Preparation and application method of geotextile for repairing or blocking heavy metal contaminated soil

Abstract

The invention relates to the technical field of soil remediation, and discloses a preparation method and an application method of geotechnical cloth for remediation or barrier of heavy metal contaminated soil. The graft modified keratin geotextile is prepared through pretreatment, cleaning, geotextile processing preparation and modification treatment. When the graft modified keratin geotextile is used for repairing the heavy metal contaminated soil, the graft modified keratin geotextile is laid below or inside the contaminated soil, and heavy metal ions in the soil are released into a liquid phase through leaching treatment and are adsorbed and fixed by the graft modified keratin geotextile. The method is efficient in treatment, can adsorb and remove heavy metals in the soil within a week, solves the problem of heavy metal migration and diffusion in a traditional remediation technology, is free of secondary pollution, can guarantee the original physicochemical properties of the soil, treats pollution with waste, and is low in cost. In addition, the composite material can also be used as an isolating layer, effectively avoids diffusion of heavy metal in soil, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil remediation, in particular to a method for preparing and applying geotextile for remediation or barrier of heavy metal contaminated soil. BACKGROUND

[0002] At present, the remediation technologies for heavy metal contaminated soil mainly include solidification and stabilization technology, soil leaching technology, phytoremediation technology, thermal desorption technology and electrokinetic remediation technology. However, these technologies have many problems: solidification and stabilization technology cannot completely remove heavy metals and may damage soil fertility; soil leaching method is easy to cause secondary pollution; phytoremediation technology has a long cycle; thermal desorption technology has limited application scope; electrokinetic remediation technology has low efficiency and is difficult to be applied on a large scale. Therefore, it is urgent to develop an efficient, green and non-secondary pollution remediation or barrier technology for heavy metal contaminated soil.

[0003] Keratin is a kind of natural polymer protein, which widely exists in animal hair, horn and other parts, such as wool, rabbit hair, etc. Its molecular chain is rich in a large number of disulfide bonds. Natural keratin material has excellent biological activity, biocompatibility, biodegradability, good mechanical properties and the advantage of wide source, and is widely used in textile, leather and other industries. However, waste keratin is generally treated as waste, which is not fully utilized. It is estimated that the total amount of waste keratin produced in the world each year is about 12 million to 16 million tons, but the actual recycling rate is less than 10%, most of which is landfilled or incinerated, which not only causes resource waste, but also causes environmental problems such as air pollution.

[0004] Therefore, how to efficiently utilize the abundant waste keratin resources and develop a green, efficient and non-secondary pollution remediation or barrier technology for heavy metal contaminated soil has become an important problem to be solved at present. SUMMARY

[0005] In view of this, the purpose of the present application is to provide a method for preparing and applying geotextile for remediation or barrier of heavy metal contaminated soil to solve the problems pointed out in the background.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted is as follows: The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil comprises the following steps: S1, pretreatment The keratin material is pretreated, wherein the fibrous keratin is opened and impurities are removed to become single fiber; the feather keratin is crushed, and the average area of the crushed feather keratin particles is controlled at 0.2cm²-2cm²; S2, washing The keratin material is classified and washed; S3, geotextile processing preparation The cleaned keratin fibers are carded into 10-100 g / m 3 of thin fiber web by using a carding machine, 1-100 layers of thin fiber web are laid, 0-100 layers of feather keratin are evenly spread between the layers (feather keratin can not be spread, and a thick fiber web of pure keratin fiber is made), and then a needle punching machine or a hydroentangling machine is used for reinforcement treatment to form a keratin geotextile with a thickness of 0.1-100 cm. The thickness of the keratin geotextile is preferably 5 cm.

[0007] S4, modification treatment S4-1, disulfide bond reducing agent reduction treatment The keratin geotextile is soaked in a mixture of 0.1-100 g / L disulfide bond reducing agent and 0.1-10 g / L urea to reduce the high-density disulfide bond in the keratin geotextile to sulfhydryl; the addition of urea can promote the swelling of the keratin material and facilitate the reaction, and a large number of sulfhydryl groups will be generated on the surface and inside the keratin material after reduction treatment; S4-2, graft modification treatment The reduced keratin geotextile is soaked in a treatment solution containing 0.1-100 g / L graft modification reagent and 0.1-100 g / L urea for 10-60 min, and then dried at 80°C to obtain a graft modified keratin geotextile; wherein the solid-liquid mass ratio of the keratin geotextile to the treatment solution is 1:10-500, the graft modification reagent contains at least one sulfhydryl group and one carboxyl group, and the graft modification reagent is at least one of reduced glutathione, 2,3-dimercaptosuccinic acid, 3-mercaptopropionic acid and cysteine.

[0008] As a further improvement of the present application, in step S1, the fiber keratin includes animal fibers such as wool and rabbit hair; and the feather keratin includes duck feather and goose feather.

