Systematic Electrochemical Investigation of Iron Removal from Coal Fly Ash Acid Leaching Solution by Electrodeposition

Electrodeposition is a clean, efficient method for separating Al and Fe from coal fly ash acid leachate. This study systematically investigates Fe electrodeposition removal. Thermodynamic and electrochemical analyses confirm theoretical feasibility, Pb, Cu, Ni co-deposit with Fe, while Na, K, Ca, Mg, Li, Zn, Ga, Cr, Ti do not interfere. Increasing temperature and Fe2+ concentration shifts Fe2+/Fe reduction potential positively, promoting deposition. Titanium and lead electrodes suppress hydrogen evolution. High AlCl3 concentration effectively suppresses hydrogen evolution without significantly inhibiting Fe deposition. Kinetics show that both Fe2+/Fe and Fe3+/Fe2+ reductions are diffusion-controlled, with diffusion coefficients ~2.4×10-5 and 1.0×10-6 cm2/s. With increasing applied potential, Fe nucleation changes from progressive to instantaneous, reducing grain size and transforming morphology from irregular flakes to star-shaped pentagonal structures. This work provides electrochemical theoretical support for optimizing Fe electrodeposition removal from coal fly ash acid leachate.