Investigation of Equilibrium Isotherm and Kinetic Modeling to Asses Sorption Characteristics of Nitrate onto Palm Leaf Biochar

Abstract

Application of agriculture residue especially in biochar form seems to be effective in the removal of contaminants such as nitrate pollution. The effectiveness of biochar produced from palm leaf residues (pyrolyzed at 600 ˚C) in the removal of nitrate from aqueous solution was studied at different pH. The pH value at the point of zero charges (pHpzc) and surface functional groups of biochar were also investigated. The result showed that the pHpzc of palm leaf biochar was about 8 and the most adsorption of nitrate from solution (90%) was obtained at pH 2. The fit of experimental data to six adsorption isotherm and eight kinetic models showed satisfied fits to Freundlich and Langmuir 2 isotherm and pseudo-second-order, power function, Intraparticle diffusion and simplified Milovich models due to their low values of Standard Errors (SE) of estimate and high values of coefficients of determination (R2). The result implied that the adsorption of nitrate onto palm leaf biochar was through favorable and multi-step chemisorption processes. According to the result reported herein the use of palm leaf biochar is promising for nitrate removal from aqueous solution.

Keywords

• biochar
• equilibrium adsorption models
• kinetic models
• nitrate
• palm leaf