CN-119971784-B - Preparation method of nanofiltration membrane with high pollution resistance

Abstract

The invention discloses a preparation method of a nanofiltration membrane with high pollution resistance, which uses a polyether sulfone membrane as a supporting layer and uses chitosan quaternary ammonium salt and trimesoyl chloride to carry out interfacial polymerization. The hydrophilic functional group of the chitosan quaternary ammonium salt enhances the interaction between water molecules and the surface of the membrane, and relieves the adsorption and deposition of pollutants on the surface of the membrane, thereby enhancing the organic pollution resistance of the membrane. In addition, the positive charges carried by the chitosan quaternary ammonium salt can destroy bacterial cell membranes, and bacteria death is caused, so that the anti-biological pollution performance of the membrane is enhanced. The nanofiltration membrane prepared by the invention has excellent capability of resisting organic pollution and biological pollution under the condition of keeping good water flux and separation performance, and has better application prospect.

Inventors

• YANG LINYAN
• HUANG WEIMING
• QIAN RICHENG
• ZHANG ZEYAN
• TAO MIN
• WU YI
• HE XIAOWEI
• JIANG XINYI
• WANG DUANDUAN

Assignees

• 华东理工大学

Dates

Publication Date

20260512

Application Date

20250304

Claims (3)

1. 1. A method for preparing a nanofiltration membrane with high pollution resistance, which is characterized by comprising the following steps: (1) Cutting a polyethersulfone membrane with proper size, and soaking in deionized water for 24 hours to remove the surface preservative and impurities; (2) The front surface of the polyethersulfone membrane is contacted with an aqueous phase monomer solution for 20min, then the excessive aqueous phase monomer solution on the surface of the membrane is removed, and the membrane is dried for 1min for later use, wherein the aqueous phase monomer is chitosan quaternary ammonium salt, the mass fraction of the aqueous phase monomer solution is 1.0wt%, and the solvent is an aqueous solution containing 1.0wt% of acetic acid; (3) Contacting one surface of the membrane obtained in the step (2) with a water phase monomer solution, contacting the surface with a sodium hydroxide solution with the pH value of 8-13 for 2 hours, removing redundant sodium hydroxide solution on the surface of the membrane, and airing for 1min for later use; (4) Contacting one surface of the film obtained in the step (3) with a sodium hydroxide solution for 1min, then removing redundant organic phase monomer solution on the surface of the film, airing for 1min for later use, wherein the mass fraction of the organic phase monomer solution is 0.5wt% and the solvent is n-hexane; The organic phase monomer is selected from one or more of terephthaloyl chloride, isophthaloyl chloride, adipoyl chloride, phthaloyl chloride, trimesoyl chloride, cyclohexanetricaoyl chloride, pyromellitic acid chloride, cyclobutane tetracarboxylic acid chloride and cyclopenta tetracarboxylic acid chloride; (5) And (3) placing the film obtained in the step (4) in an oven, heating and curing for 30min, taking out, placing in deionized water, and preserving at the temperature of 4 ℃.
2. 2. The method for preparing nanofiltration membranes having high resistance to contamination according to claim 1, wherein in step (3), the pH of the sodium hydroxide solution is 12.
3. 3. The method for preparing a nanofiltration membrane with high pollution resistance according to claim 1, wherein the temperature of the oven heating is 55-65 ℃.

Description

Preparation method of nanofiltration membrane with high pollution resistance Technical Field The invention belongs to the field of nanofiltration membranes, and particularly relates to a preparation method of a nanofiltration membrane with high pollution resistance. Background With the increase of global water resource shortage and water quality safety problems, the development of water treatment technology with high efficiency and sustainability has become a core topic in the field of environmental engineering. Under the background, the membrane separation technology is an important way for solving the water resource crisis by virtue of the advantages of low energy consumption, high selectivity and the like. However, one major challenge faced by membrane technology is membrane fouling, including inorganic, colloidal, organic and biological. Among them, organic and biological contamination of membranes are two types of contamination that are relatively common in membrane separation processes. Organic pollution means that organic substances in water are adsorbed or deposited on the surface of a membrane or in a membrane hole, and interact with the membrane through physical adsorption or chemical adsorption to form an organic pollution layer. Biological contamination refers to the growth, proliferation and formation of a biofilm of microorganisms on the surface or within the pores of the membrane. Biological pollution and organic pollution can occur simultaneously and interact, and complex combined pollution phenomenon is formed. After the microorganisms form a biological film on the surface of the film, the adsorption or deposition of organic matters on the film is promoted, and the organic matters provide rich nutrition sources for the microorganisms, so that the growth and propagation of the microorganisms are facilitated, the film pollution is further aggravated, and the film flux attenuation and the effluent quality degradation are finally caused. Therefore, the preparation of the membrane material with the resistance to both organic pollution and biological pollution has important significance. The semi-aromatic polyamide nanofiltration membrane is a common separation membrane material, and is formed by interfacial polymerization of two monomers of aromatic polyamine (such as piperazine) and aromatic polybasic acyl chloride (such as trimesoyl chloride) on a porous support layer. The membrane material can effectively remove harmful substances such as salt, hardness ions, heavy metal ions, organic matters and the like in water, produce high-quality purified water or treated water meeting specific water quality requirements, and can be widely applied to the fields of sea water desalination, brackish water desalination, industrial pure water preparation and the like. However, membrane fouling remains an important factor limiting its long-term stable operation. Prior studies have attempted to alter the polymerized monomers to improve membrane performance, however, difficulties in terms of contamination resistance and separation efficiency are generally faced with difficulty in co-promotion. According to the invention, chitosan Quaternary Ammonium Salt (CQAS) is innovatively used as a water phase functional monomer, and is subjected to interfacial polymerization reaction with trimesic acid chloride (TMC) to construct the novel polyamide separation layer. The hydrophilicity of the chitosan quaternary ammonium salt can promote the rapid transmission of water molecules, thereby improving the water flux of the membrane. On the other hand, the chitosan quaternary ammonium salt has a quaternary ammonium group with positive electricity, and the bacterial cell membrane is destroyed through electrostatic adsorption, so that the anti-biological pollution capability of the membrane is improved, and the hydroxyl and amino groups of the chitosan quaternary ammonium salt form a compact hydration layer on the surface of the membrane, so that the permeation of organic pollutants can be blocked, and the anti-organic pollution capability of the membrane is improved. The invention uses polyether sulfone membrane as carrier, uses chitosan quaternary ammonium salt and organic acyl chloride as water phase and oil phase monomer, and adopts interfacial polymerization method to prepare new nanofiltration membrane. The nanofiltration membrane prepared by the invention has excellent organic pollution resistance and biological pollution resistance under the condition of not affecting even better water flux and separation performance. Disclosure of Invention Aiming at the existing problems, the invention provides a preparation method of a nanofiltration membrane with high pollution resistance. The technical scheme of the invention is as follows: a preparation method of nanofiltration membrane with high pollution resistance takes a polyethersulfone membrane as a carrier, and specifically comprises the following steps: providing an acetic