Vol. 12, Special Issue 10 (2023)

Author(s):
Premkumari, M Veerangouda, Vijayakumar Palled, M Anantachar, Sharanagouda Hiregoudar, Nagaraj Naik and RV Beladhadi

Abstract:
Some fossil fuels could be replaced by the bioconversion of lignocellulosic biomass into second generation ethanol. From a variety of lignocellulosic biomass, ethanol can be created. An illustration of a lignocellulosic agricultural waste is cotton stem. Ethanol can be produced from a variety of lignocellulosic biomass. Cotton stalk is an example of a lignocellulosic agricultural waste. The enzymatic saccharification of alkali pretreated cotton stalks at varying pretreatment conditions viz., temperature, time and alkalinity concentration was investigated. The results indicated that both solids and lignin content were found to be inversely proportional to the severity of the pretreatment conditions. Total sugar released after pretreatment ranged between 268.01-419.51 mg/g with a maximum total sugar content release of 419.51 mg/g at 120 °C with 2% KOH concentration for 1 h, whereas, a minimum of 268.01 mg/g was observed with 1% KOH at 50 °C, 6 h combination. The enzymatic saccharification of untreated and selected pretreated samples was carried out using CTec2® Cellulase enzyme at 8% solid loading rate with 0 to 30% enzyme loading level. Total sugar release peaked when cotton stalks were pretreated at 120 °C with 2% KOH for 1 h and loaded with enzyme loading rate of 30%. The maximum yield of saccharification (518.9 mg/g biomass) was achieved after 72 h incubation, with a saccharification rate of 7.2 mg/g/h. As the enzyme loading level increased, the sugar yield also increased for all the hydrolyzed samples. As the enzyme loading level increased, the carbohydrate conversion percentage also increased for both untreated and pretreated samples with a maximum conversion efficiency of 88.45%.