Modified Clay Sorbents

Field of the invention

The present invention relates to biocompatible, non-toxic modified clay sorbents and methods for their use. The sorbents are used for the sorption of contaminants such as hydrophobic or amphiphilic contaminants, particularly constituents of AFFFs, surfactants, perfluorinated and polyfluorinated compounds, as well as carbon containing contaminants, such as greenhouse gases.

Background

Fire suppression systems using aqueous film forming foam (AFFF) solutions are often installed in facilities containing flammable or combustible liquids because of the rapid and efficient fire extinguishing capability of such foams. Although various types of fire fighting foams are available, AFFF is used almost exclusively due to its superior fire extinguishing capacity. AFFF formulations contain a class of chemicals known as perfluorinated compounds (PFC). Examples of PFCs include perfluorooctanesulfonic (PFOS) and perfluorooctanoic acid (PFOA), collectively known as "polyfluoroalkyl substances" (PFAS).

Suitable methods for immobilising PFCs in soil are lacking. Traditional soil remediation often relies on dig and dump strategies, however owing to the high cost of landfilling of contaminated soils and the current lack of proper handling and disposal facilities that can receive PFAS contaminated soils, this option is limited in application. Alternative remediation methods must be found that are both sustainable, cost effective and minimise the environmental burden.

Naturally occurring materials have found many applications as sorbents. Various types of organoclay and surface-tailored organoclays have been synthesised that are effective to immobilise PFAS in soil and prevent PFAS leaching to groundwater. The addition of the sorbent material to the contaminated soil results in a stabilisation or immobilisation of the pollutants making them unavailable to leach to the surroundings and to be taken up by organisms. For example, MatCARE™ is commercially available clay based sorbent based on palygorskite-based material modified with oleylamine which is use for PFOS adsorption. However, known organoclay and surface-tailored organoclays are associated with soil microbe disruption and even toxicity, particularly at the concentrations of these materials required for effectiveness of PFAS adsorption in soil.

Provision of sorbents which minimally toxic to, or preferably not toxic to, and indeed in some cases, are supportive of native soil microorganisms, particularly native soil microbial communities is desirable, as soil amendment with existing sorbents can negatively impact microbial community function, biodegradation potential and ecosystem health and prolonging soil recovery time after treatment.

As such, a need exists for sorbents which are suitable for the sorption of hydrophobic and/or amphiphilic organic contaminants such as constituents of AFFFs, surfactants, perfluorinated and polyfluorinated compounds, particularly which have less impact on native soil microbes or more preferably are supportive of growth of native soil microbes and/or substantial preservation of microbe diversity and abundance in treated soil compared to native soil.

Furthermore, non toxic sorbents which can sorb greenhouse gas (GHG), including carbon dioxide, methane, nitrous oxide emission from various human activities, including industrial emission, agriculture and cattle farming, energy and transport sectors would be hugely advantageous in adherence to net zero emission targets.

CN111592170 proposes preparation and a colloidal aqueous suspension of dispersant coated Fe ₂ 03 nanomagnetic particles loaded into certain mineral solids for forming a colloidal solution which is used as an adsorbent for reducing COD and heavy metals in liquid and solid biological fertiliser made from manure and biogas slurry wastewater arising as a by-product of biogas production from organic waste. Flowever, the actual examples only relate to ethylene glycol coated Fe304 nanoparticles loaded into 4A zeolite molecular sieves at a nanoparticle loading of 10%, acetate coated Fe304 nanoparticles loaded into 5A zeolite molecular sieves at a nanoparticle loading of 25%, dodecylbenzene sulfonate coated Fe304 nanoparticles loaded into bentonite at a nanoparticle loading of 21.6%, polypyrrolidone coated Fe304 nanoparticles loaded into sepiolite at a nanoparticle loading of 16%. There are no specific examples of iron oxide nanoparticle modified clays where the iron nanoparticles are coated with amino acids, much less further modified with other components such as fatty acid, urea or cationic surfactant. CN111592170 describes a two-step process for forming the Fe ₂ 0 ₄ nanoparticles in a first step involving a reducing agent such as ammonia to form the nanoparticles which are then dried and washed with deionised water. The nanoparticles are then dispersed in water and coated with a coating agent which is required to aid dispersion of the nanoparticles so as to form the colloidal solution. Nanoparticle aggregation is to be prevented to avoid loss of the essential magnetic properties. CN111592170 teaches it is essential to first wash the formed the nanoparticles prior to adding the coating agent, as otherwise surfactants, other ions and impurities are retained in the nanomagnetic colloidal solution when formed. The coating agent wraps the nanoparticles and forms a protective film that prevents agglomeration of the nanoparticles in the colloidal solution A coating agent concentration of 60 -150g/L is optimal. When used as a sorbent to remove pollutants such as heavy metals in water, the mineral/clay adsorbs the pollutants while the magnetic nanoparticles facilitate fast and convenient solid-liquid separation enabling removal of the sorbent when remediation is complete. Flowever, it would be more preferably to avoid the need for magnetic separation at al by providing a non-toxic sorbent that could be permanently left in situ in the environment. The water based magnetic fluid is used to treat wastewater. There this no teaching in this document of using a solid, nanoparticle based modified clay sorbent as a leave in material for polluted solid. CN111592170 focuses on the magnetic properties of non-aggregated Fe203 nanoparticles to enable separation from waste water after treatment, there is no consideration or suggest of a solid leave in sorbent capable of sorbing PFOS etc. and which is non toxic and even supportive of microbial growth in soil. 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.

Where any or all of the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components.

Statements of the Invention

In a first aspect, the invention provides a biocompatible, solid modified clay sorbent comprising a modified layered type clay mineral and non-zero valent iron nanoparticles whereby the metal nanoparticles are capped with one or more amino acids, amino acid salts and mixtures thereof, and wherein the metal nanoparticles are iron oxide nanoparticles, wherein the iron oxide nanoparticles are formed in a one pot synthesis from an iron (II) salt and the at least one amino acid or salt thereof, and wherein the clay mineral is modified with one or more of fatty acid, urea and cationic surfactant, which is one or more of: (i) non-toxic to soil microbes as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies and (ii) supportive of microbial growth as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies.

In a second aspect, the invention provides a modified clay sorbent comprising a blend of an aluminosilicate clay mineral modified with a cationic surfactant comprising a dimethyldioctadecyl ammonium cation, and non-zero valent iron nanoparticles whereby the non-zero valent iron nanoparticles are capped with L-arginine, wherein the metal nanoparticles are iron oxide nanoparticles formed in a one pot synthesis from ferrous chloride and the at least one amino acid or salt thereof, and wherein the clay mineral is modified with one or more of fatty acid, urea and cationic surfactant, and the sorbent is one or more of: (i) non-toxic to soil microbes as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies and (ii) supportive of microbial growth as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies.

