Lignin/mesoporous hollow silica nanosphere thin film nanocomposite loose nanofiltration membrane for dye/salt separation

Abstract

It has been still expected to explore a green and low-cost raw material for fabricating high performance loose nanofiltration (LNF) membrane with high permeance and dye/salt selectivity. In this report, aminated mesoporous hollow silica (AHS) nanospheres are first synthesized. Then, a lignin-based LNF membrane is fabricated employing aminated lignin as raw material, trimesoyl chloride as a crosslinker, and AHS nanospheres as nano additives by interfacial polymerization. It shows excellent pure water permeance, high dye rejection, and salt permeation. After being modified with L-arginine, the PWP (49.9 LMH bar−1) and salt permeation are further improved. Simultaneously, the dye rejections are kept at a high level. The AHS nanospheres provided abundant water/salt diffusion channels for the lignin-based separation layer. The hollow structure of the nanospheres decreases the diffusion resistance of the water and salt. Moreover, the membrane shows satisfactory structural and separation performance stability during immersion in acid and/or alkaline solutions. After being treated with 5500 ppm h chlorination strength, it still exhibits excellent BBR/NaCl selectivity accompanied by a small permeance increase. Furthermore, the membrane shows excellent fouling resistances, satisfactory bactericidal (92.5 %) and bacterial anti-adhesion properties. The membrane shows excellent performance stability in a long-term (80 h) dye/salt separation process.