Removal of mercury ions from industrial wastewaters by adsorption on a magnesium silicate modified with 2-mercaptobenzoxazole

Mercury can be removed from water by several methods, such as chemical precipitation, membrane filtration, ion exchange, electrodialysis, solvent extraction and adsorption [1, 2]. Adsorption ((bio)-adsorption/ion exchange) appears to be the most promising technique to remove mercury from aqueous solutions with mercury concentrations below 100 µg/mL.Several materials such as activated carbon, resins, clays and silica - some of them are modified with organic functional groups to improve the selectivity-have been studied for adsorption of mercury [3].In this study, the performance of magnesium silicate coated by 2-mercaptobenzoxazole (MS-MBZ) as a new adsorbent for removal of mercury ions from industrial wastewater samples was investigated. The traces of mercury ions after treatment by MS-MBZ was monitored by a cold vapour atomic absorption spectrometry. The adsorption isotherms showed favorable adsorption. The adsorption isotherms were analyzed using Langmuir and Freundlich models. The Freundlich model yielded the best fit for MS-MBZ. The results indicated that the complete removal of mercury ions can be reached after just 10 min after starting a batch experiment. The maximum adsorption capacity was 58 mg/g. MS-MBZ was capable of purifying water to parts per trillion levels. The removal efficiencies of the spiked mercury ions in two petrochemical wastewater samples containing low- and high- total dissolved solids were above 98%, pointing out the high potential of MS-MBZ for water treatment.