In a third aspect, the invention provides a modified clay sorbent comprising a blend of an aluminosilicate clay mineral modified with a cationic surfactant comprising a dimethyldioctadecyl ammonium cation and further modified with palmitic acid, and non-zero valent iron nanoparticles whereby the metal nanoparticles are capped with L-arginine, wherein the metal nanoparticles are iron oxide nanoparticles formed in a one pot synthesis from ferrous chloride and the at least one amino acid or salt thereof, and wherein the clay mineral is modified with one or more of fatty acid, urea and cationic surfactant, and the sorbent is one or more of: (i) non-toxic to soil microbes as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies and (ii) supportive of microbial growth as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies.

In a fourth aspect, the invention provides a modified clay sorbent comprising a blend of halloysite nanotubes and urea and non-zero valent iron nanoparticles or complex whereby the non-zero valent iron nanoparticles are capped with L-arginine, and wherein the metal nanoparticles are iron oxide nanoparticles, wherein the iron oxide nanoparticles are formed in a one pot synthesis from ferrous chloride and the at least one amino acid or salt thereof, wherein the metal nanoparticles are iron oxide nanoparticles formed in a one pot synthesis from an iron (II) salt such as ferrous chloride and the at least one amino acid or salt thereof, and wherein the clay mineral is modified with one or more of fatty acid, urea and cationic surfactant, and the sorbent is one or more of: (i) non-toxic to soil microbes as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies and (ii) supportive of microbial growth as determined by one or more of 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies.

In a fifth aspect of the invention, there is provided a use of a modified clay sorbent according to the first, second, third or fourth aspects for removal of contaminants from a gas such as air, soil or water, particularly hydrophobic or amphiphilic contaminants or greenhouse gases in the case of air.

In a sixth aspect of the invention, there is provided a method for separating a contaminant from a sample containing the contaminant, the method comprising contacting the sample with a modified clay sorbent according to the first, second, third or fourth aspects under conditions suitable for sorption of the contaminant to the modified clay sorbent.

In a seventh aspect of the invention, there is provided a use of a modified clay mineral sorbent comprising a modified layered type clay mineral and non-zero valent iron nanoparticles capped with one or more amino acids or salts thereof in contaminant remediation.

In an eighth aspect of the invention, there is provided a use of non-zero valent iron nanoparticles capped with arginine in contaminant remediation.

In a ninth aspect of the invention, there is provided a use of non-zero valent iron nanoparticles capped with arginine to modify a clay mineral sorbent for use in contaminant remediation.

In a tenth aspect of the invention, there is provided a use of a modified clay sorbent according to the fourth aspect for removal of contaminants from air particularly greenhouse gases, such as atmospheric carbon dioxide, methane and/or nitrous oxides. The invention also extends to use of captured atmospheric carbon dioxide, methane and nitrous oxides as a combustible material, building material and soil amendment or fertilizer. In some embodiments the modified clay sorbent according to the fourth aspect may used as a ruminant feedstock, particularly for as an additive for cattle feed or use in dung stockpile and feedlots.

Also described is a modified clay sorbent comprising a modified layered type clay mineral and non-zero valent iron nanoparticles whereby the metal nanoparticles are capped with one or more of amino acids, amino acid salts and mixtures thereof.

Also described is a modified clay sorbent comprising a blend of an aluminosilicate clay mineral modified with a cationic surfactant comprising a dimethyldiooctadecyl ammonium cation, and non-zero valent iron nanoparticles whereby the non-zero valent iron nanoparticles are capped with L-arginine.

Also described is a modified clay sorbent comprising a blend of an aluminosilicate clay mineral modified with a cationic surfactant comprising a dimethyldiooctadecyl ammonium cation and further modified with palmitic acid, and non-zero valent iron nanoparticles whereby the metal nanoparticles are capped with L-arginine.

Also described is a modified clay sorbent comprising a blend of halloysite nanotubes and urea and non-zero valent iron nanoparticles whereby the non-zero valent iron nanoparticles and complexes are capped with L-arginine.

In some embodiments, the non-zero valent iron nanoparticles have a core-shell structure capped with one or more amino acids or salts thereof.

Description of the Drawings

Figure 1 shows transmission Electron Microscopy (TEM) images of FeNPs, FeNP modified bentonite (FeNP@B), organoclay composite FeNP@AB (Embodiment 1) and FeNP@ABP (Embodiment 2). The white arrow indicates an iron nanoparticle and the black arrow represents clay layers;

Figure 2 shows scanning electron microscopy (SEM) images (right side) and the energy-dispersive X-ray spectroscopy (EDS) spectra (left side) of the composites, FeNP@ABP (Embodiment 2), FeNP@AB (Embodiment 1) and FeNP@B (control). The SEM images demonstrate co-existence of the nanoparticles grafted on well defined layers of the organoclay AB and ABP. The FeNP@B (control) image shows a different morphology. The yellow arrow indicates an iron nanoparticle and the white arrow represents clay layers;

Figure 3 illustrates X-ray photoelectron spectroscopy (XPS) signatures of FeNP, and the FeNPs on the composite materials FeNP@B, FeNP@AB, and FeNP@ABP;

Figure 4 illustrate the composites FeNP@AB and FeNP@ABP are much more effective at immobilising PFAS a in soil sample than control bentonite B, organo clay FeNP@B and control FeNP alone. Indeed, there are non-detectable PFAS in the soil leachate after two weeks of amendment and soil incubation with the composites FeNP@AB and FeNP@ABP. NA= no amendment of soil. The leachate test was conducted following a modified simple one-step European Standard leaching test method "EN 12457-2". The plot also demonstrates the better performance of the organoclay composites against matCARE™ and FeNP alone;

Figure 5 shows the results of the biocompatibility test using soil bacterial colony-forming unit (CFU) studies. The organoclay composites of the invention are either supportive (FeNP@ABP) or not detrimental (FeNP@AB) to soil bacteria compared to the control soil (NA);

Figure 6 illustrates the images of the plates and CFU of bacteria on agar plate which correspond to the results presented in Figure 5;

Figure 7 illustrates the 16S rRNA metagenomic signature which shows that soil amendment with either composites (FeNP@ABP or FeNP@AB) did not significantly change the native soil microbial diversity after treatment, where key role players, including hydrocarbon-degrading bacteria Proteobacteria, Actinobacteria and Bacteroidetes would have otherwise been impacted, e.g., significantly altered, reduced and/or abolished;

Figure 8 illustrates the composite of Embodiment 3 where the iron oxide nanoparticles where composited with urea-blended halloysite nanotubes. The strong energy-dispersive x-ray spectroscopy (EDS) peak confirms the presence of iron in the composite;

