Impact of feed spacer thickness on nanofiltration membrane performance for metal plating wastewater treatment
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1Chemical engineering department, Tarbiat modares university, Tehran, Iran
2Dept. of Chemical Engineering, Tarbiat Modares University
3Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering and Technology, University of South Africa, Johannesburg, South Africa
In this study, The effect of three types of feed spacers with different thicknesses was investigated on the nanofiltration (NF) membrane performance for nickel ion separation from aqueous solution. The NF membrane was made of polyacrylonitrile (23% wt) as the main membrane material as well as poly(ethylene glycol) (0.5% wt) as additive. Feed spacers were used in this study are the diamond shape and have three different thicknesses. The experiments were tested in a channel membrane test cell with three layers, permeate spacer, membrane, and feed spacer. The feed concentration of nickel ion was (200 ppm) dissolved in deionized (DI) water and feed had pH=7. The operational condition was pressure (P=6bar). The thickest feed spacer showed the highest membrane initial permeate flux after 30 min, As well as with decreasing the thicknesses of feed spacers, membrane’s initial permeate fluxes reduced after 30 min. the membrane initial permeate fluxes with feed spacers thicknesses (680, 497, 298 µm) respectively were (28.83, 28.54, 27.96 l.m-2.hr-1). after the three-cycle of 3-hour testing for each cycle with cleaning processes between every cycle, the thickest feed spacer showed the lowest membrane permeate flux reductions compared with initial membrane flux, and with decreasing the thicknesses of feed spacers, membrane permeate flux reduction was increased. the membrane permeates fluxes reduction with feed spacers thicknesses (680, 497, 298 µm) respectively were (15.123%, 22.599%, 31.402%). As well as feed spacer thickness does not significantly affect the amount of the membrane nickel ion rejection in each cycle and can be negligible.