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EP2178635A1 - Préparation de nouveaux adsorbants de type hydrotalcite utiles pour l'adsorption de matériaux anioniques - Google Patents

Préparation de nouveaux adsorbants de type hydrotalcite utiles pour l'adsorption de matériaux anioniques

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Publication number
EP2178635A1
EP2178635A1 EP08773855A EP08773855A EP2178635A1 EP 2178635 A1 EP2178635 A1 EP 2178635A1 EP 08773855 A EP08773855 A EP 08773855A EP 08773855 A EP08773855 A EP 08773855A EP 2178635 A1 EP2178635 A1 EP 2178635A1
Authority
EP
European Patent Office
Prior art keywords
extract
acid
adsorbent
magnesium
source
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08773855A
Other languages
German (de)
English (en)
Inventor
Jose Antonio Ortiz Niembro
Eduardo Gonzales Lozano
Fidel Pacheco Garcia
Genoveva Rosano Oertega
Veronica Martinez Quevedo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sued Chemie IP GmbH and Co KG
Original Assignee
Sued Chemie AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sued Chemie AG filed Critical Sued Chemie AG
Priority to EP08773855A priority Critical patent/EP2178635A1/fr
Publication of EP2178635A1 publication Critical patent/EP2178635A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/78—Compounds containing aluminium, with or without oxygen or hydrogen, and containing two or more other elements
    • C01F7/782—Compounds containing aluminium, with or without oxygen or hydrogen, and containing two or more other elements containing carbonate ions, e.g. dawsonite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/78—Compounds containing aluminium, with or without oxygen or hydrogen, and containing two or more other elements
    • C01F7/784—Layered double hydroxide, e.g. comprising nitrate, sulfate or carbonate ions as intercalating anions
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/20—Two-dimensional structures
    • C01P2002/22—Two-dimensional structures layered hydroxide-type, e.g. of the hydrotalcite-type
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
    • C02F2001/422—Treatment of water, waste water, or sewage by ion-exchange using anionic exchangers
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/101—Sulfur compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/06—Contaminated groundwater or leachate
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/42—Nature of the water, waste water, sewage or sludge to be treated from bathing facilities, e.g. swimming pools
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents

Definitions

  • This invention relates to a method for the synthesis of an adsorbent which is in particular suitable for the adsorption of sulfur-containing anions in water purification. Further, the invention relates to a method for purification of water.
  • Layered Double Hydroxides are a class of ionic lamellar solids comprising positively charged layers formed of divalent and trivalent metal cations, for example Mg 2+ and Al 3+ .
  • a typical representative of this class of minerals is hydrotalcite .
  • the general formula of hydrotalcite is Mg 6 Al 2 (OH) 6 CO 3 * 4H 2 O.
  • the crystal structure of hydrotalcite may be derived from brucite, (Mg(OH) 2 ), which forms an octahedron as a subunit of a layered structure. Partial replacement of Mg 2+ ions with Al 3+ ions in the brucite structure results in an excess of positive charge, which is compensated in the hydrotalcite structure by anions introduced between the layers of the crystal structure.
  • Suitable anions are e.g. hydroxide and carbonate anions, which also may be hydrated.
  • the anions introduced into interlayer spaces as well as crystal water molecules are only weakly bonded to the crystal layers. Therefore, hydrotalcite-like compounds can be used e.g. as anion exchangers, polymer stabilizer, antiacids, anion scavengers, adsorbents and for the controlled release of anions.
  • US 4,458,030 discloses an adsorbent composition comprising a combination of a hydrotalcite compound and activated carbon.
  • the hydrotalcite compound has a relatively high specific surface area, for example a BET specific surface area of about 50 to about 200 m 2 /g and a secondary particle diameter of about 0.1 -
  • the composite adsorbent shows an increased adsorptive power in comparison to the individual compounds, in particular for anions like nitrate, chloride, sulfate, acetate, oxalate and iron hexacyanoferrate.
  • the hydrotalcite used in the adsorbent may be available in the market or may be produced by methods known per se.
