WO2020010407A1 - Sorbent compositions - Google Patents

Abstract

The present disclosure relates to sorbent compositions, their use for adsorption of agents, and to products using the sorbent compositions. In certain embodiments, the present disclosure provides a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker. Other embodiments are described.

Description

SORBENT COMPOSITIONS

PRIORITY CLAIM

[001] This application claims priority to Australian Provisional Patent Application 2018902544 filed on 13 July 2018, the content of which is hereby incorporated by reference in its entirety.

FIELD

[002] The present disclosure relates to sorbent compositions, their use for adsorption of agents, and to products using the sorbent compositions.

BACKGROUND

[003] A variety of toxic or undesirable substances have been released into the environment over the years. Aside from their effect on reducing the quality of the environment into which they have been released, the substances sometimes make their way into the ecosystem and pose a risk to organism exposed to the substances.

[004] For example, perfluorooctanoic acid (PFOA) and other polyfluorinated alkyl substances have been used for decades in the production of fluoropolymers such as Teflon®, protective coatings, lubricants, and fire-fighting foams. In the early 2000s, these poly- and perfluorinated substances were found to be distributed widely in the environment and in humans, prompting more thorough evaluations of their toxicity. Exposure to PFOA has been implicated in a variety of health issues including hepatic and renal toxicity, thyroid disease and kidney and testicular cancers. Accordingly, governments have issued guidance and regulations on emissions and exposure limits of poly- and perfluorinated alkyl substances.

[005] A variety of technologies have been developed to try and remove substances contaminating the environment, and in particular from water. One goal of these technologies is to provide efficient, scalable and cost-effective technologies to remove the contaminants. Activated carbon is an attractive sorbent because of its low cost and scalability. Indeed, remediation using granulated activated carbon filters is the most common method for purifying drinking water contaminated with PFOA, although reverse osmosis, membrane filtration, and ion exchange treatment are sometimes used at industrial and municipal facilities. Powdered activated carbon is also routinely used in removing micro-pollutants from water, including PFOA. Powdered activated carbon benefits from a higher surface area and faster uptake of contaminants such as PFOA, relative to granulated activated carbon.

[006] However, use of activated carbon has a variety of disadvantages. Activated carbon is prone to caking and/or clogging during filtration, and provides a significant challenge to using activated carbon in high volume situations such as municipal water treatment, and in the use of packed columns. In addition, the use of powdered activated carbon generates significant amount of dust which poses an inhalation risk and increased flammability.

[007] Accordingly, there is a need for improvements in the use of activated carbon in filters and the like.

[008] SUMMARY

[009] The present disclosure relates to sorbent compositions, their use for adsorption of agents, and to products using the sorbent compositions.

[0010] The present disclosure is based, at least in part, on the development of a new sorbent made from a blend of a sulfur-based polymer and activated carbon. The sorbent blend retains the high surface area and affinity of the activated carbon, but benefits from ease of handling, low dust and minimal clogging and caking during filtration. The blend can also be made entirely from industrial waste and reclaimed biomass.

[0011] Certain embodiments of the present disclosure provide a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

[0012] Certain embodiments of the present disclosure provide a method of adsorbing an agent from a product, the method comprising exposing the product to a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker to adsorb the agent, and thereby adsorbing the agent from the product.

[0013] Certain embodiments of the present disclosure provide an article comprising a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

[0014] Certain embodiments of the present disclosure provide a method of producing a sorbent composition, the method comprising combining an effective amount of an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

[0015] Certain embodiments of the present disclosure provide a method of reducing dust associated with use of activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon.

[0016] Certain embodiments of the present disclosure provide a method of reducing dust from an adsorbent article comprising activated carbon during production and/or use of the article, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

[0017] Certain embodiments of the present disclosure provide a method of reducing clogging and/or caking of an adsorbent article comprising activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

[0018] Certain embodiments of the present disclosure provide a method of improving operating functionality of an adsorbent article comprising activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

[0019] Other embodiments are described herein.

BRIEF DESCRIPTION OF THE FIGURES

[0020] Certain embodiments are illustrated by the following figures. It is to be understood that the following description is for the purpose of describing particular embodiments only and is not intended to be limiting with respect to the description.

[0021] Figure 1 shows A) Canola oil polysulfide (1.0 - 2.5 mm), B) Canola oil polysulfide (2.5 - 5.0 mm), C) Canola oil polysulfide (> 5 mm).

[0022] Figure 2 shows SEM micrographs of the porous canola oil polysulfide (50 wt% sulfur). (A) SEM micrograph, with the scale bar showing a distance of 300 mM. (B) SEM micrograph, with the scale bar showing a distance of 30 pM.

[0023] Figure 3 shows (from left to right) porous canola oil polysulfide (800 g), powdered activated carbon powder (PGW 150 MP, 200 g) and the carbon-polysulfide blend (1 kg).

[0024] Figure 4 shows SEM micrographs of powdered activated carbon (Kuraray, PGW 150 MP). (A) SEM micrograph with the scale bar showing a distance of 500 pM. (B) SEM micrograph with the scale bar showing a distance of 200 pM. (C) SEM micrograph with the scale bar showing a distance of 50 pM. (D) SEM micrograph with the scale bar showing a distance of 10 pM.

[0025] Figure 5 shows EDX imaging of powdered activated carbon (Kuraray, PGW 150 MP).

[0026] Figure 6 shows SEM micrographs of granular activated carbon (GC 1200, 0.5- 0.7 mm, Activated Carbon Technologies).

[0027] Figure 7 shows EDX imaging of granular activated carbon (GC 1200, 0.5-0.7 mm, Activated Carbon Technologies).

[0028] Figure 8 shows SEM micrographs of carbon-polysulfide blend.

[0029] Figure 9 shows EDX map of carbon-polymer blend.

[0030] Figure 10 shows ¹⁹F NMR analysis of PFOA sorption using the canola oil polysulfide. [0031] Figure 11 shows SEM micrographs of the porous canola oil polysulfide after exposure to a saturated solution of PFOA in water. A) The cross section of a polymer particle B) The same particle at increased magnification C) Higher magnification of point of interest, with hemi-micelles bound to the surface of the polymer D) Hemi- micelles bound at another location on the polymer.

[0032] Figure 12 shows EDX analysis of hemi-micelles on the polymer surface. The polymer was platinum coated for analysis and the sample holder was aluminium. Sulfur, carbon and oxygen are all present within the polymer. Sodium and chlorine originate from residual NaCl porogen not removed during the washing step in the polymer synthesis. A distinct fluorine peak was detected at the hemi-micelle, indicating this feature is formed from PFOA.

