Removal and recovery of mercury from chlor-alkali petrochemical wastes using [gamma]-Fe^sub 2^O3 nanoparticles

One of the main sources of mercury pollutions in Bandar Imam petrochemical company is its chlor-alkali unit. The unit uses mercury to convert sodium chloride (NaCl) to chlorine and sodium hydroxide. In this study, removal and recovery of mercury from wastewater of the chlor-alkali unit before its conversion to cake using γ-Fe 2O3 nanoparticles were reported. It was shown that the magnetic nanoparticles can adsorb and remove mercury from the chlor-alkali unit wastes and the resulting sorbents effectively separated from the solution by a 1.4 T magnet. Different parameters, which could affect the adsorption process, such as the amount of nanoparticles, pH and volume of buffer, and contact time were optimized. Under the optimized conditions, 94.59 % of mercury was removed using bare nan γ-Fe 2O3 with RSD of 1.7 % (n = 5). Adsorbed Hg(II) was successfully desorbed using 1 M HCl, then the resulting solution's mercury content was reduced to elemental mercury. The elemental mercury was finally collected in a hollow glass gas chromatographic column half filled with distilled water, providing a green chemistry for reuse of mercury. The method of mercury determination was cold vapor atomic adsorption spectrometry throughout this study.