[0009] As a further improvement of the present application, in step S2, the keratin geotextile is classified and cleaned, specifically including the following steps: S2-1, cleaning and removing impurities: the keratin material to be treated is cleaned in a water solution cleaning tank with a permeating agent of 1 g / L, a temperature of 50°C and a pH value of 8.0 for 20 min to remove solid impurities, and then dried and sterilized by ultraviolet sterilization, spraying of sterilizing agent, etc., preferably ultraviolet sterilization, which has no chemical residues. S2-2, enzyme washing: the cleaned keratin material is washed in a complex enzyme solution, under the conditions of temperature 30-50℃, pH value 2-10, for 5-120 min, and then transferred to 70℃ hot water for cleaning and inactivation of the proteinase (inactivation of the proteinase adsorbed on the surface of the material), the complex enzyme solution comprising lipase 0.1-100 g / L, cellulase 0.1-100 g / L and proteinase 0.1-100 g / L.

[0010] As a further improvement of the present application, in step S2-2, the cleaned keratin material is washed in a complex enzyme solution, under the conditions of temperature 45℃, pH value 7-8, for 60 min, and then transferred to 70℃ hot water for cleaning and inactivation of the proteinase, the complex enzyme comprising lipase 0.3 g / L, cellulase 0.2 g / L and proteinase 0.5 g / L.

[0011] As a further improvement of the present application, in step S4-1, the disulfide bond reducing agent is one of tris (3-hydroxypropyl) phosphine, ammonium thioglycolate, mercaptoacetic acid, mercaptoethanol and tris (2-carboxyethyl) phosphine, preferably one of tris (3-hydroxypropyl) phosphine, mercaptoacetic acid and tris (2-carboxyethyl) phosphine, and more preferably tris (3-hydroxypropyl) phosphine.

[0012] As a further improvement of the present application, in step S4-1, the reaction formula of the reduction of the disulfide bond to the mercapto group is as follows: .

[0013] As a further improvement of the present application, in step S4-2, the solid-liquid mass ratio of the keratin geotextile and the treatment solution is 1:30-50, the grafting modification reagent is reduced glutathione, and in the treatment solution of the grafting modification reagent and urea, the solution concentration of the grafting modification reagent is 12-18 g / L, and the urea concentration is 5 g / L.

[0014] As a further improvement of the present application, in step S4-2, during the drying process at 80℃, the mercapto group in the grafting modification reagent reacts with the mercapto group in the keratin material to form a disulfide bond, and when the grafting modification reagent is reduced glutathione, the reaction formula is as follows: .

[0015] The application method of the geotextile prepared by any of the above methods for remediation or barrier of heavy metal contaminated soil, comprising the following steps: a. Remediation of heavy metal contaminated soil: according to the content of heavy metals in the soil, a certain thickness of the grafted and modified keratin geotextile is selected, which is laid under or in the contaminated soil, and then leaching treatment is carried out, the leaching solution is water, or a solution of citric acid, oxalic acid, phosphoric acid or acetic acid with a concentration of 0.1-10 g / L, preferably citric acid solution, preferably with a concentration of 2 g / L, the soaking treatment time is 0.5-7 days, preferably 5 days, the solid-liquid mass ratio of soil to soaking solution is 1:1-10, preferably 1:4, and the heavy metal ions in the soil are released into the liquid phase under the action of the leaching solution and are adsorbed and fixed by the grafted and modified keratin geotextile; b. Regeneration of grafted and modified keratin geotextile: the adsorbed and saturated grafted and modified keratin geotextile is uniformly recovered and regenerated, first, the surface solid impurities are removed by water leaching, and then the geotextile is soaked in an acid solution with a mass percentage concentration of 0.1%-25%, wherein the acid solution is hydrochloric acid, sulfuric acid or acetic acid, preferably hydrochloric acid, preferably with a concentration of 1-15%, and more preferably with a concentration of 5%.

[0016] As a further improvement of the present application, when the grafting and modification reagent is reduced glutathione, the adsorption and regeneration reaction of the grafted and modified keratin geotextile is as follows: .

[0017] The grafted and modified keratin geotextile can also be used as a barrier layer for heavy metal contaminated soil, which can be laid vertically or horizontally in the soil to effectively prevent the diffusion of heavy metals in the soil.

[0018] The beneficial effects of the present application are: 1. High treatment efficiency. Traditional soil remediation techniques require several months or even years, and heavy metals continue to migrate and diffuse during the remediation process, resulting in an increase in the contaminated area. The present application can efficiently adsorb and remove heavy metals in the soil within 7 days by using modified keratin geotextile combined with leaching treatment, thereby effectively preventing the expansion of the contaminated area caused by the migration of heavy metals during the long treatment process.

[0019] 2. No secondary pollution and protection of soil properties. The geotextile prepared in the present application can adsorb heavy metals inside the geotextile, and after the adsorption treatment is completed, the geotextile can be uniformly collected and regenerated by acid pickling. During the acid pickling process, the heavy metals are dissolved in the acid pickling solution. This method does not produce secondary pollution to the soil and can effectively remove heavy metals from contaminated soil while protecting the physical and chemical properties and ecological activity of the soil.

