Method for preparing low-pressure high-selectivity nanofiltration membrane

Abstract

The invention provides a method for preparing a low-pressure high-selectivity nanofiltration membrane. According to the method, a small amount of amantadine is put into an oil-phase solution, the amantadine joins in an interface polymerization process in a mode of reacting with a part of acyl chloride groups in trimesoyl chloride in advance, and thus the amantadine is successfully introduced intopolyamide. Due to the amantadine which is uniformly dispersed into a polyamide layer and is of a special cage structure, the free volume of a polymer chain can be increased; in addition, as the amantadine selectively passes through magnesium ions and sodium ions, the cross-linking structure of the generated polyamide and corresponding membrane properties are remarkably affected, and the membrane has wide application prospects in fields such as industrial wastewater zero omission and organic small molecule grade concentration.

Description

technical field [0001] The invention belongs to the technical field of nanofiltration, and in particular relates to a preparation method of a low-pressure high-selectivity nanofiltration membrane. Background technique [0002] Nanofiltration is a pressure-driven membrane separation process between reverse osmosis and ultrafiltration. The core of nanofiltration technology is nanofiltration membrane. It is generally believed that the pore size of the nanofiltration membrane is about 1nm, which can effectively separate nanoscale components, such as the removal of high-priced salts, small molecular organics, and micro-pollutants, or as a molecular sieve to classify, purify, and filter high-value molecules. desalination etc. The characteristics of nanofiltration membranes determine its application fields, especially in water softening, fractional concentration of small organic molecules (relative molecular mass: 200-1000), desalination, purification and concentration of organic ...

AI Technical Summary

Problems solved by technology

CN 105435653 A improves the rejection rate of the nanofiltration membrane to divalent ions by adopting the mixed cross-linking method of aromatic amine and aliphatic amine, but the rejection rate of monovalent salt (NaCl) is greater than 30%, and does not realize the rejection of divalent salt and Thorough separation of monovalent salts, while preparing nanofiltration membranes with low water flux

In addition, many researchers control the porosity of the polyamide layer by adding inorganic nanoparticles to the water phase or adding an aprotic solvent with a solubility parameter close to that of polyamide to the oil phase. Although these methods can improve the nanofiltration membrane However, the reduction of polyamide cross-linking density will lead to a decrease in the salt rejection rate of the membrane, and the improvement of membrane selectivity cannot be achieved.

In summary, simultaneously improving the water flux and ion selectivity of nanofiltration membranes is an important challenge for nanofiltration membrane technology.

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