Nanofiltration membrane for chlorine-resistant and anti-pollution soft water and preparation method thereof

Abstract

The invention provides a chlorine-resistant and anti-pollution soft water nanofiltration membrane and a preparation method thereof. The nanofiltration membrane includes a polysulfone base membrane, and the polysulfone base membrane is sequentially covered with a polypiperazine amide layer and a surface modification layer; Wherein, the surface modification layer is formed by reacting thiourea dioxide and polyvinyl alcohol on the surface of the polypiperazine amide layer. The nanofiltration membrane has the advantages of the traditional salt separation nanofiltration membrane, and has excellent hardness removal ability, chlorine resistance and anti-pollution performance. The modified nanofiltration membrane has significantly improved chlorine resistance and anti-pollution performance, and can maintain its High calcium chloride retention rate. The nanofiltration membrane prepared by the invention has broad application prospects in the field of advanced treatment of municipal drinking water where the water quality is relatively hard or groundwater is used as the water source.

Description

technical field [0001] The invention belongs to the technical field of water treatment membranes, and in particular relates to a chlorine-resistant and pollution-resistant nanofiltration membrane for soft water and a preparation method thereof. Background technique [0002] Nanofiltration is a pressure-driven membrane separation process between reverse osmosis and ultrafiltration. The core of nanofiltration technology is nanofiltration membrane. The largest application field of nanofiltration membrane is the softening of drinking water and the removal of organic matter. Nanofiltration membranes can intercept microorganisms, bacteria and pathogens in water. Not only that, nanofiltration membranes can also effectively reduce water hardness, effectively remove chroma, heavy metals, and small molecule organic pollutants (natural organic matter, disinfection by-products, pesticides, endocrine disruptors, etc.) objects, personal protective equipment and medicines, etc.), thus gre...

AI Technical Summary

Problems solved by technology

However, nanofiltration membranes prepared by changing the surface charge properties of the polyamide layer will encounter many problems in practical use.

For example, since the surface of most colloidal particles present in natural water bodies is usually negatively charged, the surface of positively charged nanofiltration membranes will cause serious pollution problems due to the adsorption of colloidal particles

In addition, since municipal tap water pretreatment usually adds sterilizing agents such as sodium hypochlorite and chlorine dioxide, the raw water often contains a certain concentration of residual active chlorine, and the abundant amino groups on the surface of the positively charged nanofiltration membrane are easily oxidized by active chlorine. damage, thereby weakening the charge repulsion effect, resulting in a decrease in the desalination rate of the nanofiltration membrane

[0006] In addition, some researchers adjusted the polyamide cross-linking structure by using aromatic amine and aliphatic amine mixed cross-linking method. Although this method can improve the rejection rate of nanofiltration membranes for divalent cations, the prepared nanofiltration The water flux of the membrane is generally not high, and the surface roughness of the membrane is relatively large, which reduces the anti-fouling performance of the membrane

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