A heavy metal contaminated soil remediation conditioner and preparation method thereof

Abstract

The present invention relates to the technical field of soil remediation, specifically to a heavy metal contaminated soil remediation conditioner and a preparation method thereof, comprising the following process: in deionized water, modified polyphosphazene, poly (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and epoxy crosslinking agent are mixed, iron-modified woody peat and electrogenic bacteria powder are added and stirred, poured into a mold, placed at 32-37°C for reaction for 8-10 hours, demolded, and a conditioner is obtained. The present invention prepares a soil conditioner by compounding a polymer with iron-modified woody peat and electrogenic bacteria, wherein the electrogenic bacteria uses organic matter as an electron donor and metal ions as an electron acceptor, and can improve the reaction activity of iron-modified woody peat, accelerate the rate of electron transfer, transform and fix heavy metals in the soil, reduce the concentration and mobility of heavy metals, and synergistically improve the soil remediation ability of the prepared conditioner.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a heavy metal polluted soil remediation conditioner and a preparation method thereof. Background Art

[0002] As one of the most basic material foundations for human survival, soil is an important habitat for human beings, animals and plants. In recent years, with the in-depth advancement of agricultural modernization, while agriculture has achieved great development, we have found that the soil environment has been damaged to a certain extent and is the final destination of various pollutants. With atmospheric deposition, sewage irrigation, pesticide application, and the accumulation of metal waste, the area of ​​heavy metal pollution in the soil is getting larger and larger, and the pollution is getting more and more serious. Because heavy metal pollutants have poor mobility in the soil, long retention time, cannot be degraded by microorganisms, and can eventually affect human health through media such as water and plants. Heavy metal pollution in the soil not only reduces the fertility of the soil, but also causes great harm to human health. The process of migration of heavy metals from soil particles to plants is related to their morphology and valence state. Some existing inorganic passivation materials and organic adsorption materials adsorb and chelate heavy metals to achieve passivation of heavy metals, but it is easy to cause asynchronous passivation of different heavy metals and easy to reactivate. Therefore, we propose a heavy metal contaminated soil remediation conditioner and a preparation method thereof. Summary of the invention

[0003] The object of the present invention is to provide a heavy metal contaminated soil remediation conditioner and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solution: a method for preparing a heavy metal contaminated soil remediation conditioner, comprising the following process:

[0005] In deionized water, the modified polyphosphazene, poly (3, 4-ethylenedioxythiophene) -polystyrene sulfonic acid and epoxy crosslinking agent are mixed, iron-modified woody peat and electrogenic bacteria powder are added and stirred, poured into a mold, placed at 32-37°C for reaction for 8-10 hours, demolded, and a conditioner is obtained.

[0006] Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT / PSS): S62078, from Shanghai Yuanye Biotechnology Co., Ltd.;

[0007] The epoxy crosslinking agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0008] The ratio of deionized water, modified polyphosphazene, PEDOT / PSS, and 3-(2,3-epoxypropyloxy)propyltrimethoxysilane is 100 mL: (18.0-19.5) g: (0.38-0.70) g: (17.5-20.0) g;

[0009] The mass ratio of iron-modified woody peat, modified polyphosphazene, and electrogenic bacterial powder is 100:(8-10):(1-2);

[0010] The electrogenic bacterial powder includes Shewanella putrefaciens (BMZ134712, from Ningbo Mingzhou Biotechnology Co., Ltd.) and Shewanella putrefaciens CN32 (from Guangdong Microbiological Culture Collection Center), with a mass ratio of 2:(1.0-1.5);

[0011] Further, the modified polyphosphazene is prepared by the following process:

[0012] S1. Introduction of double bonds:

[0013] Take anhydrous toluene, dissolve polydichlorophosphazene, add propyleneamine hydrochloride and triethylamine, react at 40-48°C for 24-40h; filter, take the filtrate and evaporate to remove most of the solvent, add alcohol aqueous solution, take the precipitate and wash with water to obtain polyphosphazene containing double bonds;

[0014] The ratio of polydichlorophosphazene, triethylamine and anhydrous toluene is (2.5-2.8) g: (25-28) mL: 100 mL;

