High-flux high-interception-rate positive charge composite nanofiltration membrane and preparing method of high-flux high-interception-rate positive charge composite nanofiltration membrane

Abstract

The invention discloses a high-flux high-interception-rate positive charge composite nanofiltration membrane and a preparing method of the high-flux high-interception-rate positive charge composite nanofiltration membrane. The preparing method comprises the following steps that (1) polyetherimide is dissolved into organic solvents to be prepared into a polyetherimide solution; stirring and still standing defoaming are carried out; a casting membrane solution is prepared; the casting membrane solution is scratched on the smooth surface of a non-woven fabric; the materials are put into the air, and is put into an ethylenediamine water solution to be soaked; the materials are taken out and are flushed by deionized water; an interlinked base membrane is obtained after the drying in the air; one side, with the scratched casting membrane solution, of the non-woven fabric is called as the surface A; (2) m-phenylenediamine and positive charge materials are put into water to be prepared into a water solution; (3) the surface A of the interlinked base membrane is soaked into the water solution prepared in the second step, is taken out and dried; then, the surface A is soaked into the n-hexane solution of the trimesoyl chloride, and is taken out and dried to obtain the high-flux high-interception-rate positive charge composite nanofiltration membrane. The high-flux high-interception-rate positive charge composite nanofiltration membrane has the advantages of high flux and higher interception rate. The production time is short, and the process is simple.

Description

technical field [0001] The invention relates to a positive charge composite nanofiltration membrane with high flux and high rejection rate and a preparation method thereof. Background technique [0002] Nanofiltration is a new type of membrane separation technology, and its separation accuracy is between ultrafiltration and reverse osmosis, so it is considered loose reverse osmosis and low-pressure reverse osmosis. The molecular weight cut-off of nanofiltration is between 200-1000, and the pore size is 0.5-2nm. The basic theoretical models of the main mass transfer mechanism include non-equilibrium thermodynamic model, pore flow model, dissolution-diffusion model and Donnan effect. The application of nanofiltration membranes involves various modern industries and fields. For example, in petrochemical, food and pharmaceutical, sewage treatment, seawater desalination, electronic bionics, and even military fields, membrane technology is playing an increasingly important role. ...

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Problems solved by technology

These studies have shown that chitosan and its derivatives can be used as materials for modifying the surface charge of membranes, but there is a problem of low flux, which affects the promotion of positively charged membranes [Journal of Membrane Science, 2006, 286, 237-244]

On the polyamide commercial nanofiltration membrane, Yong Zhou et al. changed the charge on the membrane surface by electrostatic deposition of polyethyleneimine with a molecular weight of 750,000. The deposition time was 2-20 hours, and the resulting membrane was improved to MgCl2. 91.2%, but the flux is lower than 15.0Lm -2 h -1 It is also obvious, and the deposition is electrostatic, the force is small, and the polyethyleneimine on the surface is easy to lose. As the concentration of polyethyleneimine decreases, the resulting film is resistant to MgCl 2 The rejection rate from 90% to 70% [Separation and Purification Technology, 2009, 66, 287-294]

[0006] In view of the common problems of low rejection rate, low flux, and easy loss of charged materials in positively charged nanofiltration membranes, there is an urgent need to develop high-performance composite nanofiltration with high flux and high rejection rate, and charged materials are not easy to lose. membrane

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