Preparation and application method of geotextile for remediation or barrier of heavy metal contaminated soil
By preparing grafted modified keratin geotextile and combining it with leaching and regeneration treatment, the problems of low remediation efficiency and secondary pollution of heavy metal contaminated soil were solved, achieving efficient and environmentally friendly heavy metal removal and resource utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JINZHONG UNIV
- Filing Date
- 2025-09-09
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies for remediating heavy metal-contaminated soil suffer from low efficiency, high cost, and a tendency to cause secondary pollution, while waste keratin resources are not being effectively utilized.
Geotextiles are prepared using waste keratin materials. Through disulfide bond reduction and grafting modification, grafted keratin geotextiles are formed for leaching remediation and barrier of heavy metal contaminated soils. They are combined with leaching solution to adsorb heavy metals and then regenerated through acid washing.
It achieves efficient and non-secondary pollution remediation of heavy metal contaminated soil, can remove heavy metals from the soil in a short time, protect the soil properties, and can be recycled to reduce costs.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of soil remediation technology, and in particular to a method for preparing and applying geotextiles for the remediation or barrier of heavy metal contaminated soil. Background Technology
[0002] Currently, remediation technologies for heavy metal contaminated soil mainly include solidification and stabilization, soil washing, phytoremediation, thermal desorption, and electrokinetic remediation. However, these technologies have many problems: solidification and stabilization cannot completely remove heavy metals and may damage soil fertility; soil washing is prone to secondary pollution; phytoremediation has a long cycle; thermal desorption has limited applicability; and electrokinetic remediation is inefficient and difficult to apply on a large scale. Therefore, there is an urgent need to develop a highly efficient, green technology that does not cause secondary pollution in the remediation or containment of heavy metal contaminated soil.
[0003] Keratin, a natural high-molecular-weight protein, is widely found in animal hair and horns, such as wool and rabbit fur. Its molecular chains are rich in disulfide bonds. Natural keratin materials possess excellent bioactivity, biocompatibility, biodegradability, good mechanical properties, and wide availability, making them widely used in the textile and leather industries. However, waste keratin is generally treated as waste material and is not fully utilized. It is estimated that the total amount of waste keratin generated globally each year is approximately 12 to 16 million tons, but the actual recycling rate is less than 10%, with most ending up in landfills or incineration. This not only wastes resources 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 pollution-free technology for the remediation or containment of heavy metal contaminated soil has become an important issue that urgently needs to be addressed. Summary of the Invention
[0005] Therefore, the purpose of this invention is to provide a method for preparing and applying geotextiles for the remediation or barrier of heavy metal contaminated soil, so as to solve the problems pointed out in the background art above.
[0006] To achieve the aforementioned objectives, the technical solution adopted is as follows:
[0007] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps:
[0008] S1, Preprocessing
[0009] 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.
[0010] S2, Cleaning
[0011] The keratin materials are sorted and cleaned.
[0012] S3, Geotextile Processing and Preparation
[0013] The cleaned keratin fibers are combed to a density of 10-100 g / m using a combing machine. 3 A thin fiber mesh is laid, with 1-100 layers of thin fiber mesh, and 0-100 layers of feather keratin are evenly spread between the layers (feather keratin can be omitted to make a thick fiber mesh of pure keratin fibers). Then, it is reinforced by a needle punching machine or a hydroentangling machine to form a keratin geotextile with a thickness of 0.1-100cm. The thickness of the keratin geotextile is preferably 5cm.
[0014] S4, Modification Treatment
[0015] S4-1, reduction treatment with disulfide bond reducing agent
[0016] 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 high density of disulfide bonds in the keratin geotextile to thiol groups. The addition of urea can promote the swelling of keratin material and facilitate the reaction. After reduction treatment, a large number of thiol groups will be generated on the surface and inside of the keratin material.
[0017] S4-2 Grafting Modification Treatment
[0018] 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.
[0019] As a further improvement of the present invention, in step S1, the fibrous keratin includes animal fibers such as wool and rabbit hair; the feather keratin includes duck feathers and goose feathers.