  • the hydrotalcite may be produced by reacting an aqueous solution of a water-soluble magnesium compound and/or a water soluble zinc compound, such as magnesium chloride, magnesium sulfate, zinc chloride and zinc sulfate, with an aqueous solution of a water-soluble aluminium compound, such as aluminium chloride, aluminium sulfate and sodium alumi- nate together with an aqueous solution of an alkali such as sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate and sodium oxalate.
  • a water-soluble magnesium compound such as magnesium chloride, magnesium sulfate, zinc chloride and zinc alumi- nate
  • an alkali such as sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate and sodium oxalate.
  • an aqueous solution of a zinc salt is used in this reaction, it is preferred to carry out the reaction at a pH of at least about 6. If an aqueous solution of a
  • DE 41 40 746 discloses a method for the sorption of weak polar and non-polar substances in polar media like process water.
  • the method comprises the use of hydrophobically modified hydrotalcite for adsorption of hydrocarbons.
  • the modified hydrotalcite is synthesized by mixing fatty acids with sodium aluminate and magnesia chloride.
  • US 5,399,329 discloses a process for producing hydrotalcite-like materials having a sheet-like morphology and having an average broadness to thickness ratio ranging from 50 to 5.000 and having the following formula:
  • crystalline hydrotalcite compounds are excellent adsorbents for a variety of anions in many different applications. Nevertheless crystalline hydrotalcite compounds are relatively expensive due to the purity of the educts and complex synthesis conditions of the high crystalline hydrotalcite product. Special crystallization treatment and especially heating steps like calcination increase the complexity and the costs of the synthesis process even more.
  • an extract produced as a by-product in the manufacturing of bleaching earth is used as a starting material in the synthesis of the adsorbent.
  • the extract is selected such that the extract is rich in aluminium ions and rich in iron ions.
  • the extract usually also contains magnesium ions such that the extract, at least in part, may also serve as a magnesium source for the production of an adsorbent.
  • the inventors have found that by using an extract obtained as by-product in the production of bleaching earth that is rich in iron ions, an adsorbent is obtained that is particularly suitable for removing sulfur-containing anions, in particular sulfide ions and sulfate ions, from drinking water.
  • the precipitate obtained by- addition of a base and carbonate ions must only be dried and optionally milled after separation from the liquid phase and must not be calcined at higher temperatures. Therefore the process of the invention may be performed in a simple and cost- efficient manner and provides an adsorbent with sufficient adsorption capacity to be used in the purification of drinking water.
  • a method for the synthesis of an adsorbent suitable for the adsorption of anions comprising at least the following steps:
  • Bleaching earths are provided by extracting naturally occurring clays with strong mineral acids.
  • Naturally occurring clays contain a variety of different cations like Na, K, Ca, Mg, Al and Fe.
  • cations like Na, K, Ca, Mg, Al and Fe.
  • This solution is separated from the extracted clay material and is used e.g. in the treatment of waste water.
  • the acid treated clay may be used as bleaching earth for the treatment of edible oils or as catalyst material. Due to the economical relevance of bleaching earths in many industrial applications, the cation rich by-product solution is highly available and cheap.
  • the acid extract obtained as a by-product in the production of bleaching earth is selected such, that it is containing at least 6,5 g/1 aluminum ions and at least 4,5 g/1 iron ions, both calculated as elemental aluminum and elemental iron. If necessary, the iron content of the acid extract may be adjusted by adding suitable iron compounds, e.g. iron oxide or iron chloride.
  • the acid extract provided as a byproduct in the production of bleaching earth is combined with a magnesium source to adjust the magnesium concentration of the acid extract to at least 6.8 g/1, preferably within a range of 11.0 to 25.0 g/1, calculated as elemental magnesium.
  • a magnesium source to adjust the magnesium concentration of the acid extract to at least 6.8 g/1, preferably within a range of 11.0 to 25.0 g/1, calculated as elemental magnesium.
  • Many of the clays used as starting material in the production of bleaching earths also contain magnesium ions which are extracted during treatment of the clay with strong mineral acids. Therefore, the acid extract used as an aluminium source and an iron source in the method according to the invention also is rich in magnesium ions and, therefore, in most cases only an amount of magnesium ions has to be added which corresponds to the difference in magnesium concentration in the acid extract and the adsorbent to be synthesized.
