Adsorption Characteristics of NH₄⁺ by Biochar Derived from Rice and Maize Residue

Abstract

BACKGROUND: Biochar has ability to reduce N loss, increase crop yield, and sequestrate carbon in the soil However, there is still limited study concerning the interactive effects of various biochars on NH 3 loss and plant growth. This study, therefore, was conducted to investigate the NH 4 + adsorption characteristics of biochar derived from rice and maize residues. METHODS AND RESULTS: By-products were pyrolyzed under oxygen-limited conditions at 300-700°C for 1 hour and used for experiment of NH 4 + adsorption in aqueous solution. The adsorption characteristics of biochar were studied using Langmuir isotherm. Biochar yield and hydrogen content decreased with increasing pyrolysis temperatures, whereas pH, EC, and total carbon content increased. The biochar pyrolyzed at lower temperatures was more efficient at NH 4 + adsorption than those produced at higher temperatures. In addition, the R L values, indicating equilibrium coefficient were between 0 and 1, confirming that the result was suitable for Langmuir isotherm. CONCLUSION:The maize stalk biochar pyrolyzed at 300°C was the most efficient to adsorb NH 4 + from the aqueous solution. Furthermore, the adsorption results of this experiment were lower than those of other prior studies, which were ascribed to different experimental conditions such as ingredients, and pyrolysis conditions.