# Fine Activated Carbon from Rubber Fruit Shell Prepared by Using ZnCl\({}_{2}\) and KOH Activation
## 4 Discussion  
The characteristics of activated carbon are highly dependent on the precursors used, the impregnation ratio, the carbonization time, and the carbonization temperature [59]. In other words, the use of different raw materials and activation treatments can result in activated carbons with very different properties. The RFSFAC6, with a ZnCl\({}_{2}\) impregnation ratio of 1:5, surpasses all other samples (seen in Table 3). Using ZnCl\({}_{2}\) as an activating agent, RFSAC formed a relatively stable carbon structure below 400 \({}^{\circ}\)C, and then began to deteriorate the carbon matrix, resulting in porosity between 400 and 500 \({}^{\circ}\)C. At higher temperatures, ZnCl\({}_{2}\) has been vaporized and decomposed into zinc and chlorine, which could cause more pores to form [60]. In fact, by increasing the impregnation ratio of the activating agent, more pores would be created. The impregnation ratio increased, the  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Precursor** & \begin{tabular}{c} **Chemical** \\ **Activation Agent** \\ \end{tabular} & **BET (m\({}^{2}\)/g)** & \begin{tabular}{c} **Adsorption** \\ **Quantity (cm\({}^{3}\)/g)** \\ \end{tabular} & \
\begin{tabular}{c} **Average Pore** \\ **Diameter (nm)** \\ \end{tabular} &
\begin{tabular}{c} **Carbon Content** \\ **(at.\%)** \\ \end{tabular} & **Ref.** \\ \hline Oil palm shell & ZnCl\({}_{2}\) & 1118 & 330 & 2.2 & 50 & [52] \\ Tamarind seeds & KOH & 2.72 & Na & Na & 23 & [45] \\ Coir pith & ZnCl\({}_{2}\) & 910 & Na & Na & 70 & [54] \\ Bambo wastes & - & 719 & Na & Na & 77 & [10] \\ Cassava peel & KOH & 1605 & Na & Na & 59 & [53] \\ Tea industry waste & ZnCl\({}_{2}\) & 1066 & Na & 2.2 & 79 & [2] \\ Cigarette filter waste & KOH & 328 & 74 & 3.01 & 69 & [55] \\  & ZnCl\({}_{2}\) & 953 & Na & 18.2 \({}^{\lambda}\) & 75 & [56] \\ Coconut shell & ZnCl\({}_{2}\) & 251 & Na & Na & Na & [57] \\  & H\({}_{2}\)SO\({}_{4}\) & 435 & Na & Na & Na & [58] \\  & RFSFAC & ZnCl\({}_{2}\) & 456 & 151 & 3.4 & 80.05 & This work \\ \hline \hline \end{tabular} Note: Na, not available.  
\end{table}
Table 4: Textural properties of activated carbon prepared from various biomass feedstocks.  
Figure 6: SEM micrographs (5000\(\times\) magnification) of RFSFACs prepared with different impregnation ratios (1:3, 1:4, and 1:5). (**a–c**) with KOH; (**d–f**) with ZnCl\({}_{2}\).  
concentration of ZnCl\({}_{2}\) attached to the sample surface increased, resulting in a more violent activation reaction, which had a good effect on porosity development. In this study, based on the general results, it can be concluded that RFSFAC treated with ZnCl\({}_{2}\) is better than that treated with KOH. This is the same result as previously reported by [PERSON], et al. [61]. Table 4 compares the textural properties of the optimal RFSFAC prepared in the present study (RFSFAC6) with those of 10 other activated carbon materials reported in the literature. As shown, RFSFAC6 has only a moderate surface area (456 m\({}^{2}\)/g) and pore size (3.4 nm) but has the highest carbon content (80.05 at.%) of all the considered materials. According to the conventions of the International Union of Pure and Applied Chemistry, pore sizes ranging from 2 to 50 nm (mesopores) provide an effective absorption performance for many contaminant materials [62]. For example, RFSFAC6 with a mesopore size of 3.4 nm has significant potential as an absorbent material for wastewater treatment and water purification purposes. Furthermore, with its high carbon content of 80.05 at.%, it also has significant promise for use as a pack carburizing medium in heat treatment processes [63].