: 2000-06-02
Also published as: HK1021111A1

Description

The present invention relates to a method and system for disinfecting air using a disinfectant substance comprising an iodine (impregnated) resin. The treatment of air with an iodine/resin disinfectant of the present invention may leave behind non-detectable (or acceptable) residual diatomic iodine in the air. The present invention in particular relates to use of a demand type broad spectrum resin-polyiodide disinfectant.

Diatomic halogen (such as I₂, Cl₂, Br₂, etc...) has traditionally been used to disinfect water. Diatomic chlorine, for example, is a widely exploited disinfectant for controlling or eliminating micro-organisms which may be present in water. A disadvantage of a sterilization regime which exploits diatomic halogen is that the regime may leave behind unacceptable (residual) levels of halogen in the water once sterilization is complete.

An iodine/resin product has, however, been proposed for use as a demand disinfectant, namely a disinfectant wherein iodine is released almost entirely on a demand-action basis. United States patent nos. 3,817,860, 3,923,665, 4,238,477 and 4,420,590 teach such a demand disinfectant wherein iodine is the active disinfectant agent; the entire contents of each of these patents is incorporated herein by reference. In accordance with the teachings of these patents the resin product may be used without fear of introducing unacceptable concentrations of diatomic iodine into the water to be sterilized.

U.S. patent nos. 3,817,860 and 3,923,665 teach an iodine/resin demand disinfectant which is the reaction product obtained by contacting a strong base anion exchange resin with a suitable source of triiodide ions. The reaction product is taught as being very stable in the sense that the amount of iodine (e.g. I₂) released into water from the reaction product is sufficiently low that the water disinfected thereby is immediately ready for use, ie. as drinking water.

In accordance with the teachings of U.S. patent nos-3,817,860 and 3,923,665 the procedure for preparing the iodine/resin comprises forming a triiodide ion (solution or sludge) by dissolving diatomic iodine in a water solution of a suitable alkali metal halide (e.g. KI, NaI,....). The triiodide solution is in particular taught as being made with a minimal (i.e. minor) water content just sufficient to avoid causing the I₂ to crystallize out; see example 1 of U.S. patent no. 3,923,665. The resulting (solution) containing the triiodide ion is then contacted with the starting resin (under ambient conditions with respect to temperature (i.e. 25 to 30°C) and pressure), the triiodide ions exchanging with the anion of the resin (e.g. exchange with chlorine, sulfate, etc., ..). The starting resin is taught as being a porous granular strong base anion exchange resin having strongly basic groups in a salt form wherein the anion thereof is exchangeable with triiodide ions. In accordance with the teachings of the above prior art references contacting is continued until the desired amount of triiodide has reacted with the strongly basic groups such that bacterially contaminated water is disinfected when passed through a bed of the obtained resin. After a suitable contact time the iodine/resin is (water) washed to remove water-elutable iodine from the resin product.

However, as indicated in U.S. patent no. 4,238,477, it is difficult to use the procedures outlined in the two previously mentioned U.S. patents so as to obtain a homogeneous iodine/resin product containing only triiodide anions and wherein all of the active sites of the resin have been converted to triiodide ions.

Accordingly, U.S. patent no. 4,238,477 teaches an alternate process whereby the iodine/resin may be produced. In accordance with this alternate impregnation/contact process a suitable resin in the iodide form (I^-) is contacted with water comprising diatomic iodine (I₂) in solution, the water being recycled between a source of a predetermined amount of diatomic iodine and the resin. The process as taught by this latter patent, however, is a relatively complicated system of pumps, vessels, heaters, etc.; by exploiting a fluidized bed, it in particular may lead to a significant degree of resin bead attrition, i.e. particle breakup.

The processes as taught in U.S. patent nos. 3,817,860 and 3,923,665 are carried out at ambient temperature and ambient pressure conditions. The U.S. patent 4,238,477 teaches that the contact may occur at a higher temperature such as 60 to 95° C but that the temperature must be a non-boiling temperature (with respect to water); see column 3 lines 55 to 66.

The above referred to U.S. patents teach the use of the demand disinfectant iodinated resins for treating water; see also U.S. patent nos. 4,298,475 and 4,995,976 which teach water purification devices or systems which exploit iodinated resins. None of these patents teaches the use of the iodinated resins for the purpose of sterilizing air.

US-A-4343765 describes a method and apparatus for removing offensive odours and infectious agents from recirculating building air, utilising a granular filter bed positioned in a conduit having an air flow therein. The conduit may be a portion of the air circulation system of a building, or may be associated with the air circulation of a single room. The granular filter bed may contain an adsorbent material such as activated carbon or a granular inert material.

EP-A-0048286 describes a process for preparing homogeneous resin-polyiodide disinfectants from strong base anion exchange resin feeds and elemental iodine. The resin is in the iodide form, and the iodine is applied with a water carrier which is recycled in contact with the resin and a stoichiometric amount of iodine to form the desired polyiodide.

EP-A-0402865 describes a method for preparing strong base anion exchange resins containing high concentrations of pentaiodide (I₅ ^-), from highly concentrated solutions of I₅ ^- and I₃ ^- ions. The resulting resins are described as highly effective as disinfectants for water, acting against waterborne bacteria, virus and Giardia.

It is also known to use iodine tincture for sterilising wounds. The sterilisation effect of iodine tincture is short-lived; this means that the tincture must be reapplied on a regular basis to maintain the sterilisation effect. However, such solutions may also damage or destroy the tissue around the wound if applied too liberally and too often. Additionally, the direct application of such solutions to a lesion or wound is usually accompanied by a painful. sensation.

According to a first aspect of the present invention, a method for disinfecting air containing microorganisms is defined in claim 1.

According to a second aspect of the present invention, a system for disinfecting air containing microorganisms is defined in claim 8.

The iodinated resin may, for example, be a known resin such as discussed herein; a resin of the type described below; nylon-based resin beads impregnated with iodine (such as MCV resin from MVC Tech. International Inc.); and the like.

The demand disinfectant may take on any desired form: it may be in bulk form; it may be in sheet form; it may be in particulate or granular form (eg. particles of resin of from 0.2 mm,to 1 cm in size); etc.

A preferred demand disinfectant iodinated resin for use in the present invention is an iodinated strong base anion exchange resin, (i.e. a demand disinfectant-resin comprising polyiodide ions, having a valence of -1, the ions being absorbed or impregnated into the resin as herein described), obtainable by a process comprising a conversion step, the conversion step comprising contacting a porous strong base anion exchange resin in a salt form with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the disinfectant-resin, said iodine-substance being selected from the group comprising I₂ (i.e. diatomic iodine) and polyiodide ions having a valence of -1, characterized in that for the conversion step at least a portion of the absorption of iodine-substance is effected at elevated temperature and at elevated pressure, said elevated temperature being 100° C or higher (e.g. a temperature higher than 100° C such as, for example, 102° C, 103° C, 104° C, 105° c, 110° C, 115° C, 150° C, etc.), said elevated pressure being greater than atmospheric pressure (e.g. a pressure greater than barometric pressure such as for example 2 psig, 3 psig, 4 psig, 5 psig, 15 psig, 25 psig, 35 psig, 100 psig, etc.).

The disinfectant-resin may be one in which diatomic iodine is incorporated. The disinfectant polyiodide-resin may in particular be triiodide-resin. Thus, for example, the iodine-substance may comprise triiodide ion of formula I₃ ^-, i.e. so as to form a disinfectant-resin which comprises (absorbed) triiodide ions of formula I₃ ^-.

