WO2013155641A1 - Sorbent material for the selective removal of pollutants from water - Google Patents

Description

 SURPRISING ENVIRONMENT FOR THE SELECTIVE CONTAMINANTS

 OF THE WATER

FIELD PE THE INVENTION

The present invention relates to a sorbent medium for the selective removal of contaminants from water. More specifically, the present invention relates to a sorbent medium that includes a matrix consisting of aerliate granules and iron oxides with magnetic properties, such as maghemite, hematlta, magnetite, among others. The present invention also relates to the method of preparing the sorbent medium with a defined particle size and its use in the removal of contaminants from water.

STATE OF THE TECHNIQUE

 Arsenic in natural waters is a worldwide problem Arsenic contamination has been reported in the United States, C ina, Chile, Sangladesh, Taiwan, lexicon, Argentina, Poland, Canada, Hungary, New Zealand, Japan and India. The most populous areas affected by this pollutant are Bangladesh and West Bengaí in India (Mohán et al .. 2007). In Chile, one of the regions with the greatest difficulties is the Aníofagasta region. due to high concentrations of arsenic from the Loa river. In addition, relatively high concentrations for human consumption have recently been observed in other regions of Chile such as Arica Parinacoia, and the Metropolitan Region,

Human consumption of water contaminated with arsenic can occur in the long term; skin, lung, and kidney cancer as well as changes in skin pigmentation, hyperkeratosis, muscle aches, loss of appetite, nausea and poisoning (the latter at higher concentrations) (WHO, 1981; Jala 2000).

The World Health Organization (QMS) proposes as a standard for drinking water concentrations of arsenic not exceeding 10 pg / L (0.01 mg / L), reducing the previous limit that reached 50 pg / ^' L The US Office of Environmental Protection (US-EPA) also reduced the limits of arsenic concentration for the production of drinking water from 50 to 10 pg / L, which is in force since January 2006. In the case of Chile, the Chilean standard of drinking water Nch409 was modified in 2001, lowering the limits of arsenic concentration from 50 to 10 pg / L for all the sanitary companies that started the operation of facilities for the production of drinking water from That year, for the old companies, on the other hand, there was a gradual deadline for compliance with the norm, with an average objective of reaching 30 ug / L in 2006, and a final one reaching 10 ug / L in the year 201

Currently in Chile, the coagulation / precipitation system with ferric chloride is used as a conventional removal mechanism, which has a good removal performance but has the disadvantages of its high cost, complex operation and of generating a large amount of arsenic sludge.

The health company of Antofagasta (ESSAN) treats water contaminated with arsenic through the coagulation / filtration process, achieving effluents with concentrations close to 10 ppb. However, the effort to achieve such concentrations has meant a significant increase in operating costs (up to 70%). In this way, the need arises to generate higher cost-effectiveness aifernaflvas for the removal of arsenic from water sources, and that do not result in the generation of toxic or difficult-to-dispose residues.

Numerous techniques have been developed for the removal of arsenic from water. Arsenic removal technologies can be divided into four main groups that comprise (Motan et al., 2007; US-EPA, 2000):

! - · Oxidation / precipitation, in which the oxidation can be with air or chemical. This methodology is characterized by simple, inexpensive, allows removal of arsenic in your _s,: and oxidizes other organic and inorganic compounds, in turn, allows the chemical oxidation ta microbe removal. However, this methodology has the disadvantage of removing only As (V) and requires a complementary precipitation process, and in the case of chemical oxidation, an efficient control of H and a pre-oxidation step are also required.

2··. Coagulation / Co-precipitation: This technique includes coagulation with aluminum, coagulation with iron, and softening with lime. This methodology offers the advantage of the high availability of chemical reagents. However, the disadvantage of these methods is the production of toxic potentiating sludge, low efficiency Arsenic removal and generally requires previous stages, such as sedimentation and filtration in the case of coagulation - with Fe, or pH adjustment in the case of lime softening.

3 ^» . Membrane Techniques: encompasses nanophyration, reverse osmosis and electroanalysis techniques. The advantages of this technology are related to the high removal capacity, they do not produce toxic solid wastes, the eieetredláiisls also allows to remove other pollutants other than arsenic. The great disadvantage of membrane-related techniques is the great loss of water, high operating costs, and high maintenance technology. The electrodlalisi also produces ID toxic liquid waste.

4- .. Sorption techniques: these techniques are highly efficient to remove contaminants and can be enhanced with activated alumina, iron oxides or ion exchange resins,

The sorption technique with activated alumina is well known and available in the commercial market, presenting the disadvantages that replacement of the material is required after several uses, pH adjustment, which is affected by interference.

The sorption technique through the use of Ionic exchange resins, have good contaminant removal capacity, independent of pH, and there are exclusive Ionic exchange resins for arsenic. The disadvantages of the 20 ion exchange resins are their cost, their maintenance and operation technology, and their regeneration causes problems in sludge disposal, Adielonalmenfe, As (III) is difficult to remove, and the shelf life of Resins in general is limited.

Sorption techniques that use iron oxides have the advantages of being low cost, do not require regeneration as in the case of ion exchange resins, and remove both As (III) and As (V), the main disadvantages The use of iron oxides is the need to adjust the pH since it is affected by interference and can produce toxic waste.

Sorption systems work with the medium medium arranged as a fixed bed in 30 configuration of filtration columns. To remove contaminants from water in general, they have high removal efficiency, are simple to operate and do not They require practically start-up time. On the other hand, they have advantages of not producing sludge in large quantities, which significantly reduces the costs for disposal and transportation of these toxic wastes.

A sorbent means to remove arsenic from water must meet certain physicochemical properties that allow it to be cost-effective, that is, to be a low-cost medium with high arsenic sorption capacity. Within the chemical properties are the zero charge point (PZQ), the surface reactivity • based on its chemical structure and functional groups (both for sipping and for being coated by a metal oxide), the chemical reactivity with the characteristic IDs of the water matrix (for example H, affinity for anions similar to arsenate or arsenite, ionic strength, redox conditions, etc.), and the ability of the medium to be regenerated by chemical treatment.

Because the pH of the water to be treated (for example groundwater) fluctuates between 7 and 9, the P2C of the sorbent medium must be equal to or greater than the pH of the water matrix, thus, the electrostatic attraction between a medium positively charged and the arsenic anions (arsenate) are favored, improving the capacity of sorption of the medium (Gregory J „2006).

