Kinetic study of the enzymatic hydrolysis of sugarcane straw for 2G ethanol production

One of the main challenges involved in the production of second generation ethanol (2G) is obtaining high conversion rates of polysaccharides into fermentable sugars during the hydrolysis step. This way, studies for evaluating the effect of different operational conditions are necessary. The aim has been reaching yields that make the process economically feasible. In this context, the objetive of this work was to study the effect of both substrate and enzyme concentrations on the kinetics of hydrolysis of cellulose from sugarcane straw. Experiments using hydrothermally pretreated sugarcane straw (195 °C, 10 min, 200 rpm) with and without alkaline delignification (NaOH 4% w/v, 30 min., 121 °C) were carried out in shake flasks (50 °C, pH 5.0, 200 rpm). The effect of substrate concentration was studied varying solid load in the range of 2.5 to 10.0% (w_solid/v_solution), in short and long term assays. Enzyme concentration was varied from 275 to 5,000 FPU/L (corresponding to 5 to 80 FPU/g_cellulose), respectively) in order to assess the effect of the enzymatic concentration, with solid load set at 10% (w_solid/v_solution). Finally, it was possible to fit Michaelis-Menten (MM), modified MM and Chrastil models for both sets of experiments. The fitted models are able of identifying key features of the hydrolysis process. They can be applied to simulate different operating strategies of the enzymatic reactors, as well as to assess the technical and economic feasibility of the process.

Acknowledgements: Program of Human Resources from the National Agency of Petroleum (PRH-ANP), CAPES and PPG-EQ/UFSCar.