  • the acid extract provided by the extraction of clays may therefore also serve at least in part as a magnesium source. Use of the extract therefore allows a very cost- efficient synthesis of the adsorbent. Besides aluminum, iron and magnesium ions the extract also may contain a high number of further ions. However, it was found that the presence of these further ions does not have any detrimental effect on the adsorption capacity of the adsorbent and no heavy metal ions are leached out during treatment of water with the adsorbent obtained by the method according to the invention.
  • a precipitate is produced.
  • an alkaline solution may be used a solution of e.g. NaOH, KOH, Ca(OH) 2 , Mg(OH) 2 -
  • NaOH is used as a base to neutralize the aluminium/magnesium source mixture.
  • the solution may be a concentrated solution.
  • a diluted aqueous alkaline solution is used to allow better handling and a better removal of the heat produced during neutralization.
  • the aqueous alkaline solution comprises 1 to 40 wt.-%, particularly preferred 10 to 30 wt.-% of the base.
  • a carbonate source to introduce carbonate ions as gallery ions and to thereby obtain a carbonated extract.
  • Any suitable carbonate source may be used.
  • a suitable carbonate source may be selected from the group of Na 2 CO 3 , NaHCO 3 , K 2 CO 3 , KHCO 3 , CaCO 3 , Ca (HCO 3 ) 2 , MgCO 3 , Mg (HCO 3 ) 2 .
  • the compounds may be used in pure form or as a mixture.
  • sodium carbonate (soda) is used as the carbonate source.
  • the pH of the mixture is preferably adjusted to at least 8, particularly preferred within a range of 8,5 to 9,5.
  • the precipitate is separated from the carbonated extract by suitable means, e.g. by filtration.
  • the separated precipitate is then dried and optionally milled.
  • the precipitate is dried at a low temperature at which the carbonate ions and the water bound in the adsorbent will not be separated from the crystal structure.
  • the temperature used for drying therefore is adjusted to 200 0 C at most, preferably within a range of 100 0 C to 150 0 C, particularly preferred within a range of 100 to 130 0 C. It is not necessary to calci- nate the precipitate to thereby obtain a well established hydro- talcite structure.
  • the precipitate preferably is not treated at a temperature of more than 300 0 C, particularly preferred not more than 200 0 C and most preferred is not treated at a temperature of more than 150 0 C.
  • the method according to the invention therefore does not comprise a calcination step and therefore the corresponding costs for energy are saved.
  • the dried precipitate may be milled to adjust the particle size.
  • the particle size is preferably adjusted to ⁇ 200 ⁇ m, particularly preferred within a range of 50 to 100 ⁇ m.
  • the particle size may be determined e.g. by sieving or laser granulatometry.
  • the adsorbent may be used in the form of a powder or may be formed to shaped bodies in a known manner.
  • the aqueous alkaline solution is added under high shear.
  • the high shear condition supports an uniform product forming process and prevents an early agglomeration and flocculation.
  • every suitable (slurry) mixing device including ultra-sonic treatment, can be used to induce the high shear agitation.
  • the duration and intensity of the high shear agitation can be varied depending on educt and product properties, like solubilty, particle size and dispersity.
  • the high shear condition is continued throughout the synthesis, i.e. until separation of the precipitate from the liquid phase.
  • the carbonate source may be added to the neutralized extract in solid form.
  • the carbonate source is added in the form of an aqueous solution to achieve a rapid reaction with the precipitate.
  • the aqueous carbonate source solution may be used in concentrated or diluted form.
  • the aqueous carbonate source has a solid content within a range of 1 to 40 wt.-%, particularly preferred within a range of 10 to 25 wt.-%.
  • the liquid acid extract phase provided as the starting material for the method according to the invention may be adjusted to any suitable temperature.
  • the liquid acid extract phase provided from the bleaching earth production is preferably adjusted to a temperature in a range of 50 to 90 0 C, particularly preferred in a range of 55 to 75 0 C. Handling of the liquid acid extract phase at temperatures above 90 0 C causes problems because of high corrosion of the apparatuses used for the synthesis of the adsorbent.
  • the aqueous alkaline solution and/or the carbonate source is preferably added at such a rate to the acid extract, that the heat produced by the neutralization reaction can be conveniently removed.