Another alternative is the preconditioning of pH for media with lower FZC. In the case of arsenide, due to its lower oxidation state (p _s <Ǥ _< 2) _? even higher means with PZC are required, having as an alternative a process of pre-oxidation of the arsenide to transform it into arsenate to facilitate its sorption,

On the other hand, the physical properties of greatest interest in a sordic arsenic medium are the BET surface area (> 100 m ² / g) tc I-Black ood et al., 2008; Park et al., 2008; Gu et ai, 2005), porosity, a pore size that is

25 larger than the size of arsenate and arsenium ions (mesoporous medium with pore size between 2 and 50 nm) (Qiu et al., 2007), the mesoporous structural arrangement of the sorbent (Gu el al, 2007; Jang el al, 2004: Jang et al., 2003), the degree of integrity of the sorbent (Fark et al., 2008), the decay resistance resulting from the flow forces (Zeng L, 2003; Mitcheli-Blackwood J, et ai, 2008} , the granular form (Gu et al., 2005), and a particle size that reduces the load losses in a configuration of sorption columns for water treatment (Yeorn et ai., 2009). A medium with a high surface area does not necessarily mean that it has a high sorption capacity (Moh n et ai .. 2007; And rson et al, 1985), the ionic charges and the types of chemical bonds formed {"bondirsg str & ngttf) can allow better affinity and sorption capacity to less porous and physically less appropriate media.The combination of electrostatic affinity (good chemical properties) with mesostruciufa, amorphous medium and resistance to disintegration, together with the low cost, are the ideal properties for a good sórbante medium of arsenic,

A large number of arsenic sorbols have been developed, however, only a few have been successfully marketed, due to their high costs and / or low sorption performance. Commercial sorbents, in general, are composed of mixtures of polymers, anion exchange resins, high-cost geomediums with surface metal oxides such as titanium, aluminum, iantane and iron. Or on the other hand, common filter materials such as zeolites or activated carbon have been tested as arsenic sorbents, but with very low yields.

US Patent 7,388,412 is based on sorption techniques and describes a method for removing arsenic, semenium and / or antimony from a feed flow, by passing it through an adsorption medium consisting of a polyacrylonitrile matrix (PAN) and a metal hydrate, homogeneously dispersed in the matrix, removing at least one of the constituents of the feed flow, US Patent 7.291578 develops ammonium exchange polymers that are used as alloyed materials for hydrated iron oxides (HFO), which are irreversibly dispersed at the sites of the exchangers, anionic infiltrators with HFO macroparticle support exhibit a greater ability to remove arsenic and other ligands than the cation exchangers.

Other patents that follow the same line of development of arsenic sorbents are those assigned to SOL ETEX INC. (WO2008 / 021940A2} and GALGON CARBON CORPORATION (WO2005 / 082523). The first is to precipitate metal hydrides via wet impregnation to an anion exchange material. Several coating cycles are proposed to improve surface adhesion of nanoparticle iron oxides on the resins. used are commercial: Puro! ie A400, ParoOte ASüOP, Thermax A-23P, While WO20D5 / U82523, develops adsorbents that remove anions made of a porous material (carbon or dííca) that contains an iron oxide, copper, aluminum, titanium or zirconium These metal oxides are incorporated into the porous medium by impregnating or dispersing a compatible precursor of the compound. Synthesized adsorbents allow arsenic removal from water sources.

The inventors of the present invention have developed a product for removing arsenic from contaminated water based on the sorption technique, which present additional advantages to the techniques known in the prior art. ic The aforementioned documents have in common the synthesis and development of sorbent media of arsenic and other metals from a medium of the exchange resin type, of high technology, complexity and high cost, together with a coating or impregnation of metal oxides generic to form the reactive surface of the medium sor.

15 The present invention advocates the use of generic residualilmetiirnetacriíaío [PIVI A] generic residual waste air) as a support material for the arsenic sorbent medium, recovered as a byproduct for the generation of aerial plates for different uses such as advertising, construction, commercial showcases, decoration, among others. £ 1 support material fill the function of giving

20 structure and density to the sorbent medium, allowing configurations in rapid filtration processes, backwashing and regeneration of the medium. The use of waste products in the support medium, in addition to lowering production costs, allows focusing on the synthesis of reactive surface of the sorbent medium, such as ferromagnetic iron oxides, obtained

25 specifically by thermal treatment or others.

Metal oxides are not used by themselves in the sorption techniques, since they are characterized by low resistance to disintegration and durability under conditions of large-scale flow rates. For this reason, they can be added, for example, silica (Si0 ₂ } to improve the properties of their resistance to disintegration and durability, to the detriment of inhibiting the arsenic sorption capacity; this is because the silica interferes in the arsenate sorption (Zeng et af., 2003). When synthesizing silica-iron compound media, it is necessary to limit the silica content so that it does not inhibit arsenic sorption, and in turn make the material more durable. This limit generates fractions (Si / Fe) between 0.04 and 0.35 (Zeng et al 2003), which implies the use of a large amount of iron, with the consequence of making the medium more expensive. On the other hand, it should be considered that the sorbent medium is limited by its surface structure (porosity and surface area), so that the excess Iron in the medium does not ensure greater arsenic sorbon, and only increases the sorbent costs ( Mohán & Pittman, 2007).

Despite the good properties of iron as an arsenic sorclone agent, it is essential to consider a suitable support material that avoids the problems of disintegration and low durability. Therefore, the use of a support material for the metal oxides that cover it must ensure maximum adhesion, maximum resistance to flows on an industrial scale, and a minimum cost. Therefore, the choice of a support material is critical for the synthesis of cost-effective sorbent media.

In the present invention, it has been determined that one of the supports that meets the stated requirements is acrylic. The acrylic used as a structural support for a coating of iron oxide can be a residual ground acrylic of stripping processes. This material meets the expectations of being low-cost (because it is residual) _: generate resistance to flow in a fixed-bed industrial filtration column, and- in addition, ensure chemical adhesion, through a dissolution process, to coat this support with the iron oxide coating,

DESCmRAÓN OF THE FIGURES Figure 1 Chorographs with Optical Microscope of Synthesized Sorbent Media. (Al) Hematlia-Aorilic; (A2) Hematiia-Acrylic ground; (81) Maghemite-Acrylic; B2) ground aghemlta-Acrylic; (C1) agnetite-Acylco; (C2) Magnetiía-Acrieo ground. gur 2, Image of Electron Microscopy §B ÍSoann g Ei & cfron Microscopy) of Acrilic support to recover or with Hematifa, 200x, WD »12 mm. Detector ^™ SE; EHT ~ 25.00 b; System - empty ^ SS and ^HEARD ¾Bar; Camera-5.05 e ^"005 mBar. Figure 3. Image of SEM Electron Microscopy of Acri ^' iieo Support coated with Hemat ta, 2Q00x, O «12 mm, Deiector = SE1; EHT * 25.0Ü Kb; Vacuum System H93 e ° ¾8ar; Camera * ¾05 e ^" 00-3 mBar.

