Determination of the best conditions of physical hydrolysis by power ultrasound in agroindustrial wastes

Abstract

Considerable resource amounts have being invested in developing innovative technologies appropriated for exploiting sub-products or residues from the agro- industrial sector aiming production of second generation ethanol. One of these technologies is the power ultrasound (US) that has being tested in areas such as pre-treatment of cellulosic material and as a combined method to improving reaction rates in fermentative processes. The present proposal has the main objective of studying the power ultrasound application on the pre-treatment of lingo-cellulosic material from agro-industrial residues (orange bagasse, mango peels, passion fruit rinds and peanut shells). The residues will be firstly chemically characterized and the effects of power ultrasound on the respective lingo-cellulosic material will be evaluated. All the residues will be dried and, afterwards, will be dispersed at different concentrations to forming an aqueous biomass and permitting treatment with power ultrasound. In such a way, as a first step of the work, an evaluation of the acoustic fields in the different samples will be carried out as a function of ultrasound power and biomass concentration employing the calorimetric method. As a complementary activity to the acoustic field determination, the specific heat and density of the residue biomasses as a function of temperature and concentration will be measured in order to obtaining higher precision in the acoustic field quantification. In the second step of the work, studies of ethanol production will be carried out with basis on the better condition of power ultrasound pre-treatment. In order to attain this objective, surface response and optimization techniques will be used, following an experimental design to determine the influence of the independent variables - biomass concentration (orange bagasse, mango peels, passion fruit rinds and peanut shells), ultrasound power, and sonication time - on the responses - total sugar (TS) and reducing sugar (RS) production. In addition, studies of ethanol production will be carried out based on the better conditions resulting from the ultrasound pre-treatment optimization step. As a result it is intended to obtain a destructuring effect on the cellular walls of the lingo-cellulosic material as the biomass is exposed to higher ultrasound power, increasing the efficiency in the production of total sugar (TA) and reducing sugar (RS) for future ethanol production. (AU)