Method for long-acting remediation of o-phenylenediamine polluted underground water by using amphiphilic covalent organic polymer

Abstract

The invention discloses a method for long-acting remediation of o-phenylenediamine polluted underground water by an amphiphilic covalent organic polymer, and belongs to the technical field of site pollution treatment. Comprising the following steps: step 1, preparation of a remediation agent; step 2, in-situ injection of the amphiphilic covalent organic polymer for long-acting remediation of o-phenylenediamine polluted underground water; the remediation agent has efficient OPD adsorption capacity, the synthesis process is rapid, simple and convenient, and the remediation agent is suitable for large-scale production; the method is green and environment-friendly, simple to operate and low in cost, and can realize lasting, rapid and thorough treatment of aniline pollutants; the prepared remediation agent has low carbon footprint, and the green sustainability of the remediation agent in the aspect of OPD polluted underground water remediation is further proved.

Description

Technical Field

[0001] The invention belongs to the technical field of site pollution control, and particularly relates to a method for long-term repair of groundwater contaminated by o-phenylenediamine using an amphiphilic covalent organic polymer. Background Art

[0002] As one of the typical aniline compounds, o-phenylenediamine (OPD) is widely used in the dye and pesticide industries and discharged into water bodies through industrial wastewater and agricultural water. OPD remaining in water bodies is increasingly threatening human health and the ecological environment due to its bioaccumulation, persistence and potential carcinogenicity. In addition, studies have shown that OPD is easily adsorbed by organic matter on the surface of porous media. Therefore, it is urgent to develop efficient methods for remediation of OPD-contaminated groundwater.

[0003] Traditional extraction and treatment technologies often fail to achieve ideal results due to the strong capillary force of aquifers and low mass transfer efficiency. In contrast, in-situ injection technology can achieve remediation in a short time and in an efficient manner by injecting remediation agents directly into the aquifer. Although surfactants are widely used in in-situ remediation to alleviate the tailing-rebound phenomenon of pollutants, the large doses and high concentrations required to achieve ultra-low interfacial tension often lead to unstable remediation processes, increasing the difficulty of separating agents from pollutants after remediation. In contrast, adsorbents do not require large amounts of organic solvents or complex operating steps, and are an environmentally friendly and efficient solution for treating OPD pollution in groundwater.

[0004] Covalent organic polymers (COPs) are a class of emerging porous materials assembled by strong covalent bonds. They have a multi-level pore structure, abundant active sites, controllable synthesis technology, and excellent chemical stability, showing great potential in the field of adsorption. However, the current design of COPs is mostly limited to two-component condensation systems, which to some extent limits its structural diversity and production efficiency. In addition, existing COPs usually exhibit hydrophilicity and are mainly used for gas adsorption or antibiotic adsorption. They are difficult to adapt to the remediation needs of aniline pollutants, and their dispersion stability in the aqueous phase is poor and their transmission capacity is limited, which weakens their application effect in complex formations. Therefore, the development of amphiphilic materials with particle properties and surfactant properties has become an urgent need for current technology.

[0005] Despite their considerable potential for various applications, COPs are currently only synthesized on a laboratory scale. Before scaling up to pilot-scale production, the environmental burden caused by their synthesis must be assessed. In this context, life cycle assessment (LCA) can demonstrate and quantify the environmental impacts associated with the production of materials. Therefore, it is crucial to conduct a comprehensive LCA study of COPs production from the perspective of raw material extraction, manufacturing, use, disposal / recycling / reuse. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings of the existing repair of groundwater contaminated by o-phenylenediamine, and to provide a method for long-term repair of groundwater contaminated by o-phenylenediamine using an amphiphilic covalent organic polymer.