[0020] As a further improvement of the present invention, the keratin geotextile is sorted and cleaned in step S2, specifically including the following steps:
[0021] 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℃ temperature and pH value of 8.0 to remove solid impurities. After drying, it is disinfected and sterilized. Ultraviolet disinfection or spraying of bactericide can be used. Ultraviolet disinfection is preferred because it leaves no chemical residue.
[0022] S2-2, Enzymatic washing: The cleaned and impurity-removed 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 protease (inactivation of protease adsorbed on the surface of the material). The compound enzyme solution contains 0.1-100g / L of lipase, 0.1-100g / L of cellulase and 0.1-100g / L of protease.
[0023] As a further improvement of the present invention, 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, and then 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.
[0024] As a further improvement of the present invention, 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.
[0025] As a further improvement of the present invention, the reaction formula for the reduction of disulfide bonds to mercapto groups in step S4-1 is as follows:
[0026] .
[0027] As a further improvement of the present invention, 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 in the treatment solution of grafting modification agent and urea, the solution concentration of grafting modification agent is 12-18 g / L, and the concentration of urea is 5 g / L.
[0028] As a further improvement of the present invention, 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. When the grafting modification reagent is reduced glutathione, the reaction formula is as follows:
[0029] .
[0030] The application method of geotextiles prepared by any of the methods described above for the remediation or barrier of heavy metal contaminated soil includes the following steps:
[0031] a. Remediation of soil contaminated with heavy metals: Based on the heavy metal content of the soil, select a grafted modified keratin geotextile of a certain thickness 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, preferably citric acid solution, preferably with a concentration of 2 g / L. The soaking time is 0.5-7 days, preferably 5 days. The solid-liquid mass ratio of soil to leaching solution is 1:1-10, preferably 1:4. Under the action of the leaching solution, the heavy metal ions in the soil are released into the liquid phase and adsorbed and fixed by the grafted modified keratin geotextile.
[0032] b. Regeneration of grafted modified keratin geotextile: The saturated grafted modified keratin geotextile is uniformly recycled and regenerated. First, it is rinsed with water to remove solid impurities on its surface. Then, it is soaked and regenerated with an acid solution with a mass percentage concentration of 0.1%-25%. The acid solution is hydrochloric acid, sulfuric acid or acetic acid, etc., preferably hydrochloric acid, preferably with a concentration of 1-15%, and more preferably with a concentration of 5%.
[0033] As a further improvement of the present invention, when the grafting modification agent is reduced glutathione, the adsorption and regeneration reaction formula of the grafted modified keratin geotextile is as follows:
[0034] .
[0035] The grafted modified keratin geotextile can also be used as an isolation layer for soil contaminated with heavy metals. It can be laid longitudinally or laterally in the soil to effectively prevent the diffusion of heavy metals in the soil.
[0036] The beneficial effects of this invention are:
[0037] 1. High treatment efficiency. Traditional soil remediation technologies require months or even years, during which heavy metals continue to migrate and spread, leading to an expansion of the contaminated area. In contrast, this invention, through modified keratin geotextile combined with leaching treatment, can efficiently adsorb and remove heavy metals from the soil within 7 days, effectively blocking migration pathways and avoiding the problem of the expansion of the contaminated area due to heavy metal migration during long-term treatment.
[0038] 2. No secondary pollution and preservation of soil properties. The geotextile prepared by this invention can adsorb heavy metals inside the geotextile. After the adsorption treatment is completed, the geotextile can be collected and regenerated by acid washing. During the acid washing process, the heavy metals dissolve in the acid washing solution. This method does not produce secondary pollution to the soil and can efficiently remove heavy metals from polluted soil while protecting the physical and chemical properties and ecological activity of the soil.
[0039] 3. Waste-to-waste treatment with low cost. This invention uses waste keratin material for heavy metal removal from soil, thus treating waste with waste and reducing raw material costs. The used geotextile can be recycled and reused, further reducing operating costs and facilitating large-scale application.