Figure 9 illustrate SEM images and EDS data for raw halloysite (FINT) (on left) has been converted to the composite FeNP@UreaFINT (on right) without causing any morphological changes. The strong energy- dispersive x-ray spectroscopy (EDS) peak indicates the presence of iron in the FeNP@UreaFINT composite; Figure 10 illustrates adsorption of a PFOS+PFOA mixture to FINTs alone and to the composite materials FeNP@UreaFINT in aqueous suspension. The results show that PFOS and PFOA is absorbed to a similar level as matCare for PFOA and to better level as matCare for PFOS. Conditions: total nominal PFAS concentration was mixture of 1 pg/L of PFOS and PFOA each; pH = 5.0 in water medium;

Figure 11 illustrates CFU bacterial growth studies demonstrate that the post-adsorption materials can be safely disposed to a disposal site as the FeNP@UreaFINT composite itself does not pose any toxicity to the natural organisms;

Figure 12 illustrates changes to the soil microbial diversity profile after treatment with the FeNP@UreaFINT composite, but it is evident that the major microbial taxa originally present are substantially preserved compared to non-amended control soil (NA), also compares the MatCARE™ treated soil where skewed pattern of diversity with predominately Proteobacteria are observed.

Detailed Description of the Invention

The present invention provides a modified clay sorbent. Preferred modified clay sorbents of the invention adsorb contaminants from contaminated materials including groundwater, soils, sands and/or sediments. Preferred modified clay sorbents of the invention adsorb hydrophobic and/or amphiphilic contaminants, for example, PFAS contaminants, such as PFOS and/or PFOA contaminants in soil. Particularly preferred modified clay sorbents of the invention adsorb carbon containing gases such as greenhouse gas including carbon containing gases such as carbon dioxide and/or methane.

The preferred modified clay sorbent of the invention effectively fixes or immobilises contaminants, for example, PFAS contaminants (e.g., PFOS and PFOA) within the sorbent material. A preferred modified clay sorbent fixes or immobilises contaminants in soil treated with the modified clay sorbent of the invention.

Desirably, the modified clay sorbent is non-toxic to one or more soil microbes.

In some embodiments, the toxicity or otherwise may be determined by one or more of: metagenomics studies, e.g., 16S rRNA soil microbial diversity studies, as well as bacterial colony-forming unit (CFU) studies. In some embodiments, the modified clay sorbent is supportive of growth or proliferation of one or more soil microbes in soil treated with the modified clay sorbent compared to same soil which has not be treated with the modified clay sorbet of the invention.

In some embodiments, the growth or proliferation of soil microbes in soil after treatment with preferred modified clay sorbent of the invention may be determined by one or more of: 16S rRNA soil microbial diversity studies and bacterial colony-forming unit (CFU) studies. Desirably, the modified clay sorbent is particularly suitable for use as a soil contaminant sorbent. As preferred modified clay sorbent are non-toxic and/or supportive to one or more soil microbes, such preferred modified clay sorbents are as a "leave in" soil contaminant sorbent. While applications involving soil remediation are preferred due to the favourable microbial toxicity profile, the modified clay sorbent of the invention can also be used in water treatments such as the technology where wastewater is pumped through sorbent; in this case, the disposal of spent sorbent is not toxic to the disposal soil/land site.

Modified clay sorbent

The modified clay sorbent comprises a modified layered type clay mineral and metal nanoparticles. The modified clay sorbent is thus a composite material comprising modified layered type clay mineral and the metal nanoparticles. In a preferred embodiment, the modified clay sorbent is in the form of a mixture or a blend of the modified clay mineral and metal nanoparticles. Desirably, the metal nanoparticles are grafted onto layers of the modified clay mineral.

Suitably, the modified clay sorbent is a porous material. Suitably, adsorbed contaminants are retained within the pores of the modified clay sorbent.

Desirably, the metal nanoparticles comprise iron nanoparticles. Suitably, the iron of the iron oxide nanoparticles is not zero valent iron (Fe°), that is a strongly reducing form of iron. Desirably, the iron nanoparticles comprise iron oxide nanoparticles. Preferably, the iron nanoparticles are iron oxide nanoparticles. Preferably, the metal nanoparticles are iron oxide nanoparticles, and wherein the iron of the iron oxide nanoparticles comprises a mixture of iron in the Fe ²⁺ and Fe ³⁺ oxidation states. Suitably, the metal nanoparticles are iron oxide nanoparticles and wherein the iron oxide nanoparticles comprise one or more of: magnetite (FesC ) nanoparticles and hematite (Fe203) nanoparticles. Desirably, the metal nanoparticles, preferably, the iron oxide nanoparticles, are modified with urea. In one embodiment, the metal nanoparticles are iron oxide nanoparticles, the clay sorbent is modified with urea and wherein the iron oxide nanoparticles comprise predominantly hematite (Fe ₂ 0 ₃ ) nanoparticles.

Magnetite nanoparticles are magnetic, and this property can be used to aid in their removal from a material to be decontaminated for example wastewater or groundwater if desired. Flowever, this is less relevant where the material to be decontaminated is soil as in preferred embodiments, the sorbent is to be used as a leave in treatment and thus is not required to be removed/separated from the soil after treatment.

Amino acids

Preferably, the metal nanoparticles are capped with one or more amino acids, amino acid salts and mixtures thereof. The amino acids and amino acid salts may be in the D- or the L- form. Suitably, the one or more amino acids are selected from arginine, phenylalanine, tryptophan, glycine, and glutamic acid, or salts thereof, or mixtures thereof. Preferably, the amino acid is arginine, more preferably, L- arginine.

Preferably, the clay mineral is modified with one or more of at least one fatty acid, urea and at least one cationic surfactant.

Desirably, the clay mineral is modified with at least one cationic surfactant which may intercalate in interlayer regions of the clay mineral.

Suitably, the clay mineral may be modified with at least one fatty acid which may intercalate in interlayer regions of the clay mineral.

Desirably, the clay mineral is modified with at least one cationic surfactant and at least one fatty acid, both of which may intercalate in interlayer regions of the clay mineral.

In one embodiment, the clay mineral is modified with at least one fatty acid, urea and at least one cationic surfactant.

In one embodiment, one or more of the at least one cationic surfactant, urea and the at least one fatty acid interact together via one or more of: weak intramolecular forces, hydrophobic interactions, polar interactions and ionic interactions.