[0007] A method for long-term repair of groundwater contaminated by o-phenylenediamine using an amphiphilic covalent organic polymer comprises the following steps: Step 1: Preparation of repair agent: 1.1 Dissolve 0.20 mmol of benzene-1,3,5-trihydrazide, 0.30 mmol of 4,4'-diaminobiphenyl-3,3'-disulfonic acid, 0.06 mmol of 4-n-butylaniline and 0.60 mmol of terephthalaldehyde in 5 mL of dimethyl sulfoxide solvent, heat at 100 °C for 30 minutes, obtain the reaction product, dialyze with distilled water, remove the organic solvent, and freeze-dry the product at -40 °C to obtain an amphiphilic covalent organic polymer material; 1.2 Weigh the amphiphilic covalent organic polymer obtained in step 1.1 and dissolve it in water, and ultrasonicate it for more than 15 minutes to ensure that the material is evenly dispersed in the aqueous solution to obtain a repair agent; Step 2: In-situ injection of amphiphilic covalent organic polymers for long-term remediation of groundwater contaminated by o-phenylenediamine: 2.1 In the vicinity of the groundwater pollution source, several injection wells are set up at the upstream position of the groundwater flow direction and perpendicular to the groundwater flow direction. Several extraction wells are set up at the edge interface of the pollution plume downstream of the injection wells. Monitoring wells are set up every 3-5 meters downstream of the injection wells. The depths of the injection wells, extraction wells and monitoring wells should all reach the bottom of the aquifer; 2.2 Determine the concentration of the repair agent according to the formation conditions, inject the repair agent of the preset concentration by the pressure pulse device, and when the repair agent migrates to the extraction well, start the extraction pump to form a hydraulic gradient, realize the directional migration of the repair agent and the formation of the adsorption reaction zone; the bottom section of the injection well and the section of the air-bearing zone are closed, and the water outlet holes are evenly set in the aquifer section; 2.3 Monitor the OPD concentration in real time during the injection process and stop the injection when the desired effect is achieved.

[0008] Preferably, the concentration of the OPD is no more than 20 mg / L; 0.1-0.3 g of the covalent organic polymer is uniformly dispersed in 1 L of distilled water to prepare a repair agent; the injection flow rate is controlled by a peristaltic pump in the range of 1.59-3.18 cm / min, and the formation medium is a coarse sand medium of 0.5-1.0 mm.

[0009] Working process and working principle of the present invention: The extended alkyl chain and aromatic chain in the amphiphilic covalent organic polymer prepared in step 1 impart hydrophobicity to one side, while the other side remains hydrophilic due to the presence of amide chains and sulfonic acid groups. It has both hydrophilic and lipophilic amphiphilic properties, providing more possibilities for the application of COPs in aquifers.

[0010] Life Cycle Assessment (LCA) of Remediation Agents: The LCA boundary includes the steps from commercial monomer production to the preparation of remediation agents, with the functional unit being 1.0 kg of remediation agent. The terrestrial acidification potential (TAP), global warming potential (GWP), terrestrial ecotoxicity potential (TETP), freshwater eutrophication potential (FEP), human toxicity potential (HTP), particulate matter formation potential (PMFP) and water depletion potential (WCP) are selected, quantified and analyzed in detail.

[0011] Beneficial effects of the present invention: 1. The traditional remediation of aniline-contaminated aquifers is usually achieved by injecting surfactants (such as Tween 80), but this type of method requires high concentrations of surfactants, which may cause chemical interference to the aquifer and have low removal efficiency. The in-situ injection method proposed in the present invention uses amphiphilic covalent organic polymers to carry out long-term remediation of groundwater contaminated by o-phenylenediamine, overcoming the high concentration requirements and low efficiency of traditional surfactants. The polymer not only has particle activity, but also has the function of a surfactant, showing excellent competitive adsorption ability, making the pollutant removal rate exceed 80%. In addition, by adjusting the flow field through the injection-extraction mode to form a hydraulic gradient, the directional migration of the remediation agent can be significantly enhanced, and further filtration, separation and recycling of the agent can be achieved.

[0012] 2. The repair agent of the present invention has a high OPD adsorption capacity, a fast and simple synthesis process, and is suitable for large-scale production. The method is green and environmentally friendly, simple to operate, and low in cost, and can achieve a lasting, rapid, and thorough treatment of aniline pollutants.

