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CN-122010245-A - Electrocatalytic reduction film for high-selectivity electrocatalytic low-concentration nitrate water body reduction denitrification and preparation method thereof

CN122010245ACN 122010245 ACN122010245 ACN 122010245ACN-122010245-A

Abstract

The invention discloses an electrocatalytic reduction membrane for high-selectivity electrocatalytic low-concentration nitrate water body reduction denitrification and a preparation method thereof, and belongs to the technical field of water treatment. The invention solves the problems that the removal efficiency of the low-concentration nitrate polluted water body by adopting the conventional water treatment process is insufficient, and the electrocatalytic reduction method for directly recycling ammonia has high cost, poor economical efficiency and environmental protection. According to the invention, a Cu-CN/CB catalyst is obtained by carrying out pyrolysis on a copper-doped ZIF-8 material, and is mixed with PVDF and acidified CNT and then subjected to suction filtration to form an electrocatalytic reduction film. The invention takes carbon black as a core to grow copper doped ZIF-8, a catalyst is obtained after carbonization, metal on the catalyst is uniformly distributed and catalytic sites are dense, CNT constructs a conductive network, a reduction film is taken as a cathode, the CNT-Cu-CN/CB network in a low-concentration nitrate water body optimizes the mass transfer efficiency of the catalyst and nitrate, and nitrate adsorption-catalytic degradation is fully completed in a limited space.

Inventors

  • LIANG HENG
  • YANG JIAXUAN
  • CHEN JIALONG
  • LIANG JIAHAO
  • LIU JIE
  • WANG JINLONG
  • ZHANG HAN
  • XU DALIANG
  • BAI LANGMING

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260512
Application Date
20260202

Claims (10)

  1. 1. The preparation method of the electrocatalytic reduction film for high-selectivity electrocatalytic low-concentration nitrate water body reduction denitrification is characterized by comprising the following steps of: Adding a copper source, a zinc source and carbon black into methanol to form a dispersion liquid A, dissolving 2-methylimidazole into the methanol to form a solution B, mixing the dispersion liquid A and the solution B, carrying out ultrasonic reaction, centrifuging, cleaning and vacuum drying a product to obtain a copper-doped ZIF-8 material loaded on the carbon black; Carrying out high-temperature pyrolysis on a copper-doped ZIF-8 material loaded on carbon black in an inert gas environment, and carrying out acid washing and vacuum drying on a product to obtain a Cu-CN/CB catalyst; Adding PVDF into DMF, heating and dissolving to obtain DMF solution, cooling, adding Cu-CN/CB catalyst and acidified multiwall carbon nanotubes into the DMF solution, and obtaining a base film dispersion liquid after ultrasonic dispersion and cell disruption; and 4, carrying out batch suction filtration on the base film dispersion liquid on the inorganic film, obtaining a wet film on the inorganic film after the last suction filtration is finished, and washing, drying and stripping the wet film to obtain the electrocatalytic reduction film.
  2. 2. The preparation method according to claim 1, wherein the mass ratio of the copper source to the zinc source to the carbon black in the step 1 is (0.1-0.8): 2.0-5.0): 0.05-0.2.
  3. 3. The method according to claim 2, wherein the ultrasonic reaction power in step 1 is 200-300W, the reaction time is 30-60 min, the centrifugal strength is 5000-7000 g, and the centrifugal time is 5-15 min.
  4. 4. The method according to claim 1, wherein the high-temperature pyrolysis temperature in the step 2 is 900-1000 ℃ and the time is 2-6 h, the acid washing solution is sulfuric acid or hydrochloric acid, and the acid washing process is to wash the product by using an acid washing solution with the concentration of 2M at 80 ℃ under reflux for 12 h.
  5. 5. The preparation method according to claim 1, wherein the mass ratio of PVDF, cu-CN/CB catalyst and multi-wall carbon nanotube in step 3 is (18.88-75.52): 40-60): at least one of hydrochloric acid, sulfuric acid and nitric acid is used as the solution for the acidification process, the acidification process is that the multi-wall carbon nanotube is acidified by using an acidification solution at 90 ℃ for 6 h and then washed with deionized water to be neutral, freeze-dried, the cell disruption power is 9-900W, and the disruption time is 10-50 min.
  6. 6. The method according to claim 1, wherein each batch is filtered 5 mL in step 4 by suction, and the drying process is that 1-8 h is dried at 30-60 ℃, 1-12 h is dried at room temperature, and 2-8 h is dried at 30-60 ℃.
  7. 7. An electrocatalytic reduction membrane for high selectivity electrocatalytic low concentration nitrate water body reduction denitrification made by the method of any one of claims 1-6.
  8. 8. An electrocatalytic reduction high-efficiency denitrification method for a water body containing low-concentration nitrate is characterized in that an electrocatalytic reduction film prepared by the method of any one of claims 1-6 is used as a cathode, titanium mesh, ruthenium iridium titanium mesh, foam titanium or foam ruthenium iridium titanium is used as an anode, an insulating permeable layer is placed between the anode and the cathode, and electrocatalytic denitrification is completed in an electrolyte solution with low nitrate concentration.
  9. 9. The method of claim 8, wherein the concentration of nitrate in the electrolyte solution is 20 mg N/L and the current density of the electrocatalytic denitrification process is 1-3 mA/cm 2 .
  10. 10. The method of claim 8 or 9, wherein the electrolyte solution further comprises Na 2 SO 4 at a concentration of 20 mmol/L and NaCl at a concentration of 5 mmol/L.