[0033] Figure 13 shows from left to right: Porous canola oil polysulfide (4.00 g) in 100 mL of PFOA solution (5 ppm), carbon-polymer blend (5.00 g) in 100 mL of PFOA solution (5 ppm), powdered activated carbon (1.00 g) in 100 mL of PFOA solution (5 ppm), and granular activated carbon in 100 mL of PFOA solution (5 ppm).

[0034] Figure 14 shows pH_(pzC) determination for porous polysulfide and activated carbon powder.

[0035] Figure 15 shows from left to right: syringe filter block with granular activated carbon (GC 1200, 0.5-0.7 mm, Activated Carbon Technologies), syringe filter blocked with powdered activated carbon (Kuraray, PGW 150 MP), syringe filter used to filter the carbon-polymer blend, and an unused syringe filter. The carbon-polymer blend is easier to filter than either powdered or granular activated carbon, facilitating separation from water after remediation.

[0036] Figure 16 shows a polysulfide polymer prepared by the direct reaction of sulfur and canola oil. Sodium chloride is used as a porogen that increases surface area of the polymer upon washing with water.

[0037] Figure 17 shows PFOA forms 41 ± 16 pm hemi-micelles on the surface of the canola oil polysulfide polymer (hemispheres in SEM micrograph, average diameter calculated from 42 representative micelles). EDX analysis confirmed the presence of fluorine, derived from the PFOA (Figure 13).

DETAILED DESCRIPTION

[0038] The present disclosure relates to sorbent compositions, their use for adsorption of agents, and to products using the sorbent compositions.

[0039] Certain embodiments of the present disclosure provide a sorbent composition.

[0040] In certain embodiments, the present disclosure provides a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

[0041] Methods for producing polysulfide polymers from an unsaturated cross-linker are known in the art, for example as described in W. J. Chung et al. Nat. Chem. 2013, 5: 518-524, Lim et al. Angew. Chem. Int. Ed. 2015, 54: 3249-3258, Worthington et al. Chem. Eur. J, 2017, 23: 16219-16230 and Worthington et al. Adv. Sustainable Syst. , 2018, 2: 1800024.

[0042] The term“polysulfide polymer” as used herein refers to a material that contains multiple sulfur atoms linked together through S-S bonds, and the sulfur chains are cross-linked through reaction with an unsaturated organic compound or compounds.

[0043] In certain embodiments, the unsaturated cross-linker comprises an alkene and/or an alkyne. Examples of unsaturated cross-linkers include monoalkenes, monoalkynes, polyalkenes and polyalkynes. The unsaturated cross-linker may be a natural compound, a derivative of a natural compound or a synthetic compound.

[0044] In certain embodiments, the unsaturated cross-linker comprises an unsaturated fat. In certain embodiments, the unsaturated cross-linker comprises an unsaturated triglyceride.

[0045] In certain embodiments, the unsaturated cross-linker comprises an unsaturated vegetable oil. In certain embodiments, the unsaturated cross-linker comprises a mixture of unsaturated vegetable oils. Examples of vegetable oils include canola oil, olive oil, sunflower oil, cottonseed oil, linseed oil and mixtures thereof.

[0046] In certain embodiments, the unsaturated vegetable oil comprises canola oil.

[0047] In certain embodiments, the method of formation of the polysulfide polymer comprises the use of a porogen to increase the surface area of the polysulfide polymer product. Examples of porogens include NaCl particles.

[0048] Activated carbon may be obtained commercially or produced using a method known in the art, for example as described in J Chem. Technol. Biotechnol. (2013) 88: 1183-1190.

[0049] Activated carbon may be produced from a carbonaceous source, such as a biomass (eg bamboo, coconut husk, wood) a coal, a lignite, coal, or a petroleum pitch. Other sources are contemplated.

[0050] In certain embodiments, the activated carbon comprises a powdered activated carbon and/or a catalytic carbon. Powdered activated carbons and catalytic carbon are commercially available or may be produced by a method known in the art. The activated carbon may be physically and/or chemically activated.

[0051] In certain embodiments, the powdered activated carbon comprises a particle size in the range from 80 mesh to 325 mesh. Methods for determining the mean and distribution of the size of particles of activated carbon are known in the art.

[0052] In certain embodiments, the particle size distribution of the activated carbon is in the range from 1 micron to 30 microns.

[0053] In certain embodiments, the composition is a blend of the activated carbon and polysulfide polymer.

[0054] In certain embodiments, the composition is a cured composition or a hot pressed composition. Such compositions may be formed by a method known in the art. [0055] In certain embodiments, the composition comprises a blend of the activated carbon and the polysulfide polymer at a ratio ranging from 1 :99 (w/w) to 50:50 (w/w).

[0056] In certain embodiments, the composition is a blend of the activated carbon and the polysulfide polymer at a ratio of about 20:80 (w/w). In certain embodiments, the composition is a blend of the activated carbon and the polysulfide polymer at a ratio of 20:80 (w/w).

[0057] The sorbent composition of the present disclosure is anticipated to be useful for the adsorption of a variety of agents. Examples of agent that may be adsorbed include hydrocarbons, chlorocarbons, fluorocarbons, perfluorinated alkyl substances, heavy metals (including for example mercury, lead, cadmium), mercury gas, organomercury compounds, organic pesticides, malodourous compounds, arsenic, precious metals (including for example gold, platinum, silver). Other agents are contemplated.

[0058] In certain embodiments, the sorbent composition comprises a characteristic of adsorption of perfluorinated compounds. Examples of perfluorinated compounds include perfluorinated alkyl and aryl halides, fluorochloroalkenes, perfluoroethers and epoxides, perfluoroalcohols, perfluoroamines, perfluoroketones, perfluorocarboxylic acids, perfluoronitriles and isonitriles, and perfluorosulfonic acids.

[0059] In certain embodiments, the perfluorinated compound comprises a perfluorooctanoic acid.

[0060] In certain embodiments, the sorbent composition comprises an adsorption capacity for perfluorooctanoic acid of at least 23 mg/g activated carbon.

[0061] In certain embodiments, the sorbent composition is used to adsorb a perfluorinated compound.

[0062] In certain embodiments, the sorbent composition is used to adsorb an agent from a liquid medium, a gaseous medium, a solid, or a semi-solid medium.