  • the acid extract is kept at a temperature within a range of 50 to 90 0 C, particularly preferred within a range of 55 to 75°C. If necessary, a cooling equipment may be provided to remove the heat produced during addition of the base.
  • the acid extract phase provided by the extraction of clays in the production of bleaching earth may be used as it is obtained in the extraction process.
  • the liquid acid extract phase provided from the bleaching earth production preferably has a solid content of less than 25 wt.-%, particularly preferred within a range of 10 to 20 wt.-%.
  • a high concentration of aluminum is preferred in the acid extract liquid phase.
  • the acid extract has an aluminum concentration of at least 8.5 g/1, calculated as elemental aluminum.
  • the aluminium concentration of the acid extract phase is adjusted within a range of 7.5 to 10.8 g/1.
  • the acid extract preferably contains at least 3.0 g/1 iron ions, particularly preferred 4.5 to 6.0 g/1 of iron ions, calculated as elemental iron.
  • the acid extract used as the starting material in the method according to the invention may be used as obtained in the extraction of clay with mineral acid in the production of bleaching earth. However, it is also possible to dilute the liquid extract phase to thereby better control the neutralization process.
  • the liquid extract phase provided as an aluminium source has an acid content of less than 20 wt.-%, particularly preferred within a range of 5 to 10 wt.-%.
  • the mixture is agitated at least 5 minutes, particularly preferred at least 10 minutes, before adding the aqueous alkaline solution.
  • the carbonated extract is preferably reacted for at least 1 hour, particularly preferred for at least 2 hours.
  • the precipitate is preferably washed with water after separation of the precipitate from the carbonated extract, i.e. before drying.
  • ani- ons e.g. carbonate anions
  • tap water e.g. distilled water
  • sulfate ions present in the precipitate should be removed.
  • the washing is preferably continued until the anion concentration in the washing water is below 3650 mg/1.
  • the anion concentration may be determined by standard methods known in the field of drinking water technology.
  • the acid extract used as the starting material in the method according to the invention is obtained by extraction of clay materials with strong mineral acid. As most clays also contain magnesium, the extract also contains magnesium ions. A typical magnesium concentration in the liquid extract, calculated as elemental magnesium, is in a range of 6.5 to 7.5 g/1. If the magnesium ion concentration is not high enough to obtain the desired magnesium concentration in the adsorbent material, a magnesium source is added to the aluminium source.
  • a preferred magnesium source is Mg(OH) 2 . Such Mg (OH) 2 may be provided e.g. in the form of brucite.
  • Other suitable magnesium sources are magnesium carbonate, activated magnesium oxide, or magnesium chloride.
  • the mixture of the acid extract serving as aluminium and iron source, magnesium source, aqueous alkaline solution and carbonate source is preferably kept under high shear conditions during the synthesis.
  • the high shear condition is achieved by stirring the mixture at a rotation speed within a range of 100 to 5000 rpm, preferably within the range of 1000 to 3000 rpm.
  • every suitable (slurry) mixing device can be used to induce the high shear agitation.
  • the stirring apparatus used should withstand the highly acidic or basic conditions present during the synthesis of the adsorbent.
  • the duration and intensity of the high shear agitation can be varied depending on educt and product properties, like solubilty, particle size and dispersity.
  • the continuous high shear agitation lasts for 1 - 480 minutes, preferably lasts for 10 - 240 minutes and particularly preferred lasts for 25 - 130 minutes .
  • the clay used as a starting material for obtaining the liquid acid extract phase used as the aluminium and iron source in the method according to the invention may be every clay commonly used for the production of bleaching earth.
  • the clay is selected from the group of smectitic clays.
  • Preferred smec- titic clays are selected from the group consisting of montmoril- lonite, bentonite, hectorite, nontronite, vermiculite, illite, saponite. Bentonite is particularly preferred. Bentonite mainly comprises montmorillonite. Montmorillonite has the general formula (Al 3 . 2 lVIgo.8) (Si 8 ) O 20 (OH) 4 (CO 3 ) 0.8-
  • the strong mineral acid used for extracting the clay may be every mineral acid commonly used in the production of high performance bleaching earth.
  • the mineral acid used for extracting the clay is selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid and mixtures thereof.
  • the conditions used for extracting the clay are common to the skilled person.
