Ammonium adsorption-desorption by using rice husk biochar

Abstract

Rice husk was utilized into biochar by pyrolysis and used as adsorbent for ammonium removal. Rice husk biochar (RHB) was produced at temperature of 350⁰C, 400⁰C, 450⁰C, 500⁰C, and 550⁰C. Characteristics of biochar were analyzed by moisture content analysis, ash content analysis, pH Zero Charge analysis, Fourier Transform Infrared (FTIR) Spectroscopy, and Scanning Electron Microscope (SEM). As the temperature for the pyrolysis increases, the moisture content of RHB decreases while the ash content of RHB increases. From the pH zero charge analysis, the value obtained from analysis is pH 7. The FTIR spectra showed the organic part of RHB with different functional groups such as alkene, alcohol, phenol, ether, ester, and others. Through SEM, the surface of RHB was observed to differentiate the pores size for the RHB at different pyrolysis temperatures. Based on the result of the characterization test, RHB500 was chosen as the best biochar for the adsorption of ammonium. The equilibrium contact time was 180minute, the optimum adsorbent dosage was 0.1g.and the optimum concentration of ammonium was 1.2ppm. For the adsorption-desorption of ammonium, RHB can run up to 5 cycles for biochar regeneration. Lastly, for adsorption kinetic, pseudo-second-order model is more preferable than pseudo-first-order model because R2 value is 0.9995 which it is closer to 1.