[0013] 3. The remediation agent prepared by the present invention has a lower carbon footprint, which further proves its green sustainability in the remediation of OPD-contaminated groundwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The competitive adsorption capacity comparison between the amphiphilic covalent organic polymer repair agent prepared in the present invention and Tween 80; Figure 2 A schematic diagram of a simulation column according to an embodiment of the present invention; Figure 3 Schematic diagram of the penetration curve of OPD when 0.1 g / L of the repair agent is used to repair 20 mg / L of OPD at an injection flow rate of 3.18 cm / min; Figure 4 Schematic diagram of the penetration curve of OPD when 0.3 g / L of the repair agent is used to repair 20 mg / L of OPD at an injection flow rate of 3.18 cm / min; Figure 5 A schematic diagram of a two-dimensional simulation tank according to an embodiment of the present invention; Figure 6 The removal effect of 0.1 g / L of remediation agent on 10 mg / L OPD in a two-dimensional simulation tank.

[0015] 1 quartz sand simulation column; 2 water inlet; 3 water outlet; 4 peristaltic pump; 5 water distribution plate; 6 two-dimensional organic simulation tank; 61 simulation tank water inlet; 62 simulation tank water outlet; 63 simulation tank peristaltic pump; 64 simulation tank water distribution plate; 65 simulation tank water injection well; 66 sand box; 67 sampling port. DETAILED DESCRIPTION

[0016] See also Figures 1 to 6 Shown is an embodiment of the present invention. Example 1

[0017] A method for long-term repair of groundwater contaminated by o-phenylenediamine using an amphiphilic covalent organic polymer comprises the following steps: Step 1: Preparation of repair agent: 1.1 Dissolve 0.20 mmol of benzene-1,3,5-trihydrazide, 0.30 mmol of 4,4'-diaminobiphenyl-3,3'-disulfonic acid, 0.06 mmol of 4-n-butylaniline and 0.60 mmol of terephthalaldehyde in 5 mL of dimethyl sulfoxide solvent, heat at 100 °C for 30 minutes, obtain the reaction product, dialyze with distilled water, remove the organic solvent, and freeze-dry the product at -40 °C to obtain an amphiphilic covalent organic polymer material; 1.2 Weigh 0.1-0.3 g of the amphiphilic covalent organic polymer obtained in step 1.1 and disperse it evenly in 1 L of distilled water, and sonicate for more than 15 minutes to ensure that the material is evenly dispersed in the aqueous solution to obtain a repair agent; Step 2: In-situ injection of amphiphilic covalent organic polymers for long-term remediation of groundwater contaminated by o-phenylenediamine: 2.1 In the vicinity of the groundwater pollution source, several injection wells are set up at the upstream position of the groundwater flow direction and perpendicular to the groundwater flow direction. Several extraction wells are set up at the edge interface of the pollution plume downstream of the injection wells. Monitoring wells are set up every 3-5 meters downstream of the injection wells. The depths of the injection wells, extraction wells and monitoring wells should all reach the bottom of the aquifer; 2.2 The concentration of the repair agent is determined according to the formation conditions, and the repair agent of the preset concentration is injected by the pressure pulse device. When the repair agent migrates to the extraction well, the extraction pump is started to form a hydraulic gradient to achieve directional migration of the repair agent and the formation of an adsorption reaction zone; the bottom section of the injection well and the section of the aeration zone are closed, and water outlet holes are evenly set in the aquifer section; the injection flow rate is controlled by a peristaltic pump in the range of 1.59-3.18 cm / min, and the formation medium is a coarse sand medium of 0.5-1.0 mm 2.3 During the injection process, the OPD concentration was monitored in real time. The OPD concentration was not greater than 20 mg / L. The injection was stopped when the expected effect was achieved. Example 2

[0018] In order to simulate the saturated conditions of the underground aquifer, the experiment of this embodiment sets the soil-water ratio to 1:2. 5.0 g of sand was mixed with 10.0 mL of an OPD solution with a concentration of 1.0 g / L in six centrifuge tubes and shaken at 25 °C for 24 hours to ensure that the system reached equilibrium. After the liquid sample was discharged from the centrifuge tube, the solid sample was rinsed with 10.0 mL of distilled water and shaken again for 24 hours to remove residual OPD. Subsequently, 50.0 mL of a repair agent with a concentration of 1.0 g / L was added to three centrifuge tubes, and the same concentration of Tween 80 solution was added to the other three centrifuge tubes, and the shaking continued for 24 hours to compare the removal effects of the two on OPD. Figure 1 This is a comparison chart of the competitive adsorption amount of residual OPD on the medium surface between the repair agent and Tween 80. Example 3