[0040] 4. Can be used for the isolation of heavy metal contaminated soil. This grafted modified keratin geotextile can be laid in the soil as an isolation layer to isolate areas of heavy metal contaminated soil. It can be laid longitudinally or laterally in the soil to effectively block the diffusion and migration of heavy metals in the soil and prevent the contamination area from expanding. Detailed Implementation
[0041] The embodiments given below are intended to further illustrate the present invention, but should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.
[0042] In this invention, the geotextile can be modified first and then prepared, or the geotextile can be prepared first and then modified; that is, steps S3 and S4 can be interchanged.
[0043] Example 1: The material used is waste wool fiber keratin material.
[0044] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps:
[0045] S1, Preprocessing
[0046] The keratin in the wool fibers is loosened and impurities are removed, making them into single fibers.
[0047] S2, Cleaning
[0048] A two-step cleaning process is used for the cleaning treatment, specifically including the following steps:
[0049] S2-1. Cleaning and impurity removal: The wool fiber keratin 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 subjected to ultraviolet disinfection and sterilization.
[0050] S2-2, Enzyme Washing: Prepare a compound enzyme washing solution. Deeply wash the cleaned and impurity-removed wool fiber keratin in the compound enzyme solution, which includes 0.3 g / L lipase, 0.2 g / L cellulase, and 0.5 g / L protease. Wash for 60 minutes at 45°C and pH 7.0. After treatment, transfer the wool fiber keratin to 70°C hot water for further rinsing, simultaneously inactivating the protease adsorbed on the surface of the wool fiber keratin.
[0051] S3, Geotextile Processing and Preparation
[0052] The keratin in the washed wool fibers is combed to 70g / m² using a carding machine. 3 A thin fiber web is formed, and then 100 layers are laid out using a cross-laying method, ultimately forming a 7000g / m² fiber web. 3 A thick fiber mesh is formed, and then a needle punch is used to reinforce it, resulting in a keratin geotextile with a thickness of 4.0 cm.
[0053] S4, Modification Treatment
[0054] S4-1, reduction treatment with disulfide bond reducing agent
[0055] Keratin geotextile was soaked in a mixed solution of tris(2-carboxyethyl)phosphine and urea to reduce the high density of disulfide bonds in the keratin geotextile to mercapto groups. The concentration of tris(2-carboxyethyl)phosphine was 10 g / L and the concentration of urea was 3 g / L.
[0056] The reaction formula for the reduction of disulfide bonds to thiol groups is as follows:
[0057] .
[0058] S4-2 Grafting Modification Treatment
[0059] The keratin geotextile after reduction treatment in step S4-1 was transferred to a mixed solution containing reduced glutathione and urea and immersed for 30 minutes. The solid-liquid mass ratio of the keratin geotextile to the treatment solution was 1:50. The concentration of the reduced glutathione solution was 12 g / L, and the concentration of urea was 5 g / L. Then, it was dried at 80℃ to obtain the grafted modified keratin geotextile. During the drying process, the thiol groups in the reduced glutathione molecules grafted onto the thiol groups on the surface of the modified keratin material to form disulfide bonds, as shown in the following reaction formula:
[0060] .
[0061] The application method of the geotextile prepared by the method described above for the remediation or barrier of heavy metal contaminated soil includes the following steps:
[0062] a. Remediation of lead-contaminated soil: The lead content of the contaminated soil was 1000 mg / kg (far exceeding the national standard). A grafted 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 48 mg / kg, meeting the national standard requirement of less than 80 mg / kg, with a lead removal rate of 95.2%.
[0063] b. Regeneration of grafted modified keratin geotextile
[0064] The saturated geotextiles were collected and regenerated. First, the grafted modified keratin geotextiles that had adsorbed metals were washed with water to remove solid impurities from their surface. Then, they were regenerated by soaking in a 4% hydrochloric acid solution.
[0065] After the grafted modified keratin geotextile is regenerated and the soil is repeatedly treated, the lead removal rate in the soil can still reach 85.6% after 10 cycles.
[0066] The adsorption and regeneration reaction formula for grafted modified keratin geotextile is as follows:
[0067] .
[0068] Comparative Example 1: The material used was waste wool fiber keratin material.
