Impacts of recycled polysulfone on the salt separation performance of thin film poly(piperazine-amide) membranes

Abstract

The reusability provisions for finding out the feasibility of a polysulfone (PS) membrane structure are considering the type of stimulating system. On the successive non-solvent phase inversion of PS, the Newtonian flow of PS solutions at different stages is well observed from the rheological study. The viscosities of PS solutions decrease with stages. The membranes (Memb.-I-Ps to Memb.-VIII-Ps) are prepared from PS, recycled from successive phase inversion stages. It develops better porosities and higher Molecular weight Cut-off (MWCO) (PEO 200,400KDa)). Poly(piperazine-amide) coating on different recycled stages of PS membranes (Memb.-I-Pip to Memb.-VIII-Pip) shows an MWCO (PEG 400 Da, 1000 Da) property. The wettability property, zeta potential, morphological features of the membranes vary with the number of recycled stages. The salt rejection profiles (NaCl and Na2SO4) increase with the successive stages of recycled PS, and the selectivity (Na2SO4/NaCl) decreases a little. The Marangoni effect can explain the rise in salt separation with the subsequent recycled stages. The study extends to the defluoridation of water and quite promising. The ~15% increase in separation for 10 mg/L fluoride from Memb.-I-Pip to Memb.-VIII-Pip. The maximum separation of fluoride is 84.9% for Memb.-VIII-Pip. The decrease in separation results when the fluoride concentration increases from 10 to 100 mg/L.