Comparative study of single and multi-layered fixed bed columns for the removal of multi-metal element using rice husk adsorbents

The effect of mechanical and multi-step chemical treatments on the adsorptivity of rice husk for the removal of multi-metal element from simulated wastewater was evaluated in this study. Furthermore, the adsorption performance of single- and multi-layered fixed bed columns were also studied using Blended Rice Husk as adsorbent. The metals being studied are: Be, Ca, Cd, Cr, Cu, Fe, Li, Mg, Mn, Mo, Ni, Pb, Sb, Sr, Tl, V and Zn. There are two types of rice husk adsorbents prepared from hybrid modification of mechanical and multi-step chemical treatments, namely Acetone-Benzene Treated Rice Husk (ABRH) and Acetone-Benzene-Methanol Treated Rice Husk (ABMRH). Surface morphology and BET analyses of ABRH and ABMRH revealed that the application of acetone, benzene and methanol solvents able to open up internal surface area of top and bottom part of the pores, predicting a new structure of pore shape termed as Hypothetical T-shirt Pore Model. This pore shape exhibited larger pore diameters, higher porous and surface areas, as well as higher adsorption capacity, owing to its middle narrow section which reducing desorption rate. The theory of Hypothetical T-shirt Pore Model coincided with results obtained by adsorption studies based on numerical technique of area under the graph. With respect to Raw Rice Husk in single-layered bed, the highest percentage reduction of area under the graph was demonstrated by ABMRH in multi-layered bed by 94.49%. The present work also found that, the adsorption was favored for multi-layered with 82.45% reduction of area under the graph by using numerical technique, as compared to single-layered fixed bed columns. © 2014 Asian Network for Scientific Information.