Search

CN-121991381-A - Nanocrystalline modified hydrogel and preparation method thereof

CN121991381ACN 121991381 ACN121991381 ACN 121991381ACN-121991381-A

Abstract

The invention discloses a nano-micro crystal modified hydrogel and a preparation method thereof, the method comprises the steps of adding 5-10 parts by mass of sodium hydroxide and 10-20 parts by mass of acrylic acid into 50 parts by mass of water for neutralization reaction, sequentially adding 5-15 parts by mass of reaction monomers, 0.1-0.5 part by mass of cross-linking agent and 0.05-0.2 part by mass of initiator into a reaction system every 3-5 minutes, stirring and reacting for 10-20 minutes at a rotating speed of 150-300 r/min, adding 2-8 parts by mass of ettringite and 1-5 parts by mass of hydrotalcite, continuously stirring for 5-10 minutes at a rotating speed of 300-700 r/min to enable nano-micro crystals to be uniformly dispersed, adjusting the rotating speed to 400-600 r/min, heating in a water bath at 50-70 ℃ for 10-30 minutes until the reaction system forms a stable polymerization network, and drying a product to constant weight at 60-80 ℃ to obtain the nano-micro crystal modified hydrogel.

Inventors

  • LONG YONG
  • Gai Keyu
  • BAI MIN
  • FAN SHAOXUAN
  • LIAO QINGYAO
  • Shu Jianjian
  • ZHANG YANG
  • WANG SHUO
  • CHEN SIYU
  • WANG JINGYU
  • MA MENGYANG
  • YANG JIN
  • WANG BO
  • PENG XUMIN
  • FAN XIANZHENG
  • GUO BIN
  • QIN JIAN
  • WANG YU

Assignees

  • 中铁大桥局集团有限公司
  • 中铁大桥科学研究院有限公司

Dates

Publication Date
20260508
Application Date
20260206

Claims (10)

