Thermodynamic Studies of the Arsenic Adsorption on Iron Species Generated by Electrocoagulation

Abstract

Protection of global environment and sustainable sources of clean water are a necessity for human survival. The wide use of heavy metals by modern industries has generated heavy metals containing wastes and by-products. Specifically, large quantities of arsenic compounds are being discharged into the environment. The full potential of Electrocoagulation (EC) with air injection as an alternative wastewater treatment technique to remove arsenic from water showed more than 99 percent of removal without adding any chemicals. This study has been carried out to determine the feasibility of arsenic adsorption on iron species by EC process using the Langmuir’s Isotherm. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were calculated. It was found that the adsorption process is exothermic and spontaneous. Some experiments were conducted to determine the optimum operating conditions such as current density, pH, and residence time. Also in this study, X-Ray Diffraction, Scanning Electron Microscopy, Mössbauer Spectroscopy, and Fourier Transform infrared spectroscopy were used to characterize the EC solid products that revealed the expected crystalline iron oxides (lepidocrocite, magnetite, gohetite, and iron oxide).