Figure 4, EOS Analysis (Dispersive Speotro ^ copy Beci n) of Hematite-coated acrylic support: a: elementary attachment of Fe to small particle size; b: Faith mapping on a smaller scale. Figure S. Microscopy Image. SEM Electronics of Air Support Re-Coating with Maghemlta, 200x, WD »13 mm, Detector ~ SE1: ΕΗΤ ~ 2δ _! 00 Kb; Vacic system = 4.0 $ e ^ mBa; Camera at * ^ é * ⁰³ mBar. Figure $ „. SEM Electron Microscopy image of air carrier coated with ag emita, 200Qx, WD * 13 mm, Detector ~ SE1; EHT-25.00 Kb; Vado system * 3.81 8 ^ ar8ar; Camera * 4.9S e ^'¾3 mBar. figure ?. Analysis Support ACN EOS ^'Lico coated maghemite: Fe elemental mapping scale particle size. Figure 8. Image of SEM Electron Microscopy of Magnetite Coated Air Support, 20ux, WD * 14 mm, Detection = SEi: EHT = 2S, Q0 Kb; Camera * 4.97 mBar; (to). Vacfo system ¾38 e ° ¾Bar; (); Vacuum System * 3 _s S4 e ^"mBar : figure, Image of SEM Electron Microscopy of Magnetite-coated air carrier; (a) 2000 x, WD-14 mm, Detector * SE1; ΕΗΤ ^« 25.00. Kb; System Vacuum * 3 @ ^" °% Bár; Camera ~ 4, $ 4 e ^' mBar: (b) 7000 x; WD-14 mm Deleetor ~ 8E1: EHT 25.0Q Kb; Vacuum System ~ 3 _: 23 ^G06 mBar; Chamber = 4.9 e ^ ³ mBar.

Figure 10. EOS Analysis of Aerodynamic Support Coated with Magnetite; Elemental mapping of Fe to particle size scale. Figur 11 Arsenic sorption isotherms. Sorption capacity (pg / g) versus Concentration of As in Liquid Phase (pg / L): Comparison of maximum arsenic capacities in batch isotherms for media of the present Magnetite-Acrllioo M52B Invention with sorbents AAFS50 Activated Alumina ~ of NAFTA ~ US Patent 8,599,429, and half sorbent Pómez Hierro US Patent 7,491,336. Figure 12. Influences and anionic interfensnies and competitors in the arsenic sardon of the sorbent media of the invention and the state of the arle as a percentage of reduction of sorption capacity. M5: LAYNE RT (US Patent 2008/0035564); 52B: Acrylic magnet of the present invention; M52Á: I have atiatta-acrylic of the present invention; M28: PÜC synthesized medium (Pumice stone re-coated with aluminum oxides); Mi 5: Synthesized medium PÜC (Expanded polystyrene with iron oxides), M3; Zeoiite re-coated with aluminum oxides; MI: Pumicata coated with iron oxides US Patent 7,491,335.

Figure 13. Effect of the pH of the water on the arsenic sorption capacity of the different sorbent media, Patented commercial sorbent medium: LAYNE RT (US Patent 2008/0035564): Pumice Iron Sorbent Medium (US Patent 7,491,335); Half sorbenie of the invention; M52B ^■ · Magnetite with acrylic support.

Figure 14, B ak-Throug curve with arsenic sorbent yield in pilot column tests. As concentration (μ / L) depending on the volume of treated water (L), using: Raw Water-Control; Pumice-Iron Sorbent US Patent 7,481,335; Sorbent 52B; Dotted line: Limit As Chilean Standard 409.

Figure 1S Leaching tests m eoritent sorbent media in lotus columns »As concentration (mg / L) in three sections of the sorbent column, Measurements made for sorbent media Pómez-Hierro US Patent 7.491335; 52A (Hematite-Acrylic) and M52B (Agnetite-Acrylic),

Figure 16 .. Asor desorption tests of sorbent media »Percentage of desorption of As in three sections of the sorbent medium column. Measurements made for sorbent media Pómez-Hierro US Patent 7,491,335; MS2A (Hematite-Acniic) and M628 (Magnetiia-Acrylic).

Figure i ?, Prue as «le resorption of sorbent media. Effective Resorption Rate of As in three sections of the column of the sorbent column. Measurements made for sorbent media Pómez-Hierro Pétente US 7,491,335; M52A (Hematite-Acrylic) and M528 (Magnetite ~ Acrylic)> DESCRIPTION OF THE INVENTION

The present invention relates to a sorbant medium for the selective removal of pollutants from water, in arsenic particulate »The sorbene medium- consists of a reactive material and a support on which the reactive material, B reactive material used in the This invention corresponds to metal oxides, and in particular iron oxides. The support material corresponds to aerllioos materials.

The acrylic material can be residual and controlled granulometry, which is coated with iron oxides as reactive materials. These iron oxides have ferromagnetic iCBS characteristics. Metal oxides can be generated through a thermal calcination or oxidation treatment at a controlled temperature, prior to a dissolution of iron salts under controlled conditions of electrical conductivity and pH.

The present invention also describes the process of preparation of the sórbante product comprising the mixture of iron oxides and residual acrylic as support material.

Regarding iron oxides for coating, maghemphta (- ¾0 _¾ ) _> he atita ("-F¾O _s ), magnetite (Fe _s 0} _; ferdhydrite and goethite can be used. Comparing magnetite and goethite, magnetite synthesis is preferred , due to the more favorable preparation and kinetic times of sorclone for magnetite with respect to goeihiia (Guo, R et al. 2009).

One of the main objectives of the present invention is to determine a selective arsenic sorbent medium that meets the requirements of good chemical and physical properties for arsenic sorption in a suitable support.

Among the chemical properties required by arsenic sorbon are:

 «Adequate zero load point (P2C) (between 7-9).

 * Surface reactivity based on its chemical structure and functional groups,

* Chemical reactivity with the characteristics of the water matrix (for example pH, affinity for anions similar to arsenate or arsenite, Ionic nut, redox conditions, etc.). * Generate low concentrations of arsenic once subjected to a leaching process, so that e! Residual sorbene medium can be arranged in a safe place of coupling and avoid contamination to the environment.

 * Ability to regenerate the medium through a chemical treatment. s Within the physical properties of the selective arsenic sórbante medium s:

 * Porosity.

 * Resistance to the disintegration product of the flow nuts,

 * Shape (granular).

0 * Particle size.

The selected physical properties must be such that they meet the objectives of reducing load losses in a configuration of sorption columns for water treatment.

Another objective of the present invention is to determine and select methods5 of synthesis of sorbent media that provide a reactive material with optimal surface and chemical characteristics by means of a fast efficient method of synthesis of sorbenye. Within the methods tested in the present invention, different methods of synthesis through heat treatment are included. 0 In order to achieve the objectives of the present invention, various iron oxides have been used as reactive media, such as magnetite, maghemite and íiematite.

The maghemite and the hematite can be obtained by calcination. The calcination process used is defined by a muffle (Barnstead Thannolyne), a ramp of 10 ^* C mft, a calcination time of 30 minutes, a maximum calcination temperature of 550 ° C.

