Synthesis of polyamide thin film composite nanofiltration membrane for Arsenic removal

Abstract

Arsen (As) is one of the most detrimental substances in drinking water owing to its carcinogenic impact on human health. Among many techniques for removing Arsenic, membrane filtration process has emerged as an efficient technology for removing As from water. In this study, nanofiltration (NF) thin-film composite membrane based on polyamide is synthesized via interfacial polymerization between piperazine (PIP) in water and trimesoyl chloride (TMC) in hexane onto polyacrylonitrile (PAN) supporting substrate. The influence of PIP and TMC concentrations in the two insoluble solvents on the separation performance (flux and rejection) of the obtained membrane is studied. The physicochemical properties of the derived membranes are characterized by ATR-FTIR and pure water contact angle measurements. The separation performance of the membrane is evaluated for filtering pure water and 150 ppb arsenate (Na₂AsHSO₄) aqueous solution. The results indicate that the PIP and TMC concentrations affect the physicochemical properties and thus the separation performance of the polyamide membrane. The hydrophilicity of the membrane surface increases as rising the TMC concentration. Nevertheless, the increment of PIP concentration results in the decline of hydrophilic property of the membrane. The increase in TMC and PIP concentrations lead to increasing the As(V) rejection, while the TMC concentration is dominant to an increment of the thickness of the synthesized membrane. Thus, the permeability of the membrane decreases more significantly with an increase in TMC concentration. The PIP concentration of 2 wt.% and TMC concentration of 0.15 wt.% is found to produce the NF membrane for reducing As(V) in drinking water with high flux of 64 Lm^-2 h^-1 and good rejection of 95%.