[0020] 3. Waste treatment with waste, low cost. The present application uses waste keratin materials for heavy metal removal from soil, which is a waste treatment with waste, and the raw material cost is low. The used geotextile can be reused after regeneration, further reducing the operating cost and facilitating large-scale application.

[0021] 4. Isolation of heavy metal contaminated soil. The grafted keratin geotextile can be laid in the soil as a barrier layer for isolating the heavy metal contaminated soil area. It can be laid vertically or horizontally in the soil to effectively block the migration of heavy metals in the soil and prevent the expansion of the contaminated area. DETAILED DESCRIPTION

[0022] The following examples are intended to further illustrate the present application but not be understood as limiting the scope of the present application. Some non-essential improvements and adjustments of the present application made by those skilled in the art according to the content of the present application still fall within the scope of the present application.

[0023] In the present application, the geotextile can be modified first and then prepared, or the geotextile can be prepared first and then modified, i.e. steps S3 and S4 can be exchanged.

[0024] Example 1: The material used is waste wool fiber keratin material.

[0025] The method for preparing a geotextile for heavy metal contaminated soil remediation or blocking comprises the following steps: S1, pretreatment The wool fiber keratin is opened and impurities are removed to make it into a single fiber form.

[0026] S2, washing The washing treatment is carried out by a two-step washing process, which specifically comprises the following steps: S2-1, washing and removing impurities: the wool fiber keratin to be treated is washed in a water solution cleaning tank with a permeating agent 1 g / L, at a temperature of 50°C and a pH value of 8.0 for 20 min to remove solid impurities. After drying, ultraviolet disinfection and sterilization treatment is carried out.

[0027] S2-2, enzyme washing: a composite enzyme cleaning solution is configured, and the wool fiber keratin after washing and removing impurities is subjected to deep cleaning in the composite enzyme solution, which comprises lipase 0.3 g / L, cellulase 0.2 g / L, and protease 0.5 g / L. The cleaning is carried out at a temperature of 45°C and a pH value of 7.0 for 60 min. After the treatment, the wool fiber keratin is transferred to hot water at 70°C for washing, and the protease adsorbed on the surface of the wool fiber keratin is inactivated.

[0028] S3, geotextile processing and preparation The washed wool fiber keratin is carded into a thin fiber web of 70 g / m 3 using a carding machine, and then is stacked into 100 layers by cross-laying to form a thick fiber web of 7000 g / m 3 , and then is reinforced by a needle punching machine to obtain a keratin geotextile with a thickness of 4.0 cm.

[0029] S4, modification treatment S4-1, disulfide bond reducing agent reduction treatment The keratin geotextile is soaked in a mixed solution of tris (2-carboxyethyl) phosphine and urea to reduce the high-density disulfide bonds in the keratin geotextile to sulfhydryl groups, wherein the concentration of tris (2-carboxyethyl) phosphine is 10 g / L, and the concentration of urea is 3 g / L.

[0030] The reaction formula for reducing disulfide bonds to sulfhydryl groups is as follows: .

[0031] S4-2, graft modification treatment The keratin geotextile after the reduction treatment in step S4-1 is transferred to a mixed solution containing reduced glutathione and urea for soaking for 30 min, and the solid-liquid mass ratio of the keratin geotextile to the treatment solution is 1:50. The concentration of the reduced glutathione solution is 12 g / L, and the concentration of urea is 5 g / L. Then, drying treatment is performed at 80°C to obtain the graft-modified keratin geotextile. During the drying process, the sulfhydryl groups in the reduced glutathione molecules graft with the sulfhydryl groups on the surface of the modified keratin material to form disulfide bonds, and the reaction formula is as follows: .

[0032] The application method of the geotextile prepared by the above method for remediation or barrier of heavy metal contaminated soil includes the following steps: a. Remediation of lead-contaminated soil: the lead content of the contaminated soil is 1000 mg / kg (much higher than the national standard requirement). The prepared graft-modified keratin geotextile is laid under the contaminated soil, and the mass ratio of the soil to the geotextile is 100:1. Then, the contaminated soil is soaked and leached with a 2 g / L citric acid solution, and the mass ratio of the citric acid solution to the soil is 3:1. The soaking time is 2 days. After treatment, the lead content in the soil is reduced to 48 mg / kg, meeting the national standard requirement of less than 80 mg / kg, and the lead removal rate is 95.2%.

[0033] b. Regeneration of graft-modified keratin geotextile The saturated geotextile is uniformly collected and subjected to regeneration treatment. First, the graft-modified keratin geotextile adsorbed with metals is washed with water to remove solid impurities on its surface, and then it is soaked in a 4% hydrochloric acid solution for regeneration.