It is possible to synthesize iron oxides {¥ ímaghemlia range), through thermal decomposition of ferrous carbonate (Narasimh.an, BR et al, 2002). According to what is described in the state of the art, in order to achieve oxides of iron range with magnetic properties, usually a long process of synthesis must be followed, consisting basically of 3 steps: (i) Alkaline precipitation of Fe oxides;

(2) Magnetite formation;

(3) Controlled oxidation of Magnetite to give way to the formation of maghernlta

A proposed medium is an iron oxide range of magnetic properties {Maghemita}. It is interesting as a sorbent due to the proposed rapid effective synthesis of Narasimhan et ai, (2002). In the present invention, a rapid method for obtaining oxides of gamma iron in a single step is proposed.

It should be noted that a good sorclone yield of reactive metal oxides at the laboratory test level is not necessarily replicated when performing an Industrial scaling. An optimal sorclone performance is based on good physical properties (surface area crystallinity) and good chemical properties (affinity surface chemistry, ion selectivity in water matrix) of the sorbent medium. The present invention considers generating an optimal sorclone performance both at the level of the mioscale, and in the large-scale industrial operational operation (see Figures 1 to 10). This objective is achieved by maintaining the reactivity and optimal chemical properties of metal oxides at the micro level, in a configuration with robust support and with optimal physical properties for a maoro level.

In the present invention, the suitable support material for metal oxides is described, so that the support material optimizes the macro physical properties of the sorbent, allowing the generation of an arsenic sorbent or other contaminants with convenient and suitable functional and operational characteristics for Water treatment plants. The combination of a support material, with a suitable sorbent medium, makes the present invention differ from that described in the state of the art and also presents unexpected and more efficient results with respect to what is disclosed in the prior art, In accordance with the present invention, the support material, in addition to contributing to the characteristics of structural stability, resistance to disintegration of the sorbent medium, and the regenerative and retrovavated capacity of the filter, has the advantage of being of minimal cost.

The support material for iron metal oxides such as the hematite, maghemite and magnetite of the present invention corresponds to a residual acrylic of the type Polylmethylmethary (PUMA).

This acrylic material of the Polymethylmethacrylate (PUMA) type can be obtained as a residual product or dispose of acrylic sheets for different uses such as advertising, construction, commercial display cabinets, decoration, among others.

The sorbent medium, according to the present invention, comprises a matrix consisting of residual or waste acrylic material from Polymethylmethacrylate {P Iv! A} coated with a sorbent material that can be an iron oxide such as hematite, maghemite and magnetite or a mixture of them.

In the present invention, three sorbent media have been prepared which are not limiting of the invention and comprise sorbent media of Hematite-Aeniieo, Staghemita-Aerilico Üagsieílta-Acrí leo.

The general synthesis of the acrylic sorbent medium coated with calcined iron oxides such as Magnetite, Maghemlta and Hematite, consists of the stages of;

 a) synthesize the specific iron oxide

 b) provide acrylic support; Y

 c) dissolve the acrylic with one or more of the iron oxides to generate the sórbante.

Step (a) of synthesis of iron oxide consists in the mixture of solutions of iron sulfate and sodium carbonate under controlled conditions of pH and temperature. The wet iron carbonate paste resulting from the previous mixture is dried at 105 ° C for 48 hours and then calcined at S5CTC for 30 min, at a calcination rate of 10 ° C / min. In this way, a calcined iron oxide such as hematite is generated (maghemiia and magnetite follow a different synthesis). The step (b) of providing an acrylic support consists of the fractionation and specific grinding of the material! residual acrylic at granulometries suitable for the sorption process. This particle size varies in the range of 0.425 ~ 10 mm. The granulated aerobic material thus obtained is washed to remove impurities. Step (e) allows the arsenic sorbent to be generated by mixing the carrier of stage (b) with the calcined iron oxide step (a), through chemical dissolution with an organic solvent, the organic solvent can be Acetone technique The plateau obtained is dried to be ground again and crushed with specialized mills to achieve the desired granuiemelna, the EU is in the range of 0.425 to 1.0 rnm (32 - 16 mesh). The granules obtained are washed with deionized water to remove the excess of calcined iron oxides. The finished and wet sorbent medium is placed in trays and dried for 3 days in an oven at 40 ^and C. EXAMPLE 1

 Preparation of the medium so bente Ú Hematita-Ácrlfco

so 1: Synthesis of Hematite (& ~ Fc¾G ₃ )

1 L of a 0.45 M solution of Fe $ Q ₄ x? H ₂ Q is prepared. Heat to 7CTC with constant stirring for 30 minutes. Then 1.5 L of MasCOs 0.5 are added until pH 9.5 Once the mixture is ready, the precipitate is allowed to decant and the excess water is removed, - CÍÍ. ¾ «s pS -% S · - · - ·> Fs ¾Csí The result of step 1 is a wet paste of Fe € 0. ₃ . which is dried at 105 for 48 hours and then calcined at 550 ^* 0 for 30 min, at a calcination rate of 10 ^s C / min. Emalite is the product of this calcination, which is ground in the mortar before being used,

Step 2: Preparation of acrylic support

Chunks of residual acrylic are slowly crushed from transparent clear Polymethylmetayl (PMMA) sheets as the hardness of the material overloads the mill. The residual acrylic pieces have a transparency index of 93% and a thermal conductivity 0.16 klocalonas / meter-hour * 0). To generate 1 L of acrylic, with a granuometna of 0.425 - 1.0 mm, it is released by approximately 1-1.5 h. Then, the desired granulometal acid acrylic is washed with forgiveness of deionized water to remove residues (2-3 L) and dried for 3 days in an oven at 40 ^* C.

 Step -3: Pre ar dor! e med o «ortente

s 500 g (1 L) of hematlta are mixed with 800 g (1 1} of washed acrylic, obtained from steps 1 and 2, it is enough to obtain a homogeneous mixture.Due to the volume, the mixture is divided into 10 precipitated vessels of 250 mi (approximately 150 ml. of mixture in each one.) Approximately 100 ml of technical acetone is added slowly and with constant stirring under a hood. A thick paste is generated, which is allowed to dry for approximately 3 days in an oven at 40 ^¾ C. The dried paste is subjected to grinding, until small pieces are generated, which are introduced into the mill.To crush all the medium, it is ground for approximately 1-1.5 h. The ground mixture is sieved to obtain the useful fraction of particle size between 0.425 and 1.0 mm. It is washed with deionized water (3-45 1} to remove excess hematlta. The wet half-finished medium is placed in trays and left to dry for 3 days in a 40-oven *C.

