Removal of phenol from aqueous solution by adsorption onto baobab fruit shell activated carbon: equilibrium and kinetics studies

Phenol compounds are considered one of the major problems faced by many countries owing to their release in wastewaters from various industries. These pollutant compounds are harmful to marine life and human beings. Therefore, in the present study, Baobab Fruit Shells (BFS) were used as a precursor for the production of activated carbons for the removal of phenol. The chemical activation of BFS using ZnCl2, H3PO4, and KOH with an impregnation ratio of 1:1 at 500 ̊C for 1 h in Nitrogen (N2) atmosphere was investigated. The effects of these chemicals on the performances of the prepared activated carbons (yield, surface area, adsorption properties) were studied. Fourier transform infrared (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and N2 adsorption analyses were performed for the characterization of BFS-ACs. SEM results showed that porous structures were formed on the surface of different sizes. FTIR analyses show the presence of different surface groups on the activated carbons. The highest BET surface area and micropore volume were obtained by KOH with 1029.435 m2/g and 0.369 cm3/g, respectively. The developed BFS-ACs were used for the removal of phenol from the aqueous solution. The results indicated KOH in terms of adsorption and efficiency showed better results with a maximum adsorption capacity of 36.90 mg/g at a higher initial concentration (600 mg/L). The adsorption rate of phenol by BFS-ACs was rapid and more than 95.02 % phenol could be absorbed by KOH-AC within the initial 15 min. Phenol adsorption behavior can be described by the Langmuir isotherm model and the pseudo-second-order kinetics. This study provided an effective source that could be used in the production of activated carbon for the treatment of wastewaters as it could be attained at a low cost