Rice husk and activated carbon-silica as potential bioadsorbents for wastewater purification

Heavy metals are generally found in industrial wastewaters, affecting human health and living organisms. This study was therefore aimed to use bioadsorbents rice husk and activated carbon-silica to efficiently remove the heavy metals including lead (Pb) and cadmium (Cd) from an aqueous wastewater. The effects of bioadsorbent content, initial concentration, contact time, and pH value on the metal removal were investigated. An increased metal initial concentration lowered the removal efficiency of the bioadsorbents, and pH 6 provided the best condition for the removal of Pb and Cd. The use of rice husk and activated carbon-silica at pH 6 resulted in a maximum metal removal of 81% and 98% for Pb, while 88% and 100% for Cd respectively. The adsorption parameters were then determined by the Langmuir and Freundlich adsorption isotherms, and the experimental data were better fitted in the Freundlich adsorption isotherm model in comparison with the Langmuir adsorption isotherm model.