  1. 1. The preparation method of the nano-crystal modified hydrogel is characterized by comprising the following steps of: S1, adding 5-10 parts by mass of sodium hydroxide and 10-20 parts by mass of acrylic acid into 50 parts by mass of water for neutralization reaction; S2, sequentially adding 5-15 parts by mass of reaction monomers, 0.1-0.5 part by mass of crosslinking agent and 0.05-0.2 part by mass of initiator into the system obtained in the step S1 every 3-5 minutes, and stirring and reacting for 10-20 minutes at the rotating speed of 150-300 r/min, wherein the reaction monomers are one or more of acrylamide, metakaolin and hydroxymethyl cellulose, the crosslinking agent is one of N, N' -methylenebisacrylamide and trimethylolpropane triacrylate, and the initiator is one of ammonium persulfate and potassium persulfate; S3, adding 2-8 parts by mass of ettringite and 1-5 parts by mass of hydrotalcite, wherein the particle size of the ettringite is 50-200 nm, the particle size of the hydrotalcite is 100-300 nm, and continuously stirring for 5-10 min at the rotating speed of 300-700 r/min to uniformly disperse nano-crystallites; S4, adjusting the rotating speed to 400-600 r/min, heating in a water bath at 50-70 ℃ for 10-30 min until a reaction system forms a stable polymerization network, and stopping stirring; and S5, drying the product to constant weight at 60-80 ℃, crushing, and screening out resin with the particle size of 0.3-0.45 mm to obtain the nano-micro crystal modified hydrogel.
  2. 2. The method for preparing a nano-crystal modified hydrogel according to claim 1, wherein in the step S1, the neutralization temperature is controlled to be 30-40 ℃ and the neutralization degree is controlled to be 70-100%.
  3. 3. The method for preparing nano-crystal modified hydrogel according to claim 2, wherein the mass of the reaction monomer in the step S2 is 30-100 wt% of the total mass of the reaction monomer, the cross-linking agent and the initiator; The mass of the cross-linking agent in the step S2 accounts for 0.01-0.5wt% of the total mass of the reaction monomer, the cross-linking agent and the initiator; The mass of the initiator accounts for 0.5-3wt% of the total mass of the reaction monomer, the cross-linking agent and the initiator.
  4. 4. A method for producing a nano-crystal modified hydrogel according to any one of claims 1 to 3, wherein the ettringite production in step S3 comprises the steps of: Dissolving 6-12 parts by mass of CaO reagent in 14 parts by mass of deionized water to prepare a lime solution, adding 1-2 parts by mass of aluminum sulfate into the lime solution, and simultaneously adding sodium hydroxide reagent to control the pH value of a system to be 12; Placing the mixed solution in a 20 ℃ constant temperature water bath box, continuously stirring for 4 hours at a rotating speed of 1000r/min, sealing and maintaining for 7 days at 20 ℃, washing by absolute ethyl alcohol, filtering, and drying in a 25 ℃ vacuum drying box to constant weight to obtain an ettringite sample.
  5. 5. The method for preparing a nano-crystal modified hydrogel according to any one of claims 1 to 3, wherein the hydrotalcite in step S3 is magnesium aluminum hydrotalcite, and the method comprises the following steps: dissolving magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in 200mL deionized water according to a magnesium-aluminum molar ratio of 3:1, and stirring at a rotating speed of 1000r/min until the magnesium nitrate hexahydrate and the aluminum nitrate nonahydrate are dissolved to prepare a metal salt solution; preparing NaOH into 1mol/L alkali solution, adopting a peristaltic pump to drop the metal salt solution and the alkali solution into a beaker filled with deionized water, and controlling the pH value of the system in the dropping process to be 9; After the dripping is finished, continuously stirring the mixed solution for 30min at the rotating speed of 1000r/min, then aging for 24h in an 80 ℃ oven, centrifuging the mixed solution at the rotating speed of 1000-1200 r/min, collecting the lower-layer solid, washing for 5 times with deionized water, and then drying for 12h in a 60 ℃ constant temperature drying oven to obtain the magnesium aluminum hydrotalcite sample.
  6. 6. The method of claim 5, wherein the concentration of magnesium nitrate hexahydrate in the metal salt solution is 0.7mol/L.
  7. 7. The method for preparing a nano-crystal modified hydrogel according to any one of claims 1 to 3, wherein the total mass of ettringite and hydrotalcite in step S3 is 5 to 50wt% of the mass of acrylic acid, and the mass ratio of ettringite to hydrotalcite is 1:1.
  8. 8. The method for preparing a nano-crystal modified hydrogel according to any one of claims 1 to 3, wherein the stable polymeric network in step S4 has a viscosity of 5000-10000 mPas at 25 ℃.
  9. 9. A nano-crystallite-modified hydrogel prepared by the preparation method according to any one of claims 1 to 8, comprising a neutralization reaction component, a polymerization reaction component and a nano-crystallite-modified component; the neutralization reaction component is prepared from the following raw materials, by mass, 5-10 parts of sodium hydroxide, 10-20 parts of acrylic acid and 50 parts of deionized water, wherein the neutralization degree of the sodium hydroxide and the acrylic acid is 70-100%; The polymerization reaction component comprises a reaction monomer, a cross-linking agent and an initiator; The reaction monomer is one or more of acrylamide, metakaolin and hydroxymethyl cellulose, and accounts for 30-100wt% of the total mass of the reaction monomer, the cross-linking agent and the initiator; the cross-linking agent is one of N, N' -methylene bisacrylamide and trimethylolpropane triacrylate, and accounts for 0.01-0.5wt% of the total mass of the reaction monomer, the cross-linking agent and the initiator; The initiator is ammonium persulfate or potassium persulfate, and accounts for 0.5-3wt% of the total mass of the reaction monomer, the cross-linking agent and the initiator; the nano-crystal modified component comprises magnesium aluminum hydrotalcite and ettringite, wherein the total mass of the magnesium aluminum hydrotalcite and ettringite accounts for 5-50wt% of acrylic acid, and the mass ratio is 1:1.
  10. 10. The nano-crystal modified hydrogel according to claim 9, wherein the magnesium aluminum hydrotalcite is synthesized from magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and sodium hydroxide by a coprecipitation method; The ettringite is prepared by adjusting pH to 12 by 6-12 parts by mass of CaO, 1-2 parts by mass of aluminum sulfate, 14 parts by mass of deionized water and sodium hydroxide, and then carrying out reaction curing.