[0063] In certain embodiments, the sorbent composition is used for environmental remediation, to reduce contaminants in water, to reduce concentration of heavy metals, or to reduce concentration of hydrocarbons. Other uses are contemplated.

[0064] In certain embodiments, the sorbent composition has an adsorption characteristic of reducing the level of a contaminant to 5 ppb or less, 4 ppb or less, 3 ppb or less, 2 bbp or less, 1 bbp or less, 0.9 bbp or less, 0.8 bbp or less, 0.7 bbp or less, 0.6 bbp or less, 0.5 bbp or less, 0.4 bbp or less, 0.3 bbp or less, 0.2 bbp or less, 0.1 bbp or less, 0.09 bbp or less, 0.08 bbp or less, 0.07 bbp or less, 0.06 bbp or less, or 0.05 bbp or less.

[0065] In certain embodiments, the sorbent composition may be used to sequester an agent.

[0066] In certain embodiments, the sorbent composition comprises one or more further components, such as polymer supports, binding agents and/or adhesives.

[0067] In certain embodiments, the sorbent composition comprises a regenerated form of the composition previously used to adsorb or purify an agent as described herein. For example, the sorbent composition may be regenerated and reused, for example by treating or washing with a solvent such as an alcohol (for example methanol, ethanol, isopropyl alcohol, or mixtures of solvents). Other additives such as acids or bases can also be added to assist with regeneration, such as being added to the regeneration solution using the solvent. Further articles as described herein containing the sorbent composition may, under some circumstances, also be similarly regenerated.

[0068] Certain embodiments of the present disclosure provide a method of adsorbing an agent.

[0069] In certain embodiments, the present disclosure provides a method of adsorbing an agent from a product, the method comprising exposing the product to a sorbent composition as described herein.

[0070] In certain embodiments, the present disclosure provides a method of adsorbing an agent from a product, the method comprising exposing the product to a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker to adsorb the agent, and thereby adsorbing the agent from the product.

[0071] Sorbent compositions are described herein.

[0072] Examples of polysulfide polymers formed from an unsaturated cross-linker are described herein.

[0073] In certain embodiments the polysulfide polymer formed from an unsaturated cross-linker comprises a polysulfide polymer formed from an alkene and/or an alkyne. In certain embodiments, the polysulfide polymer formed from an unsaturated cross- linker comprises a polysulfide polymer formed from an unsaturated vegetable oil. In certain embodiments, the unsaturated vegetable oil comprises a triglyceride. In certain embodiments, the unsaturated vegetable oil comprises canola oil.

[0074] Examples of activated carbon are described herein. In certain embodiments, the activated carbon comprises a powdered activated carbon and/or a catalytic carbon.

[0075] In certain embodiments, the sorbent composition comprises a blend of the activated carbon and the polysulfide polymer. In certain embodiments, the sorbent composition comprises a blend of the activated carbon and the polysulfide polymer at a ratio ranging from 1:99 (w/w) to 50:50 (w/w). In certain embodiments, the sorbent composition comprises a blend of the activated carbon and the polysulfide polymer at a ratio of about 20:80 (w/w).

[0076] In certain embodiments, the agent comprises a perfluorinated compound. Examples of perfluorinated compounds are described herein. In certain embodiments, the agent comprises perfluorooctanoic acid.

[0077] In certain embodiments, the sorbent composition comprises an adsorption capacity for perfluorooctanoic acid of at least 23 mg/g activated carbon.

[0078] In certain embodiments, the method comprises adsorbing an agent to a level of 5 ppb or less, 4 ppb or less, 3 ppb or less, 2 bbp or less, 1 bbp or less, 0.9 bbp or less, 0.8 bbp or less, 0.7 bbp or less, 0.6 bbp or less, 0.5 bbp or less, 0.4 bbp or less, 0.3 bbp or less, 0.2 bbp or less, 0.1 bbp or less, 0.09 bbp or less, 0.08 bbp or less, 0.07 bbp or less, 0.06 bbp or less, or 0.05 bbp or less.

[0079] In certain embodiments, the product comprises a liquid. In certain embodiments, the product comprises water. In certain embodiments, the method comprises absorbing the agent from a liquid. In certain embodiments, the method comprises adsorbing the agent from water.

[0080] Examples of products include a gas, a liquid, a solid, or an environment sample. For example, for a gas containing an agent the method may comprises passing a gas containing the agent through a filter containing the sorbent composition and adsorbing the agent. This may be used for example to purify the gas.

[0081] In certain embodiments, the exposure of the product to the sorbent composition comprises contacting the product in a liquid medium with the sorbent composition.

[0082] In certain embodiments, the exposure of the product to the sorbent composition comprises contacting the product in a gaseous medium with the sorbent composition.

[0083] In certain embodiments, the exposure of the product to the sorbent composition comprises contacting the product in a solid medium with the sorbent composition. In this embodiment, typically the solid medium would be mixed to assist with contact of the agent with the sorbent composition.

[0084] In certain embodiments, the method is used to purify a product, to reduce the concentration of an agent, to reduce the concentration of contaminants, to reduce concentration of heavy metals, or to reduce concentration of hydrocarbons. Other uses are contemplated.

[0085] Certain embodiments of the present disclosure provide a method of purifying a product, the method comprising using a sorbent composition as described herein to purify the product.

[0086] Certain embodiments of the present disclosure provide an article comprising a sorbent composition. [0087] In certain embodiments, the present disclosure provides an article comprising a sorbent composition as described herein.

[0088] In certain embodiments, the present disclosure provides an article comprising a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

[0089] In certain embodiments, the article is a filter, a filter block, a filter cartridge, a column or a bunded container. Methods for producing such products using sorbent compositions are known in the art.

[0090] In certain embodiments, the article comprises reduced clogging upon use and/or reduced caking upon use. Clogging and caking are two characteristics which have the ability to significantly affect the efficiency or usability of the article. In certain embodiments, the article comprises reduced clogging upon use and/or reduced caking upon use as compared to an equivalent article comprising an activated carbon sorbent composition.

[0091] Certain embodiments of the present disclosure provide a method of purifying a product, the method comprising using an article as described herein to purify the product.

[0092] Certain embodiments of the present disclosure provide a method of producing a sorbent composition.

[0093] In certain embodiments, the present disclosure provides a method of producing a sorbent composition, the method comprising combining an effective amount of an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

[0094] Activated carbon and polysulfide polymers are described herein.

