Search

CN-117023761-B - Water treatment method based on non-free radical synergistic oxidation

CN117023761BCN 117023761 BCN117023761 BCN 117023761BCN-117023761-B

Abstract

The invention discloses a water treatment method based on non-radical synergistic oxidation, which comprises the steps of adding an Mn-C-N catalyst and persulfate into water, decomposing the persulfate to form singlet oxygen by utilizing the Mn-C-N catalyst and performing non-radical synergistic oxidation purification treatment on pollutants in the water by electron transfer, wherein the preparation method of the Mn-C-N catalyst comprises the steps of adding sodium alginate solution into calcium chloride solution in a dropwise manner, sieving to obtain calcium alginate hydrogel, then obtaining Mn-based precursor through ion exchange, mixing the Mn-based precursor with urea, then calcining in nitrogen atmosphere, pickling to remove surface Mn ions, washing to be neutral by water, and drying to obtain the Mn-C-N catalyst. The Mn-C-N catalyst has a simple preparation method, has two active sites capable of respectively generating singlet oxygen and two non-radical active species for electron transfer, and can synergistically accelerate the degradation and mineralization of organic pollutant wastewater.

Inventors

  • HUANG BAOCHENG
  • HUANG YUNXIN
  • LU YAN
  • CHEN KEYU
  • JIN RENCUN

Assignees

  • 杭州师范大学
  • 浙江水利水电学院

Dates

Publication Date
20260508
Application Date
20230818

Claims (9)

  1. 1. A water treatment method based on non-free radical synergistic oxidation is characterized in that an Mn-C-N catalyst and persulfate are added into water, and the Mn-C-N catalyst is used for catalyzing the decomposition of the persulfate to form singlet oxygen and carrying out electron transfer to carry out non-free radical synergistic oxidation purification treatment on pollutants in the water; The preparation method of the Mn-C-N catalyst comprises the following steps: (1) Dropwise adding a sodium alginate solution into a calcium chloride solution, sieving to obtain calcium alginate hydrogel, soaking the calcium alginate hydrogel in hydrochloric acid, carrying out ultrasonic exchange between Ca 2+ and H + , sieving, adding the obtained hydrogel into a MnCl 2 solution, carrying out ion exchange between H + and Mn 2+ , filtering and drying to obtain a Mn-based precursor, wherein the concentration of the MnCl 2 solution is 0.08-0.12M; (2) And mixing the Mn-based precursor with urea, then sequentially calcining in a nitrogen atmosphere, pickling to remove surface Mn ions, washing with water to be neutral, and drying to obtain the Mn-C-N catalyst, wherein the mass ratio of the Mn-based precursor to the urea is 3-5:1.
  2. 2. The water treatment method based on non-radical co-oxidation according to claim 1, wherein in step (1): The mass concentration of the sodium alginate solution is 0.8% -1.2%; the mass concentration of the calcium chloride solution is 0.4% -0.6%; The volume ratio of the sodium alginate solution to the calcium chloride solution is 0.2-0.3:1.
  3. 3. The water treatment method based on non-radical co-oxidation according to claim 1, wherein in step (1): The concentration of the hydrochloric acid is 0.8-1.2M.
  4. 4. The water treatment method based on non-radical co-oxidation according to claim 1, wherein in the step (2), the calcination temperature in the nitrogen atmosphere is 780-820 ℃ and the time is 1.5-2.5 h.
  5. 5. The method for water treatment based on non-radical co-oxidation according to claim 1, wherein in the step (2), the acid used for the acid washing is 1 mol-L -1 of hydrochloric acid, and the number of acid washing is three.
  6. 6. The method for water treatment based on non-radical co-oxidation according to claim 1, wherein in the step (2), the drying temperature is 60-70 ℃.
  7. 7. The method for water treatment based on non-radical co-oxidation according to any one of claims 1 to 6, wherein the persulfate is potassium hydrogen peroxymonosulfate compound salt 2KHSO 5 ·KHSO 4 ·K 2 SO 4 , and the pollutant in water is diclofenac.
  8. The application of Mn-C-N catalyst in catalyzing persulfate to decompose to form singlet oxygen and transferring electrons to perform non-radical synergistic oxidation purification treatment on pollutants in water is characterized in that the preparation method of Mn-C-N catalyst comprises the following steps: (1) Dropwise adding a sodium alginate solution into a calcium chloride solution, sieving to obtain calcium alginate hydrogel, soaking the calcium alginate hydrogel in hydrochloric acid, carrying out ultrasonic exchange between Ca 2+ and H + , sieving, adding the obtained hydrogel into a MnCl 2 solution, carrying out ion exchange between H + and Mn 2+ , filtering and drying to obtain a Mn-based precursor, wherein the concentration of the MnCl 2 solution is 0.08-0.12M; (2) And mixing the Mn-based precursor with urea, then sequentially calcining in a nitrogen atmosphere, pickling to remove surface Mn ions, washing with water to be neutral, and drying to obtain the Mn-C-N catalyst, wherein the mass ratio of the Mn-based precursor to the urea is 3-5:1.
  9. 9. The use according to claim 8, wherein the persulfate is potassium hydrogen persulfate complex salt 2KHSO 5 ·KHSO 4 ·K 2 SO 4 and the water contaminant is diclofenac.