Clay mineral

Suitably, a preferred clay mineral is a hydrous aluminosilicate. Preferably, the clay mineral is a phyllosilicate, for example, a 1:1 or 2:1 phyllosilicate. More preferably, the clay mineral is a smectite such as saponite and montmorillonite, or palygorskite. Preferably, the clay mineral is a halloysite. Halloysite is a kaolin derivative where the mineral occurs as nanotubes. In one embodiment, the clay mineral comprises halloysite nanotubes. Preferred halloysite nanotubes range from about 1 to about 15 nm in length and from 10 to 150 nm of inner diameter.

Particularly preferred halloysite nanotubes are around from 12 nm to 33 nm of inner diameter. In one embodiment, the halloysite nanotubes are further modified with urea. In one embodiment, the metal nanoparticles are seeded and/or embedded within the halloysite nanotubes.

Cationic surfactant

Preferably, the cationic surfactant comprises at least one quaternary ammonium cation. Desirably, the cationic surfactant comprises a quaternary alkylammonium cation. Desirably, the cationic surfactant comprises one or more hydrocarbon tail groups comprising one or more alkyl chains at least 8 carbons in length, at least 12 carbons in length, or at least 16 carbons in length. Suitably, the cationic surfactant comprises one or more alkyl chains of 18 carbons in length. Preferably, the cationic surfactant comprises a dimethyldioctadecyl ammonium cation and salts thereof. In one embodiment, the cationic surfactant comprises dimethyldiooctadecyl ammonium chloride. A suitable cationic surfactant is available under the trade name Arquad ^® 2HT-75. Preferably, the surfactant is a cationic surfactant. Suitably, the cationic surfactant is present in an amount corresponding to not more than 100% cationic exchange capacity of the particular clay used. It is believed that higher amounts of surfactant may increase the toxicity of the composition to microbes.

Fatty acid

Suitable fatty acids comprise at least one alkyl chain of at least 10 carbons in length, at least 11 carbons in length, at least 12 carbons in length, at least 13 carbons in length, at least 14 carbons in length, at least 15 carbons in length, at least 16 carbons in length, at least 17 carbons in length, at least 18 carbons in length, at least 19 carbons in length, or at least 20 carbons in length. Preferably, the fatty acid is a saturated alkyl chain of 13 to 18 carbons in length. Preferably, at least one fatty acid is palmitic acid or stearic acid.

Preferably, the fatty acid is present in an amount corresponding to not more than 100% cationic exchange capacity of the particular clay used. It is believed that higher amounts of fatty acid may increase the toxicity of the composition to microbes.

Urea

In preferred embodiments involving urea, 1-10 M urea solution using Milli-Q water was used to modify clay where 10 mg clay per mL was maintained in the aqueous system. For example, 30 mis of 5 M urea may be used with 300 mg of clay.

Nanooarticles

Preferred nanoparticles are those with average diameters in the range of from about 5 nm to about 30 nm. In preferred embodiments, the composition comprises nanoparticles in an amount up to 50%wt of the total composition. Preferably, wherein the iron nanoparticles are iron oxide nanoparticles, the iron oxide nanoparticles are formed in a one pot synthesis from an iron (II) salt, such as ferrous chloride, and one or more amino acids, amino acid salts and mixtures thereof. Preferably, wherein the iron nanoparticles are iron oxide nanoparticles, the iron oxide nanoparticles are formed in a one pot synthesis from a Fe(ll) salt, such as ferrous chloride, and arginine, phenylalanine, tryptophan, glycine, and glutamic acid, or salts thereof, or mixtures thereof. Preferably, the iron oxide nanoparticles are formed in a one pot synthesis from a Fe(ll) salt, such as ferrous chloride, and arginine, particularly L-arginine.

Preferably, the iron nanoparticles are iron oxide nanoparticles, the iron oxide nanoparticles are formed in a one pot synthesis from a Fe(ll) salt, such as ferrous chloride, and one or more amino acids, amino acid salts and mixtures thereof and urea. Preferably, wherein the iron nanoparticles are iron oxide nanoparticles, the iron oxide nanoparticles are formed in a one pot synthesis from ferrous chloride and arginine, phenylalanine, tryptophan, glycine, and glutamic acid, or salts thereof, or mixtures thereof and urea. Preferably, the iron oxide nanoparticles are formed in a one pot synthesis from a Fe(ll) salt, such as ferrous chloride, and arginine, particularly L-arginine and urea. Other suitable Fe ²⁺ salts can be used such as ferrous sulfate.

Toxicity

A substantial advantage of the modified clay sorbents of the invention over existing sorbents used in contamination remediation from soil is their less detrimental overall effect on soil microbe diversity and abundance than existing solutions such as MatCARE™. As shown in the diversity data described herein for soil treated with the modified clay sorbents of the invention, the sorbents are less disruptive to the soil microbe diversity and abundance, at least over 7 and 14 days after treatment, than MatCARE™, at least at the concentrations of sorbent used to inhibit the leaching potential to the degree as described herein.

The results show that the functional group of soil microbes (in most cases, Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi and Bacteroidetes) are not abolished by the material.

While the microbial diversity and relative abundance is altered to a degree by the amendment, alteration does not occur to any significant degree, at least compared to that experienced using a comparable amount of MatCARE™. Therefore, where the existing microbial groups are still viable and still functioning, ultimately restoration of the land or remediation site is more easily attained when the sorbents of the invention are used. In the case of MatCARE™, while these group are present after material amendment, in cases where too much alternation in diversity and relative abundance occurs, the overall recovery time of the natural biota or the biodegradation efficiency of other pollutants in the land/remediation sites may be negatively influenced. In summary, the results demonstrate that soil bacterial growth is not significantly reduced by the sorbent materials of the invention and in fact as demonstrated by the results may even be supportive of soil microbial growth after treatment, particularly with FeNP@ABP. The minimal effect on treated soil soil microbe diversity and abundance compared to untreated soil is described herein as "non-toxic" in the sense that sorbent of the invention is not harmful to the preservation of the overall native/natural living state of the microbes present in the soil prior to treatment.

Applications

Also described herein is a method for separating a contaminant from a sample containing the contaminant, the method comprising contacting the sample with a modified clay sorbent according to the first aspect of the invention under conditions suitable for sorption of the contaminant to the modified clay sorbent.

The term "separating" a contaminant from a sample containing the contaminant should be understood to include any reduction of the amount of contaminant determinable in the sample after contact with the modified clay sorbent relative to the amount of contaminant in the sample prior to contacting of the sample with the modified clay sorbent. As set out above, separation of a contaminant from a sample is effected by sorption of the contaminant in the sample to the modified clay sorbent, thus fixing or immobilising the contaminant on the sorbent, and in this sense, removing it from the sample. In other words, the separation as described herein means the sorbed contaminant is unable to leach out of the sample for example in water or wash off. Separating a contaminant from a sample may include complete or partial separation between the contaminant and sample.