[0095] In certain embodiments, the combining of the activated carbon and the polysulfide polymer comprises blending of the components. In certain embodiments, the method comprises blending the activated carbon with the polysulfide polymer. Methods for blending are described herein. [0096] In certain embodiments, the method comprises blending the activated carbon with the polysulfide polymer at a ratio ranging from 1 :99 (w/w) to 50:50 (w/w).

[0097] In certain embodiments, the method comprises blending the activated carbon with the polysulfide polymer at a ratio of about 20:8 (w/w).

[0098] In certain embodiments, the method reduces production of dust from the activated carbon and/or the composition during production and/or use of the sorbent composition. The use of activated carbon generates significant amount of dust which poses an inhalation risk and increased flammability.

[0099] Certain embodiments of the present disclosure provide a sorbent composition produced by a method as described herein.

[00100] Certain embodiments of the present disclosure provide a method of reducing dust associated with use of activated carbon.

[00101] In certain embodiments, the present disclosure provides a method of reducing dust associated with use of activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon.

[00102] Blending of a polysulfide polymer with activated carbon is described herein.

[00103] Certain embodiments of the present disclosure provide a method of reducing dust from an adsorbent article.

[00104] In certain embodiments, the present disclosure provides a method of reducing dust from an adsorbent article comprising activated carbon during production and/or use of the article, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

[00105] Certain embodiments of the present disclosure provide a method of reducing clogging and/or caking of an adsorbent article comprising activated carbon.

[00106] In certain embodiments, the present disclosure provides a method of reducing clogging and/or caking of an adsorbent article comprising activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

[00107] Articles are described herein.

[00108] Certain embodiments of the present disclosure provide a method of improving operating functionality of an adsorbent article.

[00109] In certain embodiments, the present disclosure provides a method of improving operating functionality of an adsorbent article comprising activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

[00110] In certain embodiments, the improvement in operating functionality comprises reduced clogging and/or reduced caking.

[00111] The present disclosure is further described by the following examples. It is to be understood that the following description is for the purpose of describing particular embodiments only and is not intended to be limiting with respect to the above description.

EXAMPLE 1 - Remediation of water contaminated with perfluorooctanoic acid (PFOA) using a blend of powdered activated carbon and a sustainable polymer prepared by inverse vulcanisation

[00112] Abstract

[00113] Perfluorinated alkyl substances such as perfluorooctanoic acid (PFOA) have caused increasing international concern as persistent contaminants of ground water, surface water, and drinking water. These substances are commonly used as emulsifiers in the production of fluoropolymers and also as components of protective coatings and fire-fighting foams. These materials can be released directly into the environment, especially near airports and defence bases that regularly test or deploy fire- extinguishing systems that contain these perfluorinated materials. PFOA has been found to reside in both the environment and humans for years, and may be linked to several adverse health effects. Accordingly, there is a need for efficient, scalable and cost- effective methods to remove perfluorinated alkyl substances from water.

[00114] In this study, we have developed a novel sorbent made from a blend of powdered activated carbon and a polysulfide polymer made through the inverse vulcanisation of canola oil. The blend is effective at removing PFOA from water and in some cases reduces it to levels that meet most current regulatory limits (< 0.070 ppb). Both the polymer and the carbon contribute to PFOA binding. The carbon-polymer blend benefits from lower hydraulic resistance and less caking relative to powdered carbon alone, which facilitates continuous processing of contaminated water. The carbon-polymer blend also does not produce plumes of fine carbon particles during handling, which enhances its safety profile.

[00115] Introduction

[00116] Perfluorooctanoic acid (PFOA, Fig. 1) and other polyfluorinated alkyl substances have been used for decades in the production of fluoropolymers such as Teflon®, protective coatings, lubricants, and firefighting foams. In the early 2000s, these poly- and perfluorinated substances were found to be distributed widely in the environment and in humans, prompting more thorough evaluations of their toxicity. While a full assessment of the burden of PFOA pollution on public health requires additional epidemiological studies, exposure to PFOA has been implicated in a variety of health issues including hepatic and renal toxicity, thyroid disease and kidney and testicular cancers. Accordingly, governments have issued guidance and regulations on emissions and exposure limits of poly- and perfluorinated alkyl substances. The United States Environmental Protection Agency, for instance, has issued an advisory limit of 70 ng/L (0.070 ppb) for PFOA in drinking water, based on a toxicological study in mice.

[00117] To meet these limits, it is critical to develop new technologies to remove PFOA and related contaminants from water and other environmental situations.

[00118] In this study, we report a new sorbent developed to remove PFOA from water and other samples. The featured sorbent is a 20:80 blend by mass of powdered activated carbon and a polysulfide polymer made by the inverse vulcanisation of canola oil. The polymer provides a support for the powdered activated carbon that helps prevent caking during filtration and facilitates separation of the sorbent from water, overcoming a common challenge using powdered activated carbon in municipal water treatment and packed columns. The carbon powder adheres to the polymer, so the blend does not produce plumes of fine carbon particles during handling, which enhances its safety profile. Both the polymer and the activated carbon contribute to PFOA binding, so the polymer is more than just a solid support. In one test, PFOA was reduced from 5000 pg/L to 60 ng/L when contaminated water was passed through a column packed with the carbon-polymer blend. The low-cost, scalability, safety and effectiveness of this sorbent system provides various advantages in the removal of PFOA from water and other samples.

[00119] Materials and Methods

[00120] IR Spectroscopy: Infrared (IR) spectra were recorded on a Fourier Transform spectrophotometer using the ATR method. Transmission maxima (u_max) are reported in wavenumbers (cm ¹).

[00121] SEM and EDS: Scanning Electron Microscopy (SEM) images were obtained using an FEI F50 Inspect system, while corresponding EDS spectra were obtained using an ED AX Octane Pro detector.

[00122] ¹⁸ F NMR Spectroscopy: ¹⁹F NMR spectra were recorded using a Bruker ETltrashield 600. Deuterium oxide (D₂0/H₂0, 1 :9) was used as the solvent and for internal locking. All chemical shifts (d scale) were measured in parts per million (ppm) and referenced to the internal standard trifluoroacetic acid (d = -76.55 ppm).

[00123] PFOA Analysis by Liquid Chromatography Mass Spectrometry: Certified PFOA analysis was carried out by Envirolab Services Pty Ltd, with accreditation by the National Association of Testing Authorities, Australia. Briefly, water samples containing PFOA were analyzed by direct injection (negative mode) after spiking with surrogates and internal standards and filtering through a 0.2 pm disposable syringe filter. The concentrations are calculated using internal standard calibration with linear regression, l/x weighting and band integration to cover both the linear and the branched isomers. The test method was based on EPA/600/R-08/092 Method 537: Determination of Selected Perfluorinated Alkyl Acids In Drinking Water By Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS). Version 1.1, September 2009.

