Preparation and properties of a novel pH-stable nanofiltration membrane embedded with amino-modified silicon carbide

Nanofiltration (NF) membranes usually exhibit poor chemical stability when treating acidic/alkaline wastewater and using acidic or alkaline surface fouling cleaners. In this study, a novel pH-stable NF membrane embedding amino-modified silicon carbide (NH2-SiC) nanoparticles was prepared via interfacial polymerization method, which exhibited excellent both acid-resistance and alkali-resistance without sacrificing separation performance. Amino modification of SiC using gamma-aminopropyltriethoxysilane (KH550) made the nanoparticles be incorporated in the membrane via chemical bonding and relieved the nanoparticle agglomeration in the membrane matrix. When the NH2-SiC dosage in the water phase was 0.008 wt%, the membrane (PA/NH2-SiC) showed a higher pure water permeability, increasing by-32.4 % compared to the original NF membrane without NH2-SiC, and a stable Na2SO4 rejection of-98.2 %. In addition, PA/NH2-SiC membrane possessed excellent long-term anti-acid and anti-alkali performances by soaking in 0.2 M H2SO4 solution for 720 h and in 0.1 M NaOH/EDTA-2Na mixed solution for 192 h. The Na2SO4 rejection of PA/NH2-SiC membrane maintained at-90.1 % and 86.7 %, respectively, while the corresponding Na2SO4 rejection of the original NF membrane declined to-55.0 % and 60.9 %, respectively. The PA/NH2-SiC membrane prepared in this study will provide a new material for the efficient treatment of acidic and alkaline wastewater.

Automated summary

In this study, a pH-stable nanofiltration (NF) membrane embedding amino-modified silicon carbide (NH2-SiC) nanoparticles was prepared. The membrane showed excellent acid-resistance and alkali-resistance without sacrificing separation performance. The NH2-SiC nanoparticles were chemically bonded with the membrane matrix to prevent agglomeration. The modified membrane exhibited improved pure water permeability and stable Na2SO4 rejection. It also showed long-term resistance to acid and alkali solution soaking compared to the original NF membrane.