Bentonite as an adsorbent for the removal of Cr(III) ions from galvanic wastewater: equilibrium, kinetics and thermodynamics in batch and column systems

Abstract

The presence of heavy metals such as chromium in waterways can lead to various health problems in humans and animals. Due to its negative effects, chromium-rich wastewater needs to be treated before being discharged into waterways. In this study, the possibility of using bentonite as an adsorbent for the removal of Cr (III) from galvanic wastewater was investigated. First, the physicochemical characterization of the used bentonite was performed, followed by the examination of process parameters such as pH value, concentration, mass, and time. Based on the obtained data, adsorption isotherms, kinetic models, and thermodynamic parameters were determined. All experiments were carried out in both batch and column systems. The results showed that bentonite can be used as a low-cost adsorbent for the efficient removal of chromium ions from galvanic industry wastewater, achieving the highest removal efficiency (99.97%) at pH 5 and a mass of 1 g. The Langmuir and Temkin adsorption isotherm models showed good agreement with the experimental data (R2 > 0.9), while the best fit for the kinetic study was observed with the pseudo-first-order model.