Cellulose fibres from soybean hulls: efficiency and sustainability of different isolation methods

Biopolymers are becoming more and more employed in several field and the studies for innovative application are widespread. However, the use of virgin crops for their extraction is being overcome and the choice increasingly falls on agro-industrial residues which are thus valorised rather than simply managed as waste. Such residues often consist of lignocellulosic biomass which mainly contains cellulose, hemicellulose and lignin whose fractionation can be achieved through different strategies 1. Traditional extraction method usually employed multi step processes in strong acidic or alkaline conditions to promote the hydrolysis and allow components’ isolation 2. At the same time, alternative methodologies have been developed. Among them microwave assisted subcritical water extraction (MASWE) represent an interesting option since the extraction occurs in water, in more efficient heating conditions and in less time 3. In this research work we isolated fibrous cellulose from soybean hulls, one of the most abundant by-products of soybean crushing, through both multi step hydrolysis and MASWE followed by an alkaline treatment. Processes and resulting cellulose have been compared to select the best extraction option in term of selectivity, yield, final product quality, process efficiency and sustainability.