PREPARATION OF POROUS CARBON FROM POPPED RICE VIA IMPREGNATED WATER COUPLED WITH FREEZE-DRYING PROCESS

Abstract

Activated carbon is an interesting material due to its high surface area derived from the highly porous structure. This material is suitable for using as a good adsorbent in various applications such as wastewater treatment, gas absorption and medicine. Production of activated carbon typically consists of two steps which are carbonization and activation. Agricultural wastes are used as carbon sources. This research focuses on the production of activated carbon from popped rice due to its appropriate chemical and structural characteristics, including highly starch content and connected-pore structure. Therefore, it should potentially be applied to produce activated carbon if the surface of popped rice is activated properly. Herein, this work aims to study the feasibility of an alternative way to produce activated carbon, which is activation-then-carbonization method. Water impregnation coupled with freeze-drying method is as used an activation technique. The results show that the proposed activation method can create small pores on the surface of the carbon derived from popped rice. The pores appear after the freeze-drying process. Adsorption capacity of methylene blue on the popped rice-derived carbon was less than that of the commercial activated carbon. Brunauer–Emmett–Teller (BET) indicates that the surface area and pore volume of the popped rice-derived carbon is smaller than the one without activation despite having additionally generated pores on the surface. Again, both types of the popped rice-derived carbon have much smaller surface area and pore volume than the commercial product. The reason is that, the structure of the popped rice with water impregnation collapsed and became overlapped, resulting in overall decreased surface area. Therefore, although the proposed activation method can induce the formation of small pore, the obtained carbon black cannot provide adsorption capacity comparable to the commercial product. This research may be useful for further developing procedures that use water activation before carbonization in the future.