The terms "triiodide", "triiodide ion" and the like, as used in the context herein, refer to or characterize a substance or a complex as containing three iodine atoms and which has a valence of -1. The triiodide ion herein therefore is a complex ion which may be considered as comprising molecular iodine (i.e. iodine as I₂) and an iodine ion (i.e. I^-). "Similarly the terms "polyiodide". "polyiodide ions" and the Tike, refer to or characterize a substance or a complex as having three or more iodine atoms and which may be formed if more of the molecular iodine combines with the monovalent triiodide ion. These terms are more particularly described in the above referred to U.S. patents.

Another preferred demand disinfectant iodinated resin for use in the present invention is an iodinated strong base anion exchange resin, (i.e. a demand disinfectant-resin comprising polyiodide ions, having a valence of -1, the ions being absorbed or impregnated into the resin as herein described), obtainable by a process comprising a conversion step, the conversion step comprising contacting a porous strong base anion exchange resin in a salt form other than the iodide form I^-, with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the disinfectant-resin, said iodine-substance being selected from the group comprising polyiodide ions having a valence of -1, characterized in that for the conversion step at least a portion of the absorption of iodine-substance is effected at elevated temperature and at elevated pressure, said elevated temperature being 100° C or higher (e.g. a temperature higher than 100° C), said elevated pressure being greater than atmospheric pressure (e.g. a pressure greater than barometric pressure).

The strong base anion exchange resin may be in a salt form such as for example a chloride or hydroxyl form.

The conversion step may essentially or at least partially be effected at said elevated temperature and elevated pressure. The conversion may, thus for example, be effected in one, two or more stages. For example, the elevated pressure/temperature conditions may be divided between two different pairs of elevated pressure/temperature conditions, e.g. an initial pressure of 15 psig and a temperature of 121° C and a subsequent pressure of 5 psig and a temperature of 115° C.

If the conversion is to be carried out in two stages, it may for example, comprise a first stage followed by a second stage. The first stage may, for example, be effected at low temperature conditions (e.g. at ambient temperature and ambient pressure conditions) whereas the second stage may be effected at elevated conditions such as described herein.

Thus, another preferred demand disinfectant iodinated resin for use in the present invention is an iodinated strong base anion exchange resin, (i.e. a demand disinfectant-resin comprising polyiodide ions, having a valence of -1, the ions being absorbed or impregnated into the resin as herein described), obtainable by a process comprising a conversion step, the conversion step comprising contacting a porous strong base anion exchange resin in a salt form with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the demand disinfectant resin, said iodine-substance being selected from the group comprising I₂ and polyiodide ions having a valence of -1, characterized in that said conversion step comprises an initial conversion stage followed by a second conversion stage, in that said initial conversion stage comprises contacting the anion exchange resin with the iodine-substance at a temperature of 100° C or lower so as to obtain an intermediate composition, said intermediate composition comprising residual absorbable iodine-substance and an intermediate iodinated resin, (i.e. a resin comprising absorbed polyiodide ions having a valence of -1), and in that said second conversion stage comprises subjecting the intermediate composition to elevated temperature and elevated pressure, said elevated temperature being 100° C or higher (e.g. a temperature higher than 100° C), said elevated pressure being greater than atmospheric pressure.

Yet further, a demand disinfectant iodinated resin for use in the present invention is an iodinated strong base anion exchange resin, (i.e. a demand disinfectant-resin comprising polyiodide ions, having a valence of -1; the ions being absorbed or impregnated into the resin as herein described), obtainable by a process comprising a conversion step, the conversion step comprising contacting a porous strong base anion exchange resin in a salt form other than the iodide form I^- with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the disinfectant-resin, said iodine-substance being selected from the group comprising polyiodide ions having a valence of -1, characterized in that said conversion step comprises an initial conversion stage followed by a second conversion stage, in that said initial conversion stage comprises contacting the anion exchange resin with the iodine-substance at a temperature of 100°C or lower so as to obtain an intermediate composition, said intermediate composition comprising residual absorbable iodine-substance and an intermediate iodinated resin (i.e. a resin comprising absorbed polyiodide ions having a valence of -1), and in that said second conversion stage comprises subjecting the intermediate composition to elevated temperature and elevated pressure, said elevated temperature being 100° C or higher (e.g. a temperature higher than 100° C), said elevated pressure being greater than atmospheric pressure.

In accordance with the above-described process, for the first stage, the low temperature may, for example, be a non-boiling temperature of not more than 95° C; e.g. 15 to 60° C; e.g. ambient temperature or room temperature such as a temperature of from about 15° C to about 40° C, e.g. 20 to 30° C. The pressure associated with the low temperature condition of the first stage may, for example, be a pressure of from O (zero) to less than 2 psig; the pressure may in particular be essentially ambient pressure (i.e. a pressure of less than 1 psig to 0 (zero) psig; 0 psig reflecting barometric or atmospheric pressure).

For the second stage, the elevated temperature may, for example, be: a temperature of 102° C or higher; e.g. 105°C or higher; e.g. 110°C or higher; e.g. 115°C or higher; e.g. up to 150°C to 210°C; e.g. 115°C to 135° C. The elevated pressure associated with the elevated temperature condition of the second stage may, for example, be: a pressure of 2 psig or greater; e.g. 5 psig or greater; e.g. 15 psig to 35 psig; e.g. up to 100 psig.

It is to be understood herein, that if a "range" or "group of substances" is mentioned with respect to a particular characteristic (e.g. temperature, presssure, time and the like) of the present invention, the present invention relates to and explicitly incorporates herein each and every specific member and combination of sub-ranges or sub-groups therein whatsoever. Thus, any specified range or group is to be understood as a shorthand way of referring to each and every member of a range or group individually as well as each and every possible sub-ranges or sub-groups encompassed therein; and similarly with respect to any sub-ranges or sub-groups therein. Thus, for example,

with respect to a pressure greater than atmospheric, this is to be understood as specifically incorporating herein each and every individual pressure state, as well as sub-range, above atmospheric, such as for example 2 psig, 5 psig, 20 psig, 35.5 psig, 5 to 8 psig, 5 to 35, psig 10 to 25 psig, 20 to 40 psig, 35 to 50 psig, 2 to 100 psig, etc..;
with respect to a temperature greater than 100° C, this is to be understood as specifically incorporating herein each and every individual temperature state, as well as sub-range, above 100° C, such as for example 101° C, 105° C and up, 110° C and up, 115° C and up, 110 to 135° C, 115° c to 135° C, 102° C to 150° C, up to 210° C, etc.;
with respect to a temperature lower than 100° C, this is to be understood as specifically incorporating herein each and every individual temperature state, as well as sub-range, below 100° C, such as for example 15° C and up, 15° C to 40° C, 65° C to 95° C, 95° C and lower, etc.;
with respect to residence or reaction time, a time of 1 minute or more is to be understood as specifically incorporating herein each and every individual time, as well as sub-range, above 1 minute, such as for example 1 minute, 3 to 15 minutes, 1 minute to 20 hours, 1 to 3 hours, 16 hours, 3 hours to 20 hours etc.;
and similarly with respect to other parameters such as low pressures, concentrations, elements, etc...

It is also to be understood herein that "g" or "gm" is a reference to the gram weight unit; that "C" is a reference to the celsius temperature unit; and "psig" is a reference to "pounds per square inch guage ".

In the above-described process the anion exchange resin may, for example, as described below, be a quaternary ammonium anion exchange resin; the anion exchange resin may be in the chloride form Cl^- , in the hydroxyl form OH^-; etc....

The obtained iodide-resin may be treated prior to use to remove any water-elutable iodine from the iodide-resin. The treatment (e.g. washing) may be continued until no detectable iodine is found in wash water (the wash water initially being ion free water). Any suitable (known) iodine test procedure may be used for iodine detection purposes (see for example the above mentioned U.S. patents.

