Thermodynamic Study for Arsenic Removal from Freshwater by Using Electrocoagulation Process

Industrial treatment of mineral-processing and non-ferrous metal-smelting acid wastewater effluents is becoming an enormous worldwide problem. In Mexico, heavy metals contaminated natural waters, including freshwater, surface water and ground water, are a significant problem as some of these compounds are known to be toxic, mutagenic, and carcinogenic. A very promising electrochemical treatment technique that does not require chemical additions to remove arsenic is electrocoagulation (EC) with air injection. The purpose of this research was to investigate the thermodynamics of arsenic adsorption on iron species using Langmuir’s Isotherm. Thermodynamic parameters such as ∆H°, ∆S°, and ∆G° were calculated, revealing that the adsorption process was exothermic and spontaneous. Techniques like X-ray Diffraction and Scanning Electron Microscopy were used to characterize the solid products formed during EC. Results suggest that magnetite particles and amorphous iron oxyhydroxides are present in the examined EC products, indicating that arsenic can be successfully adsorbed on iron species.