Characterization and Valorization of Humins Produced by HMF Degradation in Ionic Liquids: A Valuable Carbonaceous Material for Antimony Removal

Abstract

The processing of biomass in ionic liquids has demonstrated many benefits compared to organic solvents. This includes the maximization of 5-hydroxymethylfurfural (HMF) yield from sugars through the suppression of byproducts, such as formic acid and levulinic acid. Inefficiencies still exist due to the low stability of HMF at high temperature, leading to side reactions which ultimately result in the undesirable formation of humins. Valorization of this polymeric side product is thus needed to improve the economics of the biorefinery and could lead to humins being viewed as valuable materials for various applications. However, a much better understanding is needed of how humins form from HMF in the various ionic liquids proposed for the biorefinery. In this contribution, humin formation is probed by a range of analytical techniques, including FT-IR, SEM, solid state 13 C NMR, MS, GPC and XPS. This reveals that the structure and morphology of the humins formed does not resemble those reported in the literature and the material displays a number of unique aspects. The hydrogen bonding proprieties of the ionic liquids employed exert a strong influence on the chemical functionality of the humins and this is used to demonstrate their potential as functional materials. To demonstrate this, the humins produced in various ionic liquid environments are applied to metal extraction and compared with commercial activated carbon. This revealed that humins are superior for the extraction of antimony ions from waste water, showing promise as an adsorbent additive for water purification.

Heterogeneous Catalysis to Drive the Waste-to-Pharma Concept: From Furanics to Active Pharmaceutical Ingredients

“…A recent report by Hallet et al discloses the use of ionic liquids (ILs) for the production of humins in view of applications as valuable carbonaceous materials for antimony removal [14]. Additionally, we recently reported a plausible structure for humins obtained via several hydro/oxy-deconstruction strategies [15], following previous reports on structural characterisation of humins [8,14,[16][17][18].…”

“…A recent report by Hallet et al discloses the use of ionic liquids (ILs) for the production of humins in view of applications as valuable carbonaceous materials for antimony removal [14]. Additionally, we recently reported a plausible structure for humins obtained via several hydro/oxy-deconstruction strategies [15], following previous reports on structural characterisation of humins [8,14,[16][17][18]. New and alternative ways to synthesize APIs are largely needed in the EU due to their generally complex synthetic processes (typically 6-10 synthetic steps) and multiple rounds of quenching, separation and purification [19].…”

“…With the primary aim of valorising biorefinery side streams to improve the bio-based economy, innovative potential applications for humins as renewable raw materials have been identified mainly in catalysis, water purification, matrix of impregnation materials, CO 2 sequestration and energy storage [6,10,11], with very few reports to date on the valorisation of humins towards valuable chemicals production [12,13]. A recent report by Hallet et al discloses the use of ionic liquids (ILs) for the production of humins in view of applications as valuable carbonaceous materials for antimony removal [14]. Additionally, we recently reported a plausible structure for humins obtained via several hydro/oxy-deconstruction strategies [15], following previous reports on structural characterisation of humins [8,14,[16][17][18].…”

From sugars to FDCA: a techno-economic assessment using a design concept based on solvent selection and carbon dioxide emissions

“…The solvent is the main component in the transformation of sugars into FDCA since it influences the formation of side products 100 and impacts the technoeconomic feasibility of the process. For safety reasons, flammability, toxicity, stability and biodegradability need to be considered.…”

Production of 5-hydroxymethylfurfural from Japanese cedar (Cryptomeria japonica) in an ionic liquid, 1-methylimidazolium hydrogen sulfate

“…Recently, there is a study in which the reaction that produces humin from 5-HMF is not regarded as a side reaction, but is positively used to produce humin. The humin produced was revealed to show the metal ion adsorption capacity 39 .…”