Preparation method of composite base-membrane nanofiltration membrane

Abstract

The invention provides a preparation method of a composite basal membrane nanofiltration membrane. the prepration method compriss the following steps: S10, forming step of a composite base-membrane: a non-woven fabric supporting layer is knife-coated with a polysulfone layer by a continuous knife-coating mode; the polysulfone layer is knife-coated with a sulfonated polysulfone layer; the non-woven fabric supporting layer with the polysulfone and sulfonated polysulfone feed liquor enters a gel tank, and polysulfone and sulfonated polysulfone feed liquor undergo phase separation so as to form the composite base-membrane; and S20, interfacial polymerization reaction: 2.1) the composite base-membrane is immersed in a water phase for 2-30 s and then taken out of the water phase, and residual solution on the surface of the composite base-membrane is removed; 2.2) the composite base-membrane is immersed in an oil phase for 2-30 s and then taken out of the oil phase, and a polyamide desalination layer is formed on the surface of the polysulfone-sulfonated polysulfone composite base-membrane; and 2.3) the membrane is further immersed in 5-30 wt% of a pore-keeping solution for 30s-30min and then is taken out and dried so as to prepare the nanofiltration membrane. The prepared nanofiltration membrane has good desalinization rate and water flux level, and service life of the nanofiltration membrane is prolonged due to the composite base-membrane.

Description

technical field [0001] The invention relates to a membrane treatment technology, in particular to a preparation method of a composite base membrane nanofiltration membrane. Background technique [0002] Nanofiltration is a new membrane separation technology between ultrafiltration and reverse osmosis, its operating pressure range is 0.2-1.0MPa, and the molecular weight cut-off is in the range of 200-2000. Compared with ultrafiltration membranes and reverse osmosis membranes, nanofiltration membranes have the advantages of high water flux and high rejection at lower operating pressures, especially for divalent ions and low molecular weight organic small molecules. It has a high interception rate (greater than 96%), and has the advantages of no phase change, low cost, easy integration, modularization and automation. Filtration technology is widely used in many water purification-related fields such as sewage recycling, separation of valuable materials, landfill leachate treat...

AI Technical Summary

Problems solved by technology

However, due to the strong hydrophobicity of the polysulfone-based membrane, to a certain extent, it affects the uniformity of the adsorption of the polyamine aqueous solution on the membrane surface, thereby affecting the desalination rate and uniformity of the final polyamide. Therefore, how to improve the polysulfone-based membrane The bonding strength between the membrane and the polyamide desalination layer is an important issue affecting the final performance of nanofiltration

[0004] The charge effect plays an important role in the separation effect of nanofiltration membranes. The conventional method of making nanofiltration membranes is to carry out interfacial polymerization on polysulfone base membranes, but the extraction rate of calcium chloride from the prepared nanofiltration membranes is generally Only 40-60%, and even if it is improved by adjusting the formulation and process of interfacial polymerization, it is difficult to make the sodium chloride rejection rate exceed 60%