[0015] The mass ratio of polydichlorophosphazene to acrylamine hydrochloride is 10:(14.0-14.5);

[0016] The alcohol-water solution is anhydrous ethanol and deionized water solution in a volume ratio of 1:1;

[0017] Polydichlorophosphazene is obtained by ring-opening polymerization of hexachlorocyclotriphosphazene. The specific process is: in a nitrogen atmosphere, hexachlorocyclotriphosphazene is placed at a temperature of 250°C for constant temperature reaction for 24 to 48 hours; it is washed three times with petroleum ether to remove unreacted monomer hexachlorocyclotriphosphazene to obtain linear polydichlorophosphazene with a molecular weight of 2800 to 3500.

[0018] Take N, N-dimethylaminopyridine, riboflavin and acetic anhydride, heat to 37-42°C in a nitrogen atmosphere, react for 24 hours; cool to room temperature, mix with dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add anhydrous methanol, stir, filter, filter the precipitate under reduced pressure, and vacuum dry to obtain acetylated riboflavin;

[0019] The mass ratio of N, N-dimethylaminopyridine, riboflavin, and acetic anhydride is 1:10:(42-45);

[0020] Take acetylated riboflavin, potassium iodide and dichloromethane, add propylene bromide, heat to 37-42°C and react for 24 hours; cool to room temperature, mix with dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add dichloromethane and isopropyl ether in turn, filter under reduced pressure, and dry in vacuum to obtain propylene-modified acetylated riboflavin;

[0021] The ratio of acetylated riboflavin, potassium iodide, and dichloromethane is 10 g: (0.30-0.35) g: 250 mL;

[0022] The mass ratio of acetylated riboflavin to propylene bromide is 10:(48.2-48.5);

[0023] Take propylene-modified acetylated riboflavin, p-toluenesulfonic acid and ethanol, stir and mix, heat to reflux the reaction solution, react for 5 hours; rotary evaporate and dry to obtain riboflavin containing double bonds;

[0024] The ratio of propylene-modified acetylated riboflavin, p-toluenesulfonic acid, and ethanol is 10 g: (10.1-10.3) g: 150 mL;

[0025] S2. Click reaction:

[0026] A double-bond polyphosphazene, a double-bond riboflavin, polylactic acid-polycysteine, benzoin dimethyl ether and tetrahydrofuran are mixed and irradiated with ultraviolet light for 2 to 4 hours under the protection of a nitrogen atmosphere; ether is added for precipitation, N,N-dimethylformamide is used for dissolution, water is added for rotary evaporation and drying is performed to obtain a modified polyphosphazene;

[0027] The ratio of double-bond polyphosphazene, double-bond riboflavin, polylactic acid-polycysteine, benzoin dimethyl ether, and tetrahydrofuran is 10g: (1.07-1.2)g: (2.7-3.0)g: (23.0-25.6)g: (12.5-15.0)mL;

[0028] Polylactic acid-polycysteine: molecular weight 4500, lactic acid mass fraction 82%, from Xi'an Qiyue Biotechnology Co., Ltd.

[0029] Furthermore, the iron-modified woody peat is prepared by the following process:

[0030] Take deionized water and anhydrous ethanol to mix to obtain an alcohol-water solution, add woody peat and ferrous sulfate heptahydrate, stir evenly, and ultrasonicate for 15 to 20 minutes; stir at a speed of 500 to 800 rpm for 25 to 30 minutes, and add sodium borohydride solution until no obvious bubbles are generated; continue stirring and react for 60 to 80 minutes; use an external magnetic field for sedimentation separation, wash with anhydrous ethanol for 3 times, collect by rapid magnetic separation, and vacuum dry to obtain iron-modified woody peat.

[0031] The volume ratio of deionized water and ethanol is 2:1;

[0032] The mass ratio of woody peat, ferrous sulfate heptahydrate, and sodium borohydride is 10: (0.67-1.11): (7-8);

[0033] The concentration of sodium borohydride solution is (25-32) g / L;

[0034] Woody peat: from Beijing Zhongxiang Xuyao ​​Technology Co., Ltd., pH 4.47, total humic acid content 60.64%, free humic acid content 48.30%, exchange capacity 102.17 cmol / kg, bulk density 0.41 g / cm 3 .

