CN-121797100-B - Method for constructing reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction

Abstract

The invention relates to a method for constructing a reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction, which belongs to the technical field of reverse osmosis membrane preparation, and comprises the steps of pouring a mixed aqueous solution of m-phenylenediamine, triethylamine, camphorsulfonic acid and green cosolvent on the surface of a polysulfone-based membrane, and removing an aqueous solution on the surface to obtain a membrane I; and finally, after the solution on the surface of the membrane II is drained, solidifying and drying in an oven, cooling to room temperature, and finally immersing in deionized water for preservation, thus obtaining the reverse osmosis membrane. The introduction of the green cosolvent can improve the diffusion rate of m-phenylenediamine, reduce the cross-interface energy barrier of the m-phenylenediamine, effectively induce and construct a polyamide separation layer with a ridge-valley structure, effectively maintain higher rejection rate of sodium chloride, remarkably improve pure water flux and provide a new method for the structural design and preparation of the high-performance reverse osmosis membrane.

Inventors

• WANG HAITAO
• GENG HUIBIN
• CHANG NA
• TAN CHENCHEN
• Jing Zhaojing

Assignees

• 天津工业大学

Dates

Publication Date

20260505

Application Date

20260306

Claims (9)

1. 1. The method for constructing the reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction is characterized by comprising the following steps of: S1, taking a mixed aqueous solution of m-phenylenediamine, triethylamine, camphorsulfonic acid and a green cosolvent as an aqueous phase reaction solution, pouring the aqueous phase reaction solution on the surface of a polysulfone-based membrane, and removing the aqueous phase solution on the surface after the solution stays to obtain a membrane I; The green cosolvent is N-butyl pyrrolidone, wherein the mass fraction of the N-butyl pyrrolidone is 0.05-2 wt%; S2, taking normal hexane solution with trimesic acid chloride as organic phase reaction solution, pouring the organic phase reaction solution on the surface of the membrane I obtained in the step S1, and removing the organic phase solution on the surface after the solution stays to obtain a membrane II; And S3, standing the membrane II obtained in the step S2, solidifying and drying the surface solution of the membrane II in an oven after the surface solution is drained, cooling to room temperature, and finally immersing the membrane II in deionized water for preservation to obtain the reverse osmosis membrane.
2. 2. The method for constructing a polyamide layer structure of a reverse osmosis membrane by low-dose green cosolvent induction of claim 1, wherein in step S1, the mass fraction of N-butylpyrrolidone is 0.05-0.5wt.%.
3. 3. The method for constructing a polyamide layer structure of a reverse osmosis membrane by low-dose green cosolvent induction of claim 1, wherein in step S1, the solvent of the aqueous reaction solution is deionized water.
4. 4. The method for constructing a reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction of claim 1, wherein in step S1, the mass fraction of m-phenylenediamine in the aqueous phase reaction solution is 1-2 wt%, the mass fraction of triethylamine is 1.1-2 wt%, and the mass fraction of camphorsulfonic acid is 1.5-2.6 wt%.
5. 5. The method for constructing a reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction of claim 1, wherein in step S1, the dosage of the aqueous phase reaction solution is 20mL, and the residence time is 30-60S.
6. 6. The method for constructing a reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction of claim 1, wherein in step S2, the mass fraction of trimesoyl chloride in the organic phase reaction solution is 0.1-0.15 wt.%.
7. 7. The method for constructing a reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction of claim 1, wherein in step S2, the dosage of the organic phase reaction solution is 20mL, and the residence time is 10-30S.
8. 8. The method for constructing a reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction of claim 1, wherein in step S3, the curing and drying temperature is 100 ℃ and the time is 3-5 min.
9. 9. The method for constructing a polyamide layer structure of a reverse osmosis membrane by low-dose green cosolvent induction of claim 1, wherein in step S3, pure water flux of the prepared reverse osmosis membrane reaches 93.11 L.m -2 ·h -1 under the pressure of 1.55Mpa, and NaCl rejection rate reaches more than 96.95%.

