No abstract

AbstractThis study provides a complete evaluation of a sustainable zero-waste process for the recovery of added value biomaterials from the abundant shrimp shell biomass waste using natural deep eutectic solvents (NADES). The process parameters for the fractionation of α-chitin, minerals and protein was followed using on-line measurements. Furthermore, the quantitative analysis of isolated chitin, minerals and solvent waste streams were examined. The dominant fractionation mechanisms are explained through the analysis of the liquid and solid fractions. Four of the most promising, and commercially available, NADES consisting on mixtures of Choline Chloride-Lactic Acid (CCLA), Choline Chloride-Malonic Acid (CCMA), Choline Chloride-Urea (CCUR) and Choline Chloride-Citric Acid (CCCA), were tested. The highest chitin extraction yield obtained was < 90% using CCLA, leading to purity higher than 98%. Moreover, it is possible to recycle this particular NADES several times, while having no loss in the shrimp shell fractionation capability.

No abstract

No abstract

Background: 2,5-Furandicarboxylic acid (FDCA) is one of the top biomass-derived value-added chemicals. It can be produced from fructose and other C6 sugars via formation of 5-hydroxymethilfurfural (HMF) intermediate. Most of the chemical methods for FDCA production require harsh conditions, thus as an environmentally friendly alternative, an enzymatic conversion process can be applied. Results: Commercially available horseradish peroxidase (HRP) and lignin peroxidase (LPO), alcohol (AO) and galactose oxidase (GO), catalase (CAT) and laccase (LAC) were tested against HMF, 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furoic acid (HMFA) and 5-formyl-2-furoic acid (FFA). Enzyme concentrations were determined based on the number of available active sites and reactions performed at atmospheric oxygen pressure. AO, GO, HRP and LPO were active against HMF, where LPO and HRP produced 0.6 and 0.7% of HMFA, and GO and AO produced 25.5 and 5.1% DFF, respectively. Most of the enzymes had only mild (3.2% yield or less) or no activity against DFF, HMFA and FFA, with only AO having a slightly higher activity against FFA with an FDCA yield of 11.6%. An effect of substrate concentration was measured only for AO, where 20 mM HMF resulted in 19.5% DFF and 5 mM HMF in 39.9% DFF, with a K m value of 14 mM. Some multi-enzyme reactions were also tested and the combination of AO and CAT proved most effective in converting over 97% HMF to DFF in 72 h. Conclusions: Our study aimed at understanding the mechanism of conversion of bio-based HMF to FDCA by different selected enzymes. By understanding the reaction pathway, as well as substrate specificity and the effect of substrate concentration, we would be able to better optimize this process and obtain the best product yields in the future.