REMOVAL OF METAL IONS FROM AQUEOUS SOLUTION USING RICE HUSK-BASED ACTIVATED CARBON

Industrial wastewaters frequently contain high levels of heavy metals and treatment is needed before disposal, in order to avoid water pollution. Research in recent years has focused on the use of rice husk as low-cost adsorbent for heavy metals removal. Since rice is the main food source in Malaysia with more than 2.4 million tonnes of paddy produced in Malaysia each year, it is possible to utilize rice husk as an alternative to existing activated carbon. This project focuses on the removal metal ions from aqueous solutions using rice husk-based activated carbon (RHAC). Rice husk-based activated carbon was prepared via chemical activation process using NaOH followed by carbonization process at 500oC. Morphological analysis was conducted using field emission scanning electron microscope (FESEM) on three samples, i.e. raw rice husk, treated rice husk and rice husk-based activated carbon. These three samples were also analyzed for their C, H, N content using CHN elemental analyzer. The textural properties of rice husk based activated carbon, i.e. surface area (354 m2/g), pore volume (0.29 cm3/g) and average pore diameter (6.84 nm) were determined. The adsorption studies using activated carbon for the removal of Pb(II), Zn(II) and Ni(II) ions from aqueous solution were carried out at fixed adsorbent dose (0.1 g) with varying initial metal ions concentration as a function of contact time at room temperature. The concentration of metal ions was determined using atomic adsorption spectrophotometer (AAS). Indicated by adsorption capacity, rice husk-based activated carbon adsorb Zn(II) ion better than Pb(II) and Ni(II) ions in single aqueous solution. Ni(II) has high adsorption selectivity compared to other metal ions when they are mixed together in a solution. The equilibrium data obtained from adsorption studies was found to fit Freundlich isotherm model.