Removal of zinc ions from model wastewater system using bicopolymer membranes with fumed silica

Abstract

In this paper, the performances and efficiency of some novel polymer membranes doped with fumed silica powder were investigated. The membranes obtained using a laboratory electrodialysis system was involved in zinc ions removal from model wastewater system. The experiments were carried out using three concentrations of zinc ions: 500, 1000 and 1500ppm, respectively; an applied voltage of 5, 10 and 20V; flow rate: 13mL/min; time for each experiment: 2h. The removal ratio (R) and mass flow (J) of zinc ions and also water content (% wt.) were determined. Membranes were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results indicated that the membranes doped with fumed silica powder significantly influenced the zinc ions removal process from wastewater, this fact being proved by a strong enhancement of the removal ratio from 27.56±0.38% to 96.30±0.11% and by the increase of the mass flow from 8.79±0.12g/m2h to 92.33±0.10g/m2h. The FTIR-ATR spectra showed the existence of a peak located at ∼1079cm−1 indicating the presence of silica. The TGA results indicated an improvement of the fouling resistance of the membranes doped with incorporated fumed silica powder. Other properties are also enhanced by the addition of fumed silica, namely the membrane hydrophilicity and the ionic conductivity. The highest ionic conductivity was 0.8937mS/cm at 20V.