A sulfide pollution control and resource processing method based on a conductive composite film coupling system

Abstract

A sulfide pollution control and resource processing method based on a conductive composite membrane coupling system belongs to the technical field of wastewater treatment. By constructing a composite membrane coupling system, more than 99% of the sulfur ions in the wastewater can be removed; the reaction product ZnS-NiS-ACF Powder is loaded to the composite membrane, and a multifunctional catalytic membrane is successfully prepared; under the synergistic action of visible light and PMS, the removal rate of tetracycline by the catalytic membrane reaches 87.0%, which exhibits excellent catalytic activity and PMS activation ability. The present application efficiently couples the membrane separation technology with the adsorption-catalytic oxidation technology, realizes the dual goals of efficient removal and resource utilization of sulfides, and activates PMS to degrade pollutants at low cost, high efficiency and green. The method has the advantages of high treatment efficiency, low operation cost and environmental friendliness, and is not only suitable for industrial wastewater and urban black and odorous water treatment, but also provides a new idea for the development of catalytic materials and the application of advanced oxidation technology.

Description

Technical Field

[0001] This invention provides a method for controlling and recycling sulfide pollution based on a conductive composite membrane coupling system, belonging to the field of wastewater treatment technology. It involves constructing a conductive composite membrane coupling system that couples membrane separation technology with adsorption-catalytic oxidation for synergistic effects, achieving efficient removal of sulfur ions (S2-) from wastewater. It also involves the recovery and utilization of sulfur resources, converting S2- in wastewater into a ZnS-NiS-ACF powder catalyst, preparing a catalytic membrane, and using the prepared catalytic membrane to couple photocatalytic activation of persulfate (PMS) technology for efficient degradation of water pollutants. Background Technology

[0002] Sulfides are a widespread pollutant in wastewater, primarily originating from production processes in industries such as petrochemicals, leather manufacturing, and papermaking, as well as from anaerobic treatment processes involving sulfates or organic sulfur compounds. Dissolved sulfides are corrosive, easily damaging steel, concrete, and other materials, causing economic losses and posing safety hazards. Furthermore, sulfides readily convert to hydrogen sulfide (H2S) in water, producing a foul odor and harming the human respiratory and nervous systems; increasing disease and mortality rates in fish; and forming complexes with heavy metals, inhibiting plant root growth. To improve water quality, ensure drinking water safety, and extend the lifespan of equipment and pipelines, effective measures must be taken to remove sulfides and control their emissions. Traditional treatment methods include filtration, chemical methods, and biological methods, but these all have drawbacks to varying degrees, such as high investment costs, inability to treat high-concentration wastewater, low treatment efficiency, and the need for secondary treatment. More importantly, these traditional processes typically convert sulfur ions into elemental sulfur or sulfate ions and then remove them directly, leading to two prominent problems: on the one hand, elemental sulfur is difficult to effectively recover and utilize; on the other hand, the emission of large amounts of sulfate will disrupt the natural sulfur cycle balance, triggering new environmental problems and wasting sulfur resources.

[0003] Transition metal sulfides (TMS) have shown great potential in the field of catalysis due to their unique photoelectric properties. Among them, zinc sulfide (ZnS) has significant application value in photocatalytic degradation due to its unique photoelectric properties and suitable band gap (~3.6 eV); nickel sulfide (NiS), with its abundant Ni-S and Ni-Ni active sites, has become a hot topic in catalytic materials research. However, powdered catalysts have the inherent drawback of being difficult to recycle and reuse. Loading catalysts onto conductive composite membranes to achieve catalyst immobilization can also utilize catalysis to control membrane fouling. In recent years, advanced oxidation technologies (AOPs) have received widespread attention due to their excellent efficiency in treating recalcitrant organic pollutants. Among them, persulfate (PMS)-based AOPs are considered a highly practical treatment method because they can generate a large number of strongly oxidizing active species after catalytic activation, and possess characteristics such as high stability, low cost, and mild products. In terms of reaction mechanism, the catalyst breaks the O-O bonds in PMS through electron transfer, thereby generating highly reactive sulfate radicals. In particular, due to their intrinsic photocatalytic activity, ZnS and NiS are used in this invention to enhance the pollutant degradation efficiency and PMS activation rate by coupling membrane catalysis with photocatalysis.

