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The management of grape pomace (GP), the main winery solid residue, is presently supported by government subsidies, promoting the energetically expensive recovery of ethanol by distillation. This work proposes and assesses a novel sustainable alternative GP valorisation strategy: chain elongation fermentation. Besides, the proof-of-concept of a multipurpose cascading scheme is presented based on experimental data for each step on the laboratory scale. The new cascading biorefinery scheme includes: (1) the ethanol upgrade into highly concentrated (ca. 900 g L−1) n-hexanoic acid (C6) by anaerobic acidogenic fermentation and a simple downstream; the exploitation of the obtained C6 as (2) a reagent for obtaining an ester-alcohol mixture as well as (3) a substrate for the production of medium chain length polyhydroxylalkanoates (mcl-PHAs), and (4) the complementary biomethanization of the solids leftovers from the acidogenic step. Specifically, the identified fermentation conditions (pH 7, 37 °C and P > Patm) allowed obtaining the highest C6 titer (22 g L−1) and productivity (6.2 g L−1 d−1) ever achieved from non pre-treated biowaste and without the need of either exogenus ethanol or methanization inhibitor or expensive in-line extraction methods. Such titer, allowed employing a cheap easy-direct C6 downstream leading to 54% C6 recovery (87% purity) at potentially competitive overall costs. Although a preliminary assessment showed that this partial valorisation could be economically sustainable in itself for GP-management, the exploitation of the highly concentrated GP-derived C6 was demonstrated for the first time. Heterogenous catalytic hydrogenation (180 °C and 115 bar), with pre-reduced commercial catalyst Re/C 5 wt%, allowed the conversion of the obtained C6 into a mixture of 1-hexanol and hexyl-hexanoate (molar yield of 75%), which represents a promising blendstock for both diesel and biodiesel fuels. On the other hand, a fed-batch culture system, carried out on a bench-top bioreactor, allowed obtaining 60% PHA content with a yield of 0.30 g g−1. The recovered sticky bioelastomer was mainly composed of 3-hydroxyhexanoate (90%). Complementarily, ca. 200 N-L kgVS−1 of biomethane was obtained from GP leftover solids. [ABSTRACT FROM AUTHOR]

Lignin is the most abundant renewable source of phenolic compounds with great application potential in renewable materials, biofuels and platform chemicals. The current technology for producing cellulose-rich fibers co-produces heterogeneous lignin, which includes an untapped source of monomeric phenolics. One such monomer also happens to be the main monomer in soft wood lignin biosynthesis, namely coniferyl alcohol. Herein, we investigate the potential of coniferyl alcohol as a platform monomer for the biomimetic production of tailored functionalized oligolignols with desirable properties for material synthesis. Accordingly, a bifunctional molecule with at least one carboxyl-ended functionality is included with coniferyl alcohol in biomimetic lignin synthesis to, in one pot, produce a functionalized lignin. The functionalization mechanism is a nucleophilic addition reaction to the quinone methide intermediate of lignin polymerization. The solvent system applied was pure water or 50% aqueous acetone. Several bi-functional molecules differing in the second functionality were successfully inserted in the lignin demonstrating the platform component of this work. Detailed characterization was performed by a combination of NMR techniques which include 1H NMR, COSY-90, 31P NMR, 13C NMR, 13C APT, HSQC, HMBC and HSQC TOCSY. Excellent selectivity towards benzylic carbon and a high functionalization degree were noted. The structure of lignin was tailored through the solvent system choice, with 50% aqueous acetone producing a skeletal structure favorable for a high degree of functionalization. Finally, material concepts are demonstrated using classical thiol–ene- and Diels–Alder-chemistries to show the potential for the thermoset and thermoplastic concepts, respectively. The functionalization concept presents unprecedented opportunities for the green production of lignin-based recyclable biomaterials. [ABSTRACT FROM AUTHOR]

Aerogel microspheres of chitosan, an abundant biopolymer obtained from marine crustaceans, have been successfully applied to catalyze the asymmetric aldol reaction in water, providing the products in high yields and with good stereoselectivity (up to 93% ee) and recyclability (up to 4 runs). Yields were favourably affected by additives such as DNP and stearic acid. [ABSTRACT FROM AUTHOR]