Kinetics and Isotherms Adsorption of Reactive Dye by Thermally Treated Dolomite

Kinetic and equilibrium data of the adsorption of reactive black 5 (RB5) from synthetic solutions on Algerian dolomite were determined experimentally. The obtained samples, i.e., raw dolomite and its form heated at 900 °C (D900), were characterized by XRD and SEM. The kinetic mechanism is enough complex, involving different models such as those of pseudo-second order, intraparticle diffusion, and Elovich. The adsorption of RB5 at equilibrium increases strongly with increasing adsorption temperature. The affinity sequence is D900 >> raw dolomite with amounts adsorbed of 125.9 and 38.20 mg g⁻¹, respectively. This difference would be correlated with the weight loss percentage and crystallographic properties. The kinetic mechanism involving different models such as those of pseudo-second-order, intraparticle diffusion, and Elovich. The isotherms are found to be suitably fitted by the Redlich-Peterson equation, a model including three adjustable parameters and requiring nonlinear least-square analysis. A close agreement exists between the evolution of kinetic, thermodynamic and equilibrium, parameters, indicate chemisorption process. The fact that maximum adsorption occurs at isoelectric point emphasizes the prevalence of the non-electrostatic interaction. The process reflects for D900 a weak chemical interaction via a mechanism of surface complexation. In view of its adsorbed amount, D900 appears very effective for removing reactive dyes from wastewaters.