The sample for use in accordance with the second aspect of the invention may be any sample which contains a contaminant. When the contaminant is an environmental contaminant, the sample may be an environmental sample such as a water sample, a soil sample, a soil dilution sample, a sand sample, a sediment sample, a gaseous or atmospheric sample and the like. In some embodiments the sample may be an effluent sample from industry including liquid effluents such as wastewater, gaseous effluents, solid effluents or contaminated land sites. In some embodiments the sample may be environmental water or air for which the removal or one or more contaminants is desirable. For example, the modified clay sorbent may be incorporated into air filters or water filters to produce air or water for human or animal consumption or industrial or agricultural use. In some embodiments, the gaseous or atmospheric sample may be a gas such as air whereby the contaminant is a carbon containing gas, for example, a green house gas including carbon containing gases such as carbon dioxide, methane, etc. The halloysite clays of the invention are particularly preferred GFIG remediation applications.

In light of the foregoing, the sample may be contacted with the modified clay sorbent in any suitable manner. For example, in some embodiments, an effective amount of the modified clay sorbent may be stirred in a settling tank or other reaction vessel, reactor or structure into which an effluent or slurry containing a contaminant may be pumped. In the vessel, the effluent or slurry may be contacted with the modified clay sorbent and sorption of the contaminant to the modified clay sorbent may occur. Following sorption of the contaminant by the modified clay sorbent, the modified clay sorbent with associated contaminant may be separated from the remaining liquid (now having a reduced level of available/detectable contaminant) by any suitable means, such as flocculation, filtration, sedimentation, centrifugation or the like.

In some embodiments, a liquid sample may be introduced into and/or pumped through one or more reactors, fluidized beds, columns, filters or landfills containing the modified clay sorbent such that outlet liquid from the above structures will have reduced contaminant concentration due to sorption of the contaminant by the modified clay sorbent in the structure.

The structure housing the modified clay sorbent may be on a large scale such as for the treatment of industrial effluents or slurries or may be on a smaller scale such as respirator filters, personal or domestic water filters and the like.

In some embodiments, the sample may be in situ and the modified clay sorbent may be applied to the sample. For example, a modified clay sorbent may be applied to a pond, waterway, soil or land site which comprises the contaminant.

In some embodiments, after sorption of a contaminant by the modified clay sorbent, the modified clay sorbent may be disposed of and/or the contaminant may be desorbed from the modified clay sorbent and the modified clay sorbent may then be reused. An example of a suitable desorption method includes solvent extraction using methanol.

As described later, once fixed, adsorbed or immobilised to a sorbent of the present invention, contaminants (including at least perfluorinated compounds), do not substantially desorb from the sorbent under environmental conditions for at least a defined period of time. For example, in some embodiments, once adsorbed to a sorbent of the present invention, contaminants (including at least perfluorinated compounds), do not substantially desorb from the sorbent under environmental conditions for at least 15 days, at least 30 days, at least 45 days, at least 90 days, at least 120 days, at least 150 days, at least 180 days, at least 210 days, at least 240 days, at least 270 days or at least 300 days.

In light of the above, in some embodiments, a sorbent may be incorporated into a sample in situ in the environment (such as soil or water in situ) and remain in the sample in order to adsorb and reduce the availability of the contaminant in the sample. Such contaminants cannot readily leach from the sample.

The present method contemplates sorption of any suitable contaminant that may be adsorbed to, or absorbed by, a modified clay sorbent according to the first aspect of the invention.

In some embodiments, the contaminant is a hydrophobic contaminant, more particularly a hydrophobic organic contaminant or one which contains one or more hydrophobic subunits, for example, PFOS comprises a C ₈ FI ₇ in its molecule, its adsorption occurs mainly through the hydrophobic interactions (partitioning) with the long chains of the surfactant molecules attached to the modified clay. In these embodiments, sorption between the hydrophobic organic contaminant and the modified clay sorbent may occur through adsorption or absorption of the hydrophobic contaminant, more particularly a hydrophobic organic contaminant or hydrophobic subunit thereof, to the hydrophobic tail groups of one or more of the surfactant and the fatty acid (when present) in the modified clay sorbent.

Examples of hydrophobic organic contaminants which may be adsorbed or absorbed using the modified clay sorbents of the present invention include, for example, phenol, phenol derivatives, BTEX (such as benzene, toluene, ethylbenzene and xylenes), and the like.

In some embodiments, the modified clay sorbents of the present invention have particular application for the sorption of surfactants. As would be readily understood by a person skilled in the art, a "surfactant" is an amphipathic molecule comprising both a hydrophobic portion and hydrophilic portion. Examples of surfactants include amphiphilic surfactants, anionic surfactants, cationic surfactants, zwitterionic surfactants and nonionic surfactants. In each case, sorption between the surfactant and the modified clay sorbent may occur through adsorption or absorption of a hydrophobic tail of the surfactant to a hydrophobic tail group of a fatty amine in the modified clay sorbent.

In some embodiments, the contaminant comprises an anionic surfactant. In the case of an "anionic surfactant", the hydrophilic portion of the molecule generally carries a negative charge at least at a pH of 7 or greater. As such, the term "anionic surfactant" may include molecules such as carboxylic acids which may form an anion (i.e., a conjugate base) at a pH of 7 or greater, but which may not necessarily be in an anionic form at a pH lower than 7. For example, a carboxylic acid surfactant in an environmental sample may be regarded as an anionic surfactant even if the carboxylic acid surfactant is not necessarily in an anionic form until it is in the presence of a base such as a basic cationic dye. Exemplary anionic surfactants include, for example, linear alkylbenzene sulfonate (LAS), sodium dodecyl sulfate (SDS), fluorinated anionic surfactants such as perfluorooctane sulfonate (PFOS) or perfluorooctanioic acid (PFOA), and the like.

In some embodiments, the contaminant is a perfluorinated or polyfluorinated hydrophobic contaminant. Perfluorinated compounds (PFCs) refer to a class of organofluorine compounds that have all hydrogens replaced with fluorine on a carbon chain. Such compounds may be an unsubstituted fluorocarbon or may also contain at least one different atom or functional group. PFCs may be used to make other materials stain, oil, and water resistant, and are widely used in diverse applications. PFCs persist in the environment as persistent organic pollutants, but unlike PCBs, they are not known to degrade by any natural processes due to the strength of the carbon-fluorine bond.

