Pyrolyzed bone char for nitrobenzene adsorption: Insight into the physicochemical characterizations and adsorption mechanisms

In this study, the preparation of pyrolyzed bone chars for the removal of nitrobenzene (NB) from the water was examined. Adsorption properties of bone chars prepared at diverse pyrolysis temperatures (300-900 degree celsius) were investigated for removing NB from aqueous solutions. At higher temperatures (700 and 900 degree celsius), bone chars showed superior adsorption properties for NB removal, and physicochemical characterizations showed that the pyrolyzed bone chars possessed improved properties and amended porous structure after pyrolysis treatment. Pyrolysis temperatures of > 700 degree celsius contributed to the dehydroxylation of hydroxyapatite of bone chars, increasing their NB adsorption performance. Maximum NB adsorption capacity of higher temperature pyrolyzed bone chars calculated from the Langmuir isotherm model was 142.41 and 204.34 mg/g for bone char-700 and bone char-900, respectively, indicating that the bone chars had the potential for enhanced NB adsorption. For adsorption isotherm parameters, two-parameter (Langmuir and Freundlich) models showed satisfactory results of NB adsorption on bone char from aqueous solution. Adsorption kinetic parameters of NB adsorption on bone chars showed pleasing results for the pseudo 2nd order model. This study shows that the pyrolyzed bone char is an efficient adsorbent for removing NB from water.