[0035] In the above technical scheme, (1) Iron-modified woody peat: Woody peat is organic matter formed by woody plants in the natural high temperature, high humidity and anaerobic environment, with high content of humic acid and organic matter; it is loose and porous, with a large specific surface area, rich in functional groups such as carboxyl and hydroxyl, and can strongly adsorb heavy metals, stabilize organic matter in the soil, and reduce the toxicity risk of heavy metals in the soil environment. Sodium borohydride is used as a reducing agent to reduce ferrous sulfate and load it into the pores of woody peat to obtain nano-zero-valent iron-modified woody peat, i.e., iron-modified woody peat; the nano-zero-valent iron on its surface also has the potential to repair soil, with the characteristics of large specific surface area, large surface energy, strong reducing ability, and environmental friendliness. It can undergo various reactions with heavy metals such as adsorption, complexation, and oxidation-reduction, and can degrade organic pollutants, affect the form of heavy metals in the soil, and fix heavy metals. However, zero-valent iron has strong reducing properties and is easily oxidized and precipitated during soil remediation, forming a passivation layer and losing its activity, which is not conducive to electron transfer in soil remediation. It is also magnetic and prone to agglomeration, which limits its use in soil remediation.

[0036] (2) Loading of electrogenic bacteria: Electrogenic bacteria Shewanella putrefaciens and dissimilatory iron-reducing bacteria are introduced into the conditioner, and polymers are used to encapsulate the electrogenic bacteria and iron-modified woody peat to provide an anaerobic environment. The electrogenic bacteria use organic matter as electron donors and metal ions as electron acceptors. The electrogenic bacteria can reduce the iron ions in the iron-modified woody peat and maintain its activity; and can weaken the adhesion between the electrogenic bacteria and the iron-modified woody peat, accelerate the rate of electron transfer, and synergistically improve the soil repair ability of the prepared conditioner. Humus in the iron-modified woody peat can accelerate the dissolution of the zero-valent iron surface passivation layer and enhance the reduction effect of electrogenic bacteria on heavy metals; and through the composite structure, it prevents the extension of heavy metals into the conditioner, avoids the reduction and dissolution of heavy metals bound to iron oxides, and the release of heavy metals, and achieves the synchronous passivation of heavy metals.

[0037] (3) The polymer formed by modified polyphosphazene, poly (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and epoxy crosslinker can act as an electron shuttle, accelerate the transfer of electrons, promote the outward transfer of electrons generated by electrogenic bacteria, and enhance the reduction effect of the prepared conditioner on soil heavy metals; among them, the modified polyphosphazene is obtained by crosslinking double-bond polyphosphazene, double-bond riboflavin and polylactic acid-polycysteine, and contains functional groups such as carboxyl, hydroxyl, amine, carbonyl, and sulfonic acid. It can chelate metal ions and reduce the migration ability and bioavailability of heavy metals; it can also be degraded, while increasing the number of functional groups and the chelating effect, it provides organic matter for electrogenic bacteria. It is rich in organic matter and nutrients such as N, P, and K, which can improve soil fertility.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The heavy metal contaminated soil remediation conditioner of the present invention and its preparation method are prepared by compounding a polymer with iron-modified woody peat and electrogenic bacteria. The electrogenic bacteria use organic matter as electron donors and metal ions as electron acceptors, which can improve the reaction activity of iron-modified woody peat, accelerate the rate of electron transfer, transform and fix heavy metals in the soil, reduce the concentration and mobility of heavy metals, and synergistically improve the soil remediation ability of the prepared conditioner.

