Fabrication of high-performance pervaporation membrane for sulfuric acid recovery via interfacial polymerization

Industrial acid wastewater is one of the top hazardous wastes to environment. Acid-resistant nanofiltration membrane has been applied in acid wastewater reclamation but is limited to the high osmotic pressure for treating concentrated acid solution. On the other hand, pervaporation (PV) technology has been industrialized for dehydration from organic solvents. It has the potential to extract water from concentrated acid solutions. Nevertheless, PV membrane must have excellent acid resistance besides good ion rejection. Here, we prepared a series of thin-film composite PV membranes based on polysulfonamide (PSA)/polyethersulfone (PES). The PSA selective layer was formed by interfacial polymerization (IP) between a polyethyleneimine (PEI)/m-phenylenediamine (MPD) mixed aqueous solution and a hexane solution of m-phenylenedisulfonyl chloride (BDSC). By optimizing the preparation conditions, the PSA/PES membrane exhibited a water flux of 51.1 ± 2.3 kg m−2 h−1 with a NaCl rejection of 99.60% when desalinating a 35000 ppm NaCl solution at 75 °C. After soaking in 20 wt% H2SO4 solution for one month, the desalination performance of the membrane was maintained. Furthermore, the membrane showed a water flux of 47.5 ± 1 kg m−2 h−1 and a rejection to H2SO4 over 99.9% when separated a 10 wt% H2SO4 solution at 75 °C for at least 20 h. All these results demonstrate that the thin film composite PV membrane is very suitable for treating concentrated acid wastewater.