The absorbable iodine substance may, for example, be provided by a composition consisting of mixture of KI, I₂ and a minor amount of water, the mole ratio of KI to I₂ initially being about 1; the expression "minor amount of water" as used herein shall be understood as characterizing the amount of water as being sufficient to avoid I₂ crystallization.

The present invention can be practised with any (known) strong base anion exchange resin (for example, with those such as are described in more detail in the above-mentioned United States patents such as United States patent no 3,923,665). A quaternary ammonium anion exchange resin is, however, preferred. As used herein, it is to be understood that the expression "strong base anion exchange resin" designates a class of resins which either contain strongly basic "cationic" groups, such as quaternary ammonium groups or which have strongly basic properties which are substantially equivalent to quaternary ammonium exchange resins. United States patent nos. 3,923,665 and 3,817,860 identify a number of commercially available quaternary ammonium resins, as well as other strong base resins including tertiary sulphonium resins, quaternary phosphonium resins, alkyl pyridinium resins and the like.

Commercially available quaternary ammonium anion exchange resins which can be used in accordance with the present invention include in particular, Amberlite IRA-401 S, Amberlite IR-400 (Cl^-), Amberlite IR-400 (OH^-), Amberlite IR-402 (Cl^-), etc., (from Rohm & Hass) which may be obtained in granular form. These resins may for example, contain quaternary ammonium exchange groups which are bonded to styrene-divinyl benzene polymer chains.

The resins which may be used herein may be in a hydroxyl form, a chloride form or in another salt (e.g. sulphate) form provided that the anion is exchangeable with the iodine member (e.g. with triiodide ion).

The starting resin may, for example, be granular (i.e. comprise a plurality of particles) such that the final product will likewise have a granular or particulate character; the granular form is advantageous due to the high surface area provided for contact with microorganisms. The starting resin may, for example, comprise granules having a size in the range of from 0.2 mm to 0.8 cm (e.g. of from 0.35 mm to 56 mm).

Commercially available resins such as those mentioned above are available in the salt form (e.g. as the chloride) and in the form of porous granular beads of various mesh sizes; the resin may of course be used in a bulk or massive form such as a plate, sheet, etc..

For example, a resin may be converted from a non-iodide form (e.g. a chloride form, a sulphate form) to the I₃ ^- form. Suitable halide salts include alkali metal halides (such as KI, NaI,...); potassium iodide is preferred. Alternatively, an iodide form of the resin may be used and the resin contacted with a source of diatomic iodine.

Any material or substance capable of donating an iodine-member absorbable by the anion exchange resin so as to convert the anion exchange resin to the desired polyiodide-resin may be used, as long as the denotable iodine-member thereof is a polyiodide ion having a valence of -1 and/or diatomic iodine. Examples of such materials in relation to iodine are shown in the above mentioned U.S. patents; e.g. compositions comprising iodine (I₂) and alkali metal halide (KI, NaI, etc.., KI being preferred) in association with water. Alternatively, if the resin is in an iodide salt form (I^-1), the material may comprise the corresponding iodine in gaseous form.

Thus, for example, if a triiodide-resin is desired the resin may be contacted with an alkali metal iodide/I₂ mix wherein the iodide and the diatomic iodine are present in more or less stoichiometric amounts (i.e. a mole ratio of 1); see the previously mentioned U.S. patents. By applying stoichiometric amounts of the iodine ion and iodine molecule (i.e. one mole of I₂ per mole of I^-1), the iodide sludge will comprise substantially only the triiodide ions. If stoichiometric excess quantities of I₂ are used some of the higher polyiodide ions may be formed. Preferably, no more than the stoichiometric proportions of I^- and I₂ are used in the initial aqueous starting sludge so that substantially only triiodided attaches to the resin.

For example iodine may be combined with sodium, potassium or ammonium iodide and some water. The composition will contain monovalent iodine ion which will combine with diatomic iodine (I₂) to form polyiodide ion. The molar ratio of iodine ion to diatomic iodine will dictate the nature of the polyiodide ion present , i.e. triiodide ion, mixtures of triiodide ion and other higher polyiodides ions, pentaiodide ion, etc.... Using about 1 mole of iodine ion per mole of diatomic iodine the formation of triiodide ion will be favoured. If stiochiometric excess of diatomic iodine is used this will favour the formation of higher polyiodides.

The determination of the (total) amount of iodine to be contacted with the resin, residence times etc.., will depend upon such factors as the nature of the polyiodide it is desired to introduce into the structure of a resin; the nature of the starting resin (i.e. porosity, grain size, equivalent exchange capacity of the resin, etc.), etc.. Thus, for example, to determine the amount of iodine required to prepare a polyiodide resin, the equivalent exchange capacity of the resin needs to be known. If necessary, this can be readily determined for example by the procedure described in U.S. patent no. 3,817,860 (column 9, lines 15 to 28). The components of the process may be chosen such that the obtained iodinated strong base anion exchange resin may comprise a strong base anion exchange resin component which represents from 25 to 90 (preferably 45 to 65) percent by weight of the total weight of the obtained iodinated resin.

The conversion at elevated conditions may be effected in a reactor which is pressure sealable during conversion but which may be opened for recovery of the resin product after a predetermined reaction time. The process may thus be a batch process wherein conversion at elevated temperature and pressure is effected once the reactor is sealed. The reactor may be sized and the amount of reactants determined so as to provide a void space in the reactor during reaction. In the case, for example, wherein the material having the denotable iodine-member is a sludge of alkali metal/I₂ and water, the weight ratio of sludge to resin may be 1:1 or higher, eg. 1:1 to 5:1; a weight ratio of 1:1 (if Amberlite 401-S is used as the resin) is preferred so as to minimize the amount of unabsorbed iodine which must be washed from the iodine/resin product.

The high temperature/pressure contact conditions may as mentioned above be chosen with a view to maximizing the iodine content of the obtained iodine (e.g. iodine) demand resin.

Conversion of the resin to a polyhalide (e.g. I₃ ^-) form may be effected at elevated temperature greater than 100° C, for example in the range of 105° C to 150° C (e.g. 110-115° C to 150° C) ; the upper limit of the temperature used will, for example, depend on the characteristics of the resin being used, i.e. the temperature should not be so high as to degrade the resin.

As mentioned in order to effect the conversion at elevated pressure, the conversion may take place in a closed vessel or reactor. The pressure in such case may be a function of the temperature such that the pressure may vary with the temperature approximately in accordance with the well known gas equation PV = nRT, wherein V = the constant (free) volume of the reactor, n = moles of material in the reactor, R is the universal gas constant, T is the temperature and P is the pressure. In a closed vessel, the temperature of the system may therefore be used as a means of achieving or controlling the (desired) pressure in the vessel depending upon the makeup of the Iodine mix in the reactor. Thus, a reaction mix disposed in a pressure sealed reactor may be, for example, subjected to a temperature of 105° C and a pressure of 200 mmHg, the pressure being induced by steam.

Alternatively, a relatively inert gas may be used to induce and\or augment the pressure in the reactor. Thus, a pressurized relatively inert gas may be injected into a sealed reactor. The chosen gas must not unduly interfer with the production of a suitable iodinated resin. The high temperature/pressure treatment may be conducted in a closed reactor in the presence of (trapped air), a non-interfering gas such as iodine itself or of some other relatively inert (noble) gas; the pressure as mentioned above may be augmented by the pressuring gas. Air, carbon dioxide, nitrogen or the like may also be used as a pressuring gas, if desired, keeping in mind, however, that the use thereof must not unduly interfer with the production of a suitable iodinated resin. If pressure is to be induced by steam then as mentioned below steps should be taken to isolate the reaction mix from (excess) water.