Description

Water treatment method based on non-free radical synergistic oxidation Technical Field The invention relates to the technical field of water catalytic oxidation treatment, in particular to a water treatment method based on non-free radical synergistic oxidation. Background Refractory organic pollutants have attracted considerable attention in the last decades due to their potential adverse effects on human and wild animal health. The ring opening and mineralization of these contaminants by peroxides allows one of the commonly used remediation strategies. In recent years, advanced oxidation techniques based on persulfates have shown great potential in removing refractory organic contaminants, mainly due to the activation of the Persulfates (PMS) by catalysts or external energy, yielding active species with high redox potentials, i.e. hydroxyl radicals (OH, E 0＝1.9～2.7VNHE) and sulfate radicals (SO 4·-,E0＝2.6～3.1VNHE). While free radicals can efficiently mineralize contaminants to CO 2 and H 2 O, they are easily annihilated by solute components, inorganic ions, and even pH fluctuations, thereby increasing the ineffective consumption of oxidants. Therefore, there is an urgent need to improve the effective utilization efficiency of PMS, thereby improving the sustainability of wastewater remediation processes while reducing the running costs. In addition to the radical mechanism, PMS also uses non-radicals as the primary degradation mechanism in heterogeneously catalyzed degradation of contaminants, including Electron Transfer Processes (ETP), singlet oxygen (1O2), and high valence metal oxides. The above-described non-radical oxidation process has been observed on a variety of catalysts such as single-atom catalysts, nanocarbon materials, metal oxides, and the like. Compared with free radicals, the non-free radicals have higher catalytic efficiency and stronger selectivity on electron-rich organic pollutants in complex water matrixes, and can effectively solve the problem of ineffective consumption of interfering substances on active species. The above properties result in reduced PMS consumption during non-radical oxidation. From this perspective, non-radical oxidation provides a clear direction for facilitating the sustainability of advanced oxidation techniques that are highly dependent on chemicals. However, non-radical species such as electron transfer have poor mineralization of contaminants due to their low redox potential. Therefore, the improvement of the treatment efficiency of the non-radical oxidation process is of great significance to the application of the non-radical oxidation process in the treatment of refractory pollutant wastewater. During contaminant degradation, various intermediates with different structural properties are produced. Thus, we reasonably speculate that by synergistically coupling different non-free mechanisms in one catalytic system, more efficient and rapid contaminant removal performance may be achieved. Although different non-radical activation mechanisms have been reported previously on carbon catalysts and MnO x catalysts, there are problems such as non-ideal handling properties. It is therefore highly desirable to properly design two independent active sites on a catalyst and adjust their exposure to achieve a rate tradeoff that does not go through a non-radical pathway. Carbon materials are widely focused by researchers because of the characteristics of large specific surface area, abundant reserves, acid and alkali resistance and the like. Over the last few years, it has been demonstrated that activation of persulfates by carbon materials produces some active species that can rapidly degrade contaminants. For example, reduced graphene oxide can activate PMS and degrade phenols as well as organic dyes, and carbon nanotubes can activate PMS to produce 1O2 and SO 4·- to degrade benzyl alcohol. More importantly, the use of carbon catalysts in wastewater remediation can break narrow pH range limitations. Sodium alginate is one of the organic cross-linking agents, is a natural polysaccharide, is abundant in source and nontoxic, contains a large number of "egg-box" structures, and can accommodate metal ions by coordinating with negatively charged gluconates. By changing the metal salt solution, the type and the quantity of metal ions fixed on the egg box can be regulated, and the ideal effect is achieved. Disclosure of Invention Aiming at the technical problems and the defects existing in the field, the invention provides a water treatment method based on non-free radical synergistic oxidation, and the Mn-C-N catalyst prepared by adopting a specific method has two active sites with different functions, wherein the active sites C-N can efficiently catalyze persulfate to decompose to form singlet oxygen (1O2), the active sites Mn-N can efficiently catalyze persulfate to decompose to form Electron Transfer (ETP), and the synergistic effect of the active sites Mn-N and the act