EXAMPLE 2

 Preparation of! m gave s rbersta of Maghemtta ~ Acrli! co

0 Faso 1: Synthesis of 88agh «miia (y-FésQs)

1 L of a 0.45 M solution of FeSO ^ x HsO is prepared. Heat to? 0 ° C with constant stirring for 30 minutes. Then 1.5 L of 0.5 M Na ₂ C03 is added until pH 9.6. Once the mixture is ready, the precipitate is allowed to decant and the excess water is removed,

s ¾S¾ (0. Ϊ í _¾ O _s {ií.S M. ^7Q:)

The result of step 1 is a wet FeCOa paste, which is washed with a portion of distilled water to obtain an electrical conductivity of 2 mS ern \ 0 The paste is centrifuged to obtain a thick residue which is calcined directly at 550 ^to C for 30 min, at a calcination rate of 10 ^e C / min The maghemlta is a product of this calcination process, then it is ground in mortar before being used.

 Faso 2: Support preparation «te acrylic

5 Repeat step 2 of Example 1. P so Z Pre aration of half sorbet

This step is analogous to step 3 of Example 1,

AXIS! PiO 3

Pre a tion of the Magnetite-Acriiico environment

 Step 1; SMmte of «Agnetite (ψβ &

1 L of a 0.5 solution of FeS0 x7H _¾ G is prepared. It is heated to 90 "C with constant stirring and N ₂ flow for 30 minutes. Then 0.4 L of a 0.25 NaN0 ₃ solution is added. and 3.3 M HaOH. It is mixed with a flow of N ₂ for 1 hour. Once the mixture is ready, it is left to stand overnight. The precipitate is washed with portions of distilled water to an electrical conductivity of 2 m 2 cm ^' and then the supernatant is discarded.The resulting suspension is placed in trays and dried at 40 * C for 5-7 days.The magnetite so synthesized is ground in mortar before use.

Step .2: Preparation of acrylic support

 Step 2 of Example 1 is repeated

 Faso 3: Preparing for a medium

1600 g (1 L) of magnetite are mixed with 600 g (1 1} of washed acrylic, obtained from steps 1 and 2, until a homogeneous mixture is obtained, due to the volume, the mixture is divided into 10 precipitated vessels of 250 ml (Approximately 150 ml of mixture in each one.) Approximately 100 ml of technical acetone is added slowly and with constant stirring. A thick paste is generated, which is allowed to dry for approximately 3 days in a stove at 40. The dried paste is subjected to grinding, until small pieces are generated, which are introduced into the mill.To crush all the medium, it is ground for approximately 1-15 N. The ground mixture is screened to obtain the useful fraction of particle size between 0.425 and 1.0 mm Wash with deionized water (3 - 4 L) to remove excess magnetite 8 half finished and wet sorberte is placed in trays and left to dry for 3 days in an oven at 4G ^C C.

RESULTS

With the products obtained from the invention, various measurements and tests were carried out both in the laboratory and in a pilot scale configuration to determine physicochemical characteristics of the sórbante medium, and the advantages that they provide when comparing them with sórbanles arsenic media of the state of the art. In Figure 1: Micrographs with Optical Microscope of Sórbanles Media, three iron oxide sorbent media prepared according to the invention are observed. From Figure 1 it is evidenced that the structural problem of detachment of .material is overcome by adding a base matrix of acricium to the calcined oxides. In addition, it allows cost savings to use a waste material as a porous core of the surface reactive material. Micrographs of magheml a and ground hematite (A2, 82) are observed, compared with the mixed medium with asrlco support and coated with the calcined iron oxide (Al 81). It is observed how the acrylic support provides a well-structured granular and porous characteristic to the reactive surface of iron. The mixed media are very similar to each other, with Irregular shape, porous surface and with a visible surface coating with high adhesion performance, where you can see) some white-transparent spaces with acylic. The only major visible difference is the color of the oxide, ia maghemlta is light brown, and the bematite is red. Magnetite (Ci and C2), black in color, does not require calcination for its synthesis.

 In Figures 2 to 10 SE Electronic Micrographs of the Somantes Means of the invention are presented.

 In Figures 2, 3 and 4 it is observed that the hematite has a very dense coating, with micrometric flat concession particles on the acrylic support material, reaching a 48% Fe coating on the sorbenfe particle. Table 1 shows the composition and percentages of the elements present through an EOS analysis.

labia l:; 5 ?:; | «Weight% Aiomü» giérosntc% Weight% A comic

C C

O K ¿s¾.as

 ífe K o.o Hs.

 r- «Ug K

 Cu 0.S.Í5: ϊ ¾ K & 26.

 48.83 is.s.y

0: 3l?> In Figures 5, 6 and 7 it can be seen that the magnemite has a coating with a lower density than hematite, with a heterogeneous distribution of iron oxides (areas of greater accumulation) and lamellar deposit of layers of oxides. The lower coating density on the air carrier is corroborated in the EDS analysis with Fe of 18.6% as can be seen in Table 2.

Table 2

In Figures 8, 9 and 10 it is observed that the magnetite coated medium shows an intermediate density between hematite and maghemite, which is corroborated in the EDS analysis (Fe ~ 2S%} ₍ according to Table 3, Deposited particles they show eoloimatic formations with greater distribution of sizes product of heterogeneous accumulations of iron particles (order submlcrometer enough 10 um).

Table 3

? <- R »s¾% Atom co

3 .7S $ 43.3

 or «4.83 3S.27

 r ¿S. ; 4.18

 rs K 25.S2 s.os

 C K O.i? 0.US ISCOO

Acrylic support sorbent © ré iertc with magnetite (Figure 11 M52B) was subjected to arsenic sorption isotherm tests with concentrations in the range from 0.05 to 120 mg / ^' L The trials considered a concentration of sorbenie medium of 2 g / L and a reaction time of 48 hours for each point.

Adsorption isothermal assays were performed from a standard solution Títrisoí® Merck of 1000 mg / ^' t Dilutions were prepared in iiG water from 0.05 to 120 rng / L with pH adjustment with Buffer BES and ionic strength with nitrate of sodium (NaNC¾l) The concentration of sorbenie medium used was 2 g / L with an equilibrium time of 48 h at a controlled temperature (25 ^S C). The solids were subsequently separated by filtration (0.45 pm). of X-ray fluorescence by total reflection 82 Picofox (Broker GmBH, Germany) for the determination of arsenic in the liquid ration.

The objective was to quantify sorption capacities of the proposed medium for the invention in high ranges of arsenic and to compare these yields with other patented media. Figure 11 shows the results of these tests. The patented commercial medium of ALCAN (AAFSSG US Patent 6,599,429), shows a maximum sorption capacity above ios 25 mg of Asb / g of sórbante, while the patented medium of Pómez Hierre (US Patent 7,491,335) does not reach 5 mg / g On the other hand, the medium proposed for the invention of magnetite with acrylic supports had an intermediate yield, of the order of magnitude of the known sorbent media, with an identified capacity of 13 mg of As sorbed per gram of sorbenie for this high concentration range of Ace,

This result shows that the sórbante medium proposed for invention has a lower sorption capacity in the high range of concentrations than the AAFS50 medium, however, its relative cost balloon elevates it as an option of greater cost-effectiveness.

