Parameterization, kinetics, and adsorption isotherm of electrocoagulation processof bromothymol blue in aqueous medium using aluminum electrodes

Abstract

The removal of bromothymol blue (BTB) from aqueous solution was studied by electrocoagulation (EC) technique using aluminum electrodes. The various experimental conditions known to influence the EC process were parameterized, including the effects of temperature, concentration, current density, pH, and treatment time. The results obtained have shown that optimum removal efficiency of 99.9% was realized at a current density of 20 mA/cm$^{2}$ and pH of 4.7. The adsorption process showed a pseudo-first-order kinetic model as the best fit to the EC data. Freundlich and Langmuir adsorption isotherms supported the adsorption of BTB on aluminum hydroxide being the in situ generated electrocoagulant. From the thermodynamic parameters, the adsorption of BTB is spontaneous, as indicated by the negative value of the Gibbs free energy.