[0069] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps:
[0070] S1, Preprocessing
[0071] The keratin in the wool fibers is loosened and impurities are removed, making them into single fibers.
[0072] S2, Cleaning
[0073] A two-step cleaning process is used for the cleaning treatment, specifically including the following steps:
[0074] S2-1. Cleaning and impurity removal: The wool fiber keratin 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 subjected to ultraviolet disinfection and sterilization.
[0075] S2-2, Enzyme Washing: Prepare a compound enzyme washing solution. Deeply wash the cleaned and impurity-removed wool fiber keratin in the compound enzyme solution, which includes 0.3 g / L lipase, 0.2 g / L cellulase, and 0.5 g / L protease. Wash for 60 minutes at 45°C and pH 7.0. After treatment, transfer the wool fiber keratin to 70°C hot water for further rinsing, simultaneously inactivating the protease adsorbed on the surface of the wool fiber keratin.
[0076] S3, Geotextile Processing and Preparation
[0077] The keratin in the washed wool fibers is combed to 70g / m² using a carding machine. 3 A thin fiber web is formed, and then 100 layers are laid out using a cross-laying method, ultimately forming a 7000g / m² fiber web. 3A thick fiber mesh is formed, and then a needle punch is used to reinforce it, resulting in a keratin geotextile with a thickness of 4.0 cm.
[0078] S4, Modification Treatment
[0079] Disulfide bond reducing agent reduction treatment
[0080] Keratin geotextile was treated by soaking it in a mixed solution of tris(2-carboxyethyl)phosphine and urea to reduce the high density of disulfide bonds in the keratin geotextile to thiol groups. The concentration of tris(2-carboxyethyl)phosphine was 10 g / L and the concentration of urea was 3 g / L. After treatment, the geotextile was dried to obtain the modified keratin geotextile.
[0081] The application method of the geotextile prepared by the method described above for the remediation or barrier of heavy metal contaminated soil includes the following steps:
[0082] 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%.
[0083] As can be seen from Example 1, grafting modification treatment can significantly improve the adsorption effect of keratin geotextile on metal ions.
[0084] Example 2: The materials used are waste wool fiber keratin material and feather material.
[0085] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps:
[0086] S1, Preprocessing
[0087] 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.
[0088] S2, Cleaning
[0089] 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:
[0090] 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.
[0091] 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.
[0092] S3. Modification treatment, which involves two steps.
[0093] 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.
[0094] S3-2. Grafting Modification Treatment. The reduced keratin material was transferred to a mixed solution containing reduced glutathione and urea and immersed for 30 minutes. The solid-liquid mass ratio of the keratin material to the treatment solution was 1:30. The concentration of the reduced glutathione solution was 15 g / L, and the concentration of urea was 5 g / L. Then, it was dried at 80℃ to obtain grafted modified keratin materials (including grafted modified wool fiber keratin and grafted modified feather keratin). During the drying process, the sulfhydryl groups in the reduced glutathione molecules grafted onto the sulfhydryl groups on the surface of the modified keratin material to form disulfide bonds.
[0095] S4. Geotextile processing and preparation
[0096] The grafted modified wool fiber keratin obtained in step S3 was combed using a carding machine to a density of 80 g / m². 3 Thin fiber webs are formed, and then 100 layers are laid out using a cross-laying method. Grafted modified feather keratin is evenly spread between the thin fiber webs to form a thick fiber web composed of grafted modified wool fiber keratin and grafted modified feather keratin, ultimately forming an 8000g / m² fiber web. 3 A thick fiber mesh is formed, and then reinforced by hydroentangling to obtain a grafted modified keratin geotextile with a thickness of 4.5 cm.
[0097] The application method of the geotextile prepared by the method described above for the remediation or barrier of heavy metal contaminated soil includes the following steps:
[0098] a) Remediation of heavy metal contaminated soil
[0099] Lead-contaminated soil with a lead content of 1000 mg / kg (far exceeding national standards) was treated. A grafted modified keratin geotextile was laid beneath the contaminated soil at a soil-to-geotextile ratio of 100:1. The soil was then soaked and leached with a 0.5 g / L hypophosphite solution at a 3:1 acid-to-soil ratio for two days. After treatment, the lead content in the soil decreased to 32 mg / kg, meeting the national standard requirement of less than 80 mg / kg, achieving a lead removal rate of 96.8%.