There are many PFCs, but the two most studied compounds are: perfluorooctanoic acid (PFOA) used to make fluoropolymers such as Teflon, among other applications; and perfluorooctanesulfonic acid (PFOS) used in the semiconductor industry, 3M's former Scotchgard formulation, and 3M's former fire fighting foam mixture. Further examples of PFCs include: perfluorononanoic acid (PFNA) used as surfactant in the emulsion polymerization of fluoropolymers, like PFOA; perfluorobutanesulfonic acid (PFBS) used as a replacement for PFOS in 3M's reformulated Scotchgard; perfluorooctanesulfonyl fluoride (POSF) used to make PFOS-based compounds; perfluorooctanesulfonamide (PFOSA) formerly used in 3M's Scotchgard formulation; and FC-75, a 3M Fluorinert liquid and perfluorinated cyclic ether.

Polyfluorinated compounds, such as fluorotelomers, can serve as precursors that degrade to form perfluorinated carboxylic acids, such as PFOA and PFNA.

The modified clay sorbents of the present invention also have particular application for the sorption of contaminants which are constituents of aqueous film forming foams (AFFF), such as the fluorinated surfactants mentioned above. Exemplary AFFFs include Light Water™ (3M, St. Paul, MN, USA) and Ansulite (Ansul Incorporated, Marinette, Wl, USA).

As set out above, a sample is contacted with a modified clay sorbent according to the first aspect of the invention "under conditions suitable for sorption of the contaminant to the modified clay sorbent". Such conditions include suitable concentrations of the sample and modified clay sorbent, suitable temperature, suitable pressure, suitable pH and the like. In general, these could be determined by a person skilled in the art for any combination of contaminant and modified clay sorbent.

In some embodiments, it has been determined that the modified clay sorbents of the present invention can adsorb or absorb hydrophobic contaminants, such as PFOS and PFOA, from soil and/or wastewater over a broad range of TOC, pH, temperature and salinity.

In existing solutions, the concentration of sorbent used depends on the remediation site in question, but typical application involve use of up to about 5% wt of sorbent to soil to be treated. By contrast, the effectiveness of the present sorbents is such that excellent results for PFAS contaminants is achievable at a sorbent concentration of about 1% wt of sorbent to soil. For treatment of a water based sample, the sorbet concentration is less than 0.5% and more preferably at around 0.1 % w/v sorbent to water. It is clearly favourable to use lower concentrations of sorbent insofar as possible as low dosage use is associated with a more desirable cost-benefit profile as well as avoiding extra burden of any ecotoxicity associated with higher concentrations of the sorbent material. However, as necessary, the sorbet of the invention can be used at up to about 2% wt, up to about 3% wt, up to about 4% wt of sorbent to soil and higher than 5 % wt if required for a particular application.

Also described herein is a modified clay sorbent for removal of PFOS contaminants from soil or water. Suitably, a preferred modified clay sorbent comprises a quaternary ammonium surfactant, fatty acid modified bentonite and iron oxide nanoparticles whereby the iron oxide nanoparticles are capped with arginine. Also described herein is a modified clay sorbent for removal of PFOS contaminants from soil or water. Suitably, a preferred modified clay sorbent comprising urea modified halloysite nanoparticles and iron oxide nanoparticles whereby the iron oxide nanoparticles are capped with arginine.

Also described herein is a method for separating a contaminant from a sample containing the contaminant, the method comprising contacting the sample with a modified clay sorbent according to the first aspect under conditions suitable for sorption of the contaminant to the modified clay sorbent.

Suitably, the sample comprises one or more of soil, sand, rock, sediment and gas such as air.

Suitably, the sample comprises water. In one embodiment, the sample is primarily water.

The method as described herein, wherein the sample is in situ in the environment. In some embodiments soil is preferred. In other embodiments, gas such as air is preferred.

Desirably, one or more contaminants is a hydrophobic contaminant as PCBs or pharmaceutical residues or a predominantly hydrophobic contaminant, such as PFOS. Preferably, at least one contaminant is an amphiphilic contaminant or an anionic contaminant. Suitably, the contaminant comprises a perfluorinated or polyfluorinated compound. Desirably, at least one contaminant comprises an aqueous film forming foam (AFFF) or a constituent thereof. Preferably, at least one contaminant comprises one or more of PFOA and PFOS.

Also described herein is the use of a modified clay mineral sorbent comprising a modified layered type clay mineral and metal or metal oxide nanoparticles whereby the metal or metal oxide nanoparticles are capped with one or more amino acids or salts thereof in contaminant remediation. Suitably, the nanoparticles used are iron oxide nanoparticles capped with arginine. Preferably, contaminant remediation removes contaminates from soil or water.

Also described herein is a use of iron oxide nanoparticles whereby the iron oxide nanoparticles are capped with arginine in contaminant remediation, preferably contaminant remediation in soil or water.

Also described herein is a use of iron oxide nanoparticles whereby the iron oxide nanoparticles are capped with arginine to modify a clay mineral sorbent for use in contaminant remediation, preferably contaminant remediation in soil or water. Suitably, in such use, the contaminant is PFOS, phenanthrene, and/or heavy metals or metalloids such as copper.

In order to quantify the leaching of PFAS from soil which has been subjected to sorbent amendment and which has not been subjected to sorbent amendment, a standard one step batch leach test is carried out according to method EN 12457-2 with a few modifications before and after sorbent amendment.

Briefly soil (2 g taken from a PFAS-mixed homogenised subsample of soil) was shaken with water for 8 days at a liquid to solid ratio of 10 and then filtered (through 0.7 mm polyethersulfone membrane) before analysis. For sorbent amended samples, 1% of each sorbent material was homogenously mixed with soil. Leachate water was stored at prior to analysis. The concentration of each individual PFAS in the filtered water at the end of the experiment mg L ¹ ) was measured, and the concentration leached per dry weight of soil, Ca _ched (mg kg *) was calculated as follows: is the volume of water in the batch system, and is the solid (soil or soil + sorbent) dry weight (kg).

The leaching potential was expressed as percentage individual PFAS detected in leachate out of the spiked amount of the same compound.

The present inventors have developed metal nanoparticles, particularly iron oxide nanoparticles (referred to herein as "FeNP") using only ferrous chloride and L-arginine. The metal nanoparticles are then grafted to two types of organoclay which were designed to make active modified clays that can trap PFAS in soil without posing excessively diversity disruptive or toxicity to native soil microbiota. Description of preferred embodiments of the invention

Exemplary embodiments of the present invention are further described by the following non limiting examples:

FeNPs@AB - Embodiment 1

The first embodiment involves a modified organoclay which is a cationic surfactant modified Australian smectite clay (more specifically saponite, collected from a Western Australian deposit) referred to herein as "AB". A particular cationic surfactant available under the trade name, Arquad was used (Arquad 2HT-75). The iron oxide/cationic surfactant modified Australian smectite clay is referred to herein as FeNPs@AB.

