Adsorption of Cr(VI) from aqueous solutions by adsorbents produced from coal mining wastes

Abstract

Large amounts of coal-mining wastes contaminate the environment and reprocessing of them as valuable products such as adsorbents will be a good approach from an environmental and economic point of view. Therefore, in this study some adsorbents were produced from these wastes and used for batch removing experiments of chromium(VI) ions from aqueous solutions taking into considerational parameters such as initial concentrations, pH, temperature and time. The adsorption kinetic results were interpreted by the Lagergren equation and the rate constant of intraparticle diffusion was calculated. The adsorption process was described with the Langmuir and Freundlich isotherms and also their constants were calculated. Additionally, the effect of different anions on the adsorption of Cr(VI) was studied. The presence of the anions reduced the adsorption capacity for Cr(VI). The experiments were also carried out at different temperatures. Endothermic effects of temperature played an important role in the adsorption process.