Showing papers by "Vitaliy L. Budarin published in 2019"

Geminal Diol of Dihydrolevoglucosenone as a Switchable Hydrotrope: A Continuum of Green Nanostructured Solvents.

Abstract: The addition of water to dihydrolevoglucosenone (Cyrene) creates a solvent mixture with highly unusual properties and the ability to specifically and efficiently solubilize a wide range of organic compounds, notably, aspirin, ibuprofen, salicylic acid, ferulic acid, caffeine, and mandelic acid. The observed solubility enhancement (up to 100-fold) can be explained only by the existence of microenvironments mainly centered on Cyrene's geminal diol. Surprisingly, the latter acts as a reversible hydrotrope and regulates the polarity of the created complex mixture. The possibility to tune the polarity of the solvent mixture through the addition of water, and the subsequent generation of variable amounts of Cyrene's geminal diol, creates a continuum of green solvents with controllable solubilization properties. The effective presence of microheterogenieties in the Cyrene/water mixture was adequately proven by (1) Fourier transform infrared/density functional theory showing Cyrene dimerization, (2) electrospray mass-spectrometry demonstrating the existence of dimers of Cyrene's geminal diol, and (3) the variable presence of single or multiple tetramethylsilane peaks in the 1H NMR spectra of a range of Cyrene/water mixtures. The Cyrene-water solvent mixture is importantly not mutagenic, barely ecotoxic, bioderived, and endowed with tunable hydrophilic/hydrophobic properties.

Lipid production through the single-step microwave hydrolysis of macroalgae using the oleaginous yeast Metschnikowia pulcherrima

Abstract: Macroalgae (seaweeds) represent an emerging resource for food and the production of commodity and specialty chemicals. In this study, a single-step microwave process was used to depolymerise a range of macroalgae native to the United Kingdom, producing a growth medium suitable for microbial fermentation. The medium contained a range of mono- and polysaccharides as well as macro- and micronutrients that could be metabolised by the oleaginous yeast Metschnikowia pulcherrima. Among twelve macroalgae species, the brown seaweeds exhibited the highest fermentation potential, especially the kelp Saccharina latissima. Applying a portfolio of ten native M. pulcherrima strains, yeast growth kinetics, as well as production of lipids and 2-phenylethanol were examined, with productivity and growth rate being strain dependent. On the 2 L scale, 6.9 g L−1 yeast biomass – a yield of 0.14 g g−1 with respect to the supplied macroalgae – containing 37.2% (w/w) lipid was achieved through utilisation of the proteins, mono- and polysaccharides from S. latissima, with no additional enzymes. In addition, the yeast degraded a range of fermentation inhibitors released upon microwave processing at high temperatures and long holding times. As macroalgae can be cultured to food grade, this system offers a novel, potentially low-cost route to edible microbial oils as well as a renewable feedstock for oleochemicals.

A one-pot microwave-assisted NaCl–H2O/GVL solvent system for cellulose conversion to 5-hydroxymethylfurfural and saccharides with in situ separation of the products

Abstract: This work addresses a microwave-assisted, NaCl–H2O/γ-valerolactone (GVL) solvent system for the co-production of 5-hydroxymethylfurfural (HMF) and saccharides from cellulose, examining the effects of the solvent system (H2O/GVL), NaCl concentration and reaction time. Oligosaccharides and glucose were completely recovered in the aqueous phase and their yields varied between 4–67 and 0–16 wt%, respectively, while HMF was largely recovered in the organic phase, in a yield between 0 and 13 wt%. Increasing the proportion of H2O in the system promoted cellulose depolymerisation and increased the production of oligosaccharides and glucose. This latter underwent a further decomposition to yield HMF and carboxylic acids when long times were used. An increase in NaCl not only kinetically promoted cellulose decomposition, but also modified the solubility of cellulose decomposition products in the aqueous phase, thus playing a very important role on the products distribution within both phases. With a solvent system consisting of 67/33 vol% H2O/GVL, with 30 wt% NaCl at 220 °C for 18 min, it is possible to selectively convert 76% of the cellulose into a sugar-rich aqueous solution and a rich HMF organic phase. The former was made up of glucose (25%) and oligosaccharides (64%), while the later mainly comprised HMF (75%). This might help the development of new biomass pre-processing technologies, allowing the co-production of precursors for the chemical and biological industries.

