Biochar from waste Sterculia foetida and its application as adsorbent for the treatment of PAH compounds: Batch and optimization

Polyaromatic hydrocarbons (PAHs) are organic pollutants with known health hazards and have been reported worldwide in many water sources. The present study reports the easy and green formulation of KOH-modified biochar from Sterculia foetida shells capable of adsorbing acenaphthene and naphthalene from water. To elevate process efficiency, response surface methodology (RSM) was applied to optimize the sorption process. Batch study data were also analysed to understand the process isothermal, thermodynamic and kinetic characteristics. Characterization of the biochar was done using SEM, EDS, BET, FT-IR and XRD. The results display that the formulated biochar was able to remove approximately 92% and 94% of acenaphthene and naphthalene respectively from aqueous solutions. Further the process was found to follow Langmuir and Temkin isotherms and pseudo-second-order kinetics. The thermodynamic study suggested that the adsorption was endothermic and spontaneous in nature. The activation energy of the process suggested that chemical adsorption was the mode of PAH removal.