Combined Effects of Ionic Liquid and Tungsten-Halogen Radiation on Heterogeneous Hydrolysis Kinetics of Waste Papaya Epidermis for Production of Total Reducing Sugar

This article reports on optimization and kinetic modeling of Amberlyst-36 heterogeneous catalytic hydrolysis of papaya (Carica Papaya) epidermis (PE) in conjunction with ionic liquid (1-butyl-3-methylimidazolium chloride, [BMIM]Cl) for total reducing sugar (TRS) production. The intensification effects in presence of tungsten-halogen radiator (THR) on sequential pretreatment and hydrolysis have been optimized. In pretreatment and hydrolysis, the optimized factors were 70 and 80 degrees C reactor temperature, 20 and 10min batch time, water to PE ratio (w/w) of 5 and 20 respectively. An optimum 2.5 (w/w) NH4OH loading in pretreatment while 7.5wt% catalyst concentration and 20 (w/w) [BMIM]Cl loading in hydrolysis using the tungsten-halogen radiated reactor (THRR) yielded maximum 89.02mol% TRS which was significantly greater than that obtained (37.41mol%) through the conventionally heated reactor (CHR). Eley-Rideal mechanism best fitted the hydrolysis kinetics while pseudo-homogeneous model could best represent pretreatment kinetics. Remarkably, the larger activation energy (69.02 kJ/mol) in CHR in comparison with THRR evidently established the greater energy-efficiency of the THRR system. The evaluated kinetic parameters can be useful for reactor design and scale-up studies. The developed energy-efficient, green hydrolysis for optimum TRS synthesis from papaya epidermis also provides sustainable valorization of similar lignocellulosic biomass waste. [GRAPHICS] .