Utilization of bark waste of Acacia mangium: The preparation of activated carbon and adsorption of phenolic wastewater

Abstract

After the extraction of industrial tannins from Acacia mangium, there is a lot of bark waste. Thus, we use these bark wastes to produce activated carbon using the phosphoric acid activation method. The information entropy weight method is employed to select the best process according to the weight coefficients of the activated carbon yield and value of methylene blue adsorption. In this study, the phenol adsorption behaviors of activated carbon and its thermodynamic and kinetic characteristics are investigated. The results indicate that the best process for the preparation of activated carbon from the bark waste of Acacia mangium involves phosphoric acid concentration of 50 %, carbonization temperature of 500°C, and carbonization time of 90 min. Under these conditions, activated carbon obtained from the bark waste of Acacia mangium in this study is 53.04 %, and the value of methylene blue adsorption is 6.0 mL/0.1 g. In liquid, the adsorption capacity of activated carbon increases with the initial content of phenol, and the highest value is around 96.92 mg g−1, which is obtained at 25°C. The adsorption thermodynamic is well expressed by the Freundlich isotherm adsorption equation, and the adsorption behavior curves flow McKay second-order adsorption kinetic equation. This result indicates that phenol wastewater is absorbed very well by activated carbon prepared from the bark waste of Acacia mangium. This study lays the foundation for further development of biomass-activated carbon strategy and provides a promising insight into the enhancement utilization of Acacia mangium.