[00124] Canola Oil Poly sulfide Synthesis

NaCl (70.0 grams) was ground into a fine powder using a mortar and pestle. Sulfur (technical grade, 15.00 g) was added to a 250 mL round bottom flask and then melted, with stirring, before heating further to 180 °C. Canola oil (15.00 g) was added drop wise over 2 minutes. The reaction mixture was stirred at a rate that ensured efficient mixing of the two phases. The NaCl powder was then added over 5-10 minutes, and the stirring rate was continually adjusted to ensure efficient mixing. Heating was continued for an additional 10-15 minutes at 180 °C, over which time the reaction mixture formed a brown solid. The reaction was cooled to room temperature and removed from the flask. The product (100.0 g) was milled for 1 minute in a blender (8.0 cm rotating blade) to give various particle sizes (typically between 0.1 mm and 3.0 cm). The particles were then transferred to a beaker and washed with 500 mL of water for 1 hour with stirring. The washing process was repeated at least one more time to remove as much sodium chloride as possible. Drying in a desiccator under vacuum provided the porous polymer as a soft rubbery sponge, shown in Figure 1. If sodium chloride was visible as a white solid on the surface of the polymer, the washing and drying steps were repeated until a constant mass was obtained. Near quantitative yields (>29.4 g, >98%) were typically obtained in this process. The particles could be further separated by size using sieves:

[00125] Canola oil polysulfide large-scale synthesis (900 gram scale)

[00126] Canola oil (450.0 g) was added to a stainless steel reaction vessel (4.7 L, 20 cm diameter) that was placed on a hotplate. An overhead stirrer with a stainless steel impellor, used to stir the reaction mixture, was set to 90 rpm. The hotplate was turned on and the oil was heated to 170 °C. Sulfur was then added (450.0 g) through a funnel over 5-10 minutes ensuring the temperature never drops below 155 °C. At this point two transparent liquid phases exist. Over the period of 5-10 minutes the 2 separate layers combine forming a single opaque mixture. At this point the sodium chloride porogen (2100 g, finely ground in a blender) was added through the funnel over approximately 15-20 minutes. Once again the rate of addition was such that the temperature of the reaction never dropped below 155 °C. At this point the mixture was an orange, opaque, and relatively free flowing liquid. After approximately 10-15 minutes of continuous heating the mixture turns from orange to brown. At this point the viscosity increases and the polymer product starts to form. Once the overhead stirrer registers a torque of approximately 40 N cm, the reaction was stopped. The reaction vessel was removed from the heat plate and placed on a trivet to prevent the flask heating up any further. Due to the potential for H₂S release this reaction was carried out inside a fume hood. The polymer was removed from the vessel using a metal spatula and processed using a mechanical grinder to provide particles between 0.5 and 3 mm in size. Finally this polymer was washed with 17 L of water in a 20 L bucket whilst stirring the mixture using the overhead stirrer (200 rpm, 30 min). Finally the polymer was isolated by filtration through a sieve (0.5 mm cut-off). These washing steps were repeated three times to ensure that the final product had as much salt as possible removed. The polymer was then dried by passing warm air though the material (5-24 hours, 18 - 42 °C) using a space heater and then leaving it to dry in the fume hood until the mass of the material was constant. Typically a final yield of between 850-900 grams of the final product was achieved using this procedure.

[00127] Preparation of 1 kg of a carbon-polysulfide blend (80% canola oil polysulfide by mass and 20% powdered activated carbon by mass)

[00128] 800 grams of porous polysulfide was added to a 2.5 L plastic container. Next, 200 grams of activated carbon powder (PGW 150 MP, Kuraray) was added. The containers lid was closed and the container was inverted 20 times to ensure the carbon and polymer mixed sufficiently to create a homogenous blend. The carbon bound to the canola oil polysulfide, leaving minimal free-flowing powdered carbon. This blend was then used for subsequent PFOA experiments.

[00129] SEM micrographs of the porous canola oil polysulfide (50 wt% sulfur) are shown in Figure 2 (A) and (B). These micrographs indicated that the canola oil polysulfide blend supports the activate carbon without blocking pores or reducing the surface area.

[00130] Figure 3 shows porous canola oil polysulfide (800 g) (left), powdered activated carbon powder (PGW 150 MP, 200 g) (centre) and the carbon-polysulfide blend (1 kg) (right).

[00131] Figure 4 shows SEM micrographs of powdered activated carbon (Kuraray, PGW 150 MP).

[00132] Figure 5 shows EDX imaging of powdered activated carbon (Kuraray, PGW 150 MP).

[00133] Figure 6 shows SEM micrographs of granular activated carbon (GC 1200, 0.5- 0.7 mm, Activated Carbon Technologies).

[00134] Figure 7 shows EDX imaging of granular activated carbon (GC 1200, 0.5-0.7 mm, Activated Carbon Technologies).

[00135] Figure 8 shows SEM micrographs of carbon-polysulfide blend.

[00136] Figure 9 shows EDX map of carbon-polymer blend.

[00137] PFOA sorption using the porous canola oil poly sulfide

[00138] A PFOA solution (5 mL, 2 mg/mL PFOA in H₂0) was added to a glass vial containing the porous 50% w/w sulfur polysulfide (2.00 g) and incubated without mixing at room temperature. At 5, 10, 60, 120 and 240 minutes, a 600 pL aliquot of the water was sampled and analysed by ¹⁹F NMR spectroscopy. The NMR sample was prepared by adding 60 pL of D₂0 spiked with TFA (5.4 mg/ml) to the 600 pL sample of water. The amount of remaining PFOA in the aqueous solution was determined by the relative integration of the CF₃ signals, at d -76.55 ppm for TFA and at d -81.85 ppm for PFOA. After 5 minutes, 30% of the PFOA was removed from solution. After 4 hours, 47% of the PFOA was removed from solution. [00139] Figure 10 shows ¹⁹F NMR analysis of PFOA sorption using the canola oil polysulfide at t = 0, 5, 10 60, 120 and 240 mins.

[00140] SEM micrographs of PFOA hemi-micelles bound to the poly sulfide surface

[00141] The porous canola oil polysulfide (2.0 grams) was added to a 20 mL glass vial with 5 mL of a saturated PFOA solution. This solution was incubated for 24 hours, after which time the polymer was isolated by filtration and dried in open air. Before SEM analysis, the polymer was coated with a 5 nm platinum coating.

