Effect Of Ions On Nanofiltration Of Ibuprofen And Its Chlorine-resistance Analysis

Trace organic pollutants as PPCPs in the water environment has been concerned due to their health effect on human and ecosystem. This paper selected Ibuprofen as a target molecule to investigate the removal efficiency by nanofiltration, ion presence on nanofitration performance, and the chlorine-resistance propertity of the nanofiltration membrane correspondingly.(1) The adsorption of IBU on the membrane surface occurred along with the filtration until a steady state where a real retention of 38% was obtained. The permeate flux increased during filtration. When explored the desorption ability of the membrane for IBU, almost 90% IBU can be released while the other could stay in membrane structure for a potential of membrane fouling.(2) Polyamide nanofiltration performanced a higher retention for Ibuprofen solution mixed with Ca Cl2 and a lower retention for Ibuprofen solution mixed with Na Cl. The cation charge has a large impact on the retention of Ibuprofen, i.e. the more positive charge,the more strength that compressed the electric double layer of membrane surface resulting in smaller pores. On one hand it caused low flux, on the other hand it was easy to remove Ibuprofen. Thus, Ca2+ has larger impact on the removal of Ibuprofen than Na+. SO42- with two units of negative charge, its repulsive force with membrane surface was larger than Cl-, and it caused low flux and retention.(3) When soaking solution reached a certain concentration, under acidic conditions, chloride occurred by polyamide with sodium hypochlorite destroyed polyamide and membrane performance. Under neutral conditions, membrane performance was influenced by sodium hypochlorite less than acidic conditions, because of polyamide got low degree of chlorination. Under alkaline conditions, although chlorination did not occurred, it still cause a serious decline in the performance of the membrane. Membrane surface constituent was tested by ATR-FTIR, membrane surface structure was scanned by SEM, conclusion and the reasons of the decline membrane performance were very consistent.