The elevated pressure is any pressure above ambient. The pressure may, for example, be 1 psig or higher, e.g in the range from 5 to 50 psig; the upper limit of the pressure used will also, for example, depend on the characteristics of the resin being used, i.e. the pressure should not be so high as to degrade the resin.

The residence or contact time at the elevated conditions is variable depending upon the starting materials, contact conditions and amount of (tenaciously held) iodine it is desired to be absorbed by the anion exchange resin. The contact time may thus take on any value; usually, however, it is to be expected that it will be desired that the contact time (under the conditions used) be sufficient to maximize the amount of (tenaciously held) iodine absorbed from the material containing the absorbable iodine moiety. The residence time may for example be as little as 5 to 15 minutes (in the case where a preimpregnation step is used as shall be described below) or several hours or more (up to 8 or 9 hours or more). The residence time exploited for elevated the conditions, in any event, will as mentioned above depend on the starting material, temperature and pressure conditions, etc...; it may vary from several minutes to 8 or 9 hours or more; the upper time limit will in any event also, for example, depend on the characteristics of the resin being used, i.e. the residence time should not be so high as to degrade the resin.

Preferably, the contact at high temperature/pressure is preceded by an initial impregnation or absorption step (first stage). Such first stage may be carried out for only a few minutes (e.g. for from 1 to 10 minutes or more) or for up to 24 hours or more (e.g. for from one hour or more i.e. for from three to twenty-four hours). The time period of the initial stage may be relatively short. The time period, for example, may be a few minutes or so and may correpond to the time necessary to just mix the reactants together; in this case the conversion may be considered to be essentially carried out in a single stage at elevated conditions. The residence time of the first stage will also be predetermined with a view to the end product resin desired. For example, a water containing sludge of triiodide ions can be contacted with a salt form of the starting resin at ambient (i.e. room) temperature and pressure conditions to obtain an intermediate iodide-resin reaction product including residual iodine-substance. This step is preferably carried out in a batch reactor; the obtained intermediate composition comprising an intermediate iodide-resin may then be subjected to the higher temperature and pressure in accordance with the present invention in batch fashion as well. Such a first stage may be used to initiate buildup of iodine within the resin matrix.

For use in the present invention an iodide-resin demand disinfectant may, for example, be obtained by

a) bringing a porous, granular, starting resin into contact with an aqueous sludge of iodine and potassium iodide so as to obtain a paste mixture, iodine being present in the sludge essentially as triiodide ions, said starting resin being a strong base anion exchange resin having strongly basic groups thereof in a salt form the anion of which is exchangeable with triiodide ions,
b) subjecting the paste mixture to elevated temperature and pressure conditions in an enclosed container or reactor (e.g. autoclave) for a predetermined impregnating duration of time, a void space being provided in the reactor such that contact occurs under an (essentially) iodine (rich) atmosphere, and
c) washing the obtained iodide-resin product (with a suitable (i.e. purity) washing liquid, (e.g. deionised water, R/O water (at 45° C), etc.) to remove water elutable iodine such as KI from the surface of the resin so that on drying no iodine (KI) crystals will form on the surface of the iodine/resin; R/O water, is water obtained using double reverse osmosis. R/O water is defined below.

More particularly an iodide/resin demand disinfectant may be obtained using the following sequence of steps:

1. The resin is purified by triple passage of water and then disposed in ethanol in an electrosonic bath and flushed with water and drip dried;
2. (Essentially) stoichiometric amounts of I₂ and potassium iodide are admixed with a minimum amount of water which is just sufficient to obtain an I₃- slurry or sludge (with, if desired, very low heating);
3. The resin is admixed with the above-minimal water slurry in small aliquats so as to obtain a predetermined weight ratio of slurry to resin (e.g. a 50:50 weight ratio);
4. The resin-slurry mixture is then placed in a shaking bath at atmospheric pressure in a closed, airtight container (if necessary the container being provided with a small pressure release valve or opening the purpose of which will be hereinafter explained) for a predetermined time period (e.g. for up to, for example, sixteen to twenty-four hours or more [e.g. a week if desired]) to form an intermediate resin composition;
5. The container containing the reaction mixture is then disposed in a (steam) autoclave and heated at high temperature, (e.g. 120° C) to provide a super atmospheric pressure therein (with the small valve open if the container walls would not be able to resist the pressure to be exerted within the autoclave) for a predetermined residence time (e.g. a residence time of about fifteen minutes) calculated from the time the mixture reaches the predetermined high temperature (e.g. 120° C).
6. The autoclave is removed from the heat and as soon as the pressure is equalized to atmospheric, the internal container is removed and the resin product is washed (e.g. six times) with R/O water until the wash water comes out with a total iodine content of less than 0.1 parts per million.

A small hole is necessary when a container such as a glass flask is used in order to avoid a too great pressure difference being built up between the interior of the flask and the interior of the autoclave which might cause the flask to collapse. The hole in any event is just large enough to more or less allow for the equalization of pressure and to maintain a positive pressure in the flask relative to the interior of the autoclave such that any foreign material such as water vapour is inhibited from flowing into the flask. A more sturdy pressure resistant container could of course be used such that, depending on the construction of the container and the temperature/pressure conditions prevailing in the autoclave, the hole may be avoided. Alternatively, instead of using a separate container to hold the reaction mix and placing it in a separate autoclave, a single autoclave/container may be used serving to hold and heat the reaction mix under pressure; such a container must of course be constructed so as to be able to resist the predetermined reaction conditions.

As mentioned above, the present invention provides a method for disinfecting air containing airborne microorganisms. The method comprises passing the air over a demand disinfectant iodinated resin such that airborne microorganisms contact said resin and are devitalized thereby. The demand disinfectant resin may comprise an iodinated strong base anion exchange resin. The method may, for example, include passing the air through a bed of granules of iodinated resin so that the air courses over the granules (in a serpentine manner) as the air makes its way through the bed. The maximum permissible flow rates for total bacterial sterilization may vary with the concentration of the polyiodide groups in the resin, bed depth, bacterial count, etc... The iodinated strong base anion exchange resin may comprise a strong base anion exchange resin component which represents from 25 to 90 (preferably 45 to 65) percent by weight of the total weight of the iodinated resin.

In accordance with an additional aspect, the present invention provides a system for disinfecting air containing airborne microorganisms, said system, for example, comprising means for providing an air path for the movement of air therethrough, and a demand disinfectant iodinated resin disposed in said air path such that airborne microorganisms in air passing through said air path are able to be brought into contact with said resin and be devitalized thereby. The demand disinfectant may comprise an iodinated strong base anion exchange resin.

An air path means may define an air inlet and an air outlet. The resin may be disposed between said inlet and outlet or be disposed at the inlet or outlet. The air path means may take any form. It may take the form of ductwork in a forced air ventilation system with the demand disinfectant comprising a bed of resin granules through which the air is made to pass, the bed otherwise blocking off the air path. Alternatively the air path means may be defined by a cartridge used for a gas mask, the cartridge having an inlet and an outlet for air; the iodinated resin for the cartridge may, if desired, be present as a bed of granules, granules incorporated into a (fluid) porous carrier (e.g. tissue, polyurethane foam, etc.) or alternatively take a more massive form such as a plate(s), a tube(s), a block(s), etc.. Cartridge type gas masks are known; such gas masks may be obtained for example from Eastern Safety Equipment Co., Mosport, New York, USA.

The C-50 cartridge from a gas mask (from Glendale Protecting Technologies Inc. Woodbury, New York, USA) may for example be adapted to hold a bed of resin of granules of the present invention.

