# Carbon from Bagasse Activated with Water Vapor and Its Adsorption Performance for Methylene Blue
## 1 Introduction  
Adsorption systems are prevalent in many fields, and various efforts have been made, such as for air conditioning systems [1, 2] and heat pumps [3, 4, 5], to improve efficiency. Activated-carbon (AC) is a highly porous material that has generated popularity of adsorption refrigeration systems due to its strong adsorption of several refrigerants as adsorption pairs. ACs are mostly prepared from carbon resources, such as coal [6], peat [7], wood [8], shells [9, 10], and various agricultural wastes [11, 12]. Bagasse is a solid waste released by sugarcane factories during the production stage. Bagasse contains short fibers and a small amount of soluble solids [13]. Bagasse has a high content of cellulose (up to 50%), hemicellulose (25%), and lignin (25%) [13, 14]. The highcontent of cellulose is a strong reason for choosing bagasse for activated-carbon production [15; 16]. Much research on carbon and its allotrope production has been conducted due to the multi-functional properties of the carbonaceous materials, including for adsorption [17], photocatalysis [18; 19], electronic materials [20], etc. Research on the production of activated-carbon from bagasse for Cr (VI) adsorbent was conducted in which the carbon was chemically activated by ZnCl\({}_{2}\) at 600 \({}^{\circ}\)C under N\({}_{2}\) atmosphere. The surface area for the produced activated-carbon was 916.134 m\({}^{2}\)/g [21]. The carbon activated by NaOH and H\({}_{2}\)SO\({}_{4}\) was reported further, and the adsorption efficiency for methylene orange dye from aqueous solution was investigated [22]. Another analysis was also carried-out the chemical activation of carbon from bagasse by applying KOH solution with a KOH to biomass ratio of 1:3 under heat treatment of 800 \({}^{\circ}\)C for 30 min. The activated-carbon showed an adsorption capacity (51.3 mg/g) to Pb\({}^{+}\)[23]. The activated-carbon from bagasse, which is activated by a mixture of H\({}_{3}\)PO\({}_{4}\) and ZnCl\({}_{2}\), also shows good adsorption performance to remove chromophore from raw cane juice in sugar production [24]. Moreover, microwave-assisted heat treatment to sugarcane carbon produces activated-carbon powder with a maximum monolayer adsorption capacity for ammoniacal nitrogen (NH\({}_{3}\)-N-) adsorption of 138.46 mg/g and 12.81 mg/g for orthophosphate adsorption capacity. The kinetics of adsorption follows a second-order-kinetics model, indicating the potential of activated-carbon prepared from sugarcane bagasse for the adsorptive treatment of semi-aerobic landfill leachate [17]. In the above-mentioned published reports, many research works performed chemical activation by applying alkali hydroxide or acid solution along with a heat treatment. The results showed good adsorption ability of the activated-carbon. However, the chemicals chosen for activation are not environmentally-friendly. Liquid waste after activation increases environmental impacts and it requires handling for treatment. In the framework of the effective utilization of bagasse waste from the sugar factory, the effort has been made through steam activation to create activated carbon. The carbonized bagasse, activated by steam, reached an optimum condition of 800 \({}^{\circ}\)C for 1 h [25]. The steam at 110 \({}^{\circ}\)C, necessary for activation, was conducted for the carbonized residual biomass sources [26]. At an activation temperature of 900 \({}^{\circ}\)C for 45 min under steam atmosphere, activated carbon extracted from olive bagasse was prepared, and the surface area increased up to 1106 m\({}^{2}\)/g [27] compared with N\({}_{2}\) activation [21] and the activation under other chemical atmospheres [22; 23; 24]. At 700 \({}^{\circ}\)C for 1 h steam activation, the optimum surface area obtained by bagasse fly ash was only 656 m\({}^{2}\)/g, but the activation using KOH as the chemical agent at 700 \({}^{\circ}\)C increased the surface area up to 2571 m\({}^{2}\)/g [28].