[0040] 2. The heavy metal contaminated soil remediation conditioner of the present invention and its preparation method are prepared by cross-linking modified polyphosphazene with double-bond polyphosphazene, double-bond riboflavin and polylactic acid-polycysteine, and cross-linking with poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and epoxy cross-linking agent to form a polymer, which has hydrophilicity and conductivity, can chelate and fix heavy metal ions, and act as an electron shuttle for electrogenic bacteria, thereby increasing the reducing effect of the prepared conditioner on heavy metals and reducing the migration ability and bioavailability of heavy metals; it is rich in organic matter and nutrients such as N, P, K, etc., and improves soil fertility. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Example 1

[0043] (1) Preparation of modified polyphosphazene:

[0044] S1. Introduction of double bonds:

[0045] Take 100 mL of anhydrous toluene, dissolve 2.5 g of polydichlorophosphazene, add 3.5 g of propyleneamine hydrochloride and 25 mL of triethylamine, and react at 40°C for 24 hours; filter, take the filtrate and evaporate to remove most of the solvent, add alcohol aqueous solution (50 mL of anhydrous ethanol + 50 mL of deionized water), take the precipitate and wash with water to obtain a polyphosphazene containing a double bond;

[0046] Take 1.0g N, N-dimethylaminopyridine, 10g riboflavin, and 42g acetic anhydride, and heat to 37°C in a nitrogen atmosphere to react for 24h; cool to room temperature, mix with 100mL dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add 50mL anhydrous methanol and stir for 30min, filter, and filter the precipitate under reduced pressure and vacuum dry to obtain acetylated riboflavin;

[0047] Take 10g of acetylated riboflavin, 0.30g of potassium iodide and mix with 250mL of dichloromethane, add 48.2g of propylene bromide, heat to 37°C and react for 24h; cool to room temperature, mix with 100mL of dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add 20mL of dichloromethane and 150mL of isopropyl ether in turn, filter under reduced pressure, and dry in vacuo to obtain propylene-modified acetylated riboflavin;

[0048] Take 10g of propylene-modified acetylated riboflavin, 10.1g of p-toluenesulfonic acid and 150mL of ethanol, stir and mix, heat to reflux the reaction solution, react for 5h; rotary evaporate and dry to obtain riboflavin containing double bonds;

[0049] S2. Click reaction:

[0050] 10 g of double-bond polyphosphazene, 1.07 g of double-bond riboflavin, 2.7 g of polylactic acid-polycysteine, 23.0 g of benzoin dimethyl ether, and 12.5 mL of tetrahydrofuran were mixed, and irradiated with ultraviolet light for 2 h under nitrogen atmosphere protection; ether was added for precipitation, and N,N-dimethylformamide was used to dissolve it, and water was added for rotary evaporation, and it was dried to obtain a modified polyphosphazene;

[0051] (2) Preparation of iron-modified woody peat:

[0052] Take 100mL of deionized water and 50mL of anhydrous ethanol and mix them to obtain an alcohol-water solution, add 10g of woody peat and 0.67g of ferrous sulfate heptahydrate, stir evenly, and ultrasonicate for 15min; stir at a speed of 500rpm for 25min, and add 233mL of 30g / L sodium borohydride solution until no obvious bubbles are generated; continue stirring and react for 60min; use an external magnetic field for sedimentation separation, wash with anhydrous ethanol 3 times, collect by rapid magnetic separation, and vacuum dry to obtain iron-modified woody peat.

[0053] (3) Preparation of conditioning agent:

[0054] In 100 mL of deionized water, 18.0 g of modified polyphosphazene, 0.38 g of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and 17.5 g of epoxy crosslinker 3-(2,3-epoxypropyloxy)propyltrimethoxysilane were mixed, 180 g of iron-modified woody peat and 1.80 g of electrogenic bacteria powder were added and stirred, poured into a mold, placed at 32 ° C for reaction for 8 h, and demolded to obtain a conditioner.