[0004] This invention provides a method for sulfide pollution control and resource recovery based on a conductive composite membrane coupling system. This method innovatively proposes a "waste-to-waste" technical approach: constructing a conductive composite membrane coupling system, using activated carbon felt powder (ACFPowder) as an adsorbent and carrier, to remove sulfur ions (S...) from wastewater. 2- A ZnS-NiS-ACF Powder catalyst was in situ converted and loaded onto a conductive composite membrane to form a catalytic membrane. This catalytic membrane, coupled with other treatment technologies, was used to remove recalcitrant pollutants from wastewater, successfully constructing a treatment system integrating sulfide removal, resource recovery, and catalytic degradation. This not only eliminated the risk of hydrogen sulfide generation and achieved pollutant removal, but also realized the resource utilization of metal ions and sulfides, making it suitable for various scenarios such as industrial wastewater and urban black and odorous water bodies. Currently, there are no reports of similar conductive composite membrane coupling systems simultaneously achieving sulfide pollution control and resource utilization, either domestically or internationally. Summary of the Invention

[0005] This invention addresses the challenges of treating sulfide pollution in wastewater and the resulting resource waste by constructing a conductive composite membrane coupling system. This method utilizes membrane separation coupled with adsorption-catalytic oxidation to treat sulfur-containing wastewater, innovatively removing sulfur ions (S) from the wastewater. 2-In-situ conversion into a ZnS-NiS-ACF Powder catalyst enables sulfur resource recovery. The catalyst is then loaded onto a conductive composite membrane to create a catalytic membrane. This membrane not only efficiently activates persulfate (PMS) to degrade recalcitrant organic pollutants in wastewater, but also serves as a functional electrode to synergize with advanced oxidation technologies such as photocatalysis and electrocatalysis, providing an innovative solution for optimizing wastewater treatment systems.

[0006] The technical solution of the present invention:

[0007] A method for controlling and recycling sulfide pollution based on a conductive composite film coupling system, comprising the following steps:

[0008] (1) Preparation of conductive composite film:

[0009] A casting solution was prepared using polyvinylidene fluoride (PVDF) as a binder, carbon nanofibers as a conductive reinforcing phase, and polyvinylpyrrolidone (PVP) as a pore-forming agent. A conductive composite film was then prepared on a carbon fiber cloth substrate using a phase inversion method. The conductive composite film was then fixed onto a membrane module for later use.

[0010] (2) Construction of conductive composite film coupling system

[0011] One of the following methods is used to treat sulfide-containing wastewater by in-situ generating a ZnS-NiS-ACF powder catalyst on activated carbon felt powder (ACF powder) to form a suspension. The specific method is as follows:

[0012] The first approach involves adding ACF powder to the sulfide-containing wastewater and stirring to reach adsorption / desorption equilibrium, thereby effectively adsorbing sulfur ions (S ions) from the sulfide-containing wastewater. 2- Subsequently, Zn containing metal ions was added. 2+ and Ni 2+ The solution is prepared and the aeration head is inserted into the sulfide-containing wastewater. Aeration provides dissolved oxygen and mechanical force to promote the oxidation process in the reaction system.

[0013] The second approach involves first adding ACF powder to Zn containing metal ions. 2+ and Ni 2+ In the solution, adsorption occurs and equilibrium is reached. Then, wastewater containing sulfides is added, and finally, the aeration pump is turned on to carry out the reaction.

