Adsorption capacity of african pear seed (Dacryodes edulis) derived-activated carbon for sulfidic gases’ capture

This study investigates the adsorption capacity of activated carbon derived from African pear (Dacryodes edulis) seeds for the capture of sulfidic gases. Activated carbon was prepared through chemical activation by adding NaOH and characterized in terms of Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Energy dispersive x-ray (EDX) spectroscopy, and X-ray diffraction (XRD) techniquesmethods of activated carbon before and after gas adsorption. Experiments in adsorption were performed on the fixed-bed system with temperatures of 25oC and 50oC under pressure between 5 and 20 psi. The analysis of the surface area revealed that the surface area changed to 965.2 m 2/g to 999.9 m 2/g, whereas the average pore diameter changed to 2.40 nm to 3.00 nm, indicating that the restructuring of the pores slightly occurred following the interaction with gases. FTIR analysis indicated that sulfur containing functional groups were formed during the adsorption process and SEM micrographs indicated morphological changes and partial pore coverage. The XRD patterns proved the existence of crystalline sulfur-related species on the carbon surface. Pressure increased the adsorption capacity to a maximum of 2.96 mmol/g at 25oC and 2.16 mmol/g at 50oC. The isotherm analysis showed that temperature dependence was best characterized by Temkin and Freundlich models indicating that the adsorption behaviour was heterogeneous adsorption on the surface and adsorbate-adsorbent interactions. The statistical analysis also showed that the adsorption capacity was greater at lower temperature, which means that the adsorption behaviour was temperature dependent. The findings indicate that African pear seed-obtained activated carbon is a potential sustainable low-priced adsorbent of sulfidic gases in industrial gas streams.