Organosolv process for deconstruction of highly recalcitrant cotton stalks

Burning crop residues in a cotton fields adds to environmental pollution and it demands a sustainable solution. As an alternative to burning, cotton biomass can be fractionated into sugars which would not only mitigate the pollution concern but also bring value addition. Here, we propose a process for deconstruction of the highly recalcitrant cotton stalk using a combination of organic and mineral acid fractionation. It includes treatment with formic acid (67 wt. %) at a solid to liquid ratio of 1:4 for 30 min at 130°C. Subsequent treatment with 2% (w/w) nitric acid and de-esterification with 0.5 % (w/v) sodium carbonate resulted in delignification of about 89.01%. The enzymatic hydrolysis using 25 FPU of Cellic Ctec3 at a biomass load of 5% (w/v) gave a glucan yield of 68% in 48 h. This is one of the few studies on deconstruction of a highly recalcitrant biomass with high lignin content.