Preparation and Characterization of Activated Carbons from Bitter Kola (Garcinia kola) Nut Shells by Chemical Activation Method Using H3PO4; KOH and ZnCl2

Aims: Investigate the changes occurring in the composition of Garcinia kola nut shell after an activation process, especially the characteristics of the chemically activated carbons (ACs) obtained.

Study Design: Determine of the physicochemical properties of the prepared ACs using optimized experimental data.

Place and Duration of Study: Research Unit of Noxious Chemistry and Environmental Engineering, Department of Chemistry, Faculty of Science, University of Dschang, between February 2016 and March 2018.

Methodology: Garcinia kola nut shell (bitter kola nut shell) were used to prepare ACs by chemical activation using H3PO4, KOH and ZnCl2 using the carbonization temperatures 400, 450 and 500°C and the different impregnation ratios 1/1 and 2/1. The effects of the composition of the components on the iodine number and iodine methylene blue number of the ACs were investigated. The best ACs were selected after optimization of the experimental data obtained in the laboratory.

Results: Increase in carbonization temperature from 400°C to 500°C led to a decrease in the iodine number and an increase of in burn-off. For the production of ACs, the optimum temperature was found to be 400°C for 1 hour heating, with impregnation ratio of 1/1 by KOH, ZnCl2 ACs and 2/1 for the H3PO4 AC. Thermo-gravimetric analysis of the raw material was carried out to confirm the thermal stability of the ACs obtained at the optimum temperature of 400°C. The functional surfaces of the ACs and raw materials were studied by Bohem titration, pH, pzc, and FT-IR techniques. SEM analysis illustrates an irregular and heterogeneous surface morphology with a developed and fragmented porous structure of various sizes. Powder X-ray diffraction analysis showed that the raw material and ACs prepared are essentially amorphous.

Conclusion: Chemical activation is one of the appropriate methods that can be used to obtain new ACs. The maximum iodine number of the ACs was obtained at carbonization temperature of 400°C for a period of 1 hr, with impregnation ratios 2/1 and 1/1.