[0100] b. Regeneration of grafted modified keratin geotextile
[0101] The saturated grafted modified keratin geotextile was collected and regenerated. First, the grafted modified keratin geotextile that had adsorbed metal was washed with water to remove solid impurities from its surface. Then, it was regenerated by soaking in a 5% hydrochloric acid solution.
[0102] After the grafted modified keratin geotextile is regenerated and the soil is repeatedly treated, the lead removal rate in the soil can still reach 88.3% after 10 cycles.
[0103] Example 3: The material used is waste rabbit hair fiber keratin material.
[0104] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps:
[0105] S1, Preprocessing
[0106] The keratin in the rabbit hair fibers is loosened and impurities are removed to make them into single fibers.
[0107] S2, Cleaning
[0108] A two-step cleaning process is used for cleaning.
[0109] S2-1. Cleaning and impurity removal. The rabbit hair fiber keratin 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 subjected to ultraviolet disinfection and sterilization.
[0110] S2-2, Enzyme Washing. A compound enzyme washing solution is prepared to deeply wash the cleaned and impurity-removed rabbit hair fiber keratin. The washing solution used is a compound enzyme solution containing 100 g / L lipase, 50 g / L cellulase, and 50 g / L acidic protease. Washing is performed for 10 minutes at 45°C and pH 3.0. After treatment, the rabbit hair fiber keratin is transferred to 70°C hot water for further washing, simultaneously inactivating the protease adsorbed on the surface of the rabbit hair fiber keratin material.
[0111] S3, Geotextile Processing and Preparation
[0112] The keratin in the washed rabbit hair fibers was combed to a density of 20g / m² using a combing machine. 3 A thin fiber web is formed, and then laid in 80 layers using a cross-laying method, ultimately forming a 1600g / m² fiber web. 3 The thick fiber mesh is then reinforced using a needle punching machine to finally produce a keratin geotextile with a thickness of 1.8cm.
[0113] S4. Modification treatment, which involves two steps.
[0114] S4-1, Disulfide Bond Reduction Treatment. Keratin geotextile was soaked in a mixed solution of tris(3-hydroxypropyl)phosphine and urea to reduce the high density of disulfide bonds within the geotextile to mercapto groups. The concentration of tris(3-hydroxypropyl)phosphine was 50 g / L, and the concentration of urea was 3 g / L.
[0115] S4-2. Grafting Modification Treatment. The reduced keratin geotextile was transferred to a 2,3-dimercaptosuccinic acid solution and immersed for 30 minutes. The solid-liquid mass ratio of the reduced treatment solution to the treatment solution was 1:30. The concentration of the 2,3-dimercaptosuccinic acid solution was 20 g / L. Then, it was dried at 80℃ to obtain the grafted modified keratin geotextile. During the drying process, the thiol groups in the reduced glutathione molecules grafted onto the thiol groups on the surface of the modified keratin material to form disulfide bonds.
[0116] The application method of the geotextile prepared by the method described above for the remediation or barrier of heavy metal contaminated soil includes the following steps:
[0117] a. Remediation of copper-contaminated soil: The copper content of the contaminated soil was 300 mg / kg (far exceeding the national standard). Grafted modified keratin geotextile was laid as an inner layer of the contaminated soil at a soil-to-geotextile ratio of 100:1. The contaminated soil was then soaked and leached with a 0.1 g / L citric acid solution at a citric acid-to-soil ratio of 5:1 for 5 days. After treatment, the copper content in the soil decreased to 21 mg / kg, meeting the national standard requirement of less than 150 mg / kg, with a copper removal rate of 93%.