[0034] After the regeneration of the graft-modified keratin geotextile, the soil is treated repeatedly, and when the geotextile is used for 10 cycles, the lead removal rate in the soil can still reach 85.6%.

[0035] The adsorption and regeneration reaction formula of the graft-modified keratin geotextile is as follows: .

[0036] Comparative Example 1: The material used is waste wool fiber keratin material.

[0037] The method for preparing the geotextile for remediation or barrier of heavy metal contaminated soil comprises the following steps: S1, pretreatment The wool fiber keratin is opened and impurities are removed to make it into single fiber form.

[0038] S2, washing The washing treatment is carried out by adopting a two-step washing process, which specifically comprises the following steps: S2-1, washing and removing impurities: the wool fiber keratin to be treated is washed in a water solution cleaning tank with a permeating agent 1 g / L, at a temperature of 50°C and a pH value of 8.0 for 20 min to remove solid impurities, and after drying, ultraviolet disinfection and sterilization treatment is carried out.

[0039] S2-2, enzyme washing: a composite enzyme cleaning solution is configured, and the wool fiber keratin after washing and removing impurities is deeply cleaned in the composite enzyme solution, the composite enzyme solution comprises lipase 0.3 g / L, cellulase 0.2 g / L, and protease 0.5 g / L, and the cleaning is carried out at a temperature of 45°C and a pH value of 7.0 for 60 min. After the treatment, the wool fiber keratin is transferred to hot water at 70°C for washing, and the protease adsorbed on the surface of the wool fiber keratin is inactivated.

[0040] S3, geotextile processing and preparation The washed wool fiber keratin is carded into a thin fiber web of 70 g / m 3 by adopting a carding machine, and then is stacked into 100 layers by adopting a cross-laying method to form a thick fiber web of 7000 g / m 3 , and then is reinforced by adopting a needle punching machine to obtain a keratin geotextile with a thickness of 4.0 cm.

[0041] S4, modification treatment Disulfide bond reducing agent reduction treatment The keratin geotextile is soaked in a mixed solution of tris (2-carboxyethyl) phosphine and urea to reduce the high-density disulfide bonds in the keratin geotextile to sulfhydryl groups, wherein the concentration of tris (2-carboxyethyl) phosphine is 10 g / L, and the concentration of urea is 3 g / L. After the treatment, the modified keratin geotextile is dried.

[0042] The application method of the geotextile for remediation or barrier of heavy metal contaminated soil prepared by the above method comprises the following steps: a. Remediation of lead-contaminated soil: The lead content of the contaminated soil was 1000 mg / kg (far exceeding the national standard). Modified keratin geotextile was laid beneath the contaminated soil at a soil-to-geotextile ratio of 100:1. The contaminated soil was then soaked and leached with a 2 g / L citric acid solution at a citric acid-to-soil ratio of 3:1 for 2 days. After treatment, the lead content in the soil decreased to 933 mg / kg, with a lead removal rate of only 6.7%.

[0043] As can be seen from Example 1, grafting modification treatment can significantly improve the adsorption effect of keratin geotextile on metal ions.

[0044] Example 2: The materials used are waste wool fiber keratin material and feather material.

[0045] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps: S1, Preprocessing Wool fiber keratin is loosened and impurities are removed to break it down into single fibers. Feather keratin is appropriately pulverized to ensure uniform particle size, with an average surface area controlled at 1 cm². 2 about.

[0046] S2, Cleaning A two-step cleaning process is used to clean keratin materials, with wool fiber keratin and feather keratin being cleaned separately. The specific steps include: S2-1. Cleaning and impurity removal. The keratin material to be cleaned is rinsed for 20 minutes in an aqueous cleaning tank with 1g / L penetrant, 50℃, and pH 8.0 to remove solid impurities. After drying, it is subjected to ultraviolet disinfection and sterilization.

[0047] S2-2, Enzyme Wash. Prepare a compound enzyme washing solution to deeply wash the keratin material after cleaning and impurity removal. The washing solution used is a compound enzyme solution containing multiple enzymes, including 0.3 g / L lipase, 0.2 g / L cellulase, and 0.5 g / L protease. Wash for 60 minutes at 45℃ and pH 7.0. After treatment, transfer the keratin material to 70℃ hot water for further washing, simultaneously inactivating the protease adsorbed on the surface of the keratin material.

[0048] S3. Modification treatment, which involves two steps. S3-1, Disulfide Bond Reduction Treatment. Keratin materials are soaked in a mixed solution of mercaptoacetic acid and urea to reduce the high density of disulfide bonds within the keratin material to thiol groups. The concentration of mercaptoacetic acid is 5 g / L, and the concentration of urea is 4 g / L.

[0049] S3-2, Grafting modification treatment. The reduced keratin material is transferred to a mixed solution containing reduced glutathione and urea for 30 min, and the solid-liquid mass ratio of the keratin material and the treatment solution is 1:30. The concentration of the reduced glutathione solution is 15 g / L, and the concentration of the urea is 5 g / L. Then, drying treatment is carried out at 80°C to obtain the graft-modified keratin material (including graft-modified wool fiber keratin and graft-modified feather keratin). During the drying process, the sulfhydryl groups in the reduced glutathione molecules will graft with the sulfhydryl groups on the surface of the modified keratin material to form disulfide bonds.