FeNPs@ABP - Embodiment 2

The second embodiment involves a modified organoclay which is a fatty acid modified cationic surfactant modified Australian smectite clay (more specifically saponite, collected from Western Australian deposit) referred to herein as "ABP". A particular fatty acid being palmitic acid was used. The fatty acid modified/cationic surfactant modified Australian smectite clay is referred to herein as

FeNPs@ABP.

Experimental Description of AB and ABP material synthesis Synthesis ofAB and ABP:

For organoclay preparation, a cationic surfactant, Arquad ^® 2HT-75 (Sigma-Aldrich, Australia) and a chelating agent, palmitic acid (PA) (>98% pure, Sigma-Aldrich, Australia) were used. A two-step treatment was applied. First, Arquad ^® -treated bentonite (AB) was prepared with the surfactant (loading: 100% of cation exchange capacity (CEC) of a bentonite (B)) where the surfactant was dissolved in Milli-Q water (resistivity > 18 MW cm) in the ratio of 20 times volume of the mass of clay. The mixture was sonicated for 5 minutes followed by stirring at 80 °C for 4 hrs. After centrifugation, the pellet was collected, washed with mild hot Milli-Q water until a chlorine free supernatant was obtained. The freeze- dried powder form of material (AB) was stored under vacuum desiccator until further usages. This organoclay (AB) was then treated with PA (loading: 100% of CEC of B). The PA was delivered through an ethanol-water mixture (1:1 v/v). The treatment medium was gently stirred for 4 h at 25 °C by maintaining an alkaline pH (pH = 8-8.5). Similar to post-synthesis AB treatment, the powder form of ABP was obtained stored in a vacuum desiccator.

Synthesis of FeNPs@AB and FeNPs@ABP:

A one pot synthesis of FeNP@AB or FeNP@ABP was undertaken using 40 mM of L-arginine, 20 mM of FeCI ₂ where 2.5 mg of clay product (AB or ABP) was used per mL of reaction. The reaction was stirred in N ₂ flow chamber for 3 hours. The pellet was collected by centrifugation, washed twice with absolute ethanol and once with MQ water before freeze-drying to obtain powder form of material.

Experimental Description of application of FeNPs@AB and FeNPs@ABP:

Soil test conditions:

The contaminated soil was collected from Williamstown, Australia. For the experimental purpose and remediation feasibility, the soil was further spiked with elevated level of PFAS concentration (200 pg/kg soil for PFOS and 100 pg/kg soil for PFOA). Then, the composite materials were mixed with PFAS- contaminated soil maintaining the ratio of composite:soil = 1:100 ("Only 0.5% of iron nanoparticles basis) at soil's original pH (pH ~ 8.0) condition. This mixing condition was the simulation of conventional techniques of "amending materials spreading and ploughing" where the soil moisture was maintained up to only 15%.

PFAS adsorption test:

The leachate test was conducted following simple one-step European Standard leaching test method "EN 12457-2". From the supernatant, the concentration of PFOS and PFOA was measured using Liquid Chromatography Mass Spectrometry (LC-MS/MS, Agilent 1260 Infinity (LC) and AgilentTriple Quad 6470 (MS), Analytical column: Agilent C18 RRHD 2.1x50mm, 1.8 Micron and delay column: Agilent C18 RR 4.6x50mm, 3.5 Micron).

Biocompatibility tests:

Periodically (7 and 14 days), the amended soil was withdrawn to count colony forming unit (CFU) of soil bacteria while soil microbial diversity profile was assessed from 14 day incubated soil. The gDNA of soil microbe (Bacteria & Archaea) was extracted and sequenced for the 16S rRNA diversity profiling. The service was provided by Australian Genome Research Facility (AGRF).

CFU counting protocol:

For CFU study, a solution (10 mL) of sodium hexametaphosphate (35 g L ^_1 ) and sodium carbonate (7 g L ^_1 ) was used as the dispersing medium of the incubated soil (1 g). This solid-liquid mixture was kept at vigorous shaking on an orbital shaker at 300 rpm overnight, which allowed the bacteria to be dispersed and homogeneously distributed in the mixture. The bacterial growth was measured by counting CFU on plates containing nutrient agar media after 5 days of incubation at 25 °C.

16S rRNA diversity study protocol:

From the extracted gDNA of soil sample, 16S-rRNA (V3-V4) amplicons were generated using the primers 341F (5 -CCTAYGGGRBGCASCAG-3') and 806R (5 -GGACTACNNGGGTATCTAAT-3') using AmpliTaq Gold 360 mastermix (Life Technologies™, Australia) for the primary PCR. The PCR cycle conditions were: 7 min at 95 °C, followed by 29 cycles of 30 s at 94 °C, 1 min at 50 °C (ramp 3 °C/s), 1 min at 72 °C and final elongation time 7 min at 72 °C. A secondary PCR to index the amplicons was performed with TaKaRa Taq DNA Polymerase (Takara Bio USA, Inc.). The resulting amplicons were sequenced on lllumina MiSeq (San Diego, CA, USA) with 2 x 300 base pairs paired-end chemistry. The sequences were cleaned, trimmed and used to construct operation taxonomic units (OTUs), which were taken to identify the available taxon using QIIME and silva rl32 database. In this case, the phylum level was used to chart the abundance profile of detected microbial group.

FeNP@UreaHNT - Embodiment 3

The inventors used the iron oxide nanoparticles (known as FeNP) formed from only ferrous chloride and L-arginine to prepare another modified material. The FeNP nanoparticles were grafted to urea-grafted halloysite nanotubes (HNTs). This composite formed is referred to herein as "FeNP@UreaHNT". Blending the urea to the HNT influences the formation of the nanoparticles onto HNT in novel way whereby the Fe nanoparticles become embedded into the UreaHNT. This contrasts with the composite formed when iron nanoparticles seeded on raw HNT.

The FeNP@UreaHNT is found to be highly efficient at adsorbing PFAS, and, advantageously, the post adsorbed material is not toxic to the microbes and indeed is believed to be supportive of microbial growth in the soil at the disposal site.

Experimental Description of FeNP@UreaHNT material synthesis:

Synthesis of FeNP@UreaHNT:

30 mL of concentrated urea (5-10 M) was used to functionalise 300 mg HNTs with urea. The lumen of HNTs were increased using mild acid before the urea modification of HNTs. The reaction conditions were as follows: 80 h of continuous stirring at 65 °C on hot plate. The UreaHNT pellet was obtained by centrifugation and repeated washing, which was then freeze-dried to obtain powder samples.

A one pot synthesis of FeNP@UreaHNT was undertaken using 40 mM of L-arginine, 20 mM of FeCI ₂ where 2 mg of UreaHNT was used per mL of reaction. The reaction was stirred in N ₂ flow chamber for 3 hours. The pellet was collected by centrifugation, washed twice with absolute ethanol and once with MQ water before freeze-drying to obtain powder form of material.

