INTEGRATING PRETREATMENT TECHNIQUES IN A “BENIGN-BY-DESIGN STRATEGY” IN THE CONTEXT OF BIOMASS VALORIZATION
In the literature, one could find single upstream technique (process) being applied to a particular biomass to obtain platform chemicals. Due to the intrinsic recalcitrance of biomass, we began by addressing the recalcitrance issue by isolating the least recalcitrant, hemicellulose from walnut shell in a form of C5 utilizing a universal solvent (H2O) and microwave. We also presented a second possibility called a lignin-first strategy, in which the most recalcitrant lignin was extracted from walnut shell using an environmentally benign solvent (deep eutectic solvent) and ball milling. To overcome particularly cellulosic recalcitrance and liberate C6 sugars, a mechanocatalytic technique was used. Bacillus coagulants was used to convert the C5 monomer to L+lactic acid (bioplastic feedstock), whilst saccharomyces cerevisiae was used to convert the C6 monomer to bioethanol. Apparently, the upstream processes were efficient at releasing monomers of sugars while producing a small amount of breakdown products such as 5-hydroxymethyl furfural and furfural. These breakdown products might readily be identified and used as feedstock for the production of biojet fuel. As a proof of concept, we attempted to synthesize 2,5-bis(2-furylmethylidene) cyclopentanone (F2Cp) and 2-(2-furylmethylidene) cyclopentanone (FCp) from commercial furfural and cyclopentanone by aldol condensation in the presence of a metal oxide catalyst. Thus, we established a closed-loop utilization of biomass (walnut shell/poplar wood) in proof-of-concept study to support a circular bioeconomy approach. This proof-of-concept study was undertaken in accordance with Anastas’s suggested twelve principles of green chemistry
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