Preparation of dense polysulfonamide acid-resistant composite membrane with high rejection based on polyethylene substrate

Polysulfoneamide (PSA) separation membranes show promising prospects for use in acidic wastewater treatment due to their outstanding acid stability. However, current PSA membranes have the disadvantages of low flux, poor NaCl rejection, and poor acid resistance of substrate. In this paper, a positively charged PSA membrane was successfully prepared by using polyethylene (PE) stretch membrane (usually used as a battery diaphragm) as the substrate, with polyethyleneimine (PEI) and naphthalene-1,3,6-trisulfonyl chloride (NTSC) as the monomers for interfacial polymerization. The acid-resistant membrane exhibits a dense structure with an average pore size of just 0.2844 nm. Consequently, the membrane exhibits superior rejection rates for monovalent and divalent metals (MgCl2 99.15%, CaCl2 98.85%, MgSO4 94.5%, NaCl 93.27%), while also maintaining satisfactory flux. The membrane has excellent acid resistance, and maintains its superior separation performance after being immersed in 20 wt% H2SO4 at a high temperature of 24 h.