[0019] like Figure 2 As shown, a quartz sand simulation column 1 with an inner diameter of 2 cm and a height of 20 cm and a filling particle size of 0.5-1 mm is established. The water inlet 2 and the water outlet 3 are respectively arranged at the bottom and the top of the quartz sand simulation column 1, and the flow rate is controlled by a peristaltic pump 4.

[0020] 20 mg of OPD was dissolved in 1 L of distilled water to prepare the contaminated sample solution, and 0.1 g of amphiphilic covalent organic polymer was dispersed in 1 L of distilled water solution to prepare the repair agent. First, the organic glass column was saturated with water. In the first stage, 5 PV of the prepared 20 mg / L OPD sample solution was injected at 1 mL / min. In the second stage, 18 PV of distilled water was injected at 1 mL / min. In the third stage, 29 PV of the prepared 0.1 g / L repair agent was injected at a flow rate of 3.18 cm / min. In the fourth stage, 7 PV of distilled water was injected at a flow rate of 3.18 cm / min.

[0021] like Figure 3As shown, after the second stage, no OPD was detected in the effluent. In the third stage, the remediation agent migrated along the direction of the water flow and desorbed part of the OPD from the aquifer surface to the remediation agent surface through competitive adsorption. As the remediation agent migrated to the outlet 3, the total recovery rate of OPD in the effluent reached 84.98%. It can be seen that the remediation agent in the system can effectively remove OPD in the aquifer. Example 4

[0022] 20 mg of OPD was dissolved in 1 L of distilled water to prepare the contaminated sample solution, and 0.3 g of amphiphilic multi-component covalent organic polymer was dispersed in 1 L of distilled water solution to prepare the repair agent. First, the organic glass column was saturated with water. In the first stage, 5 PV of the prepared 20 mg / L OPD sample solution was injected at 1 mL / min. In the second stage, 18 PV of distilled water was injected at 1 mL / min. In the third stage, 29 PV of the prepared 0.3 g / L repair agent was injected at a flow rate of 3.18 cm / min. In the fourth stage, 7 PV of distilled water was injected at a flow rate of 3.18 cm / min.

[0023] like Figure 4 As shown in the figure, after the second stage, no OPD was detected in the effluent. In the third stage, the remediation agent migrated along the direction of the water flow and desorbed part of the OPD from the surface of the aquifer to the surface of the remediation agent through competitive adsorption. As the agent migrated to the outlet, the total recovery rate of OPD in the effluent reached 88.48%. It can be seen that the remediation agent in the system can effectively remove OPD in the aquifer. Example 5

[0024] like Figure 5 As shown, a two-dimensional organic simulation tank 6 with a length of 30 cm, a width of 2 cm, and a height of 22 cm is established, and the filling medium is 0.5-1 mm quartz sand. The middle part of the two-dimensional organic simulation tank 6 is a sand box 66. The simulation tank water inlet 61 and the simulation tank water outlet 62 are respectively arranged at the bottom of the left side and the top of the right side of the two-dimensional organic simulation tank 6, and the flow rate is controlled by the simulation tank peristaltic pump 63. A simulation tank water injection well 65 with an inner diameter of 2 cm and a height of 37 cm is set at 11 cm away from the left simulation tank water distribution plate 64, and the bottom is sealed. The sand box 66 is provided with 20 sampling ports 67 for sample collection.

