# The Effect of Chemical Activating Agent on the Properties of Activated Carbon from Sago Waste
## 1 Introduction  
Activated carbon has an amorphous, fullerene-like structure, with a large and small amount of oxygen and hydrogen, respectively [1]. This structure leads to an increase in its surface area, a high degree of porosity [2, 3], and a wide spectrum of oxygenated functional groups [4, 5]. Activated carbon has attracted attention due to its large application and environmental benefits. Furthermore, the adsorption of heavy metals [6, 7, 8], organic compounds [9], dyes [10, 11], CO\({}_{2}\) capture [2, 12, 13], catalyst [14, 15], ammonia, and methane storage [16, 17, 18], were some common applications. The use of activated carbons as materials for electrochemical double-layer capacitors (EDLC) has made them suitable for industrial applications [19, 20, 21]. Eigoncellulosic precursors and biomass sources were the main raw materials for activated carbon production. However, the need for abundant, renewable, and low-cost raw material, has motivated many studies to explore materials used in production. The studies on activated carbon were the third-highest since 2005, after graphene and carbon nanotubes, related to carbon materials [22]. Several precursors were obtained from biomass, waste, various parts of plants, cotton stalk [6], peanut shell [7], nutshells [9], pineapple waste [11], oil palm shell [17], and coffee beans [19]. In addition, chemical and physical activation are the two most important methods that activate carbonaceous materials [22], though thermal activation [23] and microwave radiation [24] methods have also been reported. Otherstudies summarized several parameters in the manufacture of activated carbon [22; 25; 26], and chemical activation agent is an important key. These agents include zinc chloride (ZnCl\({}_{2}\)), potassium hydroxide (KOH), phosphoric acid (H\({}_{3}\)PO\({}_{4}\)), sulfuric acid (H\({}_{2}\)SO\({}_{4}\)), and sodium hydroxide (NaOH). Also, H\({}_{2}\)O\({}_{2}\)[27], potassium carbonate (K\({}_{2}\)CO\({}_{3}\)) [28], CaCl\({}_{2}\) [29], KMnO\({}_{4}\)[30; 31], formamide [32] and other acid salts [33] have been used as activating agents. The high rate of studies on activated carbons mentioned above promotes this study on the effect of activating agents on the properties of activated carbon. Presently, sago waste is used as a raw material to produce activated carbon. It (_Metroxylon sago_) is an endemic plant in Indonesia, with approximately 1.2 million ha of sago forest, which is 50% of the total sago forest in the world. Indonesia has about 219,978 ha of sago starch production area by 2017, with a total production of 489,643 tons [34]. Furthermore, the plant is the main source of carbohydrates for coastal communities in eastern Indonesia, and it is included in local food commodities. On the other hand, behind the high production of sago in Indonesia, its waste causes environmental pollution [35]. However, sago waste is rich in lignocellulosic fibers, namely cellulose 36.2%, hemicellulose 15.18%, and lignin 12.34% [36; 37], making them suitable as activated carbon raw material. The fabrication of activated carbon using sago as its raw material has been studied previously, either from its waste [38; 39; 40; 41; 31], palm bark [42; 43], or pulp hydrogel [44]. In addition, the activated carbon has been synthesized using several chemical activating agents, which include H\({}_{2}\)SO\({}_{4}\), ZnCl\({}_{2}\), KOH, and KMnO\({}_{4}\), with a variety of chemical concentrations, activation temperature conditions, and agitation time. However, none of these studies focused on the effect of activator variations. Therefore, this study aims to determine the effect of activators on the properties of activated carbon from sago waste. In this study, ZnCl\({}_{2}\) and H\({}_{3}\)PO\({}_{4}\) were used as a chemical acid activator, while KOH and KMnO\({}_{4}\) as base chemical treatments. Then, the porosity, microstructural, proximate, and surface chemistry analyses helped to understand the properties of the activated carbon from sago waste and its prospective application.