In drawings which illustrate example embodiments of the present invention:

Figure 1: is a perspective view of a cartridge which may be used to house an iodinated resin as described herein for use for example in a gas mask;
Figure 2: is a cross sectional view 4-4 of the cartridge of figure 1;
Figure 3: is a schematic illustration of a system for testing a cartridge containing an iodinated resin; and
Figure 4: is a schematic illustration of another type of system for testing a cartridge containing an iodinated resin.

Referring to figure 1, the cartridge 1 comprises an a hollow, open ended, thin-walled, tubular body of circular cross section. The wall 2 may for example be of nylon. The open ends of the cartridge are each blocked off by some suitable mesh like support material 3 (e.g. 10 micron polypropylene mesh) which is held in place in any suitable known manner such as by glues, spring clip, etc. Referring to figure 2, the iodinated granular resin bed 4 occupies the entire space between the mesh supports 3 and 3'; although the granular resin is more or less tightly packed between the mesh supports 3 and 3', there are still air spaces between the granules for the passage of air through the granular bed. The mesh supports each have openings small enough to retain the iodinated resin in place while allowing air to pass therethrough into the and through the supported resin bed 4. The cartridge as shown in figure 2 may include a downstream bed 5 of granules of activated carbon, catalyst, or iodine absorbent resins, to scavenge any iodine liberated from the iodinated resin 4. The activated carbon bed 5 is held in place by a mesh support 3' and an additional mesh 6. The bed depth of the resin and carbon is shown as about 2.5 cm; wheras the bed diameter is about 8 cm. If the iodinated resin made in accordance with the process of the present invention is used the carbon bed may be omitted, i.e. only the iodinated resin bed. 4 may be present in the cartridge as the active component (in the examples below, unless the contrary is indicated, the cartridges do not include any carbon bed); in this case the bed depth may, for example, be less 2.5 cm, e.g. 0.1 cm, 0.25 cm, 0.5 cm, 0.85 cm, 1.15 cm, etc.. Such a cartridge may be disposed in an air path as shown for example in figures 3 and 4 which will be discussed below.

The resin disposed in the air path could of course take on any form other than granules such as blocks, plates, tubes etc..

The iodinated demand disinfectant resin for air treatment may be any (known) iodinated resin so long as the iodinated resin is capable of devitalizing airborne microorganisms (i.e. microorganisms transported by air) coming into contact therewith. It may, for example, be a resin as proposed in U.S. patent nos. 3,923,665 and 4,238,477; in this case, however, it may be necessary to use the resin in conjunction with an iodine scavenging material if the resin gives up too much iodine to the air. The iodine scavenging material may be an activated carbon material or an un-iodinated strong base anion exchange resin as described herein.

Alternatively, as mentioned above, iodinated resin may advantageously be a resin made by one of the processes described in detail above. In this case the resin need not be used in conjunction with an iodine scavenging material such as a (known) exchange resin, activated carbon, catalyst, etc., since an iodinated resin made in accordance with the process of the present invention may liberate iodine into the air in an amount below acceptable threshold limits for breathing by human beings.

If desired the iodinated resin for the treatment of air may be some type of mixture of iodinated resins, e.g. a mixture of a known iodinated resin and an iodinated resin prepared in accordance herewith.

Turning back to the process for making the demand disinfectant iodinated resin, if commercially available materials are to be used to make the iodine/resin then, depending on the purity thereof, the starting materials may have to be treated to remove components which may interfer with the absorption of the halide into the resin. Water if present in the initial reaction mix should be free of interfering elements such as interfering ions. Distilled or ion free water is preferably used for washing.

The following materials may be used to prepare a suitable triiodide resin for use in the present invention:

a) Amberlite 401-S (from Rohm & Hass) a strong base anion exchange resin in granular form, having the following characteristics: support matrix - styrene/divinyl benzene polymeranion - chlorinedensity - 1.06effective size (diameter) - 0.52 mmtotal exchange capacity - 0.8 meq/mlworking Ph range - 0 to 11moisture content - 62%working temperature - 170° F or less
b) I2 (solid) - U.S.P. grade (from Fisher Scientific)
c) Potassium iodide (KI) - U.S.P. grade (from Fisher Scientific)
d) Water - ultra pure: obtained using double reverse osmosis (i.e. herein sometimes.referred to simply as R/O water)
e) Ethanol - U.S.P. grade (from Fisher Scientific)

Using the above substances a resin cramed with triiodide (i.e. a triiodide jam-backed resin) may be obtained as indicated in the following examples.

For the following examples, the following procedure for the evaluation of iodine (I²) and Iodide (I^-), was conducted according to "standard methods for the examination of water and wastewater 17e Ed.":

Iodine method: mercuric chloride added to aqueous elemental iodine solutions causes complete hydrolysis of iodine and the stoichiometric production of hypoiodous acid. The compound 4, 4', 4" methylidynetris (leuco crystal violet) reacts with the hypoiodous acid to form crystal violet dye. The maximum absorbance of the crystal violet dye solution is produced in the Ph range 3.5-4.0 and measured at a wavelength of 592 nm. The absorbance follows beers' law over a wide range of iodine concentration. Iodine can be measured in the presence of max. 50 PPM iodide ions without interference.
Iodide method: iodide is selectively oxidized to iodine by the addition of potassium peroxymonosulfate. The iodine produced reacts instantaneously with the indicator reagent leuco crystal violet over the same conditions described previously for iodine methods. Total iodine + iodide results from this procedure and iodide is calculated from substraction of iodine concentration.
Readings were performed on a lkb spectrophotometer with a lightpath of 1 cm and selected at 592 nm.

EXAMPLE 1: STARTING MATERIALS PRETREATMENT:

i) Resin: The resin is water washed to remove undesirable elements such as material in ionic form. Thus, 100.00 grams of Amberlite 401 S and 200 ml of R/O water are placed in an erlenmyer of 1000 ml. The mixture is shaken for about 3 minutes and the water is then separated from the resin by drip filtration using a wathman filter paper and funnel. The resin is water washed in the same fashion two more times. After the last water wash the resin is drip dried (i.e. again using a wathman filter paper and funnel) for 15 minutes. The so recovered water washed resin is subjected to an alcohol wash to dissolve undesirable organic material which may be stuck on the resin. Thus, the water washed resin is immersed in 300.00 ml of ethanol. The resin alcohol mixture is shaken in an ultrasonic bath (Crest ultrasonic:1000 Watts - 20 liter capacity) for 5 minutes. The alcohol washed resin is drip dried, again using a wathman filter paper and funnel. The "fish" smell is removed from the alcohol washed resin by a final water washing stage wherein the wash R/O water is preheated to 40 degrees celsius. The alcohol washed resin is placed in an erlenmyer flask (1000 ml) and 250 ml of R/O water at 40 degrees celsius is added thereto. The water-resin mixture is shaken in a shaking bath (Yamata shaking bath - 1 impulse, per second/water at 32 degrees celsius) for 5 minutes; the water is then removed from the resin by drip drying as mentioned above. The water wash is repeated once more and the resin is drip dried (for 1 hour) as mentioned above. The washed resin is now ready for use in example 2 hereinbelow.
ii) Iodine sludge containing water: A mixture of iodine (I2) and potassium iodide (KI) is prepared by mixing together, in an erlenmyer flask, 60.00 grams of iodine and 40.00 grams of potassium iodide (in both cases on a dry weight basis). Thereafter R/O water is admixed slowly drop by drop with the mixture until a metallic looking sludge is obtained (e.g. with the addition of about 5.00 grams of water). The obtained iodine/potassium iodide sludge is then ready for use in example 2 hereinbelow.