Description

Nanocrystalline modified hydrogel and preparation method thereof Technical Field The invention belongs to the technical field of high polymer materials, and particularly relates to a nano-micro crystal modified hydrogel and a preparation method thereof. Background With the rapid development of industries such as iron and steel, metallurgy, printing and dyeing, a large amount of industrial wastewater containing heavy metals and nondegradable organic dyes is discharged, and meanwhile, the accumulated stockpiling amount of industrial solid wastes reaches about 620 hundred million tons. The heavy metals have the characteristics of large water quantity, complex water quality, high concentration of refractory organic matters, strong acid-base property, high chromaticity, high toxicity and the like, the discharge amount of the heavy metals accounts for about 11 percent of the discharge amount of wastewater in important industrial industries, the heavy metals become important points and difficulties in water pollution control in China, the retention time of most organic dye molecules in water bodies is long, the migration range is wide, and the ecological balance and water safety of the water bodies are seriously damaged. At present, the common adsorption material in the field of sewage treatment has a plurality of limitations that layered double hydroxides (hydrotalcite and hydrotalcite-like compounds) have the advantages of simple and convenient preparation, low cost, strong stability, reproducibility and the like, and have certain application potential in the treatment of printing and dyeing wastewater, but the contact area with dye molecules is limited, the adsorption efficiency is low, so that the large-scale application of the adsorption material is limited, ettringite serving as one of main hydration products of cement-based materials can solidify part of heavy metals through physical adsorption or ion substitution, the treatment pertinence of the industrial wastewater is extremely strong, the complex sewage system with coexisting multiple pollutants is difficult to adapt, and the hydrogel has excellent swelling property and separation convenience by virtue of a three-dimensional network structure, can adsorb part of heavy metal ions and dye molecules, but has limited adsorption functional group types, so that the adsorption capacity is low, the type of adsorbable pollutants is single, and the deep treatment requirement of the complex industrial wastewater cannot be met. Therefore, the development of the efficient adsorption material which can widen the types of adsorbed pollutants, improve the adsorption capacity and the adsorption efficiency and has good separation and recovery performance has important significance for solving the difficult problem of complex industrial wastewater treatment and promoting the upgrading of environmental protection treatment technology. Disclosure of Invention Aiming at the defects or improvement demands of the prior art, the invention provides a preparation method of nano-microcrystal modified hydrogel, which adopts a core technical scheme of compounding modification of ettringite and hydrotalcite, and cooperatively exerts the characteristics of ettringite ion substitution, surface electronegativity curing of various heavy metal ions, the advantages of electrostatic force attraction, ion exchange and chemical bonding adsorption of various dye molecules, and the high swelling property and easy separation property of a three-dimensional network structure of the hydrogel, effectively solves the technical problems of limited adsorption efficiency of traditional hydrotalcite, small one-sided property of industrial sewage treated by ettringite, small adsorption category of single hydrogel and low capacity, simultaneously, and can remarkably widen the application range of adsorption materials by precisely controlling the preparation parameters of magnesium-aluminum hydrotalcite and ettringite, optimizing the process conditions of reaction monomer/cross-linker/initiator ratio, stirring, water bath heating and the like, so as to ensure that the adsorption rate and adsorption capacity of the multi-system industrial wastewater containing heavy metals and organic dyes can be greatly improved (the maximum adsorption capacity of 18 mg/g, the adsorption time can be maximally improved, the adsorption capacity of methylene blue can be maximally utilized, the adsorption capacity can be realized by 80min, and the preparation method is easy, the preparation method has the advantages of environmental protection, the preparation method is environment-friendly, and wide, and has a wide application prospect, and environmental protection and can be realized. In order to achieve the above object, one aspect of the present invention provides a method for preparing a nano-crystal modified hydrogel, comprising the steps of: S1, adding 5-10 parts by mass of sodium hydroxide and 10-20 parts by mass of ac