Evaluation of various preparation methods of oil palm fiber (OPF) biochar for ammonia-nitrogen (NH3-N) removal

Abstract

The aim of this study is to develop a oil palm based biochar for the selective removal of NH3-N in low concentration from aquaculture wastewater. In this study, three different preparation methods of biochar were evaluated for the adsorption of NH3-N from synthetic aquaculture wastewater. The three methods are pyrolysis, activation with acid before pyrolysis and activation after pyrolysis with numerous oxidizing agents. In the 1st method, various biochars have been prepared at different pyrolysis temperatures (300 – 500 °C) and holding time (0.5 – 2 hr). The maximum removal efficiency of 50 % was achieved at preparation condition of 300 °C and 2 hr. In the 2nd method, the acid activated raw OPF was pyrolyze at 300 °C, 1 hr. The maximum removal was lower compared to the 1st method without acid treatment. In the 3rd Method, the optimized biochar from the 1st method was activated with different activating agents such as, HNO3, HCl, H3PO4, H2SO4, CH3COOH and H2O2 at 100 °C for 2 hr. It was noticed that activation after pyrolysis did not show any improvement in the removal of NH3-N from synthetic aquaculture wastewater. Characterization of optimized samples were carried out to investigate the adsorption mechanism process of NH3-N. The 1st method (pyrolysis) was the best which reported the highest (50 %) removal of NH3-N. Pyrolyzed OPF is a potential adsorbent for NH3-N.