[0118] b. Regeneration of grafted modified keratin geotextile
[0119] The saturated grafted modified keratin geotextile was collected and regenerated. First, the grafted modified keratin geotextile that had adsorbed metal was washed with water to remove solid impurities from its surface. Then, it was regenerated by soaking in a 2% sulfuric acid solution.
[0120] After the grafted modified keratin geotextile is regenerated and the soil is repeatedly treated, the copper removal rate in the soil can still reach 82.5% after 10 cycles.
[0121] The grafted modified keratin geotextile can also be used as an isolation layer for soil contaminated with heavy metals. It can be laid longitudinally or laterally in the soil to effectively prevent the diffusion of heavy metals in the soil.
[0122] Example 4: The materials used are waste wool fiber keratin material and feather material.
[0123] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps:
[0124] S1, Preprocessing
[0125] 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.
[0126] S2, Cleaning
[0127] 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:
[0128] 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.
[0129] S2-2, Enzyme Wash. Prepare a compound enzyme washing solution to deeply clean the keratin material after initial cleaning and impurity removal. The washing solution used is a compound enzyme solution containing 50 g / L lipase, 100 g / L cellulase, and 100 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.
[0130] S3. Modification treatment, which involves two steps.
[0131] S3-1, Disulfide Bond Reduction Treatment. Keratin materials are soaked in a mixed solution of ammonium thioglycolate and urea to reduce the high density of disulfide bonds within the keratin material to thiol groups. The concentration of ammonium thioglycolate is 100 g / L, and the concentration of urea is 10 g / L.
[0132] S3-2. Grafting Modification Treatment. The reduced keratin material was transferred to a mixed solution containing reduced glutathione and urea and immersed for 30 minutes. The solid-liquid mass ratio of the keratin material to the treatment solution was 1:40. The concentration of the reduced glutathione solution was 18 g / L, and the concentration of urea was 5 g / L. The material was then dried at 80°C to obtain grafted modified keratin materials (including grafted modified wool fiber keratin and grafted modified feather keratin). During the drying process, the sulfhydryl groups in the reduced glutathione molecules grafted onto the sulfhydryl groups on the surface of the modified keratin material to form disulfide bonds.
[0133] S4. Geotextile processing and preparation
[0134] The grafted modified wool fiber keratin obtained in step S3 was combed to a density of 30 g / m using a carding machine. 3 Thin fiber webs are formed, and then 70 layers are laid out using a cross-laying method. Grafted modified feather keratin is evenly spread between the thin fiber webs to form a thick fiber web composed of grafted modified wool fiber keratin and grafted modified feather keratin, ultimately forming a 2100g / m² fiber web. 3 A thick fiber mesh is formed, and then reinforced by a hydroentangling machine to obtain a grafted modified keratin geotextile with a thickness of 2.5 cm.
[0135] The application method of the geotextile prepared by the method described above for the remediation or barrier of heavy metal contaminated soil includes the following steps:
[0136] a) Remediation of heavy metal contaminated soil
[0137] Lead-contaminated soil with a lead content of 1000 mg / kg (far exceeding national standards) was remediated. A grafted modified keratin geotextile was laid beneath the contaminated soil at a soil-to-geotextile ratio of 100:1. The soil was then soaked and leached with a 0.5 g / L hypophosphite solution at a 3:1 acid-to-soil ratio for 2 days. After treatment, the lead content in the soil decreased to 58 mg / kg, meeting the national standard requirement of less than 80 mg / kg, achieving a lead removal rate of 94.2%.
[0138] b. Regeneration of grafted modified keratin geotextile
[0139] The saturated grafted modified keratin geotextile was collected and regenerated. First, the grafted modified keratin geotextile that had adsorbed metal was washed with water to remove solid impurities from its surface. Then, it was regenerated by soaking in a 5% hydrochloric acid solution.
[0140] After the grafted modified keratin geotextile is regenerated and the soil is repeatedly treated, the lead removal rate in the soil can still reach 81.2% after 10 cycles.
[0141] Example 5: The materials used are waste wool fiber keratin material and feather material.
[0142] A method for preparing geotextiles for remediation or barrier of heavy metal contaminated soil includes the following steps:
[0143] S1, Preprocessing
[0144] 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.
