Microwave-Assisted Activation of Waste Cocoa Pod Husk by H 3 PO 4 and KOH - Comparative Insight into Textural Properties and Pore Development

Abstract

This study is motivated to increase the value of cocoa pod husk (CPH), which is currently considered as waste in the cocoa farming, by converting it to activated carbon (AC). The main goal is to comparatively evaluate the impact of H 3 PO 4 and KOH as chemical-activating agents on the resulting textural properties of the obtained carbon from CPH. Furthermore, the effects of the impregnation ratio and precursor's particle size were also examined. In all cases considered, H 3 PO 4 -activated CPH obtained a higher yield and more desirable properties over KOH-activated CPH. Characterization of the physisorptive properties such as Brunauer-Emmett-Teller surface area (S BET ), total pore volume (V total ), and average pore diameter (D p ) also suggested that H 3 PO 4 is the better activating agent. The highest S BET obtained was 1237.47 m 2 /g from the 2.00:1.00 impregnation ratio. V total (1.11 cm 3 /g) was also found to be the highest at this condition. Further analyses on the D p and pore size distribution revealed that AC obtained from H 3 PO 4 was mesoporous. Proposed porosity development on both activating agents suggest that KOH is a more reactive activating agent for CPH than H 3 PO 4 , as evidenced by severe material loss and low structural integrity.