Highly efficient microwave-assisted conversion of giant reed (Arundo donax L.) carbohydrates to xylose and levulinic acid over FeCl3 catalyst in green salt solutions

A promising strategy to guarantee sustainable bio-based economy consists of the multi-stage fractionation of biomass feedstock in order to maximize sugars recovery minimizing the production of side-products. An innovative and sustainable approach is based on inorganic salt hydrolysis of lignocellulosic biomass. The present work aims to investigate and optimize the selective chemical hydrolysis of the hemicellulose and cellulose fractions of the energy crop Arundo donax L. (giant reed) to xylose and levulinic acid (LA), respectively. In order to improve the environmental and economic sustainability of this process, a microwave-assisted FeCl3 hydrolysis was implemented and the effects of hydrolysis reaction conditions were investigated and optimized. For the first step, under the best conditions, the xylose yield of 98.2 mol% was achieved. For the second step, starting from the recovered residue under optimized conditions, the LA yield of 57.6 mol% was achieved. The obtained yields in this cascade approach ensured the complete exploitation of giant reed in the perspective of Green Chemistry.