[00142] Figure 11 shows SEM micrographs of the porous canola oil polysulfide after exposure to a saturated solution of PFOA in water. A) The cross section of a polymer particle B) The same particle at increased magnification C) Higher magnification of point of interest, with hemi-micelles bound to the surface of the polymer D) Hemi- micelles bound at another location on the polymer.

[00143] EDX analysis of PFOA hemi-micelles bound to the poly sulfide surface

[00144] Figure 12A shows EDX analysis of hemi-micelles on the polymer surface. The polymer was platinum coated for analysis and the sample holder was aluminium. Figure 12B shows that sulfur, carbon and oxygen are all present within the polymer. Sodium and chlorine originate from residual NaCl porogen not removed during the washing step in the polymer synthesis. A distinct fluorine peak was detected at the hemi-micelle, indicating this feature is formed from PFOA.

[00145] PFOA sorption in batch

[00146] 5.00 grams of the carbon-polysulfide blend was added to a 200 mL plastic container along with 100 mL of a PFOA solution (5 ppm PFOA in water). In three separate 200 mL plastic containers, 4.00 grams of the canola oil polysulfide, 1.00 gram of powdered activated carbon (Kuraray, PGW 150 MP), or 1.00 gram of granular activated carbon (GC 1200, 0.5-0.7 mm, Activated Carbon Technologies) were added along with 100 mL of the PFOA solution (5 ppm PFOA in water). The solutions were stirred for 1 hour (250 rpm, 32 x 12 mm stirring bar) and then filtered through a simplepure 0.22 pm PES syringe filter into separate plastic container for further analysis. The PFOA concentrations were determined by Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS) (negative mode, ESI). Note: For the polymer control and the blend treatment only one filter was required. For the activated carbon control, 5 filters were required as they were rapidly blocked with the powdered activated carbon. For the granular carbon control, 4 filters were required as they were also blocked.

[00147] Figure 13 shows from left to right: Porous canola oil polysulfide (4.00 g) in 100 mL of PFOA solution (5 ppm), carbon-polymer blend (5.00 g) in 100 mL of PFOA solution (5 ppm), powdered activated carbon (1.00 g) in 100 mL of PFOA solution (5 ppm), and granular activated carbon in 100 mL of PFOA solution (5 ppm).

[00148] Removal of PFOA from water using a continuous process

[00149] A 30 x 1.5 cm glass column was packed with 40 grams of the carbon-polymer blend. 100 mL of PFOA solution (5 ppm) was added into the top of the column through a funnel and a beaker was used to collect the solution as it exited through the column after gravity elution. This experiment was carried out twice, with the total run times of 20 minutes and 90 minutes, with the flow rate controlled by the column tap. The PFOA concentrations were determined by Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS) (negative mode, ESI).

[00150] PFOA binding capacity for carbon-polysulfide blend

[00151] The carbon-polymer blend (50 mg) was added to a 250 mL plastic container, followed by a 50 mL solution of PFOA solution (5000 ppm). The mixture was stirred for 48 hours to equilibrate. After this time, the solution was transferred, using a 60 mL plastic syringe, through a simplepure 0.22 pm PES syringe filter into a new container. The PFOA concentrations were determined by Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS) (negative mode, ESI).

[00152] Determination of zero point charge for powdered activated carbon [00153] 50 mL of an aqueous solution of NaCl (0.1 M) was added to each of nine 50 mL centrifuge tubes. The pH of each of these tubes was adjusted by the addition of either a 0.01 M HC1 or 0.01 M NaOH solution using a pH meter so that there were two tubes with solutions of pH 2, 3, 4, 5, 6, 7, 8, 9, and 10. Next, 0.15 grams of activated carbon was added into 9 tubes at each pH. All of the tubes were placed on a rotary mixer and rotated at 25 rpm and 25 °C for 48 hours. After this time, the pH of each solution was measured using the pH meter. The pH point where the pH _mtiai=pHn_nai was estimated by the point of intersection of the line y = x (green line) and a plot of Final vs Initial pH (Figure 14).

[00154] Filtering efficiency: comparing carbon-polymer blend, granular activated carbon, and powdered activated carbon

[00155] 5.0 grams of the carbon-polymer blend was placed into a syringe with 50 mL of water. A Simplepure 22 pm PES filter was attached to the syringe and the mixture was passed through the filter. This was repeated using 1.0 gram of activated carbon (Kuraray, PGW 150 MP) in 50 mL of water and again with 1.0 grams of granular activated carbon (GC 1200, 0.5-0.7 mm, Activated Carbon Technologies). The powdered activated carbon blocked five filters, the granular activated carbon blocked three filters, and the carbon-polymer blend did not block the filter.

[00156] Figure 15 shows from left to right: syringe filter block with granular activated carbon (GC 1200, 0.5-0.7 mm, Activated Carbon Technologies), syringe filter blocked with powdered activated carbon (Kuraray, PGW 150 MP), syringe filter used to filter the carbon-polymer blend, and an unused syringe filter.

[00157] Results and Discussion

[00158] We have synthesized a polysulfide polymer made by direct reaction of equal masses of sulfur and canola oil (Figure 16 and Figures 3, 4). When the polymer is prepared in the presence of sodium chloride, the salt can be washed from the polymer product, providing channels and pores that increase surface area. Because millions of tonnes of excess sulfur are produced each year by the petroleum industry and used unsaturated cooking oils are suitable in the synthesis, the raw materials in the synthesis are very inexpensive. The polymer is also scalable and can be routinely prepared on a 1 kg scale in the laboratory.

[00159] The affinity of our canola oil polysulfide for hydrophobic materials like crude oil and other hydrocarbon pollution prompted us to test its affinity for the polyfluorinated backbone of PFOA. As a first test, PFOA was prepared as a 2 mg/mL solution in water. To 5 mL of this solution was added 2.0 g of the polysulfide. The concentration of PFOA was monitored by ¹⁹F NMR spectroscopy using trifluoroacetic acid as an internal standard to quantify the amount of PFOA in solution (Figures 10 and 11). After 4 hours of static incubation, the polymer had removed 47% of the PFOA. While these concentrations of PFOA are quite high, and the sorption is relatively low, we were still encouraged that the polymer appeared to have some affinity for PFOA. To confirm that PFOA could indeed bind to the polymer, the polysulfide was immersed in a saturated solution of PFOA for 24 hours. The polymer was then isolated by filtration, dried, and then analysed by scanning electron microscopy (SEM). The results (Figure 17) revealed the presence of 41 ± 16 pm hemi-micelles across the surface of the polymer. Analysis of these hemi-micelles by energy dispersive X-ray (EDX) spectroscopy clearly indicated the presence of fluorine, which is expected if the hemi- micelles are comprised of PFOA (Figures 12 and 13).