[0014] (3) Preparation of ZnS-NiS-ACF Powder catalyst and catalytic membrane

[0015] The suspension from step (2) was pumped into the membrane module using a peristaltic pump and loaded onto the conductive composite membrane; this process was repeated multiple times, and the membrane was then air-dried to obtain the catalytic membrane.

[0016] Furthermore, in step (1), the thickness of the conductive composite film is 200-400 μm;

[0017] Further, in the casting solution of step (1): the solvent is N,N-dimethylformamide (DMF), PVDF accounts for 10-15 wt% of the total mass of the casting solution, carbon nanofibers account for 1-3 wt% of the total mass of the casting solution, and polyvinylpyrrolidone (PVP) accounts for 5-15 wt% of the mass of PVDF.

[0018] Further, in step (2), the ACF powder is prepared as follows: Activated carbon felt (ACF) is ultrasonically treated in acetone, ethanol, and deionized water for 10-15 minutes sequentially, and then vacuum dried; next, the ACF is soaked in a dilute alkaline solution, such as 0.5-1M NaOH or KOH solution, stirred for 2-4 hours, rinsed until neutral, and then vacuum dried; finally, the alkali-treated ACF is ground, sieved through a 100-200 mesh sieve, and uniform particles are collected. The vacuum drying temperature is 60-80℃, and the time is 6-12 hours.

[0019] Further, in step (2), the mass of the ACF Powder is the S in the sulfide-containing wastewater. 2- 1-20 times the quality.

[0020] Furthermore, in step (2), Zn 2+ and Ni 2+ A mixed solution prepared from Zn(NO3)2·6H2O, Ni(NO3)2·6H2O, and deionized water, with a molar ratio of Zn to Ni of 1:5-1:1, is given. The sulfur content in the sulfide-containing wastewater is... 2- The amount of substance is 10-20 times the sum of the amounts of Zn and Ni.

[0021] Furthermore, in step (2), the aeration conditions are 1.8-3.0 L / min. -1 .

[0022] Furthermore, through the synergistic effect of membrane separation coupled adsorption-catalytic oxidation, sulfur ions in sulfide-containing wastewater are efficiently removed, and the products are recycled to realize the resource utilization of sulfides.

[0023] Furthermore, the catalytic membrane in step (3) is used to activate persulfate (PMS) to oxidize organic pollutants.

[0024] Furthermore, the catalytic membrane of step (3) can degrade more than 85% of tetracycline under the action of external visible light and PMS, and has good photocatalytic activity, PMS activation and pollutant removal effect.

[0025] The beneficial effects of this invention: This invention provides an innovative method for efficiently removing sulfides from wastewater and realizing resource utilization, with the following significant advantages: Through membrane separation coupled with adsorption-catalytic oxidation synergistic effect, it not only achieves efficient treatment of sulfur-containing wastewater and recovery of sulfur resources, but also simultaneously solves the odor and poisoning risks caused by hydrogen sulfide (H2S) generation. In particular, this method innovatively removes sulfur ions (S2S) from wastewater... 2- The catalyst is transformed into a ZnS-NiS-ACF Powder catalyst, where the introduction of ACF Powder increases the specific surface area and active sites. Using PVDF as a binder and carbon nanofibers as the conductive reinforcing phase, a catalytic membrane supported on carbon fiber cloth was successfully prepared. This membrane can efficiently activate persulfate (PMS) to remove recalcitrant organic pollutants. This invention achieves an integrated system of "pollutant removal-resource recovery-advanced treatment," possessing significant environmental, economic, and social benefits. It can be widely applied to the treatment of industrial wastewater and urban black and odorous water bodies, and has important value for promotion and application. Attached Figure Description

[0026] Figure 1 This is a comparison diagram of the removal effects of sulfur ions by the first and second operating schemes of the conductive composite film coupling system.

[0027] Figure 2 The graph shows the degradation effect of 20 mg / L tetracycline under PMS conditions using a ZnS-NiS-ACF Powder catalytic membrane coupled with photocatalysis.

