Effect of NaOH on pretreatment of Gossypium herbaceum

In present study, the substrate Gossypium herbaceum (cotton stalks) was treated with sodium hydroxide to investigate its greatest promising use as an economical substrate for bioethanol production. Initially, 2 mm mesh size cotton stalks were soaked in various concentrations of NaOH (1–3%) for different soaking intervals of 2, 4, 6, 12, 24, and 48 h. The results showed that the cellulose content and delignification increased with the increase in the concentration of alkali and soaking time. However, the maximum cellulose and delignification (60.6% and 51.5%) were observed with 2.5% NaOH after 24 h of soaking. In physiochemical pretreatment, the maximum cellulose content (73.19%) was achieved with 2.5% NaOH at 121°C after 60 min while delignification was found to be 77.7%. All these results of the present study indicate that a suitable concentration of alkali as well as an autoclaving period at specific temperature are very much crucial to expose the maximum cellulosic contents prior to employing cotton stalks as substrates for bio-fuel production.