[00160] In order to improve the rate of PFOA uptake and sorption capacity, our strategy was to blend activated carbon with the polymer. In the event, 800 grams of the polysulfide and 200 grams of powdered activated carbon (PGW 150 MP, Kuraray) were sealed in a 2 L plastic tub and inverted 20 times. The powdered carbon (100-200 mesh, point of zero charge: pH_(pzC) = 9.6) is a commercial material commonly used in the production of domestic water filters. The polymer and the carbon were highly attracted to each other— likely due to a combination of electrostatic and hydrophobic forces— to form a relatively homogenous sorbent blend. Using more than 20% carbon by mass in the blend led to significant free carbon, unbound to the polymer. This blend has several benefits over the activated carbon alone. First, we found that the blend is easy to handle and generates far less dust than the powdered carbon, an important safety aspect with respect to inhalation and respiratory risks encountered when handling powdered activated carbon. Additionally, the carbon-polymer blend is easier to remove from water by filtration than the powdered activated carbon alone. The separation of powdered activated carbon by filtration can be challenging, and a limitation highlighted in the literature as motivation for designing new forms of carbon sorbents for PFOA.

[00161] To test the sorption of PFOA on the carbon-polymer blend, 5.0 g of the blend (4.0 g polymer, 1.0 g powdered activated carbon) was added to 100 mL of a 5000 ppb stock solution of PFOA and stirred for 1 hour. For comparison, three additional control experiments were carried out using only the polysulfide polymer (4.0 g) and either the powdered activated carbon (1.0 g) or granular activated carbon (1.0 g) (Figure 14). After 1 hour of treatment, the water was filtered through a 0.22 pm polyethersulfone (PES) syringe filter and then the PFOA was quantified using mass spectrometry by a certified, independent laboratory using the standard protocol EPA/600/R-08/092 Method 537 (Table 1, Entries 1-5). The polymer alone reduced the PFOA concentration to 4400 ppb over the hour treatment, which is slightly lower than the sorption rates observed at higher concentrations by ¹⁹F NMR spectroscopy (Figures 10 and 11). Granular activated carbon reduced the PFOA concentration to 370 ppb, which is still well above the 0.070 ppb limit of the ETS EPA. The powdered activated carbon and the carbon-polymer blend, in contrast, were very effective at removing the PFOA, reducing the concentration from 5000 ppb to 0.05 ppb and 2.6 ppb, respectively. This is encouraging because these are environmentally relevant concentrations of PFOA and reduction to low ppb concentrations is very near most regulatory limits. We note that while the powdered activated carbon alone did perform slightly better than the carbon- polymer blend in this experiment, the free powdered activated carbon blocked the syringe filters and was difficult to separate from water (Figure 16). We attribute the minor difference in sorption between the free powdered carbon and the carbon-polymer blend to the slightly increased contact time when the water is forced through a dense cake of carbon during filtration. The increased pressure during filtering might also increase the amount of PFOA bound to the free carbon. Nevertheless, separating the powdered activated carbon from water by filtration led to clogging that was inefficient, costly, and ultimately impractical. Even the granular activated carbon led to filter clogging (Figure 15). In contrast, the carbon-polymer blend was far easier to filter and therefore a promising lead for a continuous remediation process. To that end, the carbon-polymer blend (40 g) was packed into a glass column and water containing 5000 ppb of PFOA was passed through the column (Table 1, Entries 6-7). With a 20 min residence time, the PFOA concentration was reduced to 170 ppb. With a 90 minute residence time, the PFOA concentration was reduced to 0.06 ppb or 60 ng/L, which is below most advisory and regulator limits for drinking water.

Table 1 : Sorption studies in which the polysulfide polymer, granular activated carbon (GC 1200, 0.5-0.7 mm, Activated Carbon Technologies), powdered activated carbon (Kuraray, PGW 150 MP), and the carbon-polymer blend were used to treat a 100 mL sample of PFOA (5000 ppb in water).

[00162] The sorption capacity of the carbon-polymer blend was estimated by adding 50 mg of the sorbent to 50 mL of a 5000 ppb PFOA solution. The mixture was stirred for 48 hours to equilibrate and saturate the sorbent. After this time, the solution was filtered and the PFOA was quantified by mass spectrometry as it was for previous experiments. The final concentration of PFOA was 390 ppb, which means that 92% of PFOA or 231 pg was bound by the carbon-polymer blend. This corresponds to a PFOA sorption capacity of approximately 4.6 mg/g of carbon-polymer sorbent. Based on the activated carbon content, this sorption capacity is 23 mg/g carbon.

[00163] In conclusion, we have developed a new sorbent made from a blend of a sustainable sulfur-based polymer and powdered activated carbon. We have directly observed, for the first time, the assembly of hemimicelles of PFOA on the sulfur polymer surface. The sorbent blend retains the high surface area and affinity for PFOA of the powdered carbon, but benefits from ease of handling, low dust and minimal caking during filtration. The blend is also superior to the granular activated carbon examined in handling, caking, and PFOA sorption. More generally, we also note that activated carbon and the polymer in this sorbent blend can, in principle, be made entirely from industrial waste and reclaimed biomass. The blend is scalable and we report the 1.0 kg preparation of the carbon-polymer blend, which we have repeated more than 20 times in our laboratory to date.

[00164] Although the present disclosure has been described with reference to particular embodiments, it will be appreciated that the disclosure may be embodied in many other forms. It will also be appreciated that the disclosure described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the disclosure includes all such variations and modifications. The disclosure also includes all of the steps, features, compositions and compounds referred to, or indicated in this specification, individually or collectively, and any and all combinations of any two or more of the steps or features.

[00165] Also, it is to be noted that, as used herein, the singular forms“a”,“an” and “the” include plural aspects unless the context already dictates otherwise.