[0028] Figure 3 This is a comparison chart of the degradation effects of ZnS-NiS-ACF Powder catalytic membrane on 20 mg / L tetracycline under PMS and non-PMS conditions.

[0029] Figure 4 This is a comparison of the degradation effect of ZnS-NiS-ACF Powder catalytic membrane on 20 mg / L tetracycline by PMS activated under light and dark conditions. Detailed Implementation

[0030] The specific embodiments of the present invention are described in detail below with reference to the technical solutions and accompanying drawings.

[0031] Example 1: Construction of a conductive composite film coupling system and preparation of a catalytic film

[0032] Step 1: Construction of the conductive composite film coupling system

[0033] (1) Preparation of ACF Powder: Cut 3×6cm 2ACF was ultrasonically treated in acetone, ethanol, and deionized water for 10 min in sequence, and then dried in a vacuum drying oven at 60°C for 8 h. The pretreated ACF was then soaked in 1M NaOH solution, stirred for 4 h, rinsed until neutral, and dried at 60°C for 8 h. Finally, the alkali-treated ACF was ground, sieved through a 200-mesh sieve, and uniform particles were collected to obtain ACF Powder for later use.

[0034] (2) Preparation of mixed solution: Add 0.03g Zn(NO3)2·6H2O (0.10mmol) and 0.01g Ni(NO3)2·6H2O (0.10mmol) to 0.5mL of deionized water and stir ultrasonically to obtain a mixed solution for later use.

[0035] (3) The first option involves selecting a cylindrical glass reactor with a volume of 250 mL. Using S... 2- The concentration is 360 mg / L -1 A 200 mL solution of sodium sulfide (Na₂S·9H₂O) (2.25 mmol, 72 mg) was used as the pollutant solution to be treated and poured into the reactor. 0.2 g of ACF powder was slowly added to the reactor, and the mixture was stirred for 1 h to reach adsorption / desorption equilibrium. Subsequently, 0.5 mL of a mixed solution (containing 0.20 mmol of metal ions) was added dropwise, and the aerator was inserted into the pollutant at an aeration rate of 1.8 L / min. -1 The reaction was carried out at room temperature for 1 hour. Samples were taken every 15 minutes after the reaction began, and the concentration of S in the solution was determined by methylene blue spectrophotometry. 2- The concentration of S in the system is calculated. 2- Concentration changes and removal efficiency.

[0036] The second method involves first adding 0.2g of ACF powder to 10ml of deionized water containing 0.5ml of the mixed solution, stirring for 30 minutes to allow adsorption and reach equilibrium. Then, the target substance is added, and finally, the aeration pump is turned on to initiate the reaction at an aeration rate of 1.8L / min. -1 The reaction was carried out at room temperature for 1 hour. The construction, sampling, and testing methods for the remaining systems were the same as those for the first scheme.

[0037] After treating the sulfide-containing wastewater using one of two methods, a ZnS-NiS-ACFPowder catalyst is generated in situ on the ACF Powder, forming a suspension.

[0038] Step 2: Preparation of Catalytic Membrane

[0039] Prepare the casting solution as shown in Table 1, stir magnetically for 4 hours to ensure uniform mixing, degas under vacuum for 30 minutes, and then use a membrane preparation device to scrape a 300 μm membrane onto carbon fiber cloth. After that, place the membrane in deionized water overnight to allow it to complete the phase inversion.

[0040] The suspension from step one was pumped into the membrane module using a peristaltic pump. After washing, the process was repeated three times to obtain the catalytic membrane.

[0041] like Figure 1 This figure compares the effectiveness of the first and second operating schemes in removing sulfide ions using the conductive composite membrane coupling system. As shown in the figure, both methods can efficiently remove sulfides, with removal efficiencies exceeding 99%. The first method is suitable for treating wastewater with high sulfide concentrations, rapidly adsorbing sulfides and initiating the oxidation reaction. The second method optimizes the catalytic oxidation capacity of the reaction system through pre-adsorption of metal ions. Both methods can be flexibly selected based on the specific wastewater characteristics and treatment requirements, demonstrating broad application prospects.