[0050] S4, Geotextile processing and preparation The graft-modified wool fiber keratin prepared in step S3 is carded into a 80 g / m 3 thin fiber web, and then is stacked into 100 layers by cross-laying, with the graft-modified feather keratin evenly spread between each thin fiber web to form a thick fiber web composed of graft-modified wool fiber keratin and graft-modified feather keratin. Finally, a 8000 g / m 3 thick fiber web is formed, which is then reinforced by a hydroentangling machine to obtain a graft-modified keratin geotextile with a thickness of 4.5 cm.

[0051] The application method of the geotextile for heavy metal contaminated soil remediation or barrier prepared by the above method includes the following steps: a, Heavy metal contaminated soil remediation The lead-contaminated soil is remediated, and the lead content of the contaminated soil is 1000 mg / kg (much higher than the national standard requirement). The prepared graft-modified keratin geotextile is laid under the contaminated soil, and the mass ratio of the soil to the geotextile is 100:1. Then, the contaminated soil is soaked and leached with a 0.5 g / L hypophosphorous acid solution, and the mass ratio of the acid solution to the soil is 3:1. The soaking time is 2 days. After treatment, the lead content in the soil is reduced to 32 mg / kg, meeting the national standard requirement of less than 80 mg / kg, and the lead removal rate is 96.8%.

[0052] b, Regeneration of graft-modified keratin geotextile The graft-modified keratin geotextile saturated with adsorption is uniformly collected and regenerated. First, the graft-modified keratin geotextile adsorbed with metals is washed with water to remove solid impurities on its surface, and then is soaked with a 5% hydrochloric acid solution for regeneration.

[0053] After the regeneration of the graft-modified keratin geotextile, the soil is treated repeatedly, and when the graft-modified keratin geotextile is used for 10 cycles, the lead removal rate in the soil can still reach 88.3%.

[0054] Example 3: The material used is waste rabbit hair fiber keratin material.

[0055] A method for preparing geotextile for remediation or barrier of heavy metal contaminated soil, comprising the following steps: S1, pretreatment The rabbit hair fiber keratin is opened and impurities are removed to make it into single fiber form.

[0056] S2, washing The washing treatment is carried out by adopting a two-step washing process.

[0057] S2-1, washing and removing impurities. The rabbit hair fiber keratin to be treated is washed in a water solution cleaning tank with a permeating agent 1 g / L, at a temperature of 50 DEG C and a pH value of 8.0 for 20 min, to remove solid impurities. After drying, ultraviolet disinfection and sterilization treatment is carried out.

[0058] S2-2, enzyme washing. The rabbit hair fiber keratin after washing and removing impurities is deeply washed by configuring a composite enzyme cleaning solution. The cleaning solution used is a composite enzyme solution of multiple enzymes, which contains lipase 100 g / L, cellulase 50 g / L and acid protease 50 g / L. The washing is carried out at a temperature of 45 DEG C and a pH value of 3.0 for 10 min. After the treatment, the rabbit hair fiber keratin is transferred to hot water at 70 DEG C for washing, and the proteinase adsorbed on the surface of the rabbit hair fiber keratin material is inactivated.

[0059] S3, geotextile processing and preparation The rabbit hair fiber keratin after washing is carded into a thin fiber web of 20 g / m 3 by using a carding machine. Then, the cross-laying method is adopted to stack 80 layers, to form a thick fiber web of 1600 g / m 3 . Then, the needle punching machine is used for reinforcement treatment, to finally obtain the keratin geotextile with a thickness of 1.8 cm.

[0060] S4, modification treatment, which is divided into two steps S4-1, reduction treatment by disulfide bond reducing agent. The keratin geotextile is soaked in a mixed solution of tris (3-hydroxypropyl) phosphine and urea, to reduce the high-density disulfide bond in the keratin geotextile to sulfydryl. The concentration of tris (3-hydroxypropyl) phosphine is 50 g / L, and the concentration of urea is 3 g / L.

[0061] S4-2, graft modification treatment. The keratin geotextile after reduction treatment is transferred to a 2, 3-dimercaptosuccinic acid solution for soaking for 30 min. The reduction treatment and the treatment liquid solid-liquid mass ratio is 1:30. The concentration of the 2, 3-dimercaptosuccinic acid solution is 20 g / L. Then, drying treatment is carried out at 80 DEG C, to obtain the graft modified keratin geotextile. During the drying process, the sulfydryl in the reduced glutathione molecule is grafted with the sulfydryl on the surface of the modified keratin material to form disulfide bond.