Description

Electrocatalytic reduction film for high-selectivity electrocatalytic low-concentration nitrate water body reduction denitrification and preparation method thereof Technical Field The invention belongs to the technical field of water treatment, and particularly relates to an electrocatalytic reduction film for high-selectivity electrocatalytic low-concentration nitrate water body reduction denitrification and a preparation method thereof. Background The nitrogen cycle is one of the core bio-geochemical cycles for maintaining the stability of the earth ecological system, and realizes the continuous conversion of nitrogen elements among air, water and organisms through the processes of nitrogen fixation, nitrification, denitrification, anaerobic ammonia oxidation, organic nitrogen mineralization and the like. The nitrogen circulation regulates the availability of nitrogen in the ecosystem, thereby controlling primary productivity, affecting microbial community structure, and maintaining nutrient balance of soil and water. Meanwhile, the nitrogen circulation process determines the persistence form and trend of nitrogen in the environment, and has profound effects on agricultural yield, fresh water quality and global climate (such as emission of N 2 O). Therefore, it is important to reasonably regulate and control nitrogen in nature. Nitrate and ammonia nitrogen are the most common inorganic nitrogen forms in natural water and pollution source emissions, and the concentration changes directly determine the nitrogen nutrition level of the water environment. When the algae is accumulated to a higher concentration in the water body, the ecological system structure can be damaged, the abnormal proliferation of the algae and the eutrophication of the water body are caused, toxic intermediates such as nitrite and the like can be generated, and the aquatic organisms are stressed. In addition, high-concentration nitrate and ammonia nitrogen migrate through surface water and underground water, so that the safety of drinking water is further threatened, for example, nitrate can be converted into nitrite in a human body to cause health risks such as methemoglobin, and the like, and ammonia nitrogen can cause the increase of disinfection byproducts to influence the stability of a water supply treatment process. Therefore, the control of release and accumulation of nitrate and ammonia nitrogen in the water body is an important precondition for guaranteeing the quality of the water environment and the safety of drinking water. Compared with the electrocatalytic nitrate for realizing ammonia resource recovery, the lower concentration nitrate has low Faraday efficiency and poor economic benefit. Meanwhile, the sanitary standard of drinking water (GB 5849-2022) in China limits the nitrate concentration to be less than or equal to 10 mg N/L and the ammonia concentration to be less than or equal to 0.5 mg N/L so as to ensure that the drinking water is within a safety threshold for a human body. However, the conventional water treatment process (coagulation-precipitation-filtration-disinfection) has limited capability of removing nitrate, and when the nitrate concentration of raw water is 10-50 mg N/L, the conventional water treatment process is relied on or ammonia is recovered by nitrate reduction, which is uneconomical and not green. Therefore, development of a new method for denitrification, which is applicable to low-concentration nitrate polluted water, has high removal performance, is economically feasible and is environment-friendly, is needed to realize rapid denitrification of nitrate in water. Disclosure of Invention The method aims at the problems that the removal efficiency of the low-concentration nitrate polluted water body by adopting the conventional water treatment process is insufficient, and the electrocatalytic reduction method for directly recovering ammonia is high in cost, poor in economical efficiency and not environment-friendly. An electrocatalytic reduction membrane for high-selectivity electrocatalytic low-concentration nitrate water body reduction denitrification is provided. The technical scheme of the invention is as follows: One of the purposes of the invention is to provide a preparation method of an electrocatalytic reduction film for high-selectivity electrocatalytic low-concentration nitrate water body reduction denitrification, which comprises the following steps: adding a copper source, a zinc source and carbon black into methanol to form a dispersion liquid A, dissolving 2-methylimidazole into the methanol to form a solution B, mixing the dispersion liquid A and the solution B, carrying out ultrasonic reaction, centrifuging, cleaning and vacuum drying a product to obtain a copper-doped ZIF-8 material (Cu-ZIF-8/CB) loaded on the carbon black; Carrying out high-temperature pyrolysis on a copper-doped ZIF-8 material loaded on carbon black in an inert gas environment, and carrying out acid washi