  • the extraction is performed at a temperature close to the boiling point of the liquid phase.
  • a preferred temperature range is 80 to 100 0 C, particularly preferred a range of 85 to 95 0 C.
  • the duration of the extraction is selected such as desired by the activation of the bleaching earth.
  • the duration of the extraction is selected within a range of 1 to 10 hours, particularly preferred 4 to 8 hours.
  • the molar ratio Al/Mg in the reaction mixture, i.e. after adding the magnesium source to the aluminium source, is preferably selected within a range of 1.0 to 5.0, particularly preferred 2.0 to 3.0.
  • the acid extract obtained from the bleaching earth production and used as the starting material for the process according to the invention may contain further metal cations.
  • Preferred further metal cations are selected from the group of Ca, Na, K, Li, NH 4 + .
  • the adsorbent obtained with the method according to the invention has a high absorption capacity for anions and may be produced in an cost efficient manner.
  • the invention therefore is directed to a method for purification of water, wherein an adsorbent is prepared with a method as described above and the water to be purified is contacted with the adsorbent.
  • the adsorbent binds a variety of inorganic anions, e.g. SO 4 2-, SO 3 2" , S 2" , NO 3 “ , NO 2 “ , CN “ , N 3 “ , CrO 4 2” , PO 4 2” and organic anions like CH 3 COO “ , H 2 COO “ and (O 2 CCO 2 ) 2" .
  • the purification is performed in a known manner by e.g. mixing the water to be purified with a powder of the adsorbent.
  • the amount of adsorbent added to the water to be purified is preferably at least 4 mg/1 and is particularly preferred selected within a range of 5 to 10 mg/1, most preferred within a range of 6 to 8 mg/1.
  • the adsorbent may be provided in the form of spherical bodies that may form a fixed bed and the water to be purified is directed through the fixed bed.
  • the water to be purified may be e.g. spring-water, ground-water or surface water derived from e.g. rivers or lakes.
  • the adsorbent may also be used for the purification of beverages, foodstuff, swimming pool water, urban or industrial waste water.
  • the adsorbent is in particular suitable for the removal of sulfur-containing anions, like S 2 ⁇ , SO 3 2" and SO 4 2" . Additionally the adsorbent decreases the hardness of water by removing carbonate anions, thereby lowering the amount of hardly soluble salts like CaCO 3 , MgCO 3 , CaSO 4 and MgSO 4 .
  • the water to be purified has a sulfur content of at least 300 mg/1, particularly preferred of at least 500 mg/1 and most preferred is within a range of 400 to 100 mg/1, calculated as SO 4 2" anions.
  • the sulfur content of the water to be purified may be detected e.g. by the method described below.
  • Fig. 1 is a XRD pattern of the adsorbent obtained by the method according to the invention.
  • Fig. 2 is a diagram showing the amount of SO 4 2- , water hardness and pH after treatment of a water sample with various amounts of adsorbents.
  • X ml of the water sample to be analyzed are accurately measured into a 25 ml Erlenmeyer flask. A magnetic bar is inserted into the flask and the sample is stirred. Then "X" ml of a buffer solution, prepared by dissolving 16.9 g of ammonium chloride in 143 ml of 1 m ammonium hydroxide and a small amount of eriochrome black indicator are added and the mixture is titrated with 0.01 M EDTA solution until the red color of the indicator turns to blue. The amount of EDTA-solution ("A" ml) used is noted and the hardness is calculated according to the following equitation:
  • B is the mg CaCO 3 equivalent to 1 ml of EDTA solution.
  • B is 1 mg CaCO 3 / 1 ml of EDTA solution.
  • the sulfate ions are precipitated in a hydrochloric acid medium with barium chloride (BaCl 2 ) so as to form barium sulfate (BaSO 4 ) crystals of uniform size.
  • barium chloride BaCl 2
  • Light absorbance of the BaSO 4 suspension is measured by a nephelometer or transmission photometer and the sulfate concentration is determined by comparison of the reading with a standard curve.
  • 100 ml of the sample to be analyzed are pipetted into a 250 ml Erlenmeyer flask.
  • a magnetic bar is inserted into the flask and the sample is stirred.
