Separation Performance of Hg2+ in Desulfurization Wastewater by the Graphene Oxide Polyethersulfone Membrane

The separation performance of Hg2+ in desulfurization wastewater by a graphene oxide (GO) polyethersulfone (PES) membrane was investigated in this article. The GO membrane was assembled on a PES microfiltration membrane by the vacuum filtration method and characterized by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The characterization results showed that the GO-PES membrane used in this experiment was compactly assembled and highly oxidized and contained a large number of oxygen-containing functional groups. Besides, the Hg2+ removal performances of the GO-PES membrane under different conditions, such as GO loading, initial Hg2+ concentration, temperature, pH value, and ion component of wastewater, were investigated. The results indicated that the Hg2+ retention rate of 80.33% and the flux of 26.3 L.m(-2).h(-1) could be achieved under typical conditions. A higher GO loading, lower initial Hg2+ concentration, and higher wastewater temperature was beneficial for the improvement of Hg2+ removal efficiency; the optimum separation performance of Hg2+ could be obtained at a wastewater pH value of 9. The influence of Ca2+, Mg2+, and K+ on Hg2+ removal was unobvious, whereas Na+ had an inhibitory effect. Furthermore, the recyclability of the GO-PES membrane was also investigated. The results showed that after three circulations, the retention rate of 60.63% could still be obtained.