Removal of Cr(VI) from aqueous solution using brick kiln chimney waste as adsorbent

Heavy metals are toxic to aquatic flora and fauna even in relatively low concentrations. Chromium is a commonly occurring toxic metal in ecosystems. This study aims the adsorption of Cr(VI) on a novel low-cost carbonaceous material under different experimental conditions such as contact time, initial concentration of metal ions, pH, and temperature. The adsorbent was characterized by using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The equilibrium data were fitted well with Langmuir and Freundlich isotherms. Adsorption kinetics of Cr(VI) ions onto chimney waste adsorbent were analyzed by pseudo-first-order and pseudo-second-order models. The adsorption process is favored by acidic pH and followed the second-order kinetics. Various thermodynamic parameters like activation energy (E-a), Gibbs free energy change (Delta G(o)), enthalpy change (Delta H-o), and entropy change (Delta S-o) were calculated. The results showed that the carbonaceous material obtains from bricks kiln chimneys can be efficiently used for Cr(VI) removal from wastewater.