  • 5.00 ml conditioning agent prepared by dissolving 30 g of magnesium chloride, 5 g sodium acetate, 1 g potassium nitrate and 20 ml of acetic acid in 500 ml of distilled water, are added and then a spoonful of BaCl 2 crystals and the solution is stirred for 1.0 min at constant speed.
  • the solution is poured into the absorption cell of the photometer (spectrometer: SPECTROQUANT Nova 60, 420 nm, light path 4 cm) and the turbidity is measured at 30 s intervals for 4 min. Maximum turbidity usu- ally occurs within 2 min and readings remain constant there after 3 to 10 min. Turbidity is considered to be the maximum reading in the 4 min interval.
  • the amount of sulfate ions is calculated according to the following equitation:
  • the pH is determined with a calibrated glass electrode.
  • the analysis of these metals is performed by means of a Spectrophotometer ICP plasma model Optima 3100 XL from Perkin Elmer, USA, according to the manufacturer's instructions.
  • the sample is injected into a high-temperature argon plasma, where the atoms are vaporized, excited and subsequently emit light that can be measured.
  • an amount of iodine solution is measured into a 500 ml flask estimated to be an excess over the amount of sulfide present. If necessary, the volume of the solution is brought to about 20 ml by addition of distilled water. Then, 2 ml of 6 N HCl are added. 200 ml of the sample to be analyzed are pipetted into the flask. The sample is back titrated with Na 2 S 2 Oa solution until the iodine color disappears. Towards the end of the titration starch solution is added for better visibility of the end point.
  • the precipitate is washed into the flask with about 100 ml of water. After addition of iodine solution and HCl, the sample may be back titrated as described above.
  • the amount of sulfide is calculated according to the following equitation:
  • a diffraction pattern of the adsorbent is displayed in fig. 1.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

L'invention concerne un procédé pour la synthèse d'adsorbant de type hydrotalcite qui conviennent en particulier pour l'adsorption d'anions contenant du soufre, par exemple dans la purification d'eau potable. Le procédé comprend le mélange d'une source aqueuse d'aluminium et d'une source aqueuse de magnésium avec une solution alcaline et/ou contenant de la soude sous agitation à haut cisaillement. On utilise comme source d'aluminium un extrait dérivé de l'extraction d'argiles par des acides minéraux forts dans la production de terre décolorante. Le produit peut être facilement séparé et directement utilisé comme adsorbant pour différents anions.
EP08773855A 2007-07-04 2008-07-03 Préparation de nouveaux adsorbants de type hydrotalcite utiles pour l'adsorption de matériaux anioniques Withdrawn EP2178635A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08773855A EP2178635A1 (fr) 2007-07-04 2008-07-03 Préparation de nouveaux adsorbants de type hydrotalcite utiles pour l'adsorption de matériaux anioniques

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EP07013095A EP2014358A1 (fr) 2007-07-04 2007-07-04 Préparation d' absorbants de type hydrotalcite utiles pour l'absorption de matériaux anioniques
PCT/EP2008/005449 WO2009003709A1 (fr) 2007-07-04 2008-07-03 Préparation de nouveaux adsorbants de type hydrotalcite utiles pour l'adsorption de matériaux anioniques
EP08773855A EP2178635A1 (fr) 2007-07-04 2008-07-03 Préparation de nouveaux adsorbants de type hydrotalcite utiles pour l'adsorption de matériaux anioniques

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CN110508261A (zh) * 2018-10-31 2019-11-29 西安电子科技大学 吸附重金属铜的钙基氢氧化镁制备方法

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JP5915834B2 (ja) * 2010-10-29 2016-05-11 三菱マテリアル株式会社 浄化処理材の製造方法
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CN109395693A (zh) * 2017-08-18 2019-03-01 湖州欧美新材料有限公司 一种吸附剂、制备方法及应用
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CN115814766B (zh) * 2022-12-06 2023-06-20 武汉市强龙化工新材料有限责任公司 一种聚乙烯亚胺复合材料及其制备方法
CN118343807B (zh) * 2024-06-17 2024-09-06 潍坊万丰新材料科技有限公司 一种湿法冶炼用氧化镁的制备方法

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CN109897954A (zh) * 2019-03-27 2019-06-18 东北师范大学 一种用于冷轧铁泥的纯化方法

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