EXAMPLE 2: LOW TEMPERATURE/PRESSURE PREIMPREGNATION OF RESIN WITH IODINE

The aqueous iodine sludge, as obtained above, is placed in a 500-00 ml Erlenmyer flask and is slowly heated to, and maintained at 40 degrees celsius for a few minutes. Once the temperature of the sludge reaches 40° C, the washed resin, obtained as above, is slowly admixed with the iodine sludge in 10.00 gram portions every 8 minutes until all of the washed resin is within the erlenmyer flask. The 500 ml Erlenmyer flask, containing the obtained starting mix (comprising the I₂/KI mixture and the washed resin - approximately 100 grams of each of the starting materials), is then sealed with a cork and is placed in a shaking water bath (Yamato BT:-25) for a period of 16 hours. The temperature of the water in the shaking bath is maintained at about 20 degrees celsius during this time period. At the end of the time period, the Erlenmyer flask is removed from the shaking bath; at this point the removed flask contains an preimpregnation mix comprising impregnated resin and remaining I₂/KI. The Erlenmyer flask is sized such that at the end of this (initial) impregnation step, it is only 50% filled with the in process resin, etc, i.e. there is a void volume above the impregnation mix. NOTE: If processing of the treated resin is stopped at this point and the obtained resin is suitably washed, a resin is obtained in accordance with the prior art i.e. U.S. patent no. 3,923,665.

EXAMPLE 3: ELEVATED PRESSURE/TEMPERATURE TREATMENT

The cork of the Erlenmyer flask of EXAMPLE 2 removed from the shaking bath and including the obtained impregnation mix comprising impregnated resin and remaining I₂/KI, is changed for a cork having a small diameter perforation passing therethrough (i.e. of about 3 mm in diameter). With the perforated cork in place, the Erlenmyer flask is disposed within a (steam pressure) autoclave along with a suitable amount of water. With the autoclave (pressure) sealed about the flask, the autoclave is heated. Heating proceeds until an internal temperature and pressure of 115 degrees Celsius and 5 psig respectively is reached. Once those parameters have been reached, they are maintained for 15 minutes of processing time. Thereafter the autoclave is allowed to slowly cool for 50 minutes of cooling time (until the internal pressure is equal to ambient pressure) before removing the Erlenmyer flask containing a (raw) product resin demand disinfectant in accordance with the present invention.

EXAMPLE 4: WASHING OF RAW PRODUCT RESIN

The (raw) disinfectant of Example 3 is removed from the autoclave Erlenmyer flask and placed in another 2000 ml Erlenmyer flask. 1400 ml of R/O water at 20 degrees Celsius is admixed with the resin in the flask and the slurry is shaken manually for 3 minutes. The wash water is thereafter removed from the flask by decantation. This wash step is repeated 7 more times. The entire wash cycle is repeated twice (i.e. eight water washes per cycle) but using water at 45 degrees Celsius for the next wash cycle and then with water at 20 degrees Celsius for the last wash cycle. The washed iodineresin is then ready to use.

EXAMPLE 5: Preparation of Resin I-A' for use in the present invention

An iodinated resin (Resin I-A') was prepared following the procedures of examples 1 to 4 except that for the resin, Amberlite IR-400 (OH^-) (was used and for the procedure of example 3 the elevated temperature and pressure conditions were set at 121° C and 15 psig respectively. Resin I-A' was used in the following examples.

EXAMPLE 6: COMPARATIVE IODINE CONTENT IN EFFLUENT AIR

Two cartridges as illustrated in figures 1 and 2 were prepared. Each cartridge contained 50.0 grammes of dry (granular) resin (i.e. and no activated carbon bed). One cartridge contained Resin I-A' and the other contained Resin I-D.

Resin I-D is an iodinated resin manufactured by water Technology Corporation in Minneapolis, sold under the Trademark : Pentapure.

The cartridges were each disposed in a system as illustrated in figure 3 but which did not contain any atomizer indicated generally by the reference number 7. The system included a housing 8 for defining an air path and had an air inlet 9. The resin cartridge 1 was disposed at the outlet of the air path. The air leaving the cartridge 1 was directed by appropriate tubing to a collector station 10. The system included a vacuum pump 11 (but not the air sterilizer system 12) for drawing air from inlet 9 through the system.

In operation a cartridge 1 was releasably placed in position (e.g. snap fit, etc.) and the vacuum pump activated so as to draw outside air (indicated by the arrow 13) into the housing 8. The air passed through the cartridge 1 as shown by the arrows 14. The air leaving the cartridge 1 was then directed to the collector station 10. The air entering the collector station 10 impinged upon a iodine collector solution 15 (comprising double reverse osmosis water, i.e. R/O water) in the collector station 10. Air leaving the collector station 10 thereafter passed through the pump 11 and was exhausted to the outside air.

Using the above described system, each, cartridge was submitted to an air velocity therethrough of 0.7 Liter/per minute for a period of 50 minutes. The collector station 10 included 50 ml purified R/O water (the water was then subjected to standard optical coloration techniques (i.e. the Leuco Crystal Violet Iodometric Spectrophotometer Technique), to determine the total iodine content).

The results of the tests are shown in table 6a:

Table 6a

Resin type
Resin I-A'	0.4 ppm
Resin I-D	1.1 ppm

The results of the tests as shown in table 6a means that each gramme of both of the resin types will add a definite amount of iodine to the effluent air, namely as indicated in table 6b.

Table 6b

Resin type
Resin I-A'
Resin I-D

Thus, for example, if a gas mask cartridge as discussed above contained 50.0 gm of iodinated resin, the resins would emit the level of iodine set out in table 6c below

Table 6c

Resin type
Resin I-A'
Resin I-D

The "Committee of the American conference of governmental industrial hygienist." emits the "threshold limit value" or T.L.V. for common chemicals. The iodine T.L.V. is 1.0 Mg/m³ for air analysis for human breathing during a period of 8 hrs. Thus, while the Resin I-D releases 50% more iodine than the maximum T.L.V. indicated above, the Resin I-A' (a preferred resin for use in the present invention) releases iodine at a level well below the T.L.V. The Resin I-A' could thus be used without an iodine scavenger; this would, for example, simplify the construction of a gas mask cartridge. The known Resin I-D on the other hand could also be used but it would require some sort of iodine scavenger (e.g. activated carbon) to obtain the necessary iodine T.V.L. level.

EXAMPLE 7:: The Resin I-A' was tested with different micro-organisms under different conditions for the sterilization of air.
EXAMPLE 7.1:: Direct contact sterilization study

Resin I-A' was evaluated for its biocidal capacity on direct contact with Klebsiella Terrigena in relation to a time reference and a humidity content variation; namely water content variations of 110%, 50% & 0% (relative to the weight of dry resin) and time variations of 2, 5, 10, and 15 seconds.

After preparing the three resins with their respective humidity content 25 glass rods were sterilized. A vial containing 25 ml of the inoculum (Klebsiella Terrigena: 10⁹ x ml) was also prepared.

The testing proceeded as follows with respect to the dry resin. A glass rod was immersed in the inoculum and then immersed in the dry resin for 2 seconds. The glass rod was then washed in 100 ml phosphate buffer to wash out the microorganisms. Following the standard method for evaluation of water, the collected sample was then plated and incubated. This procedure was then repeated for 5, 10 and 15 seconds.

The procedure was also repeated for the two other different humidity content batches of Resin I-A'. The results of the test are shown in table 7a.

Table 7a

	number of viable microorganisms per time period
	2 sec.	5 sec.	10 sec.	15 sec.
% humidity
110%	16	0	0	0
50 %	23	1	0	0
0 %	67	15	0	0

As may be seen from table 7a, the Resin I-A' whether wet, humid or dry destroys large quantities of resistant bacteria in direct contact, and this destruction occurs on a relatively rapid time base as demonstrated above.

EXAMPLE 7.2: KLEBSIELLA TERRIGENA ERADICATION STUDY: AIR FLOW.

