The Research on the extraction of value added biomaterials from biomass is one of the top most interested areas for the scientists [1]–[4]. Cellulose, the most abundant component of biomass, has been known as the essential material for the production of textile fibers, cellulose derivatives, pharmaceuticals substances, food additives, etc. Cellulose derivative, namely, cellulose acetate (CA) or an ester of cellulose, is the most commercially used and widely applied in the industrial sectors. CA is an interesting and very useful material due to its large spectrum of utilities. The main applications of CA are in the field of food packaging, textile industries, gas separator membrane, ultrafiltration membrane, coating and bioplastics [5]–[12]. CA has also been applied in the military and defence area, such as for less-prone low vulnerability ammunition (LOVA) systems. CA has been reported as promising binders for LOVA gun propellant [13], [14].
Besides thermochemical and hydrolytic routes to transform biomass into useful fuels and chemical, the catalytic conversion by using chemicals is industrially attractive because its fastest conversion rate and controllable selectivity. CA is produced by introducing the acetyl group to the cellulose. Generally, acetic anhydride is used as an acetylating agent by using H2SO4 as a catalyst [15]. However, this strong acid is considered as less environmentally friendly among other catalysts because of its toxicity properties. In another study, NaHSO4 has been used as a catalyst to reduce H2SO4 and acetylation reaction temperature [16]. Meanwhile, Wu et al. (2004) have reported synthesis CA in the absence of any catalysts by using ionic liquids at room temperature [17]. Moreover, the use of iodine has been proposed for the esterification of corn starch and rice husk (RH) [18]–[20]. On the other hand, the preparation of high-purity cellulose is an important step for CA production. Pretreatment is one of the key factors to separate cellulose from other components especially lignin and hemicellulose before the acetylation process. The biological pretreatment of biomass has been reported previously [21], [22]. Meanwhile, other methods, such as mechanical, thermal, and chemical pretreatments have been studied to purify cellulose [23]–[28]. Sodium hydroxide and elemental chlorine-free (ECF) bleaching agents are the most commonly used chemicals in the pulp and paper industries [29], [30].
Wood pulps are the most traditional source of cellulose for CA production [31]. However, deforestation issue causes shortage of wood supply. Therefore, alternative resources such as agricultural waste have been considered as potential source of cellulose. In Indonesia, there are abundant biomass resources that are especially generated from agro-industrial sectors. Cajuput twigs (CT) and sugarcane bagasse (SB) are the potential biomass resources among others. Indonesia produces 600 to 650 tons of cajuput oil in every year. After distillation, twigs and leaves are the leftovers. The calculated biomass potency from cajuput oil distillation mills is approximately 32,500–65,000 ton/year [32], [33]. Additionally, the Indonesian Ministry of Agriculture reported that sugar production is approximately 2.5 million tons in 2019 from 0.5 million hectares of planted area [34]. In the mill, sugarcane is crushed to extract the juice, and the bagasse is the leftover and usually combusted in the boiler. However, the residue can be used as potential resource for biorefinery process. SB potency was approximately 10 million tons and was continuously increasing in 2019. Therefore, CT and SB can be potential resources for the synthesis of CA.
However, there is no recorded single study on CA synthesis from CT. Meanwhile, Candido et al. (2017) have extracted CA from SB using acid (H2SO4) treatment and H2SO4 as a catalyst during acetylation [35]. In addition, prehydrolysis and Iodine as a catalyst for acetylation during CA extraction have not studied until now. Therefore, the application of environmentally friendly approach for CA production from CA and SB is contemporary considering environmental issues. That is why this study has been conducted to characterize the CA obtained from CT and SB through prehydrolysis treatment followed by soda (NaOH) pulping, ECF bleaching and acetylation using iodine as a catalyst. Furthermore, the extracted CA has been compared with commercial CA.