Physicochemical analysis of automobile effluent before and after treatment with an alkaline-activated montmorillonite

Effluents obtained from six industries were analysed for physicochemical properties. An alkaline-modified montmorillonite was used to remove heavy metals from automobile effluent. The effects of effluent pH, adsorbent dose, adsorbent particle size and contact time on adsorption were determined. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were used to analyse equilibrium isotherms. Kinetics was analysed by the pseudo-first-order, pseudo-second-order, intra-particle diffusion and film diffusion rate equations. Thermodynamic parameters including changes in free energy, entropy and enthalpy were calculated. The alkaline-modified montmorillonite was effective for treatment of effluent contaminated with heavy metals.