A study was done to evaluate the biocidal effectiveness of dry Resin I-A' versus Klebsiella Terrigena.

The system used was the system illustrated in figure 3. The system included an atomizer 7 (of known construction) disposed in a housing 8 provided with an air opening 9. The system had a vacuum pump 11 for the displacement- of air through the system. The system included an air sterilizer 12 comprising a hollow housing 10 inches high by about 2.5 inches in inner diameter and filled with about 1.5 kilograms of Resin I-A'; the sterilizer has an air inlet and outlet. The air path through the cartridge 1 is designated by teh arrows 14. The atomizer 7 contained an inoculum 16 (Klebsiella Terrigena: 10⁷ x 100 ml). For the test, the air flow at arrow 13 was set at 30 liters per minute and the air inflow at arrow 17 for the atomizer was set at 8 liters per minute; the atomizer 7 injected mist or spray 18 of inoculum into the air in the air path and the inoculated air then passed through cartridge 1 as shown by the arrows 14.

A cartridge 1 as illustrated in figures 1 and 2 was prepared using dry Resin I-A' (65.0 gm giving a bed depth of 1.15 cm) . The cartridge 1 was submitted to an injection of a total of 10 ml of inoculum over a time period of 15 minute. Sampling was done at 0 minutes, 7.5 minutes and at 15 minutes. The samples were collected in a standard impinger (10) as shown in figure 5. After, processing 100 ml of the water from the impinger on microbiological paper filter and incubation, the results show total eradication of Klebsiella Terrigena.

EXAMPLE 7.3: BACILLUS PUMILUS ERADICATION: AIR CONTACT.

A study was carried out using the system shown in figure 4. To the extent that members of the system are the same as those used in the system illustrated in figure 3, the same reference numerals are used to identify the same parts. The main difference between the system of figure 5 and that of figure 4 is that the system of figure 4 uses a microbiological filter paper 19 to collect the microorganisms leaving the cartridge 1; the filter paper is maintained in place in any (known) suitable fashion.

An inoculum 20 of the thermophilic bacteria Bacillus Pumilus was prepared and injected at a concentration of 10³/ litre of influent air. A cartridge mask containing 65.00 gm of Resin I-A' was prepared as for the previous example. The test ran for 30 minutes.

All effluent (velocity at arrow 13 being 30 litres per minute) was collected on the microbiological filter paper 19 (from millepore), then lain in a T.S.A. (trypticase Soy Agar) and incubated. the results showed total eradication of Bacillus Pumilus.

EXAMPLE 7.4: BACILLUS SUBTILIS STERILIZATION IN AIR FLOW.

This test was performed with Bacillus Subtilis in a mixture of 40% active bacteria / 60% spores. The system shown in figure 4 was used with the cartridge comprising 50 grams of Resin I-A' (giving a bed depth of .85 cm). The controlled concentration of processed air was 55 bacteriological units per litre. The air velocity was 23 litre per minute for 80 minutes.

Once the 80 minutes ended, the millepore filter paper was collected, lain on T.S.A. (after neutralisation of potential iodine with sodium thiosulfate 5%) and incubated for 48 hours at 37 degree celsius. The results show a total eradication of micro-organisms.

EXAMPLE 7.5: BACILLUS SUBTILIS: Resin I-A' versus glass beads in air flow.

In order to assess the retention factor of micro-organisms on inert materials this test was performed. Also, to evaluate the migration factor of the biological vector, a sequential incubation was performed.

Two gas cartridges were built in accordance with figures 1 and 2, namely:

a) Resin I-A' cartridge : 10 micron polypropylene upstream mesh (filter) ; : 50.00 gm of Resin I-A' giving a bed depth of .85 cm; : 10 Micron polypropylene downstream mesh (filter).
b) Glass bead cartridge : 10 micron polypropylene upstream mesh (filter); : 50.0 gm sterile glass beads (from Fisher Scientific and having the same size as the beads of Resin I-A') giving a bed depth of .85 cm; and : 10 Micron polypropylene downstream mesh (filter).

The system as shown in figure 4 was used for the tests.

Simultaneously, the two cartridges were, once inserted in their respective testing chamber, submitted to a velocity of 23 litre per minutes for 40 minutes with a microbiological load of 40 bacteria per litre in the influent.

Once the test period completed, the two cartridges were dissected in sterile conditions and the microbiological filter paper recovered. Each materials composing the masks were individually as well as the filter paper were incubated in T.S.A. for 48 hours at 37 degree celsius. The results are shown in table 11b.

Table 7b

	Resin I-A'	Glass beads
upstream mesh:	2 cfu	tnc* cfu
Resin\beads:	0 cfu	tnc* cfu
downstream mesh:	0 cfu	220 cfu
microbiological filter paper:	0 cfu	86 cfu

Table 7b

* tnc = microorganisms too numerous to count

As may be seen from table 7b the Resin I-A' eradicated all bacteria and no living micro-organism can live in the resin bed. The Glass beads on the other hand have a mechanical filtering capacity in regards to the biological vector but migration occurs rapidly thus obtaining "tnc" results (too numerous to count) on the upstream mesh and the beads themselves. The migration keeps on going through the filter until it reaches the microbiological paper filter in large number. Also, the glass beads filter becomes severely contaminated, causing a disposal problem.

EXAMPLE 7.6: BACILLUS SUBTILIS: Resin bed depth comparison

This test was performed to establish the biocidal effectiveness of the Resin I-A' in regards to the microbiological eradication of Bacillus Subtilis. The system of figure 6 was used.

Two cartridges as illustrated in figures 1 and 2 containing respectively 30.00 gm (giving a bed depth of 0.5 cm) and 50.00 Gr (giving a bed depth of 0.85 cm) of Resin I-A were submitted to 60 minutes of air pumping at a velocity of 27 litre per minutes. A total of 23 ml of inoculum at a concentration of 10⁷ per ml were injected into the system.

A positive control yielded a concentration of 275 cfu/litre of air at the microbiological sampling site.

The results show total eradication for both cartridges.

EXAMPLE 7.7: BACILLUS SUBTILIS: LONGEVITY STUDY IN AIR FLOW.

A cartridge of figure 1 and 2 containing 30.00 gr (bed depth: 0.5 cm) of Resin I-A' was submitted to an air flow velocity of 25 litre/ minute containing a concentration of Bacillus Subtilis of 112 cpu/litre (positive control for correlation) for a period of 3 hrs.

The test was done using the impinger technique (of figure 3), with 300 ml of sterile water. Once the 3 hours completed the water from the impinger was filtered on a microbiological membrane as referred in standard method for analysis of water and waste water 17 th edition, pp.9-97 To 9-99. The growth media was trypticase soy agar. The results after incubation for 48 hours at 37.5 degree celsius was total eradication.

EXAMPLE 8: Studies of the fixation of iodine at different iodine concentrations

Resin I-A', Resin I-B', Resin I-B" and Resin I-A" were prepared as follows:

Resin I-A' was prepared as described in example 5.
Resin I-B' was prepared following the procedures of examples 1 and 2 except that for the resin, Amberlite IR-400 (OH-) (from Rohm & Hass) was used.
Resin I-B" was prepared following the procedures of examples 1 and 2 (using Amberlite 401-S) except that the amount of the I2/KI mixture was adjusted so as to provide a resin comprising about 30 percent iodine at the end of the procedure in example 2; the mixture obtained at the end of the procedure of example 2 was divided into two equal parts and one part was subjected to a wash to provide the iodinated resin obtained as at the end of the procedure in example 2; and
Resin I-A" was prepared by taking the remaining one half part of the intermediate mixture obtained in the preparation of Resin I-B" (mentioned above) and subjecting the mixture to the procedure of example 3 except that the elevated temperature and pressure conditions were set at 121° C and 15 psig respectively.