[0062] The application method of the geotextile prepared by the method described above for remediation or barrier of heavy metal contaminated soil comprises the following steps: a. Remediation of copper contaminated soil, the copper content of the contaminated soil is 300 mg / kg (much higher than the national standard requirement). The prepared grafted modified keratin geotextile is embedded and laid in the inner layer of the contaminated soil, the mass ratio of the soil to the geotextile is 100:1, then the contaminated soil is soaked and leached with 0.1 g / L citric acid solution, the mass ratio of the citric acid solution to the soil is 5:1, and the soaking time is 5 days. After the treatment, the copper content in the soil is reduced to 21 mg / kg, which meets the national standard requirement of less than 150 mg / kg, and the copper removal rate is 93%.

[0063] b. Regeneration of the grafted modified keratin geotextile The saturated grafted modified keratin geotextile is uniformly collected and subjected to regeneration treatment. First, the grafted modified keratin geotextile adsorbed with metals is washed with water to remove the solid impurities on the surface, and then is soaked with 2% sulfuric acid solution for regeneration.

[0064] After the regeneration of the grafted modified keratin geotextile, the soil is treated repeatedly, and when the grafted modified keratin geotextile is used for 10 cycles, the copper removal rate in the soil can still reach 82.5%.

[0065] The grafted modified keratin geotextile can also be used as a barrier layer for heavy metal contaminated soil, and can be laid vertically or horizontally in the soil to effectively prevent the diffusion of heavy metals in the soil.

[0066] In example 4, the material used is waste wool fiber keratin material and feather material.

[0067] The preparation method of the geotextile for remediation or barrier of heavy metal contaminated soil comprises the following steps: S1, pretreatment The wool fiber keratin is opened and cleaned to become single fiber. The feather keratin is appropriately crushed to make the size of the crushed feather keratin particles uniform, and the average area is controlled to be about 1 cm 2 .

[0068] S2, cleaning The keratin material is cleaned by a two-step cleaning process, and the wool fiber keratin and the feather keratin are cleaned respectively, which specifically comprises the following steps: S2-1, cleaning and removing impurities. The keratin material to be cleaned is cleaned in a water solution cleaning tank with 1 g / L penetrant, at a temperature of 50°C and a pH value of 8.0 for 20 min to remove solid impurities, and then is dried and subjected to ultraviolet disinfection and sterilization treatment.

[0069] S2-2, enzyme washing. A composite enzyme cleaning solution is configured, and the keratin material after the cleaning is subjected to deep cleaning. The cleaning solution used is a composite enzyme solution of multiple enzymes, and the composite enzyme solution contains lipase 50 g / L, cellulase 100 g / L, and protease 100 g / L. The cleaning is performed at a temperature of 45°C and a pH value of 7.0 for 60 min. After the treatment, the keratin material is transferred to hot water at 70°C for cleaning, and the proteinase adsorbed on the surface of the keratin material is inactivated.

[0070] S3, modification treatment, which is divided into two steps S3-1, disulfide bond reducing agent reduction treatment. A mixed solution of ammonium thioglycolate and urea is used to soak the keratin material, and the high-density disulfide bond in the keratin material is reduced to a mercapto group. The concentration of ammonium thioglycolate is 100 g / L, and the concentration of urea is 10 g / L.

[0071] S3-2, graft modification treatment. The keratin material after the reduction treatment is transferred to a mixed solution containing reduced glutathione and urea for soaking for 30 min, and the solid-liquid mass ratio of the keratin material to the treatment solution is 1:40. The concentration of the reduced glutathione solution is 18 g / L, and the concentration of urea is 5 g / L. Then, drying treatment is performed at 80°C to obtain a graft-modified keratin material (including a graft-modified wool fiber keratin and a graft-modified feather keratin). During the drying process, the mercapto group in the reduced glutathione molecule is grafted to the surface mercapto group of the modified keratin material to form a disulfide bond.

[0072] S4, geotextile processing and preparation The graft-modified wool fiber keratin prepared in step S3 is carded into a 30 g / m 3 thin fiber web, and then is stacked into 70 layers by cross-laying, and the graft-modified feather keratin is uniformly spread between each thin fiber web to form a thick fiber web composed of the graft-modified wool fiber keratin and the graft-modified feather keratin. Finally, a 2100 g / m 3 thick fiber web is formed, and then is reinforced by a hydroentangling machine to obtain a graft-modified keratin geotextile with a thickness of 2.5 cm.

[0073] The application method of the geotextile prepared by the above method for remediation or blocking of heavy metal contaminated soil includes the following steps: a, remediation of heavy metal contaminated soil The lead contaminated soil is repaired, and the lead content of the contaminated soil is 1000 mg / kg (much higher than the national standard requirement). The prepared grafted modified keratin geotextile is laid under the contaminated soil, the mass ratio of the soil to the geotextile is 100:1, then the contaminated soil is soaked and leached by using a 0.5 g / L hypophosphorous acid solution, the mass ratio of the acid solution to the soil is 3:1, and the soaking time is 2 days. After the treatment, the lead content in the soil is reduced to 58 mg / kg, which meets the national standard requirement of less than 80 mg / kg, and the lead removal rate is 94.2%.

