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CN-117960125-B - Preparation method and application of ZIF/LDH-loaded biochar composite adsorbent

CN117960125BCN 117960125 BCN117960125 BCN 117960125BCN-117960125-B

Abstract

The invention discloses a preparation method and application of a ZIF/LDH-loaded biochar composite adsorbent, which comprises the following steps of (1) mixing pretreated corn stalks with alkali, calcining, washing and drying to obtain biochar BC, (2) mixing, washing, drying and calcining a certain proportion of biochar BC and acetate, mixing with 2-methylimidazole for ageing, washing and drying to obtain BC/ZIF, and (3) immersing a certain amount of BC/ZIF into a nitrate solution, stirring, standing, washing and drying to obtain the BC/ZIF8/LDH composite adsorbent. The composite adsorbent has a layered and open structure, large specific surface area, more adsorption points, high nitrosamine precursor removal rate of more than 95%, good binding capacity and selective adsorption on N-DBPs precursors of nitrogen-containing disinfection byproducts such as micromolecule amine, histidine, protein and the like, good dispersion performance, high LDH metal utilization rate, stable structure, good reaction activity, good repeated use effect, wide raw material sources, low price, low production cost and high economic benefit.

Inventors

  • YANG WEIBEN
  • MENG YU
  • LIU ZIFAN
  • Yin Zhonglong
  • DENG SHANSHAN

Assignees

  • 南京师范大学

Dates

Publication Date
20260508
Application Date
20240305

Claims (7)

  1. 1. The application of the ZIF/LDH-loaded biochar composite adsorbent in removing N-DBPs precursors of nitrogen-containing disinfection byproducts in water is characterized in that the preparation method of the ZIF/LDH-loaded biochar composite adsorbent comprises the following steps: (1) Mixing corn stalk with alkali, calcining, washing and drying to obtain biochar BC; (2) Mixing the biochar BC and acetate with the mass ratio of 1:0.37-0.74, washing, drying, calcining, mixing with 2-methylimidazole, aging, washing, drying to obtain BC/ZIF, wherein the mass ratio of the biochar BC to the 2-methylimidazole is 1:3.83-5.47; (3) Immersing the BC/ZIF into a nitrate solution, wherein the mass ratio of the BC/ZIF to the nitrate is 1:20-50, stirring, standing, washing and drying to obtain the BC/ZIF8/LDH composite adsorbent; the acetate in the step (2) is cobalt acetate or zinc acetate; In the step (3), the nitrate is cobalt nitrate Co (NO 3 ) 2 ·6H 2 O, zinc nitrate Zn (NO 3 ) 2 ·6H 2 O), nickel nitrate Ni (NO 3 ) 2 ·6H 2 O), magnesium nitrate Mg (NO 3 ) 2 ·6H 2 O), ferric nitrate Fe (one of NO 3 ) 3 ·9H 2 O and aluminum nitrate Al (NO 3 ) 3 ·9H 2 O).
  2. 2. The use of the ZIF/LDH-loaded biochar composite adsorbent of claim 1 for removing nitrogen-containing disinfection by-product N-DBPs precursors in a body of water, wherein step (1) comprises the steps of: (11) Stirring, cleaning and crushing corn stalks with deionized water at room temperature, and screening particles with 200-250 meshes; (12) Mixing the corn stalks with alkali to obtain a mixture; (13) Calcining the mixture in a muffle furnace at 300-500 ℃; (14) Soaking the calcined product in hydrochloric acid solution, stirring, separating, and washing until the pH value of the supernatant is neutral; (15) Drying the powder, then placing the dried powder into zinc chloride solution, stirring, separating, washing until the pH value of the supernatant is neutral, and drying; (16) Calcining at 500-900 ℃ under the protection of nitrogen; (17) Washing the biological carbon BC with ethanol and deionized water for 3-5 times, and freeze-drying to obtain the biological carbon BC.
  3. 3. The use of the ZIF/LDH-loaded biochar composite adsorbent of claim 1 or 2 for removing nitrogen-containing disinfection by-product N-DBPs precursors in a water body, wherein the base of step (1) is sodium bicarbonate.
  4. 4. The use of the ZIF/LDH-loaded biochar composite adsorbent of claim 1 for removing nitrogen-containing disinfection by-product N-DBPs precursors from a body of water, wherein step (2) comprises the steps of: (21) Mixing biochar BC and acetate in a mass ratio of 1:0.37-0.74, stirring in a 60 ℃ water bath, and aging at 40 ℃; (22) Separating, washing for 3-5 times, and drying; (23) Calcining at 300 ℃ under the protection of nitrogen for 20-30 mm; (24) Washing for 3-5 times, and freeze-drying to obtain freeze-dried powder; (25) Immersing the frozen dry powder into 2-methylimidazole with a certain concentration, stirring, aging for 12-24H, and separating, wherein the mass ratio of the dry powder to the 2-methylimidazole is 1:3.83-5.47; (26) Washing for 3-5 times, and drying to obtain BC/ZIF8.
  5. 5. The use of the ZIF/LDH-loaded biochar composite adsorbent according to claim 1 or 4 for removing nitrogen-containing disinfection by-products N-DBPs precursors from a water body, wherein the step (2) further comprises immersing the dry powder obtained by mixing and calcining the biochar BC and acetate in a mixed solution of zinc nitrate hexahydrate Zn (NO 3 ） 2 ·6（H 2 O) and hexamethylenetetramine C 6 H 12 N 4 for heating and reacting, thereby secondarily loading zinc ions on the biochar BC, wherein the mass ratio of the frozen dry powder to the zinc nitrate and the hexamethylenetetramine is 1:4.26:2.
  6. 6. The use of the ZIF/LDH-loaded biochar composite adsorbent of claim 1 or 4 for removing nitrogen-containing disinfection by-product N-DBPs precursors from a body of water, wherein the acetate solvent of step (2) is 50vol% ethanol or deionized water.
  7. 7. The use of the ZIF/LDH-loaded biochar composite adsorbent of claim 1 for removing nitrogen-containing disinfection by-product N-DBPs precursors from a body of water, wherein the nitrate solvent of step (3) is 33vol% ethanol.

