Electrochemical Synthesis of Green Rust and Its Modified Form Developed for Wastewater Treatment in Remote Areas

Green rust (GR) is an important intermediate in oxidative transformation of ferrous phase. It contains a mixture of ferrous and ferric hydroxides that belong to a family of layered double hydroxides. Anionic and cationic species can replace their corresponding parts in the layered structure and different species can also accumulate in between the layers. GR can play an important role in wastewater remediation, such as reduction and removal of toxic compounds. Unfortunately, GR is not stable in the oxidative atmosphere and thus cannot be efficiently used for wastewater treatment in remote areas. In this work, we prepared GR electrochemically and developed its stability by physical methods using acrylic resin, polyethylene sheet, and glycerin, and by chemical/electrochemical methods using aluminum and magnesium as dopants in its pyroaurite-type structure. Its efficiencies for wastewater treatment containing arsenic were also studied with both original and modified forms. Furthermore, these solids before and after treatment were characterized using Mssbauer, x-ray diffraction, scanning electron microscopy/energy dispersive x-ray analysis, x-ray photoelectron, and Fourier transform infrared spectroscopic techniques.