Comparative Adsorption Studies on Raw Rice Husk, Acid Leached Rice Husk and Base Leached Rice Husk by Using Methylene Blue as Dye

Abstract

Current methods for removing dyes from wastewaters are costly and cannot effectively be used to treat wide range of such wastewaters. This work describes the use of raw rice husk (RRH), acid-leached rice husk (ALRH) and base-leached rice husk (BLRH) as adsorbents for decolorization. Characterization of raw rice was done by powder X-ray diffraction (P-XRD) analysis, surface area analysis and scanning electron microscopy. Raw rice husk was collected directly from factory, ALRH was prepared from rice husk treated with hydrochloric acid (0.1N HCl) and BLRH was prepared from rice husk treated with sodium hydroxide (0.1N NaOH). Their adsorption capacity was evaluated for the decolorization of methylene blue solution (1mg/l). The effect of different parameters such as volume of adsorbate, dosage of adsorbent, initial pH and contact time were investigated. After characterization it was observed that, surface area of raw rice husk involves physical adsorption that lead to multilayer adsorption, by scanning electron microscope (SEM, JEOL JSM-6480 LV) equipped with an energy dispersive X-ray spectrometer (EDX) revealed the irregular and porous surface of rice husk suitable for adsorption. Removal efficiency was found to be 92% at dose of 1 g with contact time 45 min for RRH, 94% removal efficiency at dose 3 g with contact time 15 min for ALRH and 94% removal efficiency at dose 1 g with 15 min for BLRH. With respect to cost feasibility and environmental concern. RRH could be employed as the more effective low cost bioadsorbent for removal of methylene blue.

Keywords: Raw rice husk, acid leached rice husk, base leached rice husk, dye removal, adsorption, methylene blue.