[0025] Dissolve 10 mg of OPD in 1 L of distilled water to prepare the contaminated sample solution, and disperse 0.1 g of amphiphilic covalent organic polymer in 1 L of distilled water to prepare the remediation agent. The OPD solution with a concentration of 10 mg / L was continuously injected at a flow rate of 0.25 m / d. Based on the preliminary experiments, 1 L of remediation agent was injected into the simulated tank injection well 65 at a pulse rate of 59 mL / min. Figure 6 As shown in the figure, when the remediation agent was injected, the OPD concentration was uniformly distributed at 10.0 mg / L. One hour after injection, the OPD content at the proximal and distal ends of the simulated slot injection well 65 was significantly reduced due to the dilution and adsorption of the remediation agent. With continuous injection, the OPD concentration in the direction of groundwater flow gradually decreased. The remediation agent can effectively repair the entire OPD-contaminated aquifer within 24 hours. Affected by the competition of coexisting ions in actual groundwater, the adsorption capacity of the adsorbent for OPD is 76.96 mg / g. After 48 hours, the downstream OPD concentration exceeds 5.0 mg / L, indicating that the remediation agent begins to gradually fail in the aquifer. Example 6

[0026] 1 kg of remediation agent was prepared, and the following impact categories were quantified and compared: terrestrial acidification potential (TAP), global warming potential (GWP), terrestrial ecotoxicity potential (TETP), freshwater eutrophication potential (FEP), human toxicity potential (HTP), particulate matter formation potential (PMFP), and water depletion potential (WCP). According to the environmental impact results, 1.00 kg of SLEL-4 can avoid the HTP environmental impact of 0.047 kg 1,4-DCB-eq by adsorbing 0.383 kg of OPD in 5 cycles. The impact of the remediation agent in the GWP category was quantitatively calculated to be 12.32 kg CO 2 -eq, from an environmental perspective, remediation agents have the potential to be green and environmentally friendly.

Claims

1. A method for long-term remediation of groundwater contaminated by o-phenylenediamine using an amphiphilic covalent organic polymer, characterized in that: The steps include: Step 1: Preparation of repair agent: 1.1 0.20 mmol of benzene-1,3,5-trihydrazide, 0.30 mmol of 4,4'-diaminobiphenyl-3,3'-disulfonic acid, 0.06 mmol of 4-n-butylaniline and 0.60 mmol of terephthalaldehyde were dissolved in 5 mL of dimethyl sulfoxide solvent, heated at 100°C for 30 minutes, and after obtaining the reaction product, dialyzed with distilled water, and after removing the organic solvent, the product was freeze-dried at -40°C to obtain an amphiphilic covalent organic polymer material; 1.2 Weigh the amphiphilic covalent organic polymer obtained in step 1.1 and dissolve it in water, and ultrasonicate it for more than 15 minutes to ensure that the material is evenly dispersed in the aqueous solution to obtain a repair agent; Step 2: In-situ injection of amphiphilic covalent organic polymers for long-term remediation of groundwater contaminated by o-phenylenediamine: 2.1 In the vicinity of the groundwater pollution source, several injection wells are set up at the upstream position of the groundwater flow direction and perpendicular to the groundwater flow direction. Several extraction wells are set up at the edge interface of the pollution plume downstream of the injection wells. Monitoring wells are set up every 3-5 meters downstream of the injection wells. The depths of the injection wells, extraction wells and monitoring wells should all reach the bottom of the aquifer; 2.2 Determine the concentration of the repair agent according to the formation conditions, inject the repair agent of the preset concentration by the pressure pulse device, and when the repair agent migrates to the extraction well, start the extraction pump to form a hydraulic gradient, realize the directional migration of the repair agent and the formation of the adsorption reaction zone; the bottom section of the injection well and the section of the air-bearing zone are closed, and the water outlet holes are evenly set in the aquifer section; 2.3 Monitor the OPD concentration in real time during the injection process and stop the injection when the desired effect is achieved.

2. The method for long-term remediation of groundwater contaminated by o-phenylenediamine using an amphiphilic covalent organic polymer according to claim 1, characterized in that: The concentration of OPD was no more than 20 mg / L. 0.1−0.3 g of covalent organic polymer was evenly dispersed in 1 L of distilled water to prepare a repair agent. The injection flow rate was controlled by a peristaltic pump in the range of 1.59-3.18 cm / min, and the formation medium was a coarse sand medium of 0.5-1.0 mm.

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