The concentration of arsenic in natural systems is variable, for example, from values of concentration of parts per billion (ppb) over the norm (10 to 200 ppb) in groundwater, to values of concentrations of parts per million (ppm) in rivers or channels contaminated by amphropogenic or natural sources. The sorption isotherm in the air range of concentrations sought to test the maximum capacity of the medium, however, its sorption objective is more oriented to drinking water systems with arsenic concentrations below 1 ppm, which will be tested with pilot column tests in a range up to 80 ppb (6 times the limit concentration of the Chilean standard for drinking water). Sorbents media may have different performance behaviors depending on the range of arsenic concentrations to which they are subjected (selectivity). These comparative studies demonstrate that a sorbent arsenic medium can be affected by water matrix conditions. The sites of sorption of the medium are used by competing ions of arsenate, such as vanadates, phosphates, chlorides, sulfates, silicas, among others. For another country, the sorption capacity can be affected by matrix conditions such as pH and redox potential. The acrylic sorbent medium coated with magnetite 52). demonstrates a better sorption capacity in the presence of inferferents such as phosphate in comparison to other high-performance arsenic sorbent media such as pemez stone coated with iron oxides (US Pat. No. 7,491,335) or zeolites coated with metal oxides (US Pat. 8,921,732). In a water matrix with concentrations of 10 ppm of phosphate and 50 ppb of arsenic, the hematite-scintillating sorbent medium shows a reduction in arsenic sorption capacity of 1%, considerably lower than the 38% obtained by pumice stone - iron oxides, and ai 60% obtained by xeolites coated with metal oxides (see Figur 12). The described medium LAYNE RT (US Patent 6,599,429) obtains a slightly lower yield than the medium of the invention magnetite-acryl 52B) in the ability to be a selective arsenic medium.

On the other hand, tests were carried out on the pH range to optimize the sorption of As, by means of tests at different pH values. The operational range corresponds to that required by l Ch409 for drinking water (6.6 to 8.5). The tests correspond to Isotherms with a reaction time of 48 hours. A concentration of sorbent medium of 1 g / L and real raw water from an underground water well with an arsenic content of 60 u / L was considered

The effect of pH on adsorption capacity was evaluated by making variations to pH on the same test. The pH adjustment of the groundwater was made with dilute hydrochloric acid (HCI) or sodium hydroxide (NaOH) (0.1). The pH was measured with a Sentlx 62 (T) pH meter previously calibrated, the concentration of sorbent medium used was 1 g / L with an equilibrium time of 48 years at temperature controlled (25 ^S C). The solids were subsequently separated by filtration (0.45 μη). An X-ray fluorescence spectrum was used by total reflection S2 Picofox (Broker GmBH, Germany) for the determination of arsenic in liquid traction. The magnetite coated sorbent medium demonstrates a greater and more stable sorbon capacity in a larger pH range of water, than other sorbent media such as the Pómez Hierro medium (US Patent 7,481,335). The latter showed a good sardon yield for low pHs, however, it has much greater variability in the range of operational pHs of drinking water, as shown in Figure 13. In the pH tests it is also observed that the commercial medium LAYNE RT (US Patent 2008/0035564} maintains a constant sorclone capacity independent of the pH of the water to be treated, while the M52B medium (IVIagnetlta-AcrlIlco) has a similar yield between pHs 4 and 8, that is, the slippery medium of The invention has an Invariable sorbon behavior at pH over the operating range indicated in Figure 13, which represents an additional advantage to be used in a wide range of contaminated media that exhibited differences in pH, with respect to the means known in The state of the art.

To test the capabilities of the means of the invention in real configuration and thus demonstrate its industrial application, each of the sorbent means of the invention was tested in pilot tests of sorclone columns.

The B sk Through Cus-vas in pilot test were carried out on the ground with sardon columns of approximately 1.2 L in volume, arranged in parallel configuration. The water to be treated comes from an underground water well with an arsenic concentration of 50 ppb on average. Water is preconditioned, adjusting the pH by adding HCi (1). The treatment flow rate is approximately 150 mlimin resulting in an average EBCT (E p and Sed Count Time) between 6 and 10 minutes. The total content of soroscent medium used is 0.7 kg of iron pumice, and 0.9 kg of acrylic-acrylic medium (M52B).

The pilot tests lasted 2 months, and a daily monitoring of arsenic concentrations and pH. In these pilot tests the industry application was demonstrated! of the arsenic sorbent medium of the Invention, in Figure 14 corresponding to the curves of Br k-Twoug s observes the arsenic soreion behavior, which is very similar between the means of the Invention (M52B ~ agnetita-Aortüco) and the Pómez s Hierro medium (US Patent 7,491,335). The saturation of both media in the arsenic filtration starts between 3,000 and 4,000 L of treated water. At this time, the concentration of arsenic in the water begins to rise above the allowed limits, in a way that indicates the time in which the medium must be replaced or regenerated. This test demonstrates that the means proposed for Invention (MS28 - Magnetite-0 Acri ^' iico) does not suffer deterioration, is robust, capable of sipping arsenic in a drinking water treatment system configuration, so that the industrial application of the half sorbet of the invention.

One of the important properties of an arsenic sorbent medium is its ability to control leaching, that is, its ability to retain arsenic once it has been dry-dried in a collection place, which may be affected by liquid scorrenyl.

Leaching tests were carried out on media contained in pilot columns using the TC ^' LP Laboratory Methodology.

The protocol for the analysis of arsenic leaching is a modification of the method described by USEPA. 1986., replacing the total rotation agitation apparatus with a Lab Companion SI-30GR orbital shaker (Jong T ,, Parry David L, 2005). The choice of the extractant solution was made by adding 98.6 ml of illiQ water to 5 g of solid. After five minutes of stirring the pH for all the samples was higher than 5. Thus, a second test was performed by adding 0.35 miS of 1M HCI and heating the solution to 5CTC. Once the solutions are at room temperature, it was determined that all pH measurements were less than s, so the leaching solution is called L

The extraction was carried out with a liquid concentration 20 times higher proportional to the solid (3.5 g: TOml), stirring for 18 ± 2 hours at 25 ° C. Once the extraction was finished, it was filtered at 0.80 pro and the arsenic concentration in the liquid phase was determined. An X-ray fluorescence spectrophotometer by total reflection S2 Picofox (Broker GmBH, German) was used for the determination of arsenic in the liquid fraction. Figure 15 shows the result of the leaching test carried out according to the described methodology. It is observed that the arsenic concentrations for the means of the invention Magneifta-Aer Hco (M52B) Hematia-Aenlico (M52A) have a very high leaching capacity low (<13 pp As) in all portions of the column. The concentration of arsenic in the leaching liquid does not exceed 1% for all the means and locations of the tested column, compared to the limit required by the Chilean regulation DS148 (5 mg / L). In addition, the TGLP test (NCh 2754. Of. 2003 (TCLP-ERA 1311}} leaching test was carried out to determine mobility: give toxic organic and inorganic analytes in a certified laboratory (CES EC), where the means of the invention Magnetite -Acrlteo {S28} obtained values under the indicated norm, these results contribute to demonstrate the industrial applicability of the sorbant medium proposed for invention.

