Antimony Adsorption from Zarshouran Gold Mineral Processing Plant Wastewater by Nano Zero Valent Iron Coated on Bentonite

The effluent from Zarshouran gold mineral processing plant contains high quantities of arsenic، antimony، mercury، and bismuth. These metals and metalloids are soluble in water and very toxic when they enter the environment. Their solubility in water causes the polluted area to extend beyond their point of origin. In this article، different methods of antimony removal from water and wastewater were reviewed and the zero-valent iron nanoparticles coated on Bentonite were selected as an effective and low cost material for removing antimony from wastewater. For the purposes of this study، zero-valent iron nanoparticles of 40-100 nanometers in size were synthesized by dropwise addition of sodium borohydride solution to an Iron (III) aqueous solution at ambient temperature and mixed with nitrogen gas. To avoid particle agglomeration and to enhance the product’s environmentally safe application، the nanoparticles were coated on Bentonite and characterized by SEM/EDAX and BET. The experiments were carried out by intense mixing of the adsorbent with 10ml of real/synthtic wastewater samples in 20ml bottles. The effects of pH، contact time، temperature، and adsorbent dosage on antimony removal efficiency were investigated under intense mixing using a magnetic mixer. Finally، the effluents were filtered upon completion of the experiments and used for atomic adsorption analysis. The results of the experiments showed that the adsorption isotherms of the synthesized nanoparticles obeyed the Langmuir and Freundlich models. The experiments carried out on real samples showed that antimony adsorption capacity for B-nZVI was 2. 6 mg/g of the adsorbent and that the highest antimony removal efficiency was 99. 56%.