Adsorptive removal of methylene blue dye from industrial wastewater by using biochar derived from a brewery spent grain.

Abstract

The release of hazardous synthetic dyes into industrial effluents has emerged as an environmental problem requiring remediation. The present study focused on the preparation of a new and environmentally-friendly material for the remediation of hazardous dyes from aqueous solution. The low cost adsorbents were prepared from industrial by products including, brewery spent grain, brewery sewage sludge, municipal sewage sludge and metal processing sludge, which accumulated the industrial waste on disposal places collected in the Bedele town and Addis Ababa City, Ethiopia. The preliminary screening studied for evaluations performance of each biochar variant in removing methylene blue dye, then, the unmodified BSG biochar was selected. The comprehensive characterization studies were carried out on the biochar such as proximate analyses, point of zero charge, BET, FTIR, XRD and SEM analyzed. The batch adsorption experiments were conducted for optimizing parameter such as the pH, contact time, initial dye concentration and adsorbent dose in removing methylene blue dye. The selected unmodified biochar‖s removal efficiency 99.8% and the maximum adsorption capacity of methylene blue dye was 34.5 mg/g, the parameters optimized at the 3 h, pH 10, initial MB concentration 20 mg/L and adsorbent dose 2 g/L. The kinetic studies revealed that the adsorption process was the best fit by pseudo-second-order model, it indicated that the chemisorption mechanism and the adsorption process was the best fit by Freundlich isotherm model, it suggested that the multilayer adsorption on surface of biochar. The study demonstrated that the industrial waste biochar could be employed as an effective and eco-friendly alternative for the cleanup of dye in aqueous solution. The studies should be improve the regeneration efficiency of BSG biochar for enhance its long-term applicability in wastewater treatment.