Electrochemical removal of boron from water: Adsorption and thermodynamic studies

The present work provides an electrochemical removal of boron from water and its kinetics, thermodynamics, isotherm using mild steel and stainless steel as anode and cathode respectively. The various operating parameters on the removal efficiency of boron were investigated, such as initial boron ion concentration, initial pH, current density and temperature. The results showed that the optimum removal efficiency of 93.2% was achieved at a current density of 0.2?A?dm-2 at pH of 7.0. First-, second-order rate equations, Elovich and Intraparticle models were applied to study adsorption kinetics. Adsorption isotherms of boron on Fe(OH)3 were determined and correlated with isotherm equations such as Langmuir, Freundlich and D-R models. Thermodynamic parameters, such as standard Gibb's free energy (?G degrees), standard enthalpy (?H degrees) and standard entropy (?S degrees), were also evaluated by Van't Hoff equation. The adsorption process follows second-order kinetics. The adsorption of boron preferably fits with Langmuir adsorption isotherm suggesting monolayer coverage of adsorbed molecules. The adsorption of boron onto Fe(OH)3 was found to be spontaneous and endothermic. (C) 2011 Canadian Society for Chemical Engineering