Microwave-Assisted Activation of Waste Cocoa Pod Husk by H₃PO₄ 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 H3PO4 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, H3PO4-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 H3PO4 is the better activating agent. The highest S BET obtained was 1237.47 m2/g from the 2.00:1.00 impregnation ratio. V total (1.11 cm3/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 H3PO4 was mesoporous. Proposed porosity development on both activating agents suggest that KOH is a more reactive activating agent for CPH than H3PO4, as evidenced by severe material loss and low structural integrity.

Preparation of Acid- and Alkali-Modified Biochar for Removal of Methylene Blue Pigment

“…To study the adsorption characteristics and adsorption rates of different biochar, quasi-first-order kinetic, quasi-second-order kinetic, and intra-particle diffusion models were used to analyze them 49 , 50 where q t is the adsorption capacity (mg/g) at time t , k 1 is the quasi-first-order adsorption rate constant (min –1 ), q e is the adsorption capacity at the adsorption equilibrium (mg/g), and k 2 is the quasi-second-order adsorption rate constant [g/(mg·min)].…”

Interconnected Micro, Meso, and Macro Porous Activated Carbon from Bacterial Nanocellulose for Superior Adsorption Properties and Effective Catalytic Performance

“…On the other hand, KOH activation involves mainly fragmentation and solubilization of raw structure of precursor via a reduction reaction while leaving potassium-containing atoms within the carbon network. The potassium compound products can diffuse and intercalate into the carbon lamellae to induce the separation of layer and pore development [ 14 ]. This increases the net volume of the precursor and lowers its density.…”

Recent advancement of biomass-derived porous carbon based materials for energy and environmental remediation applications

“…H 3 PO 4 -activated porous carbon achieved higher yield, surface area (1237.47 m 2 g −1 ) and total pore volume (1.11 cm 3 g −1 ) over KOH-activated porous carbon. 116 AC prepared from sesame shell precursor by microwave and conventional heating assisted ZnCl 2 activation showed high SSA of 1254 m 2 g −1 . 117 Even so, commercial and bulk-scale development of microwave-assisted porous carbons have certain drawbacks, therefore further examination will be necessary in this area.…”