Effect of Anthraquinone on Alkaline Pretreatment and Enzymatic Kinetics of Sugarcane Bagasse Saccharification: Laboratory and Pilot Scale Approach

Abstract

A laboratory (2 L) scale alkaline pretreatment with and without anthraquinone addition was performed to evaluate the influence of temperature, alkaline loading, residence time, heating and stirring system on mass yield and solubilization rates of the main components. The best conditions were scaled up to pilot scale (350 L), and enzymatic conversion of structural carbohydrates into sugars for cellulosic ethanol production was analyzed. The tested conditions were 130–170 °C, 0.5–1.5% NaOH, 30–90 min with and without 0.15% w/w of anthraquinone (AQ). The AQ addition did not lead to substantial cellulose preservation in the laboratory scale; however, in the pilot scale the AQ addition resulted in 67.4% and 28.5% of cellulose preservation for reactions at 130 °C, 1.5% NaOH, 30 min (5Pil) and 170 °C 1.5% NaOH, 30 min (7Pil) respectively in relation to those studies without addition. The most efficient heating and agitation system of pilot reactor was probably the determining factor for effective performance. Temperature also seems to have a maximal effect on pilot AQ pretreatments, where lower temperature (5 Pil-130 °C) favored the cellulose preservation in relation to experiments at 170 °C. The scale-up was successfully made and the condition 5Pil with AQ was chosen as the best one in order to produce 293 kg of glucose from 1 ton of raw sugarcane bagasse.