[0055] Example 2

[0056] (1) Preparation of modified polyphosphazene:

[0057] S1. Introduction of double bonds:

[0058] Take 100 mL of anhydrous toluene, dissolve 2.7 g of polydichlorophosphazene, add 3.7 g of propyleneamine hydrochloride and 27 mL of triethylamine, and react at 45°C for 32 hours; filter, take the filtrate and evaporate to remove most of the solvent, add alcohol aqueous solution (50 mL of anhydrous ethanol + 50 mL of deionized water), take the precipitate and wash with water to obtain a double-bond polyphosphazene;

[0059] Take 1.0g N, N-dimethylaminopyridine, 10g riboflavin, and 44g acetic anhydride, and heat to 40°C in a nitrogen atmosphere for 24h; cool to room temperature, mix with 100mL dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add 50mL anhydrous methanol and stir for 30min, filter, and filter the precipitate under reduced pressure and vacuum dry to obtain acetylated riboflavin;

[0060] Take 10g of acetylated riboflavin, 0.33g of potassium iodide and mix with 250mL of dichloromethane, add 48.4g of propylene bromide, heat to 40°C and react for 24h; cool to room temperature, mix with 100mL of dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add 20mL of dichloromethane and 150mL of isopropyl ether in turn, filter under reduced pressure, and dry in vacuo to obtain propylene-modified acetylated riboflavin;

[0061] Take 10g of propylene-modified acetylated riboflavin, 10.2g of p-toluenesulfonic acid and 150mL of ethanol, stir and mix, heat to reflux the reaction solution, react for 5h; rotary evaporate and dry to obtain riboflavin containing double bonds;

[0062] S2. Click reaction:

[0063] 10 g of double-bond polyphosphazene, 1.09 g of double-bond riboflavin, 2.8 g of polylactic acid-polycysteine, 24.3 g of benzoin dimethyl ether, and 13.7 mL of tetrahydrofuran were mixed, and irradiated with ultraviolet light for 3 h under nitrogen atmosphere protection; ether was added for precipitation, and N,N-dimethylformamide was used to dissolve it, and water was added for rotary evaporation, and it was dried to obtain a modified polyphosphazene;

[0064] (2) Preparation of iron-modified woody peat:

[0065] Take 100mL of deionized water and 50mL of anhydrous ethanol and mix them to obtain an alcohol-water solution, add 10g of woody peat and 0.89g of ferrous sulfate heptahydrate, stir evenly, and ultrasonicate for 18min; stir at a speed of 600rpm for 27min, and add 250mL of 30g / L sodium borohydride solution until no obvious bubbles are generated; continue stirring and react for 70min; use an external magnetic field for sedimentation separation, wash with anhydrous ethanol 3 times, collect by rapid magnetic separation, and vacuum dry to obtain iron-modified woody peat.

[0066] (3) Preparation of conditioning agent:

[0067] In 100 mL of deionized water, 18.7 g of modified polyphosphazene, 0.54 g of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and 18.7 g of epoxy crosslinker 3-(2,3-epoxypropyloxy)propyltrimethoxysilane were mixed, 211 g of iron-modified woody peat and 3.33 g of electrogenic bacteria powder were added and stirred, poured into a mold, placed at 35 ° C for reaction for 9 hours, and demolded to obtain a conditioner.

[0068] Example 3

[0069] (1) Preparation of modified polyphosphazene:

[0070] S1. Introduction of double bonds:

[0071] Take 100 mL of anhydrous toluene, dissolve 2.8 g of polydichlorophosphazene, add 4.0 g of propyleneamine hydrochloride and 28 mL of triethylamine, and react at 48°C for 40 hours; filter, take the filtrate and evaporate to remove most of the solvent, add alcohol aqueous solution (50 mL of anhydrous ethanol + 50 mL of deionized water), take the precipitate and wash with water to obtain a double-bond polyphosphazene;

[0072] Take 1.0g N, N-dimethylaminopyridine, 10g riboflavin, and 45g acetic anhydride, and heat to 42°C in a nitrogen atmosphere to react for 24h; cool to room temperature, mix with 100mL dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add 50mL anhydrous methanol and stir for 30min, filter, and filter the precipitate under reduced pressure and vacuum dry to obtain acetylated riboflavin;

[0073] Take 10g of acetylated riboflavin, 0.35g of potassium iodide and mix with 250mL of dichloromethane, add 48.5g of propylene bromide, heat to 42°C and react for 24h; cool to room temperature, mix with 100mL of dichloromethane, wash the organic phase to neutrality; dry with anhydrous sodium sulfate, and concentrate under reduced pressure; add 20mL of dichloromethane and 150mL of isopropyl ether in turn, filter under reduced pressure, and dry in vacuo to obtain propylene-modified acetylated riboflavin;

