A comparison of several EFB pretreatment procedures is presented in Table 3. Jung et al. [17] reported that in EFB pretreatment using dilute sulfuric acid, enzymatic saccharification yielded nearly 90% of the pretreated materials obtained in a microwave at 190 °C. Conversely, mild steam pretreatment conditions (auto-hydrolysis) of 140 °C for 15 min resulted in 29% glucose hydrolysis [18]. Sudiyani et al. [19] reported on alkaline (sodium hydroxide) pretreatment of EFB. A 64% conversion of glucose from pretreated biomass was achieved at 30 °C for 90 min. Jung et al. [20] reported on the use of aqueous ammonia for EFB pretreatment; 41.4% cellulose was converted to glucose through pretreatment with 21% (w/w) aqueous ammonia for 12 h at 60 °C. Kim et al. [21] conducted a two-step EFB pretreatment. In the first step, 4% (v/v) H2SO4 was used as a catalyst for removing hemicellulose, and 10 M NaOH was applied in a second pretreatment step for removing lignin. Although the conversion rate of glucose was over 80%, the pretreatment process was complicated and required much time. In our CHEMEX pretreatment, 83.6% enzymatic digestibility was obtained at 130 °C for 20 min with 2.9 M sodium hydroxide. In general, acid and thermal pretreatment require high temperature and short time. In comparison, alkali-catalyzed pretreatment requires lower temperature and longer time. Increase of enzymatic digestibility due to dilute NaOH treatment is caused by the swelling of biomass, leading to an increase in the internal surface area, a decrease in crystallinity, the separation of structural linkages between lignin and carbohydrates, and the disruption of the lignin structure [22] and [23].