The ability of a sorbent medium to regenerate and be reused allows generating sentence savings and making the performance of the environment more durable. For this reason, desorption tests (chemical method to release the sorbed arsenic from the mesostructure of the sorbent medium) and resorption (also using a desorbed sorbent medium) were also carried out to the Mag etita-Acrico (! V! -S28} medium to evaluate this ability

For desorption tests, the sorbent material was treated with 0.1 M sodium hydroxide {NaOH). PHs higher than 13.0 were reached. The solid concentration used was 5 g / L with an equilibrium time of 48 hours at a controlled temperature <25 ^e C}. The solids were washed with 50 ml of water I llQ and subsequently separated by filtration (0.45 pm). An X-ray fluorescence spectrophotometer by total reflection S2 Picofox (Broker GmBR Gemiany) was used for the _. Determination of arsenic in the liquid fraction. The remaining solid was allowed to dry at room temperature for subsequent resorption test.

Figure 16 shows the result of desorption, where it can be seen that the percentage of arsenic that electively passes into the dissociative phase is between 60 and 100%. The medium pumice iron reaches an average of 78% desorption, while the medium fv1528 76%.

The resorption was carried out by performing a new adsorption test with groundwater on sorbent material previously treated with sodium hydroxide (NaOH) The solid concentration used was 5 g / t with an equilibrium time of 48 hours at a controlled temperature (25 ^* C). The solids were subsequently separated by filtration (0.45 pm). An X-ray fluorescence spectrophotometer by S2 Picofox total reflection (Broker Sm H, Germany) was used for the determination of arsenic in the liquid fraction.

In Figure 1, the resorption result is observed, where the M52B medium reaches an average effective resorption percentage of 3% _. , while the pommel iron 45%. This means that the sorbent medium of the invention can be re-twisted considering a reduction of its original arsenic sorption capacity to 40%. These tests were performed in ateh configuration, so they should only be considered as an approximation to the resorption capacity in media arranged with filtration columns.

The sorbic arsenic medium of the invention, composed of the magnetite iron oxide using as an acrylic residue, in addition to having good properties as arsenic sorption medium: good absorption capacity of 330 ug g for the concentration range of 50 ppb of arsenic, low interference to pH and other ions, regenerate, safe disposal (7CLP), robust and applicable on an industrial scale, has the advantage of being manufactured with low cost materials in a simple process, which on a large scale is translates into a sarcastic means of effective and low-cost arsenic. the iron oxides, synthesized for coating the support material of the present invention, have ferro-magnetic properties of different Intensity, the Intensity order being the one shown below:

Magnetite »» ag emlta> Hematfta

In the present invention, the inventors have demonstrated, at the laboratory level, the separation of the sorbent from the water at the level of batches (bat) and this property allows to trap colloids that are detached from a sorption column system {d iac m nt control ), ai Incorporate, for example, a magnetized and interchangeable metal filter evacuation pipe. REFERENCES

Anderson, P. ,, ^. & Benjamín, M. k (1985). Effects of sHlcon on ihe orystaifeation and adsorption properties of ferríc oxides. Environm ntal Science & T ncfogy, 19, 1048-1053.

ERA, A. P. (2005). Adsorben * twaíment iechnohgles for arsenic mmovah Awwa Research Foundation.

Gregory, J. (2006). Par c & m water: P p & tt and proc & sses. London: IWA.

Gu. Z. IvL Deng _; 8. L, & Yang, J. (2007). Synthesis and evaluation of iron-contacted mesoporous carbon (feomc) for arsenic adsorption. ictxpa us and Mesoporous Mai & dals, 102 (1-3), 265-273.

Gus Z. M-, Fang, X, & Deng, 8. L, (2006). Preparation and evaluation of gao-based Iron-eontaining adsorbent for arsenic removal Etwíronmentai Sc e & Technobgy, 39 (10) _; 3833-3843. Gu¾ H.., Siuben, D-, & Berner, Z. (2009). Characterísiícs of arsenic adsorption frorn aqueous solution: Effeot of arsenic species and natural adsorberos. AppH & cit Geoc & místiy, 24, 557-683.

Mn, C., & Aíi, I. (2000). Arsenic: Occurerence, ioxicity and speciation teehníques. ½½ er /% seafc /? (34), 4304-4312. Jang fvl, Park, J,., & Shln, E. W. (2004), Lanthanum íunctionalfeed highíy ordereá mesoporous medra: impiieations of arsenate removal .. ie perous and Mesoponous Maíaáak, 75 (1-2). 159-168.

Jang M .., Shín, EW ₍ Park, JK, & Cho SI (2003). Echanisms of arsenat adsorption by high ^' ly-ordered nano-struclured siiicate media impregnated with metal oxides. Ew cmmeniBl Sáleme & Technofog, 37 (21), 5062-5070.

Jong T., Parry David L. (2005). Evaluation of the stabilliy of arsenic immobliized by miorohial sulfate reduction using TCLP exlraetions and long-term leaching ieohnique. Chemosphere Volume 60, Issue 2, Pages 254-285. i-e! I-Blackwood, J „Qu n, P. L _: Kumar, A. _s & Sarich, M, {2008}. ! rust oxide eoat! ng of geosynthetic fibers for water treatment appiications. Qeosynthetlcs inte aiionat 15 (8k 4 / 1-479. Oh n, D., & Pitiman, G. ü. (2007). Arsenic remova! From air / wasfewater using adsorbent - a critique! Review. Joumai of Harneóos M iemts, - 142 (1 -2), 1 -53.

Narasirnhan, BRV _t Prabhakar, $., Manchar,, & Gnanarn, FD (2002). Synihesis of gamma ferric oxide by dírecf íhermaí deeomposiiion of ferrous carbonate. Meteríais tlm ,. 52 (4-5), 295-300.

Park, Y. J., Yang, J. K., & Chol, S. I (2008). The applicaiion of reused po dered wastes as adsorben! for treating arsenic containing miné drainage. Journal of Ewíronm & níal Science and Health Parí a-Toxíc / Hazardous Substances & Ewimm tal Eng ring, 43 (9), 1093-1099.

