Maher E. Saleh, Amal H. Mahmoud and Ahmed A. El-Refaey( 2014). Removal of Cadmium from Aqueous Solution by Biochars Derived from Peanut Hull and Wheat StrawAENSI Journals Advances in Environmental Biology
Abstract: The scope of this study was the amining of biochar of peanut hull (PHB) and wheat straw (WSB) in removing cadmium ions (Cd2+) from wastewater. The feedstock of peanut hull (PHF) and wheat straw (WSF) were pyrolized at 450 oC for 15 min. The properties of these adsorbents were characterized scanning electron microscopy, fourier transform IR, N2 adsorption/desorption isotherms, and particle size distribution. Adsorption isotherm of Cd2+ onto feedstock and biochar, using batch experiments, was studied for periods extended to 120 hours. Kinetic adsorption data were analyzed using Lagergren pseudo-first-order kinetic model and the pseudo-second-order model. Results showed that biochar was efficient than feedstock in Cd2+ removal from aqueous solutions throughout the reaction time. About 94.9 and 98.0 % of Cd2+ was removed within the first 15 min of adsorption by PHB and WSB, respectively, and the maximum adsorption was observed after 6 hours of reaction with both biochars. Significant increases in pH values to about 2.24 (PHF) and 1.42 (WSF) unites were observed during the reaction with Cd2+ and about 0.17 and 0.24 unit were observed with corresponded biochar sorbents. Measured values of pH in all systems were not exceeding than 8.0 and support the speculation that ion exchange, complex formation and/or diffusion are possible mechanisms controlling the removal process. Values of constants and regression coefficients of kinetic models suggested that pseudo second-order equation can be considered in the present adsorption system and was well fitted in description of removal kinetics of Cd2+ by PHB and WSB.
Keywords: (Cadmium, peanut hull, wheat straw, biochar, adsorption kinetics, wastewater)
