The efficiency of modified powdered activated carbon for removal of ammonia nitrogen from aqueous solution: a process optimization using RSM (Response Surface Methodology), adsorption isotherm and kinetic study

Abstract

The objective of this study was to determine the performance of modified commercial powdered activated carbon (MCPAC) in removal of ammonia from aqueous solution. The effects of adsorbent dosage (0.5–1.5 g/L), ammonia concentration (100–200 mg/L), pH (3 to 9) and contact time (2 to 120 min) were examined. In this study, experiments were performed based on Response Surface Methodology (RSM). The adsorption isotherm was evaluated using Freundlich and Langmuir models. Kinetics study was analyzed using pseudo first order, pseudo second order and particle penetration kinetic models. By increasing adsorbent dosage, pH and contact time, the removal efficiency increased. According to CCD results, the MCPAC was fitted to a quadratic equation. Also, ammonia adsorption for MCPAC followed the Langmuir (R² = 0.9831) isotherm model. The maximum adsorption capacity for MCPAC was 40.323 mg/g. The analysis of adsorption kinetic for MCPAC indicated that ammonia adsorption was well fitted by the pseudo second order kinetic model. As thus, we concluded that MCPAC could be considered as an appropriate and economical alternative adsorbent for water and wastewater treatment due to its high ammonia adsorption capacity.