[0074] Take 10g of propylene-modified acetylated riboflavin, 10.3g of p-toluenesulfonic acid and 150mL of ethanol, stir and mix, heat to reflux the reaction solution, react for 5h; rotary evaporate and dry to obtain riboflavin containing double bonds;

[0075] S2. Click reaction:

[0076] 10 g of double-bond polyphosphazene, 1.2 g of double-bond riboflavin, 3.0 g of polylactic acid-polycysteine, 25.6 g of benzoin dimethyl ether, and 15.0 mL of tetrahydrofuran were mixed, and irradiated with ultraviolet light for 4 h under nitrogen atmosphere protection; ether was added for precipitation, and N,N-dimethylformamide was used for dissolution, water was added for rotary evaporation, and drying was performed to obtain modified polyphosphazene;

[0077] (2) Preparation of iron-modified woody peat:

[0078] Take 100mL of deionized water and 50mL of anhydrous ethanol and mix them to obtain an alcohol-water solution, add 10g of woody peat and 1.11g of ferrous sulfate heptahydrate, stir evenly, and ultrasonicate for 20 minutes; stir at a speed of 800rpm for 30 minutes, and add 267mL of 30g / L sodium borohydride solution until no obvious bubbles are generated; continue stirring and react for 80 minutes; use an external magnetic field for sedimentation separation, wash with anhydrous ethanol 3 times, collect by rapid magnetic separation, and vacuum dry to obtain iron-modified woody peat.

[0079] (3) Preparation of conditioning agent:

[0080] In 100 mL of deionized water, 19.5 g of modified polyphosphazene, 0.70 g of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and 20.0 g of epoxy crosslinker 3-(2,3-epoxypropyloxy)propyltrimethoxysilane were mixed, 243 g of iron-modified woody peat and 4.86 g of electrogenic bacteria powder were added and stirred, poured into a mold, placed at 37 ° C for reaction for 10 hours, and demolded to obtain a conditioner.

[0081] Comparative Example 1

[0082] Compared with Example 1, 2.7 g of polylactic acid-polycysteine ​​in Comparative Example 3 was replaced by 0.32 g of polycysteine; other steps and processes were the same as those in Example 1 to obtain a conditioner.

[0083] Comparative Example 2

[0084] Compared with Example 1, the double-bond riboflavin component is deleted in Comparative Example 4, and S2. The click reaction process is:

[0085] 11.0 g of double-bond polyphosphazene, 0.32 g of polycysteine, 23.0 g of benzoin dimethyl ether, and 12.5 mL of tetrahydrofuran were mixed and irradiated with ultraviolet light for 2 h under nitrogen atmosphere protection; ether was added to precipitate, dissolved with N,N-dimethylformamide, water was added and rotary evaporated, and dried to obtain modified polyphosphazene; the other steps and processes were the same as those in Example 1 to obtain a conditioner.

[0086] Comparative Example 3

[0087] Compared with Example 1, in Comparative Example 5, the modified polyphosphazene component is replaced, and the preparation process of (3) the conditioning agent is:

[0088] In 100 mL of deionized water, 15.0 g of polyglutamic acid, 0.38 g of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and 17.5 g of epoxy crosslinker 3-(2,3-epoxypropyloxy)propyltrimethoxysilane were mixed, 180 g of iron-modified woody peat and 1.80 g of electrogenic bacteria powder were added and stirred, poured into a mold, placed at 32 ° C for reaction for 8 hours, and demolded to obtain a conditioner.

[0089] Comparative Example 4

[0090] Compared with Comparative Example 3, no electrogenic bacteria were added in Comparative Example 4; other steps and processes were the same as those in Comparative Example 3 to obtain a conditioner.

