Preparation and characterization of TFC NF membrane with improved acid resistance behavior

• DOI: 10.1016/j.memsci.2020.118620
• Publication Date: 2020-08-19T17:19:02Z
• Authors: Hee Min Park; Hiromitsu Takaba; Yong Taek Lee
• Keywords: Interfacial polymerization; Amide; Polysulfone

Abstract In this study, we prepared the novel acid-resistant thin-film composite (TFC) piperazine(PIP)-based nanofiltration (NF) membrane using melamine (Mel), sulfonated-melamine formaldehyde (SMF), and sulfanilamide (SA) through interfacial polymerization on a polysulfone (PSf) support layer. A long-term acid-resistant experiment for divalent salt was carried out with static immersion tests in a 15 wt% sulfuric acid solution. The divalent rejection of the PIP1-SMF0.3-SA0.05 in a 15 wt% sulfuric acid solution was maintained at over 96% after 10 days, and then slightly decreased to 94% for 20 days, and finally was maintained over 90% for 30 days. The flux was maintained at about 20 GFD even after 30 days of immersion in acid. In order to confirm the degree of hydrolysis in amide, the bond dissociation energy (BDE) was calculated using the density functional theory (DFT). BDE values of PIP-TMC, Mel-TMC, and SA-TMC were 79.34, 83.78, and 93.91 kcal/mol. Consequently, PIP1-SMF0.3-SA0.05 having s-triazine and sulfonyl amide group exhibited acid-stable performance because the C–N bond is more stable and the slow hydrolysis reaction in acid. Our research for preparing high perm-selectivity and long-term acid stability membrane can extend NF technology in many industries, particularly in the recovery of rare metals from acidic solutions.