[0074] b. Regeneration of the grafted modified keratin geotextile The adsorbed and saturated grafted modified keratin geotextile is uniformly recovered and subjected to regeneration treatment. First, the grafted modified keratin geotextile adsorbed with metals is washed with water to remove solid impurities on the surface, and then is soaked with a 5% hydrochloric acid solution for regeneration.

[0075] After the regeneration of the grafted modified keratin geotextile, the soil is treated repeatedly, and when the grafted modified keratin geotextile is recycled for 10 times, the lead removal rate in the soil can still reach 81.2%.

[0076] In Example 5, the materials used are waste wool fiber keratin materials and feather materials.

[0077] The preparation method of the geotextile for repairing or blocking heavy metal contaminated soil comprises the following steps: S1. Pretreatment The wool fiber keratin is opened and impurities are removed to make it into a single fiber shape. The feather keratin is appropriately crushed to make the crushed feather keratin particles uniform in size, and the average area is controlled to be about 1 cm 2 .

[0078] S2. Washing The keratin materials are washed by using a two-step washing process, and the wool fiber keratin and the feather keratin are washed respectively, which specifically comprises the following steps: S2-1. Washing and removing impurities. The keratin materials to be washed are washed in a water solution tank with a permeating agent 1 g / L, a temperature of 50°C and a pH value of 8.0 for 20 min to remove solid impurities, and then are dried and subjected to ultraviolet disinfection and sterilization treatment.

[0079] S2-2. Enzyme washing. The washed and impurity-removed keratin materials are subjected to deep washing by using a compound enzyme washing solution. The washing solution is a compound enzyme solution containing lipase 50 g / L, cellulase 100 g / L and protease 100 g / L, and the washing is performed at a temperature of 45°C and a pH value of 7.0 for 60 min. After the treatment, the keratin materials are transferred to hot water at 70°C for washing, and the protease adsorbed on the surface of the keratin materials is inactivated.

[0080] S3, modification treatment, the modification is divided into two steps S3-1, disulfide bond reducing agent reduction treatment. The keratin material is soaked in a mixed solution of ammonium thioglycolate and urea to reduce the high-density disulfide bond in the keratin material to sulfydryl, wherein the concentration of ammonium thioglycolate is 80 g / L, and the concentration of urea is 9 g / L.

[0081] S3-2, graft modification treatment. The reduced keratin material is transferred to a mixed solution of reduced glutathione and urea for soaking for 30 min, and the solid-liquid mass ratio of the keratin material to the treatment solution is 1:40. The concentration of the reduced glutathione solution is 17 g / L, and the concentration of urea is 5 g / L. Then, drying treatment is carried out at 80°C to obtain a grafted and modified keratin material (including grafted and modified wool fiber keratin and grafted and modified feather keratin). During the drying process, the sulfydryl in the reduced glutathione molecule will graft with the sulfydryl on the surface of the modified keratin material to form a disulfide bond.

[0082] S4, geotextile processing and preparation The grafted and modified wool fiber keratin prepared in step S3 is carded into a 100 g / m 3 thin fiber web using a carding machine, and then is stacked into 10 layers using a cross-laying method. The grafted and modified feather keratin is uniformly spread between each thin fiber web to form a thick fiber web composed of grafted and modified wool fiber keratin and grafted and modified feather keratin. Finally, a 1000 g / m 3 thick fiber web is formed, and then is reinforced using a hydroentangling machine to obtain a grafted and modified keratin geotextile with a thickness of 1.5 cm.

[0083] The application method of the geotextile prepared by the above method for heavy metal contaminated soil remediation or barrier includes the following steps: a, heavy metal contaminated soil remediation The lead-contaminated soil is remediated, and the lead content of the contaminated soil is 1000 mg / kg (much higher than the national standard requirement). The prepared grafted and modified keratin geotextile is laid under the contaminated soil, and the mass ratio of the soil to the geotextile is 100:1. Then, the contaminated soil is soaked and leached with a 0.5 g / L hypophosphorous acid solution, and the mass ratio of the acid solution to the soil is 3:1. The soaking time is 2 days. After treatment, the lead content in the soil is reduced to 58 mg / kg, which meets the national standard requirement of less than 80 mg / kg, and the lead removal rate is 94.2%.

[0084] b, regeneration of grafted and modified keratin geotextile The graft modified keratin geotextile saturated with adsorption is collected and regenerated. First, the graft modified keratin geotextile adsorbed with metals is washed with water to remove solid impurities on the surface, and then regenerated by soaking in 5% hydrochloric acid solution.

[0085] The graft modified keratin geotextile is regenerated and then used to treat soil repeatedly. When the graft modified keratin geotextile is used for 10 cycles, the removal rate of lead in the soil can still reach 80.7%.

