Adsorption of Acetic Acid, Cadmium ions, Lead ions and Iodine Using Activated Carbon from Waste Wood and Rice Husks

This paper presents the performance evaluation of locally prepared activated carbon from rice husk and saw dust. The raw materials were carbonized at different temperatures (600-800C) using sodium hydroxide (NaOH) as the activating agent. The study includes moisture content determination of the raw materials used in the activation and carbonization processes. The effects of variations in carbonization temperature and concentration of activating agent on various performance indices for good quality absorbent were investigated. The percentage yield of the activated carbon from the raw materials as well as iodine number and adsorption of heavy metals from aqueous solutions were also determined. The experimental data which make a comparative assessment of activated carbon obtained from rice husk and saw dust were also presented. Preliminary examination of the raw materials showed that rice husk and saw dust had a moisture content of 14.6% and 5.8% respectively. Increase in carbonization temperature decreases yield of the active carbon. The highest yield of about 48% was obtained from rice husk at 600C, with moisture content of 26%. The rice husk at 800C gave a yield of 47.2% with moisture content of 26.5%. While the yields of the saw dust were 44% at 600C and 40% at 800C with moisture content of 17% and 19% respectively. A detailed study of mass transfer processes indicated that activated carbon from these materials show good performance. @JASEM With the situation of the Nigerian economy and the population increase, the need has come for self sufficiency to achieve a stable and comfortable economy. A research on our waste materials can yield useful adsorbents, which have numerous uses and applications in our various industries land application of these materials may improve crop production. However, this practice can also degrade the environment with the introduction of potentially harmful substances such as traces of heavy metals into the soil. Heavy metals have been applied to soil with pesticides, as plant nutrients and as a constituent of waste products. These heavy metals may include cadmium, zinc, lead etc. Thus taking into account the harmful effect of these heavy metals, it was considered of great extent to study the adsorption process of these metals from aqueous solution using locally prepared activated carbon which can be produced from wide variety of these carbon rich raw materials. Over the decades there has been rapid population expansion and technological development in Nigeria. This leads to a more extensive and intensive use of available supplies of water, and ultimately to the pollution and degradation of the quality of these waters. Pollution is inevitable because domestic and industrial activities generate wastes, which are discharged into the environment. These wastes or effluent might contain non-biodegradable matter, toxic heavy metals, organic matter and also might give off some offensive odour (Webber and Vernana, 1967, Eckenfelder, 2000, Tchobanoglous et’ al., 2003.). These can cause negative impact on the people living around those areas. Activated carbon is thus used as an effective adsorbent for the removal of these dissolved organic substances, heavy metals, obnoxious odour and colour from water and waste waters. Recent researchers studied the use of chemically modified and unmodified cassava waste for the removal of Cd, Cu, and Zn ions from solution (Abia et al., 2003). While sorption of Cd, Cu, and Zn ions from aqueous solutions by cassava waste biomass was investigated by Horsfall et al., 2004. Recent reports indicate an escalating demand for and use of imported adsorbent on the developing countries, particularly Nigeria (Olafe and Bosch, 1996, Nwokoma and Anane, 2010, Okafor and Aneke, 2006, Emmanuel and Innocent, 2008). Thus in 1987, activated carbon worth N1,670,117 was imported from USA, Europe and Kuwait. In 1999, N5,096,999 worth of imports were made with brazil, China, and Taiwan (also developing countries) providing 98.9% of these imports, while the remainder was supplied by USA (Olafe and Bosch, 1996). Governments of these developing countries (Nigeria inclusive) are concerned with the amount of foreign exchange spent on importing these adsorbents, thus local substitutes are given some consideration. Amongst various substitutes considered, activated carbon has shown much potential. This is due to its versatilities and abundance of carbonaceous agricultural wastes. Despite the work done so far, there still remains according to recent reports a dearth of rigorous and comprehensive chemical engineering information