Insights into nitrobenzene adsorption mechanism on apricot stone activated carbon: A study via statistical physics models and thermodynamic analysis

Abstract

Statistical physics modelling was performed to analyze the adsorption forces and the thermodynamics of the removal of nitrobenzene molecules using an activated carbon obtained from apricot stones. This adsorbent was prepared using phosphoric acid activation and exhibited a surface area of 1762 m2 g−1, total pore volume of 1.09 cm3 g−1 and an experimental maximum adsorption capacity of 295.63 mg g−1 for nitrobenzene at 298 K. The removal of this organic molecule was exothermic. A double layer adsorption model with two energies was utilized to calculate the main steric parameters for the removal of this compound. This model was employed to perform a thermodynamic analysis of this adsorption system. It was concluded that 2 and 3 adsorption sites can be involved for the removal of nitrobenzene molecules on activated carbon surface. Physical interaction forces were expected to participate in the removal of this pollutant. This activated carbon can be regenerated with NaOH thus offering the alternative of its recycling to reduce the removal costs of this organic molecule from water.