The iodine content of the above iodinated resins was determined in accordance with the procedure outlined below. The resins were also subjected to an iodine bleed test as outlined below.

IODINE CONTENT:

1.0 gm of each of the different resins was boiled in 20 ml of water with a concentration of 5% by weight of sodium thiosulphate. Boiling was conducted for 20 minutes whereafter the water mixture was set aside to air cool for 12 hours. The resin was then recovered and washed with 50 ml of a boiling water solution of sodium thiosulphate. Thereafter the resin was dried in an oven for 12 hours at 105 degrees. The iodine desorbed resin was weighed in each case and the weight difference was used to calculate the % by weight of the initial resin represented by the active iodine removed.

IODINE BLEED TEST

The test is conducted as follows: A pressure syringe was filled with 20 grams of resin (inner chamber of 3 cm x 13 cm). Using a peristaltic pump 750 ml/min of R/O water (sterilized) was pumped through the syringe; the resin being maintained in the syringe by suitable mesh means. The total water passed through the resin was 5 liters.

The results of the tests are given in the graph shown in figure 1; i.e. ppm iodine in effluent vs total volume water passed through resin. The bleed test results as shown in the graph compares iodine (I₂) and iodide (I^-) in effluent of treated water after passing through each of the resins.

The results are shown in table 8 below:

Table 8

Resin type	Iodine %	Iodine leach
Resin I-B'	43.5	0.15 ppm
Resin I-A'	41.8	0.05 ppm
Resin I-B"	30.5	0.3 ppm
Resin I-A"	29.0	0.05 ppm

As may be seen from table 8, subjecting the resin to a high temperature/pressure treatment results in the iodine being more tenaciously fixed to the resin at different iodine concentrations.

EXAMPLE 9: Air study with I-B"

The procedure of example 7.6 was followed using 30 grams of Resin I-B" and Bacillus Subtilis at a concentration of 275000 cfu per cubic meter. It was found that the Resin I-B" eradicated only 7 to 10 % of the microorganisms. The results of the test show that the Resin I-B" is not as effective at eradicating microorganisms from air as is the Resin I-A'; it would be necessary to have substantially more of Resin I-B" in order to totally sterilize air as compared with the Resin I-A'.

Claims

A method for disinfecting air containing microorganisms, said method comprising passing air containing microorganisms through air path means and disinfecting such air in said path means by passing such air over a disinfectant resin such that airborne microorganisms contact said resin and are devitalised thereby, said disinfectant resin comprising a demand disinfectant iodinated resin.
A method as defined in claim 1 wherein said demand disinfectant iodinated resin comprises an iodinated anion exchange resin.
A method as defined claim 1 wherein said demand disinfectant iodinated resin comprises an iodinated strong base anion exchange resin.
A method as defined in claim 3 wherein said iodinated strong base anion exchange resin comprises a strong base anion exchange resin component which represents from 25 to 90 percent by weight of the total weight of the iodinated resin.
A method as defined in claim 3 wherein said iodinated strong base anion exchange resin comprises a strong base anion exchange resin component which represents from 45 to 65 percent by weight of the total weight of the iodinated resin.
A method as defined in claim 3 wherein said iodinated strong base anion exchange resin is an iodinated strong base anion exchange resin obtainable in accordance with a process comprising a conversion step comprising contacting a porous strong base anion exchange resin in a salt form with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the demand disinfectant resin, said iodine-substance being selected from the group comprising I₂ and polyiodide ions having a valence of -1, and wherein for the conversion step at least a portion of the absorption of iodine-substance is effected at an elevated temperature that is higher than 100°C and at an elevated pressure that is greater than atmospheric pressure.
A method as defined in claim 3 wherein said iodinated strong base anion exchange resin is an iodinated strong base anion exchange resin obtainable in accordance with a process comprising a conversion step, the conversion step comprising contacting a porous strong base anion exchange resin in a salt form other than the iodide form I^-, with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the demand disinfectant resin, said iodine-substance being selected from the group comprising polyiodide ions having a valence of -1, wherein said conversion step comprises an initial conversion stage followed by a second conversion stage, the initial conversion stage comprising contacting the anion exchange resin with the iodine-substance at a temperature of 100°C or lower so as to obtain an intermediate composition comprising residual absorbable iodine-substance and an intermediate iodinated resin, the second conversion stage comprising subjecting the intermediate composition to an elevated temperature that is 102°C or higher and an elevated pressure of 2 psig to 35 psig, and wherein said, iodine substance comprises triiodide ions of formula 1₃-, wherein said anion exchange resin is in the hydroxyl form OH^-, and wherein the anion exchange resin is contacted with a composition consisting of a mixture of KI, I₂ and a minor amount of water, the mole ratio of KI to I₂ initially being about 1.
A system for disinfecting air containing airborne microorganisms, said system comprising:
means for providing an air path for the movement of air therethrough, and

a disinfectant resin disposed in said air path such that airbone microorganisms in air passing through said air path are able to contact said resin and be devitalised thereby, said disinfectant resin comprising a demand disinfectant iodinated resin.
A system as defined in claim 8 wherein said demand disinfectant iodinated resin comprises an iodinated anion exchange resin.
A system as defined in claim 8 wherein said demand disinfectant iodinated resin comprises an iodinated strong base anion exchange resin.
A system as defined in claim 10 wherein said iodinated strong base anion exchange resin comprises a strong base anion exchange resin component which represents from 25 to 90 percent by weight of the total weight of the iodinated resin.
A system as defined in claim 10 wherein said iodinated strong base anion exchange resin comprises a strong base anion exchange resin component which represents from 45 to 65 percent by weight of the total weight of the iodinated resin.
A system as defined in claim 10 wherein said iodinated strong base anion exchange resin is an iodinated strong base anion exchange resin obtainable in accordance with a process comprising a conversion step comprising contacting a porous strong base anion exchange resin in a salt form with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the demand disinfectant resin, said iodine-substance being selected from the group comprising I₂ and polyiodide ions having a valence of -1, and wherein for the conversion step at least a portion of the absorption of iodine-substance is effected at an elevated temperature that is higher than 100°C and at an elevated pressure that is greater than atmospheric pressure.
A system as defined in claim 10 wherein said iodinated strong base anion exchange resin is an iodinated strong base anion exchange resin obtainable in accordance with a process comprising a conversion step, the conversion step comprising contacting a porous strong base anion exchange resin in a salt form other than the iodide form I^-, with a sufficient amount of an iodine-substance absorbable by the anion exchange resin such that the anion exchange resin absorbs said iodine-substance so as to convert the anion exchange resin to the demand disinfectant resin, said iodine-substance being selected from the group comprising polyiodide ions having a valence of -1. wherein said conversion step comprises an initial conversion stage followed by a second conversion stage, the initial conversion stage comprising contacting the anion exchange resin with the iodine-substance at a temperature of 100°C or lower so as to obtain an intermediate composition comprising residual absorbable iodine-substance and an intermediate iodinated resin, the second conversion stage comprising subjecting the intermediate composition to an elevated temperature that is 102°C or higher and an elevated pressure of 2 psig to 35 psig, and wherein said iodine substance comprises triiodide ions of formula l₃ ^-, wherein said anion exchange resin is in the hydroxyl form OH^-, and wherein the anion exchange resin is contacted with a composition consisting of a mixture of Kl, l₂ and a minor amount of water, the mole ratio of K1 to l₂ initially being about 1.
A system as defined in any of claims claims 8 to 14, said system including means for urging the air through said air path.
A system as defined in any of claims 8 to 14, said system including means disposed in said air path for scavenging iodine liberated from the disinfectant resin.