Qiü, W., & Zheng, Y. (2007), Arsenaie removal from water by an alu ina-modiíied zeoliie reexsvered from ash. Journal of Hazardous Meteríais, 148 (3}, 721-726. USEPA, 1988. Hazardous waste management syslern; iand dlsposal restriction. Appendlx I ío Parí 268: Toxtesíy charaete lsíie íeachíng procedure (TCLP), 51 (218). pp. 40643-40654

WHO, W. H, O, (1981). Env ron in the heath criiena, 18: Arsenic.

Yeorn, SH _< & Jurig, K.-Y> (2008). Recycííng wasied seaiop shell as an adsorben! for the removal of phosphate. Joumai of industrial and Engk er g Ch & mktry 15, 40-44.

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Parid _: A. (2003). Water treaiment product and method (Val 8599428). ÜSA-G8: AAFS50 - ALCAN INTERNATIONAL LIMITED 1188 SHERBROOKE STREET WEST MGNTREAL, QÜE8EC H3A 3G2, CANADA. Oiier, JT and P. Sylvesfer (2008). Sorben! for Seieofive Removal of Contaminants from Fluids. WO2008 021 40A2. U $ 2008 / 003S584. United ^' States, SOL ETEX INC, Re dy, P, G, ea (2009). emo í of arseníc frocn water ífh oxkfized meta! coated pumice (Voi 7491335); THE 80ARD OF REGENTS OF THE UNIVERSITY OF TEXAS SYSTEM 201 WEST 7TH STREET AUSTIN, TEXAS 78701.

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Claims

^• Sorbent medium for selective removal of contaminants from water CHARACTERIZED because it comprises an acrylic support coated with iron oxides. Sorbent medium according to claim 1, CHARACTERIZED in that the iron oxides are selected from hematite, maghemite and magnetite or a mixture thereof. Sorbent medium according to claim i, CHARACTERIZED in that the acne support includes waste or scraps of acrylic plates for different uses such as advertising, construction, commercial display cabinets or decoration. Sorbent medium according to claim 3, CHARACTERIZED in that the acrylic support is of the Polymethylmethachinate type. Sorbent medium according to any of the preceding claims »CHARACTERIZED because the acrylic sorbent has a granular and porous structure. Sorbent medium according to claim 2, CHARACTERIZED in that the medium has a high percentage of iron coating, corresponding to the sorbent-reactive surface. Sorbent medium according to claim 6, CHARACTERIZED in that the medium composed of bematite comprised an iron coating of approximately 48%. Sorbent medium according to claim 6, CHARACTERIZED in that the medium composed of maghemite comprises an iron coating of approximately 19%. Sorbent medium according to claim 6, CHARACTERIZED in that the medium composed of magnetite comprises an iron coating of approximately 25%. 10. Sorbent medium according to the preceding claims, CHARACTERIZED because the medium can be regenerated and reused, 11. Edio sorbent according to claim 10 _; CHARACTERIZED because the regeneration of the sorbenle medium is carried out by desorption. 12. Sorbenle medium according to claims 1. to 9 CHARACTERIZED because it has a good arsenic sorption capacity of about 330 og g in a range of 50 ppb concentrations of arsenic; it presents low interference to pH and other ions; it is re enerare, it does not generate toxic waste, it is resistant to hydraulic straining efforts in the configuration of sordén columns, 13. Sorbent medium according to claim 3, CHARACTERIZED because due to the nature of its support it has a low synthesis cost, Sorbent medium according to claims 1 to 9 characterized by good high sorption capacity arsenic in a low range (330 pg / high concentrations (13000 gi ^'g) of arsenic g, Sorbent medium according to claim 14, CHARACTERIZED in that the sorbent medium has a maximum sorption capacity of 330 pg / g in a concentration range between 50 and 60 pg / L of arsenic, ed sorbent according to claim 14 _and CHARACTERIZED because the sorbent medium has a maximum sorption capacity of 13000pg / g in a concentration range between 0, QS at 120 mg / üte arsenic, 1 ?, time to prepare a sorbent medium comprising an acrylic support coated c r? CHARACTERIZED iron oxides because it consists of the stages of: a) synthesize the specific iron oxide  b) provide an acrylic support; Y e) dissolve the acrylic with one or more of the iron oxides to generate the sorbent. 18. Method according to claim 17, CHARACTERIZED because the stage a) comprises the synthesis of hematite, maghemite and / or magnetite. 18. Method according to claim 18, CHARACTERIZED in that the hematite synthesis step comprises: heating a solution of FeS0 ₄ x? H ₂ 0 and mixing with Η & Ο ^, όφτ decanting, drying, calcining and grinding the precipitate obtained. 20. Method according to claim 18, CHARACTERIZED in that the step of synthesis of maghemite comprises: heating a solution of feS¾x7l-½0 and mixing with Na CO _¾ allowing to decant, to obtain a paste that is washed to an electrical conductivity of 2 mS cnf \ ia which is centrifuged, and calcine and grind the precipitate obtained from centrifugation, Method according to claim 18, CHARACTERIZED in that the magnetite synthesis step comprises: heating a solution of

with flow of N _2> and mix with a solution of HaN0 ₃ and NaOH and flow of Mudejar decant, wash to an electrical conductivity of 2 niS cm ^" \ dry and grind the precipitate obtained, 22. Method according to claim 1, CHARACTERIZED because the stage or) of preparation of acrylic support comprises the steps ele: crushing residual pieces of acrylic; determine desired particle granulometry; to wash; and dry 23. Method according to claim 18, CHARACTERIZED in that step o) of generating sórbante medium with hematifa, maghemita and magnetite comprises independently mixing hematite or maghemite or magnetite obtained in stage a) with the acrylic support obtained in stage b ): mix with acetone: dry the resulting paste; grind, crush, sift and wash the sorbent medium obtained. 24. Use of the sorbent medium of claim 1, CHARACTERIZED because it is useful in the selective removal of contaminants from water. 25. Use of the sorbent medium of claim 24, CHARACTERIZED in that the water contaminants comprise arsenic ions, vanadates, phosphates, chlorides, sulfates, silica. 26 ,. Use of the sorbent medium of claim 25, CHARACTERIZED in that the water contaminant is selected arsenic ions, 27. Use of the medtosorfoent of claim 24, CHARACTERIZED because the contaminated water comes from drinking water, groundwater and / or water from other agricultural or industrial uses, 28. Use of the sorbent medium of claim 24, CHARACTERIZED in that the sorbent medium can be used in configuration of sordon columns in a drinking water treatment plant or Riles. 29. Use of the sorbent medium of claim 24, CHARACTERIZED in that the sorbent medium can be used without losing capacity in a matrix of water containing interferences such as: vanadates. phosphates, chlorides, sulfates, silicas, among others. 30. Use of the sorbent medium of claim 24, CHARACTERIZED in that the sorbent medium can be used without losing capacity in a water matrix having a pH in the range of 4 to 8.