[0042] Table 1 Composition of Casting Solution

[0043] 1.5g 0.25g 8.1g 0.15g

[0044] Example 2: Degradation of tetracycline by a catalytic membrane under visible light and PMS conditions

[0045] A rectangular quartz container (4×5×22cm) 3 A reactor was used as the reactor. 300 mL of 20 mg / L tetracycline was added to the reactor, and the catalytic membrane prepared in Example 1 (with a total area of ​​2.5 cm × 5.75 cm × 2) was immersed in the solution. The bottom was stirred at 500 rpm. For the first 30 minutes, adsorption was performed in the dark, and the effluent was pumped back to the membrane assembly using a peristaltic pump to enhance mass transfer. 1 mM MPMS was added, and an external light source (20 W tungsten iodine lamp, 4 cm away from the electrode membrane, with a light-receiving membrane area of ​​2.5 cm × 5.75 cm) was turned on to start the reaction. The reaction was carried out at room temperature for 90 minutes. Water samples were taken approximately every 10 minutes, and the absorbance was measured at 357 nm using a spectrophotometer to calculate the tetracycline concentration and removal rate.

[0046] like Figure 2 As shown, the catalytic membrane can remove about 6.5% of tetracycline through adsorption. After 1.5 hours of reaction, the degradation rate can reach 87.0%, indicating that the catalytic membrane has photocatalytic activity and PMS activation, and can effectively remove the recalcitrant pollutant tetracycline.

[0047] Example 3: Catalytic membrane degradation of tetracycline under PMS and non-PMS conditions

[0048] The sampling and testing methods are the same as in Example 2, except that in the construction of the catalytic membrane coupling system: this example uses a rectangular quartz container (4×5×22cm) 3The reactor was used as a stand-up pneumococcal reactor. 300 mL of 20 mg / L tetracycline was added to the reactor, and the catalytic membrane prepared in Example 1 (with a total area of ​​2.5 cm × 5.75 cm × 2) was immersed in the solution. The bottom was stirred at 500 rpm. For the first 30 minutes, light was blocked for adsorption, and the effluent was pumped back to the membrane module using a peristaltic pump to enhance mass transfer. Then, 1 mM PMS was added to initiate the reaction. The reaction was carried out at 35°C for 90 minutes. The control group did not contain PMS.

[0049] like Figure 3 The figure shows a comparison of tetracycline removal efficiency after 2 hours of reaction in the system without and with PMS. As can be seen from the figure, after 2 hours of reaction, the removal efficiencies of the catalytic membrane coupling system without PMS and with PMS for tetracycline were 13.3% and 78.8%, respectively. This indicates that the catalytic membrane coupling system has an activating effect on PMS.

[0050] Example 4: Catalytic membrane activation of PMS for tetracycline degradation under light and dark conditions

[0051] The construction method of the catalytic membrane coupling system is the same as that in Example 2, and the sampling and testing methods are also the same as in Example 2. The control group was light-free.

[0052] like Figure 4 The figure shows a comparison of tetracycline removal efficiency under light and dark conditions after 2 hours of reaction. As can be seen from the figure, after 2 hours of reaction, the removal efficiencies of the catalytic membrane coupling system for tetracycline were 56.0% and 87.0% for the light- and dark conditions, respectively. This indicates that the catalytic membrane coupling system can activate some PMS, and coupled photocatalysis can further enhance the activation rate of PMS and the removal capacity of pollutants.