[0091] Comparative Example 5

[0092] Compared with Comparative Example 3, no electrogenic bacteria were added in Comparative Example 5, and the iron-modified woody peat was replaced with woody peat of equal mass; the other steps and processes were the same as those in Comparative Example 3 to obtain a conditioner.

[0093] The above-mentioned poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT / PSS): S62078, from Shanghai Yuanye Biotechnology Co., Ltd.;

[0094] Polylactic acid-polycysteine: molecular weight 4500, lactic acid mass fraction 82%, from Xi'an Qiyue Biotechnology Co., Ltd.

[0095] Polyglutamic acid: cosmetic grade, sourced from Xi’an Virgin Biotechnology Co., Ltd.;

[0096] Woody peat: from Beijing Zhongxiang Xuyao ​​Technology Co., Ltd., pH 4.47, total humic acid content 60.64%, free humic acid content 48.30%, exchange capacity 102.17 cmol / kg, bulk density 0.41 g / cm3 .

[0097] Polydichlorophosphazene is obtained by ring-opening polymerization of hexachlorocyclotriphosphazene. The specific process is as follows: in a nitrogen atmosphere, hexachlorocyclotriphosphazene is placed at a constant temperature of 250°C for 36 hours; it is washed three times with petroleum ether to remove the unreacted monomer hexachlorocyclotriphosphazene to obtain linear polydichlorophosphazene with a molecular weight of 3100.

[0098] The electrogenic bacterial powder includes Shewanella putrefaciens (BMZ134712, from Ningbo Mingzhou Biotechnology Co., Ltd.) and Shewanella putrefaciens CN32 (from Guangdong Provincial Microbiological Culture Collection Center), with a mass ratio of 2:1.2.

[0099] The average particle size of the conditioning agents is 8 mm.

[0100] experiment

[0101] The conditioners obtained in Examples 1-3 and Comparative Examples 1-5 were used to prepare samples, and their properties were tested and the test results were recorded:

[0102] The test soil was air-dried, rolled, and crushed, mixed with 5 wt% of a conditioner, and distilled water was added until the soil became viscous. The soil was covered with a film and cured for 14 days, and air-dried again to obtain the test soil.

[0103] Heavy metal leaching test: Take 100g of the test soil, add 1kg of distilled water, and oscillate on a reciprocating horizontal oscillator at a frequency of 110 times / min and an amplitude of 40mm for 8 hours. After standing for 16 hours, remove the soil and filter the leaching solution with a 0.45μm microporous filter membrane;

[0104] The total chromium content in the leaching solution was tested with reference to GB / T 1555.4-1995;

[0105] The total amount of cadmium and arsenic was determined by HNO3-HClO4 digestion method, and was measured using graphite furnace-atomic absorption spectrophotometer and atomic fluorescence photometer, and the reduction in chromium, cadmium and arsenic was calculated.

[0106] Table 1. Physical and chemical properties of the tested soils:

[0107] pH Organic matter (g / kg) Total Cd (mg / kg) Total As (mg / kg) Total Cr (mg / kg) 5.2 12.7 2.5 19.3 942.3

[0108] Table 2, performance test data of conditioning agent:

[0109] Total Cd reduction (%) Total As reduction (%) Total Cr reduction (%) Example 1 76.6 80.8 92.3 Example 2 77.8 82.1 95.8 Example 3 80.1 84.5 97.6 Comparative Example 1 75.2 78.4 88.5 Comparative Example 2 71.4 75.5 86.8 Comparative Example 3 67.5 62.3 82.6 Comparative Example 4 63.0 61.8 80.8 Comparative Example 5 55.3 44.7 72.8

[0110] According to the data in the above table, we can clearly draw the following conclusions:

[0111] The conditioning agents obtained in Examples 1-3 were compared with the conditioning agents obtained in Comparative Examples 1-5. The test results show that:

[0112] Compared with the comparative example, the conditioners obtained in Examples 1-3 have more excellent reduction data of chromium, cadmium and arsenic, which fully demonstrates that the present invention achieves the improvement of the soil remediation ability of the prepared soil conditioners.

