November 2, 2020

Activated carbon yield

The data obtained for activated carbon yieldcoconut shell activated carbon suppliers (Y2) were reported in our previous study [15]. Activation temperature was found to have the greatest effect on it, with the highest F value of 134.23, while activation time and chemical impregnation ratio showed almost similar effects on the response, which were less significant compared to activation temperature. The quadratic effect of activation temperature on carbon yield was relatively large compared to quadratic effects of activation time and chemical impregnation ratio. However, the interaction effects between the variables were less significant. The effects of activation temperature, activation time and chemical impregnation ratio on yield were studied as all the three variables were found to be significant terms in the model for activated carbon yield. It was concluded that the carbon yield decreased with increasing activation temperature, activation time and chemical impregnation ratio [15]. The results obtained in this study were in agreement with the work done by Sudaryanto et al. [25] where activation temperature was found to play an important role on the yield of activated carbon whereas activation time did not show much effect on the carbon yield. The increase in temperature would release increasing volatiles as a result of intensifying dehydration and elimination reaction and also increased the C–KOH and C–CO2 reaction rate, thereby resulting in decreasing yield [28,31]. Indeed, the increase in activation temperature quickens the gasification reactions of carbon and therefore, the attack of the amorphous components which obstruct the pores causes a decrease in the carbon yield [20]. S¸entorun-Shalaby et al. [26] observed that at higher activation temperature, activation of apricot stones became more extensive and resulted in a lower solid yield with a more widened porous stucture. The yield for activated carbon prepared from fir wood was also found to decrease gradually with increase in duration of CO2 gasification [29] The activated carbon yield was also strongly affected by the chemical impregnation ratio where increasing impregnation ratio decreased the yield and increased the carbon burn-off. This was because when higher impregnation ratio was used, the weight losses were due to increasing release of volatile products as a result of intensifying dehydration and elimination reactions [31]. KOH would promote the oxidation process, therefore with high KOH:char IR, the gasification of surface carbon atoms was the predominant reaction, leading to increase in the weight loss of carbon [25]. Table 3 lists the comparison of carbon yield for various activated carbons. The results obtained in the present work were comparable with the works reported in the literature. The variation in the carbon yields might be due to the different precursors as well as the activation methods and/or conditions used to prepare the activated carbons.