Claims

1. A method for controlling and recycling sulfide pollution based on a conductive composite film coupling system, characterized in that, The steps are as follows: (1) Preparation of conductive composite film: A casting solution was prepared using polyvinylidene fluoride as a binder, carbon nanofibers as a conductive reinforcing phase, and polyvinylpyrrolidone as a pore-forming agent. A conductive composite film was then prepared on a carbon fiber cloth substrate using a phase inversion method. The conductive composite film is fixed onto the membrane assembly for later use; (2) Construction of conductive composite film coupling system One of the following methods is used to treat sulfide-containing wastewater by in-situ generating a ZnS-NiS-ACF powder catalyst on activated carbon felt powder (ACF powder) to form a suspension; the specific method is as follows: The first approach involves adding ACF powder to the sulfide-containing wastewater and stirring until adsorption / desorption equilibrium is reached, thereby effectively adsorbing sulfur ions (S ions) from the sulfide-containing wastewater. 2- ; Subsequently, Zn containing metal ions was added. 2+ and Ni 2+ The solution is prepared and the aeration head is inserted into the sulfide-containing wastewater. Dissolved oxygen and mechanical force are provided by aeration to promote the oxidation process in the reaction system. The second approach involves first adding ACF powder to Zn containing metal ions. 2+ and Ni 2+ In the solution, adsorption occurs and equilibrium is reached. Then, wastewater containing sulfides is added, and finally, the aeration pump is turned on to carry out the reaction. In step (2), Zn 2+ and Ni 2+ A mixed solution prepared from Zn(NO3)2·6H2O, Ni(NO3)2·6H2O, and deionized water, with a molar ratio of Zn to Ni of 1:5-1:1, is given. The sulfur content in the sulfide-containing wastewater is... 2- The amount of substance is 10-20 times the sum of the amounts of Zn and Ni; the aeration conditions are 1.8-3.0 L / min. -1 ; By using membrane separation coupled with adsorption-catalytic oxidation synergistic effect, sulfur ions in sulfide-containing wastewater are efficiently removed and the products are recycled to realize the resource utilization of sulfides. (3) Preparation of ZnS-NiS-ACF Powder catalyst and catalytic membrane The suspension from step (2) was pumped into the membrane module using a peristaltic pump and loaded onto the conductive composite membrane; this process was repeated several times, and the membrane was then air-dried to obtain the catalytic membrane. The catalytic membrane in step (3) is used to activate persulfate PMS to oxidize organic pollutants.

2. The method for sulfide pollution control and resource recovery based on a conductive composite film coupling system according to claim 1, characterized in that, In step (1), the thickness of the conductive composite film is 200-400 μm.

3. The method for sulfide pollution control and resource recovery based on a conductive composite film coupling system according to claim 1, characterized in that, In the casting solution of step (1): the solvent is N,N-dimethylformamide, polyvinylidene fluoride accounts for 10-15 wt% of the total mass of the casting solution, carbon nanofiber accounts for 1-3 wt% of the total mass of the casting solution, and polyvinylpyrrolidone accounts for 5-15 wt% of the mass of polyvinylidene fluoride.

4. The method for sulfide pollution control and resource recovery based on a conductive composite film coupling system according to claim 1, characterized in that, In step (2), the ACF powder is prepared by ultrasonically soaking activated carbon felt (ACF) in acetone, ethanol, and deionized water for 10-15 minutes in sequence, followed by vacuum drying. Next, the ACF is soaked in 0.5-1M NaOH or KOH solution, stirred for 2-4 hours, rinsed until neutral, and then vacuum dried. Finally, the alkali-treated ACF is ground, sieved through a 100-200 mesh sieve, and uniform particles are collected. The vacuum drying temperature is 60-80℃, and the time is 6-12 hours.

5. The method for sulfide pollution control and resource recovery based on a conductive composite film coupling system according to claim 1, characterized in that, In step (2), the mass of the ACF Powder is the S in the sulfide-containing wastewater. 2- 1-20 times the quality.

6. The method for sulfide pollution control and resource recovery based on a conductive composite film coupling system according to claim 1, characterized in that, The catalytic membrane in step (3) can degrade more than 85% of tetracycline under the action of external visible light and PMS, and has good photocatalytic activity, PMS activation and pollutant removal effect.

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