Comparative study for Pb2+ adsorption from simulated wastewater of battery manufacture on activated carbon prepared from rice husk with different activation agents

Abstract

This study contains a lab-scale investigation into the feasibility of applying an adsorption technique to treat wastewater polluted with lead metal simulated to that exhaust from a battery manufactory. Rice husks have been prepared for use in three forms; natural rice husks without any activation, activated carbon of rice husks pretreated with Sulfuric acid H2SO4, and the other pretreated with Potassium hydroxide KOH. Activated carbon using KOH provided the best condition for the removal of lead than carbon activated using H2SO4 and natural rice husks. The BET surface area and surface morphology by FESEM analysis were characterized. The values of surface area were (20, 561, 722) m2/g for natural rice husk, activated carbon pretreated with sulfuric acid, and potassium hydroxide respectively. The adsorption process was studied using Pb2+ at temperatures of (25-40)o C and for a concentration range of (20-100) mg/l. The maximum removal ratios of lead Pb2+ for natural rice husks and sulfuric acid or hydroxide potassium activation after 1h were 51.21%, 92.3%, and 97.25%, respectively. The maximum adsorption capacity of lead Pb2+ onto natural rice husks, rice husks pretreated with H2SO4 or KOH, and into activated carbons was (37, 86.2 and 94.6) mg/g respectively, at a concentration of 100 ppm and at 25oC. The equilibrium adsorption curves were obtained for Pb2+ and the data was fairly well fitted with Freundlich-isotherm with a confidence level of 0.99. The kinetic of adsorption was studied by using two kinetic models, pseudo first order and pseudo second order. The results showed the rapid increase in the rate of adsorption at the initial until equilibrium achieved. Pseudo second order model was represented the data very well with confidence level 0.99.