Selective Microwave-Assisted Pyrolysis of Cellulose towards Levoglucosenone with Clay Catalysts

Abstract: Levoglucosenone (anhydrosugar) is one of the most promising chemical platforms derived from the pyrolysis of biomass. It is a chiral building block for pharmaceuticals as well as an intermediate in the production of solvents and polymers. Therefore, the development of cost-efficient, low-energy production methods is vital for a future sustainable biorefinery. Here, a novel, green approach to the production of levoglucosenone was developed by using a microwave (MW)-assisted pyrolysis of cellulose in the presence of readily available clays. It was shown that natural and pillared clays in the presence of MW irradiation significantly increase the yield of levoglucosenone from cellulose. Both the water content and the presence of acid centres are critical characteristics that influence the yield and distribution of catalysed products. A unique experiment was designed by using a synergetic effect between different types of catalysts, which enhanced the levoglucosenone yield to 12.3 wt % with 63 % purity.

New insights into the use of microwave technology for the hydrothermal valorisation of biomass: microwave-assisted liquefaction, decomposition and fractionation reactions

Abstract: espanolEl calentamiento asistido por micro-ondas se considera una tecnologia mas rapida, eficiente y selectiva en comparacion con otras tecnicas de calentamiento convencionales para el tratamiento hidrotermal de biomasa. Especificamente, esta tecnologia permite tanto lograr un mejor control del proceso, como el uso de menores temperaturas. Ademas, como el agua utilizada como disolvente en estos procesos es muy eficiente absorbiendo la energia emitida por las micro-ondas, la combinacion de condiciones hidrotermales junto con un calentamiento asistido por micro-ondas, resulta en una alternativa novedosa y muy interesante para el diseno y desarrollo de nuevos procesos hidrotermales. En este contexto, el presente articulo resume algunos de los avances mas recientes desarrollados en el Green Chemistry Centre of Excellence, del Departamento de Quimica de la Universidad de York (Reino Unido), (https://www.york.ac.uk/chemistry/research/green/research/ publications/) sobre el uso de la tecnologia de calentamiento por micro-ondas para la valorizacion hidrotermal de biomasa, incluyendo procesos de licuefaccion, descomposicion y fraccionamiento. Estas reacciones son de gran interes en la industria quimica y representan una contribucion sustancial en el desarrollo de nuevos procesos para el pre-tratamiento de la biomasa, contribuyendo sustancialmente al desarrollo de nuevas rutas para la valorizacion sostenible de biomasa y residuos. EnglishMicrowave heating represents a potentially faster and more efficient and selective technology for the hydrothermal treatment of biomass in comparison to conventional heating based technologies. Specifically, microwave heating allows not only achieving a better process control, but also lower temperatures to be used. Furthermore, as water is highly effective in microwave energy absorption, the combination of hydrothermal conditions together with microwave assisted heating offers an interesting new technology for the design and development of novel hydrothermal processes. Herein, this work summarises some recent advances achieved at the Green Chemistry Centre of Excellence, Chemistry Department, University of York (UK) (https://www. york.ac.uk/chemistry/research/green/research/ publications/), regarding the use of microwave technology for the valorisation of biomass under hydrothermal conditions, including microwaveassisted hydrothermal liquefaction (MA-HTL), decomposition (MA-HTD) and fractionation (MAF). These processes are very timely and the work conducted represents a step-change in biomass preprocessing technologies, helping the development of novel routes for biomass valorisation