[0145] S2, Cleaning
[0146] 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:
[0147] 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.
[0148] S2-2, Enzyme Wash. Prepare a compound enzyme washing solution to deeply clean the keratin material after initial cleaning and impurity removal. The washing solution used is a compound enzyme solution containing 50 g / L lipase, 100 g / L cellulase, and 100 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.
[0149] S3. Modification treatment, which involves two steps.
[0150] S3-1, Disulfide Bond Reduction Treatment. Keratin materials are soaked in a mixed solution of ammonium thioglycolate and urea to reduce the high density of disulfide bonds within the keratin material to thiol groups. The concentration of ammonium thioglycolate is 80 g / L, and the concentration of urea is 9 g / L.
[0151] S3-2. Grafting Modification Treatment. The reduced keratin material was transferred to a mixed solution containing reduced glutathione and urea and immersed for 30 minutes. The solid-liquid mass ratio of the keratin material to the treatment solution was 1:40. The concentration of the reduced glutathione solution was 17 g / L, and the concentration of urea was 5 g / L. The material was then dried at 80°C to obtain grafted modified keratin materials (including grafted modified wool fiber keratin and grafted modified feather keratin). During the drying process, the sulfhydryl groups in the reduced glutathione molecules grafted onto the sulfhydryl groups on the surface of the modified keratin material to form disulfide bonds.
[0152] S4. Geotextile processing and preparation
[0153] The grafted modified wool fiber keratin obtained in step S3 was combed to a density of 100 g / m² using a carding machine. 3 Thin fiber webs are formed, and then 10 layers are laid out using a cross-laying method. Grafted modified feather keratin is evenly spread between the thin fiber webs to form a thick fiber web composed of grafted modified wool fiber keratin and grafted modified feather keratin, ultimately forming a 1000g / m² thick fiber web. 3 A thick fiber mesh is formed, and then reinforced by a hydroentangling machine to obtain a grafted modified keratin geotextile with a thickness of 1.5 cm.
[0154] The application method of the geotextile prepared by the method described above for the remediation or barrier of heavy metal contaminated soil includes the following steps:
[0155] a) Remediation of heavy metal contaminated soil
[0156] Lead-contaminated soil with a lead content of 1000 mg / kg (far exceeding national standards) was remediated. A grafted modified keratin geotextile was laid beneath the contaminated soil at a soil-to-geotextile ratio of 100:1. The soil was then soaked and leached with a 0.5 g / L hypophosphite solution at a 3:1 acid-to-soil ratio for 2 days. After treatment, the lead content in the soil decreased to 58 mg / kg, meeting the national standard requirement of less than 80 mg / kg, achieving a lead removal rate of 94.2%.
[0157] b. Regeneration of grafted modified keratin geotextile
[0158] The saturated grafted modified keratin geotextile was collected and regenerated. First, the grafted modified keratin geotextile that had adsorbed metal was washed with water to remove solid impurities from its surface. Then, it was regenerated by soaking in a 5% hydrochloric acid solution.
[0159] After the grafted modified keratin geotextile is regenerated and the soil is repeatedly treated, the lead removal rate in the soil can still reach 80.7% after 10 cycles.
[0160] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, component splitting or combination, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
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 The keratin materials undergo pretreatment. Fibrous keratin is loosened and impurities removed to form single fibers; feather-like keratin is pulverized, ensuring the average surface area of the pulverized feather-like keratin particles is controlled to be 0.2 cm². 2 -2cm 2 ; S2, Cleaning 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 and impurity-removed 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 washing and inactivation of protease. The compound enzyme solution contains 0.1-100g / L of lipase, 0.1-100g / L of cellulase and 0.1-100g / L of protease. 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 S2-2, 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.
4. 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.
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 reaction formula for the reduction of disulfide bonds to thiol groups is as follows: 。 6. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 1, characterized in that: In step S4-2, 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.
7. The method for preparing geotextile for remediation or barrier of heavy metal contaminated soil according to claim 6, 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: 。 8. The application method of the geotextile prepared by any one of claims 1-7 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.