(468f) Chemical Activation of Biochar Made From Oil Palm Kernel Shell and Its Application to Adsorbent for p-Nitrophenol

Lignocellulosic biomass is one of the most abundant biomass resources on the earth and can be used as a feed-stock for preparing fuels and chemicals. Some of these technologies are still under development. Due to its availability in Malaysia, oil palm waste is considered to be the best biomass waste. In 2010, Malaysia was the second largest producer of palm oil, producing 17.8 million tons, or 39% of the total world supply. Indonesia was the world’s largest producer of palm oil, producing 22.2 million tonnes of oil, or 48% of the total world supply. In 2010, productive oil palm plantations in Malaysia covered 4.9 million hectares, a 3.3 % increase from 2009, when productive oil palm plantations covered 4.7 million hectares. Types of biomass produced by the oil palm industry include empty fruit bunches (EFB), mesocarp fiber, kernel shells, fronds and trunks. EFB, mesocarp fiber and kernel shells are used or discarded at palm oil mills, while fronds and trunks are used or discarded at the plantations. The total amount of the biomass residues from the oil palm industry amounts 18.2 Mtoe (million ton oil equivalent). Since the current primary energy supply in Malaysia is roughly 70 Mtoe (million tons of oil equivalent), the total oil palm biomass energy potential of 18.2 Mtoe may contribute considerably to decreasing the consumption of fossil fuels (natural gas, coal and oil). As one of the options to utilize lignocellulosic biomass, the authors have carried out pyroslysis oil production from oil palm kernel shell (PKS), and have published some papers (Proceedings for the 19th European Biomass Conference, VP2.5.33 (2011); Journal of the Japan Institute of Energy, 91, 954-959 (2012)). Pyrolysis of PKS produces not only pyrolysis oil but also biochar at the yield of 30-40 %. In this study, the biochar, which was prepared by microwave pyrolysis of PKS, was chemically activated, and utilized as an adsorbent of p-nitrophenol dissolved in water. 10 g of the biochar was impregnated with ZnCl₂ aqueous solution at 298 K for 1 h, then dried in an oven at 378 K overnight. The dried-up sample was heated up to the desired temperature (673 or 773 K) at 3 deg/min, and was maintained at the temperature for 1 or 1.5 h. The mass ratio of biochar to ZnCl₂ was 10:1 and 10:10. The eight different activated biochars prepared were used for adsorption of p-nitophenol from aqueous solution. The biochars were also characterized by BET, FTIR, XRD, SEM and TEM. The biochar activated at 673 K for 1 h with the biochar to ZnCl₂ mass ratio of 10 to 1 showed the best adsorption capability among the eight samples prepared. The adsorption isotherm was the Freundlich type.