[00166] Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as“comprises” or“comprising”, will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers. [00167] The term“about” or“approximately” means an acceptable error for a particular value, which depends in part on how the value is measured or determined. In certain embodiments,“about” can mean one or more standard deviations. When the antecedent term "about" is applied to a recited range or value it denotes an approximation within the deviation in the range or value known or expected in the art from the measurements method. For removal of doubt, it shall be understood that any range stated herein that does not specifically recite the term“about” before the range or before any value within the stated range inherently includes such term to encompass the approximation within the deviation noted above.

[00168] Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.

[00169] The subject headings used herein are included only for the ease of reference of the reader and should not be used to limit the subject matter found throughout the disclosure or the claims. The subject headings should not be used in construing the scope of the claims or the claim limitations.

[00170] The description provided herein is in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of one embodiment may be combinable with one or more features of the other embodiments. In addition, a single feature or combination of features of the embodiments may constitute additional embodiments.

[00171] All methods described herein can be performed in any suitable order unless indicated otherwise herein or clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the example embodiments and does not pose a limitation on the scope of the claimed invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential.

[00172] Future patent applications may be filed on the basis of the present application, for example by claiming priority from the present application, by claiming a divisional status and/or by claiming a continuation status. It is to be understood that the following claims are provided by way of example only, and are not intended to limit the scope of what may be claimed in any such future application. Nor should the claims be considered to limit the understanding of (or exclude other understandings of) the present disclosure. Features may be added to or omitted from the example claims at a later date.

Claims

1. A sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

2. The sorbent composition according to claim 1, wherein the polysulfide polymer formed from an unsaturated cross-linker comprises a polysulfide polymer formed from an alkene and/or an alkyne.

3. The sorbent composition according to claims 1 or 2, wherein the polysulfide polymer formed from an unsaturated cross-linker comprises a polysulfide polymer formed from an unsaturated vegetable oil.

4. The sorbent composition according to claim 3, wherein the unsaturated vegetable oil comprises a triglyceride.

5. The sorbent composition according to claims 3 or 4, wherein the unsaturated vegetable oil comprises canola oil.

6. The sorbent composition according to any one of claims 1 to 5, wherein the activated carbon comprises a powdered activated carbon and/or a catalytic carbon.

7. The sorbent composition according to claim 6, wherein the powdered activated carbon comprises a particle size in the range from 80 mesh to 325 mesh.

8. The sorbent composition according to any one of claims 1 to 7, wherein the composition comprises a blend of the activated carbon and the polysulfide polymer at a ratio ranging from 1:99 (w/w) to 50:50 (w/w).

9. The sorbent composition according to any one of claims 1 to 8, wherein the composition is a blend of the activated carbon and the polysulfide polymer at a ratio of 20:80 (w/w).

10 The sorbent composition according to any one of claims 1 or 9, wherein the sorbent composition comprises a characteristic of adsorption of perfluorinated compounds.

11. The sorbent composition according to claim 10, wherein the perfluorinated compound comprises a perfluorooctanoic acid.

12. The sorbent composition according to any one of claims 1 to 11, wherein the sorbent composition comprises an adsorption capacity for perfluorooctanoic acid of at least 23 mg/g activated carbon.

13. The sorbent composition according to any one of claims 1 to 12, wherein the sorbent composition is used for environmental remediation, to reduce contaminants in water, to reduce concentration of heavy metals, or to reduce concentration of hydrocarbons.

14. A method of adsorbing an agent from a product, the method comprising exposing the product to a sorbent composition according to any one of claims 1 to 13.

15. An article comprising a sorbent composition according to any one of claims 1 to 13.

16. The article according to claim 15, wherein the article is a filter, a filter block, a filter cartridge, a column or a bunded container.

17. A method of adsorbing an agent from a product, the method comprising exposing the product to a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker to adsorb the agent, and thereby adsorbing the agent from the product.

18. The method according to claim 17, wherein the polysulfide polymer formed from an unsaturated cross-linker comprises an alkene and/or an alkyne.

19. The method according to claims 17 or 18, wherein the polysulfide polymer formed from an unsaturated cross-linker comprises a polysulfide polymer formed from an unsaturated vegetable oil.

20. The method according to claim 19, wherein the unsaturated vegetable oil comprises a triglyceride.

21. The method according to claims 19 or 20, wherein the unsaturated vegetable oil comprises canola oil.

22. The method according to any one of claims 17 to 21, wherein the activated carbon comprises a powdered activated carbon and/or a catalytic carbon.

23. The method according to any one of claims 17 to 22, wherein the sorbent composition comprises a blend of the activated carbon and the polysulfide polymer at a ratio ranging from 1:99 (w/w) to 50:50 (w/w).

24. The method according to any one of claims 17 to 23, wherein the sorbent composition comprises a blend of the activated carbon and the polysulfide polymer at a ratio of about 20:80 (w/w).

25. The method according to any one of claims 17 to 24, wherein the agent comprises a perfluorinated compound.

26. The method according to claim 25, wherein the perfluorinated compound comprises a perfluorooctanoic acid.

27. The method according to any one of claims 17 to 26, wherein the sorbent composition comprises an adsorption capacity for perfluorooctanoic acid of at least 23 mg/g activated carbon.

28. The method according to any one of claims 17 to 27, wherein the method is used for environmental remediation, to reduce contaminants in water, to reduce concentration of heavy metals, or to reduce concentration of hydrocarbons.

29. An article comprising a sorbent composition comprising an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

30. The article according to claim 29, wherein the article is a filter, a filter block, a filter cartridge, a column or a bunded container.

31. The article according to claims 29 or 30, wherein the article comprises reduced clogging upon use and/or reduced caking upon use.

32. A method of purifying a product, the method comprising using an article according to any one of claims 29 to 31 to purify the product.

33. A method of producing a sorbent composition, the method comprising combining an effective amount of an activated carbon and a polysulfide polymer formed from an unsaturated cross-linker.

34. The method according to claim 33, wherein the method comprises blending the activated carbon with the polysulfide polymer at a ratio ranging from 1 :99 (w/w) to 50:50 (w/w).

35. The method according to claims 33 or 34, wherein the method reduces production of dust from the activated carbon and/or the composition during production and/or use of the sorbent composition.

36. A sorbent composition produced by the method according to any one of claims 33 to 35.

37. A method of reducing dust associated with use of activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon.

38. A method of reducing dust from an adsorbent article comprising activated carbon during production and/or use of the article, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

39. A method of reducing clogging and/or caking of an adsorbent article comprising activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.

40. A method of improving operating functionality of an adsorbent article comprising activated carbon, the method comprising use of a polysulfide polymer formed from an unsaturated cross-linker blended with the activated carbon in the article.