Synthesis of high surface area activated carbon derived from cocoa pods husk by hydrothermal carbonization and chemical activation using zinc chloride as activating agent

Abstract

As an important plant commodity, cacao (Theobroma cacao L) plantation generates large of waste since only its beans utilized to produce chocolate or cocoa powder. The cacao shell waste, called cocoa pods husk (CPH) was investigated as a precursor for activated carbon (AC) synthesis. This present study reported the potential of CPH as a precursor for AC production with large surface area using ZnCl2 as activating agent. In addition, our group is the first who investigated ACs synthesis by hydrothermal carbonization of CPH followed by chemical activation with ZnCl2 as an activating agent. The effect of carbonization temperature was investigated to the ACs produced. The results showed that both of FTIR and XRD analysis confirm the ACs formation. Chemical transformation from CPH to hydrochars were captured in FTIR spectra by much decreased of C-O spectra and CC spectra in hydrochars. There was not much different between hydrochar spectra at different carbonization temperature. The yield of HCs decreased from 63.16% to 57.44% and ACs was decreased from 29.69% to 23.69 % as carbonization temperatures increased. ACs produced with mesopores structure, in the range of 2–3 nm. By increasing the hydrothermal carbonization temperature from 200 to 225 °C the surface area increased significantly from 1,165 to 1,694 m2/g. These properties allow the application of ACs for various fields.