Experimental Description of FeNP@UreaHNT application: PFAS adsorption test from aqueous suspension:

Only 0.1% of FeNP@UreaHNT was applied to the contaminated water volume for the PFAS removal test. The following conditions were applied: total nominal PFAS concentration was mixture of 1 pg/L of PFOS and PFOA each; pH = 5.0 in water medium. Over a 48 h of equilibrium period, the post- adsorbed supernatant was collected to test PFAS. The concentration of PFOS and PFOA was measured using Liquid Chromatography Mass Spectrometry (LC-MS/MS, Agilent 1260 Infinity (LC) and Agilent Triple Quad 6470 (MS), Analytical column: Agilent C18 RRHD 2.1x50mm, 1.8 Micron and delay column: Agilent C18 RR 4.6x50mm, 3.5 Micron).

Results of PFAS adsorption from soil by Embodiment 1 and 2:

Among the 200 mg/kg PFOS mixed soil, the sorbent of Embodiment 1 (FeNPs@AB) prevented any leachate containing the tracing of this compound while the control soil (no amendment) released 75.36 ± 13.37% of the given PFOS into leachate. The sorbent of Embodiment 2 showed similar results. In the case of PFOA mixed soil (100 mg/kg), the sorbent of Embodiment 1 improved PFOA immobilisation in soil as only 0.35 ± 0.5% of the given concentration was leached in compared to 16.89 ± 2.45% for unamended soil. In the case of the sorbent of Embodiment 2, the immobilisation was even greater (0.11 ± 0.10%). Under the same conditions, MatCARE™ posed 2.48 ± 0.90% leaching potential of given PFOS and 0.71 ± 0.08% of given PFOA.

Biocompatibility of Embodiment 1 and 2 during soil amendment:

The unamended soil had bacterial count of (9.29 ± 2.58) x 10 ⁵ cfu per g soil after 7 days of incubation, which increased to 28.2 ± 17.5) x 10 ⁵ cfu per g soil at day 14. However, the embodiment 1 variably reduced the growth by 1.5 to 3.2 folds at 7 and 14 days, respectively. On the other hand, embodiment 2 rather increased that bacterial growth by 6.4 fold at day 7 and 1.3 fold at day 14.

On the other hand, 16S rRNA metagenomic signature shows that soil amendment with either composites (FeNP@ABP or FeNP@AB) did not overtly change the soil microbial diversity from that of the non amended soil, where key role players, including hydrocarbon-degrading bacteria Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes would have otherwise been impacted or abolished through use of matCare sorbent. However, in both cases, Chloroflexi group was replaced by Firmicutes and/or Proteobacteria, Actinobacteria. In contrast, when matCare was used, only Proteobacteria, Actinobacteria and Bacteroidetes were prevailed while Acidobacteria, Chloroflexi and Firmicutes were lost.

Biocompatibility test of material disposal for Embodiment 3:

From 1% FeNP@UreaHNT amended soil, periodically (7 and 14 days), a sample was withdrawn and used to count colony forming unit (CFU) of soil bacteria while the soil microbial diversity profile was assessed from 14 day incubated soil. The gDNA of soil microbe (Bacteria & Archaea) was extracted and sequenced for the 16S rRNA diversity profiling. The service was provided by Australian Genome Research Facility (AGRF). The results in Figure 4 demonstrate the biocompatibility of the composite in soil environment.

CFU counting protocol:

See same protocol used for Embodiment 1 and 2 biocompatibility tests.

CFU results:

The bacterial colony indicates that the material FeNP@UreaFINT is not toxic as defined herein, rather it increases bacterial growth by 18% (week 1) and 5% (week 2) than for the control (no material amendment) (Figure 11).

16S rRNA diversity study protocol:

See same protocol used for Embodiment 1 and 2 biocompatibility tests.

16S rRNA diversity Results:

In the Embodiment 3 disposal in the soil environment, only Bacteroidetes was replaced by either Firmicutes and/or Actinobacteria while other three major group i.e. Proteobacteria, Acidobacteria and Chloroflexi remained abundant. In contrast, when MatCARE™ was used, only Proteobacteria, Actinobacteria and Bacteroidetes were prevailed while Acidobacteria, Chloroflexi and Firmicutes were lost.

Discussion

Soil is considered a major reservoir of bacterial genetic diversity. The abundance and diversity of biota is soil is significant. Soil bacteria are the principal component of the decomposer subsystem regulating nutrient cycling, energy flow and ultimately plant and ecosystem productivity. Most decomposition of crop residues and organic matter in soils is done by microbial communities including bacteria. Bacterial diversities in soil can be identified by phenotypic classification whereby the phyla present in soil can be identified using next generation sequencing/metagenomic studies and involve use of a 16S rRNA gene-based metagenomics approach to produce high-resolution characterization of bacterial abundance and diversity. Commonly found phyla in the soils tested herein include one or more selected from the group of Proteobacteria, Actinobacteria, Bacteroidetes, Acidobacteria, Chloroflexi, Firmicutes, and Gemmatimonadetes.

The metagenomic studies reported in Figure 7 and 11 how that a non amended soil sample has a rich biodiversity comprising bacteria phyla including Proteobacteria, Actinobacteria, Bacteroidetes, Acidobacteria, Chloroflexi, Firmicutes, and Gemmatimonadetes at various abundances. It can be seen from Figure 7 and 11, that the FeNP@AB and FeNP@ABP and FeNP@UReaFINT are less detrimental to the soil diversity and abundance than matCare as the soil diversity and abundance profiles are more similar than to the non-amended soil sample.

In short, the FeNP@AB and FeNP@ABP and FeNP@UReaFINT materials described herein immobile more PFAS than MatCARE™ while more closely preserving the original soil microbial diversity and abundance, and in the case of FeNP@ABP and FeNP@UReaHNT enhance the total microbial population compared to the non-amended soil sample.

Thus, the materials of the invention are particularly suited to use in remediation whereby the sample to be decontaminated and substantial preservation of the original soil microbial diversity and abundance is to be preserved.

Further, the materials of the invention are particularly suited to use in remediation whereby the sample to be decontaminated is in situ in the environment and substantial preservation of the original soil microbial diversity and abundance is to be preserved.

Embodiments involving urea as particularly useful for removal of contaminant in control soil pile system where soil washing of PFAS in necessary. This is because after treatment the soil microbiota break/utilise urea and most likely the following mechanism occurs: urea-modified composite binds PFAS from soil matrix (fast reaction)^over time (~l-2 weeks), the soil microbiota break/utilise urea which significantly increase leachability, resulting a potential use in control soil pile system where soil washing of PFAS in necessary. Further there is no toxicity of these urea modified composite, rather they boost microbial growth.