Description

Method for constructing reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction Technical Field The invention belongs to the technical field of reverse osmosis membrane preparation, and particularly relates to a method for constructing a reverse osmosis membrane polyamide layer structure by low-dose green cosolvent induction. Background The problem of shortage of fresh water resources is increasingly prominent. As an important way for supplementing high-quality fresh water resources, reverse osmosis technology using polyamide composite reverse osmosis membranes as core components has been widely applied to unconventional water resource development processes such as sea water desalination and brackish water desalination. Therefore, the improvement of the performance of the polyamide film composite reverse osmosis membrane has important significance for promoting the efficient development of fresh water resources and the recycling of the water resources. The polyamide separation layer produced by Interfacial Polymerization (IP) reaction takes m-phenylenediamine (MPD) as a water phase monomer and trimesoyl chloride (TMC) as an organic phase monomer, and plays a decisive role in the separation performance of the reverse osmosis membrane. Because the interfacial polymerization reaction rate is extremely fast (typically accomplished in a few seconds), the reaction process is difficult to control precisely, resulting in uncontrolled growth of the polyamide structure, and non-uniformity and randomness in the thickness, morphology and degree of crosslinking of the separation layer structure. Therefore, the reverse osmosis membrane performance has a permeability-selectivity tradeoff effect, and the water flux and the desalination rate are difficult to be improved simultaneously, so that the development of the high-performance reverse osmosis membrane has a technical bottleneck. In order to break through the "permeability-selectivity" trade-off effect, precise regulation of the polyamide layer structure is critical. The regulation and control of the polyamide separation layer structure can be realized to a certain extent by adopting means of adjusting the monomer concentration, introducing nano particles, adding cosolvent, constructing an intermediate layer and the like. Wherein, the cosolvent-based method is a relatively simple and efficient interfacial polymerization reaction regulation method, and the fine structure of the polyamide layer is improved by adding the cosolvent into an aqueous phase or an organic phase to regulate the reaction microenvironment. However, the conventional aqueous phase cosolvent has the following limitations that firstly, a higher addition concentration (usually more than 5-10 wt%) is needed for realizing effective regulation of the polyamide structure, so that the raw material purchase cost is increased, the viscosity of an aqueous phase solution is obviously increased by a high-concentration additive, the diffusion of reaction monomers is inhibited, the interfacial polymerization reaction efficiency is possibly lowered, the risk of forming structural defects of a polyamide layer is increased, and secondly, a plurality of conventional aqueous phase cosolvents, such as alcohols, ethers and the like, belong to Volatile Organic Compounds (VOCs), and a great amount of volatilization of the conventional aqueous phase cosolvent forms potential risks for human health, and do not meet the requirements of green environmental protection and sustainable development. Therefore, based on the deep cognition of the cosolvent to the interfacial polymerization reaction regulation and control process, the cosolvent is designed to simplify the structure most by screening the specific functional group structure, and a novel method for accurately regulating and controlling the interfacial polymerization process and inducing the formation of an ideal polyamide layer structure is formed on the premise of meeting the requirements of low dosage, high efficiency and environmental friendliness, so that the method becomes a key for breaking through the bottleneck of the prior art. Disclosure of Invention The invention aims to solve the problems of overhigh addition amount of an aqueous phase cosolvent and poor environmental protection in the prior art, overcome the technical bottleneck that a polyamide layer structure is difficult to accurately regulate and control, and determine the optimal additive molecular structure combination by screening functional groups, and provides a method for constructing a reverse osmosis membrane polyamide layer structure by low-dosage green cosolvent induction of an ideal polyamide layer structure through low-dosage and environmental-friendly aqueous phase additive induction. In order to solve the technical problems, the technical scheme adopted by the invention is that the method for constructing the reverse osmosis membrane polyamide layer structu