Description

Preparation method and application of ZIF/LDH-loaded biochar composite adsorbent Technical Field The invention relates to a preparation method and application of an adsorbent, in particular to a preparation method and application of a ZIF/LDH-loaded biochar composite adsorbent. Background The disinfection treatment of drinking water and wastewater results in the production of a large amount of byproducts, wherein nitrogen-containing disinfection byproducts N-DBPs represented by halogenated acetonitrile, N-nitrosamine and halogenated nitromethane thereof have strong toxicity and carcinogenicity, the safety of drinking water and the health of an ecological system are endangered, and the research on nitrogen-containing disinfection byproducts N-DBPs is a focus of attention of a plurality of students. The adsorption method utilizes the acting force between the adsorbent and target pollutants in water to adsorb the pollutants on the surface of the solid adsorbent, thereby realizing the separation of the pollutants from the water body, and the adsorption method is widely applied to water treatment due to high adsorption efficiency, simple operation and low cost. The common adsorbents are zeolite, activated carbon, metal organic framework material MOFs and the like, wherein the biochar is the activated carbon which directly pyrolyzes various biomass raw materials under the condition of limited oxygen so that the internal structures of the biochar react to generate active groups and adsorption sites to effectively adsorb inorganic or organic pollutants. However, for water bodies with high fluidity, especially pollutants with high concentration and low molecular weight, such as secondary amine or tertiary amine in nitrosamine precursors, the biochar has few functional groups and low activity, and has limited adsorption capacity and capacity, so that N-DBPs (nitrogen-containing disinfection byproducts) in water treatment cannot be effectively adsorbed. The layered double hydroxide LDH is formed by overlapping a main layer plate, anions between layers and water molecules, and has the advantages of easy adjustment of the types and proportion of metal ions on the main layer plate, easy cutting of the structure, easy compounding with other materials to realize functionalization, and the like, so that the layered double hydroxide LDH has wide application potential in water treatment. The LDH material prepared by the traditional method has poor dispersion performance, is easy to aggregate into blocks, cannot effectively control the morphology, the particle size and the surface area, and cannot selectively, efficiently and stably adsorb pollutants. Disclosure of Invention The invention aims to provide a preparation method of the ZIF/LDH-loaded biochar composite adsorbent capable of improving the activity of biochar and increasing the adsorption selectivity function of the biochar, and the other aim of the invention is to provide application of the biochar composite adsorbent. The preparation method of the ZIF/LDH-loaded biochar composite adsorbent comprises the following steps: (1) Mixing the pretreated corn stalks with alkali, calcining, washing and drying to obtain biochar BC; (2) Mixing the biochar BC and acetate with the mass ratio of 1:0.37-0.74, washing, drying, calcining, mixing with 2-methylimidazole, aging, washing, drying to obtain BC/ZIF, wherein the mass ratio of the biochar BC to the 2-methylimidazole is 1:3.83-5.47; (3) Immersing the BC/ZIF into a nitrate solution, wherein the mass ratio of the BC/ZIF to the nitrate is 1:20-50, stirring, standing, washing and drying to obtain the BC/ZIF8/LDH composite adsorbent. Further, the step (1) includes the following steps: (11) Stirring, cleaning and crushing corn stalks with deionized water at room temperature, and screening particles with 200-250 meshes; (12) Mixing the corn stalks with alkali; (13) Calcining the mixture in a muffle furnace at 300-500 ℃; (14) Soaking the calcined product in hydrochloric acid solution, stirring, separating, and washing until the pH value of the supernatant is neutral; (15) Drying the powder, then placing the dried powder into zinc chloride solution, stirring, separating, washing until the pH value of the supernatant is neutral, and drying; (16) Calcining at 500-900 ℃ under the protection of nitrogen; (17) Washing the biological carbon BC with ethanol and deionized water for 3-5 times, and freeze-drying to obtain the biological carbon BC. Further, the alkali in the step (1) is sodium bicarbonate. Further, the step (2) includes the following steps: (21) Mixing biochar BC and acetate in a mass ratio of 1:0.37-0.74, stirring in a 60 ℃ water bath, and aging at 40 ℃; (22) Separating, washing for 3-5 times, and drying; (23) Calcining at 300 ℃ for 20-30min under the protection of nitrogen; (24) Washing for 3-5 times, and freeze drying; (25) Immersing the freeze-dried powder into 2-methylimidazole with a certain concentration, stirring for 10mi