Optimisation of Activated Carbon Preparation by Chemical Activation of Ayous Sawdust, Cucurbitaceae Peelings and Hen Egg Shells Using Response Surface Methodology

Aims: Explore the effects of the mixture of biomass materials: ayous sawdust, cucurbitaceae peelings and hen eggs shells in the preparation of activated carbon by chemical activation using the Methodology of Experimental Design.

Study Design: Determination of the physicochemical properties of the prepared activated carbons by the mixture of biomass materials: ayous sawdust, cucurbitaceae peelings and hen eggs shells using the Methodology of Experimental Design.

Place and Duration of Study: Laboratory of Noxious Chemistry and Environmental Engineering, Department of Chemistry, University of Dschang, between February 2015 and November 2016.

Methodology: A mixture of ayous sawdust, cucurbitaceae peelings and hen egg shells were used to prepare activated carbon by chemical activation using H3PO4. The effect of the composition of the components on the iodine number of the activated carbon was investigated. The Methodology of Experimental Design (MED) was used to optimize the production conditions of the activated carbons, while the analysis of variance (ANOVA) was used to determine the significance of the various variables.

Results: Using a carbonization temperature of 450°C and a H3PO4 concentration of 0.79 M, the optimum conditions for preparing the activated carbon were 2 hours of resident time, 0.549 as mass fractions for ayous sawdust, 0.450 for cucurbitaceae and 2.296×10-10 for hen egg shells. The resultant activated carbon was found to have a BET surface area of 311.23 m2/g, an iodine number of 656.70 mg/g and a carbon yield of 44.88%. It was also observed that the experimentally obtained correlation coefficient of 0.999 was in good agreement with the values predicted by the model. The iodine number, which decreased with the fraction of hen eggs shells used portrayed an antagonist effect, while its increase with the increase in ayous sawdust and cucurbitaceae peelings showed the synergetic effect.

Conclusion: The optimized activated carbon was the one produced from the near 50/50 combination of ayous sawdust and cucurbitaceae, and its BET surface area, and iodine number were superior to those from the individual materials.