[0113] Compared with Example 1, the polylactic acid-polycysteine ​​in Comparative Example 1 is replaced with polycysteine, the double-bond riboflavin component in Comparative Example 2 is deleted, the component modified polyphosphazene is replaced in Comparative Example 3, and the process is modified accordingly; compared with Comparative Example 3, no electrogenic bacteria is added in Comparative Example 4; no electrogenic bacteria is added in Comparative Example 5, and the iron-modified woody peat is replaced with woody peat of equal mass; the chromium, cadmium and arsenic reduction data of Comparative Examples 1-5 all decrease, and the data reduction rates are different. It can be seen that the setting of the soil conditioner components and the process of the present invention can promote its simultaneous passivation of different heavy metals and promote the improvement of the soil repair ability.

[0114] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process method article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process method article or device.

[0115] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a heavy metal contaminated soil remediation conditioner, characterized in that: Including the following processes: In deionized water, the modified polyphosphazene, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and epoxy crosslinking agent are mixed, iron-modified woody peat and electrogenic bacteria powder are added, stirred, poured into a mold, placed at 32-37° C. for reaction for 8-10 hours, and demolded to obtain a conditioning agent; The epoxy crosslinking agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane; The electrogenic bacterial powder includes Shewanella putrefaciens and dissimilatory iron-reducing bacteria, with a mass ratio of 2: (1.0-1.5); The modified polyphosphazene is prepared by the following process: A double-bond polyphosphazene, a double-bond riboflavin, polylactic acid-polycysteine, benzoin dimethyl ether and tetrahydrofuran are mixed, and the mixture is irradiated with ultraviolet light for 2 to 4 hours under the protection of a nitrogen atmosphere to obtain a modified polyphosphazene.

2. The method for preparing a heavy metal contaminated soil remediation conditioner according to claim 1, characterized in that: The mass ratio of the modified polyphosphazene, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, and 3-(2,3-epoxypropyloxy)propyltrimethoxysilane is (18.0-19.5): (0.38-0.70): (17.5-20.0).

3. The method for preparing a heavy metal contaminated soil remediation conditioner according to claim 1, characterized in that: The mass ratio of the double-bond polyphosphazene, double-bond riboflavin, polylactic acid-polycysteine, benzoin dimethyl ether and tetrahydrofuran is 10: (1.07-1.2): (2.7-3.0): (23.0-25.6).

4. The method for preparing a heavy metal contaminated soil remediation conditioner according to claim 1, characterized in that: The double-bond-containing polyphosphazene is prepared by the following process: Take anhydrous toluene, dissolve polydichlorophosphazene, add propyleneamine hydrochloride and triethylamine, react at 40-48° C. for 24-40 hours to obtain polyphosphazene containing double bonds.

5. The method for preparing a heavy metal contaminated soil remediation conditioner according to claim 1, characterized in that: The double-bond-containing riboflavin is prepared by the following process: N, N-dimethylaminopyridine, riboflavin and acetic anhydride were mixed, heated to 37-42°C in a nitrogen atmosphere and reacted for 24 hours to obtain acetylated riboflavin; Take acetylated riboflavin, potassium iodide and dichloromethane, add propylene bromide, raise the temperature to 37-42°C and react for 24 hours to obtain propylene-modified acetylated riboflavin; Take propylene-modified acetylated riboflavin, p-toluenesulfonic acid and ethanol, stir and mix, and heat to react for 5 hours to obtain riboflavin containing double bonds.

6. The method for preparing a heavy metal contaminated soil remediation conditioner according to claim 1, characterized in that: The iron-modified woody peat is prepared by the following process: Deionized water and anhydrous ethanol are mixed, woody peat and ferrous sulfate heptahydrate are added, and ultrasonic treatment is performed for 15 to 20 minutes; sodium borohydride solution is added and stirred to react to obtain iron-modified woody peat.

7. The method for preparing a heavy metal contaminated soil remediation conditioner according to claim 6, characterized in that: The mass ratio of the woody peat, ferrous sulfate heptahydrate and sodium borohydride is 10:(0.67-1.11):(7-8).

8. A heavy metal contaminated soil remediation conditioner prepared according to the preparation method according to any one of claims 1 to 7.