[0086] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, component disassembly or combination, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing geotextiles for remediation or barrier treatment of heavy metal contaminated soil, characterized in that, Includes the following steps: S1, Preprocessing Pretreatment of keratin materials is carried out, in which fibrous keratin is loosened and impurities are removed to make it into single fibers; feather keratin is pulverized so that the average area of ​​the pulverized feather keratin particles is controlled at 0.2cm²-2cm². S2, Cleaning The keratin materials are sorted and cleaned. S3, Geotextile Processing and Preparation The cleaned fibrous keratinocytes are combed to a density of 10-100g / m². 3 The fiber mesh is laid in 1-100 layers, and 0-100 layers of feather-like keratin are evenly spread between the layers. Then, it is reinforced by needle punching or hydroentangling to form a keratin geotextile with a thickness of 0.1-100cm. S4, Modification Treatment S4-1, reduction treatment with disulfide bond reducing agent The keratin geotextile was soaked in a mixture of 0.1-100 g / L disulfide reducing agent and 0.1-10 g / L urea to reduce the disulfide bonds in the keratin geotextile to thiol groups. S4-2 Grafting Modification Treatment The reduced keratin geotextile was immersed in a treatment solution containing 0.1-100 g / L grafting modification reagent and 0.1-100 g / L urea for 10-60 min, and then dried at 80℃ to obtain grafted modified keratin geotextile. The solid-liquid mass ratio of the keratin geotextile to the treatment solution was 1:10-500. The grafting modification reagent contained at least one thiol group and one carboxyl group, and was at least one of reduced glutathione, 2,3-dimercaptosuccinic acid, 3-mercaptomalonic acid, and cysteine.

2. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 1, characterized in that: In step S1, the fibrous keratin includes wool and rabbit hair; the feather keratin includes duck feathers and goose feathers.

3. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 1, characterized in that: In step S2, the keratin material is sorted and cleaned, specifically including the following steps: S2-1. Cleaning and impurity removal: The keratin material to be treated is cleaned for 20 minutes in an aqueous cleaning tank with 1g / L penetrant, 50℃ and pH 8.0 to remove solid impurities. After drying, it is disinfected and sterilized. S2-2, Enzymatic washing: The cleaned keratin material is washed in a compound enzyme solution at a temperature of 30-50℃ and a pH of 2-10 for 5-120 minutes. After that, it is transferred to 70℃ hot water for further washing and inactivation of proteases. The compound enzyme solution contains 0.1-100g / L of lipase, 0.1-100g / L of cellulase and 0.1-100g / L of protease.

4. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 3, characterized in that: In step S2-2, the keratin material after cleaning and impurity removal is washed in a compound enzyme solution at a temperature of 45°C and a pH of 7-8 for 60 minutes. After that, it is transferred to hot water at 70°C for cleaning and inactivation of protease. The compound enzyme contains 0.3 g / L of lipase, 0.2 g / L of cellulase, and 0.5 g / L of protease.

5. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 1, characterized in that: In step S4-1, the disulfide bond reducing agent is one of tris(3-hydroxypropyl)phosphine, ammonium thioglycolate, mercaptoacetic acid, mercaptoethanol, and tris(2-carboxyethyl)phosphine.

6. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 1, characterized in that: In step S4-1, the reaction formula for the reduction of disulfide bonds to thiol groups is as follows: 。 7. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 1, characterized in that: In step S4-2, the solid-liquid mass ratio of keratin geotextile to treatment solution is 1:30-50, the grafting modification agent is reduced glutathione, and the concentration of grafting modification agent in the treatment solution containing urea is 12-18 g / L and the concentration of urea is 5 g / L.

8. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 7, characterized in that: In step S4-2, during the drying process at 80°C, the thiol groups in the grafting modification reagent react with the thiol groups in the keratin material to form disulfide bonds, as shown in the following reaction formula: 。 9. The application method of the geotextile prepared by any one of claims 1-8 for the remediation or barrier of heavy metal contaminated soil, characterized in that, Includes the following steps: a. Remediation of soil contaminated with heavy metals: Based on the heavy metal content of the soil, select grafted modified keratin geotextile and lay it under or inside the contaminated soil. Then, perform leaching treatment. The leaching solution is water, or a solution of citric acid, oxalic acid, phosphoric acid, or acetic acid with a concentration of 0.1-10 g / L. The soaking time is 0.5-7 days. The solid-liquid mass ratio of soil to leaching solution is 1:1-10. Under the action of the leaching solution, heavy metal ions in the soil are released into the liquid phase and adsorbed and fixed by the grafted modified keratin geotextile. b. Regeneration of grafted modified keratin geotextile: The saturated grafted modified keratin geotextile is recovered and regenerated. First, it is rinsed with water to remove solid impurities from its surface. Then, it is soaked in an acid solution with a mass percentage concentration of 0.1%-25% for regeneration treatment. The acid solution is hydrochloric acid, sulfuric acid or acetic acid.

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