Vapor–Liquid Equilibria, Excess Enthalpy, and Density of Aqueous γ‑Valerolactone Solutions.

Thermodynamic measurements were made for the binary mixture of water + γ-valerolactone (GVL) and for pure GVL to facilitate the development of the technology of lignin removal from lignocellulosic biomass (Fang, W.; Sixta, H. Advanced Biorefinery based on the Fractionation of Biomass in γ - Valerolactone and Water. ChemSusChem 2015, 8, 73−76). The density and vapor pressure of pure GVL as a function of temperature were measured and correlated for a wide range of the temperatures and pressures. Isothermal vapor–liquid equilibrium (VLE) data of the binary mixture of water + GVL were measured at 350.2 K with a static total pressure apparatus. Absence of an azeotrope was confirmed by circulation still measurements with diluted GVL solutions. Excess molar enthalpy (<i>h</i>^E) of the mixture for the whole range of mole fractions including infinite dilution was measured using a SETARAM C80 calorimeter equipped with a flow mixing cell at 322.6 and 303.2 K. The VLE and <i>h</i>^E data were used for the optimization of UNIQUAC and NRTL activity coefficient model parameters. The experimental results are compared herein with those predicted by COSMO-RS and UNIFAC-Dortmund models. The water + GVL binary mixture shows positive deviation from Raoult’s law

Microwave hydrolysis, as a sustainable approach in the processing of seaweed for protein and nanocellulose management

The nature of marine biomass is very complex for a material scientist due to the large seasonal variation in the chemical composition that makes it difficult to prepare standardized products. A systematic investigation of the interaction of microwave irradiation with seaweed from Norway and Caribbean region was performed, covering a broad temperature range (130 → 170 ◦C) and without and with addition of ℽ-valerolactone (GVL) in ratios of 1:4 and 1:2. The temperatures above 150 ◦C and without addition of GVL led to the closure of mass balances up to 90 % that includes polysaccharides, “pseudo-lignin” fraction, fatty acids, and proteins. Fucoidan and mannose represented >50 % of all detected polysaccharides in ascophyllum nodosum (AN), while aegagropila linnaei (AL) contained mostly glucose. The presence of arabinose and rhamnose in the upper surface of the cell wall hinders the glucose release during microwave treatment. The differences in the polysaccharide composition among both algae samples hindered the definition of a parameters set that can be used in microwave treatment of various seaweed species. A large fraction of protein (> 95 %) remained in the seaweed solid residue. Higher amount of protein was determined in AL, which was dominated by leucine and lysine. Another potential barrier to the application of seaweed in industry is the limited knowledge on the chemical composition of “pseudo-lignin” and extractives. The total amino acid analysis was identified as the most accurate to characterize the protein yield and composition. The results showed that microwave treatment of seaweed is indeed a viable method for producing bioactives in the temperature range 120–150 ◦C, and proteins and nanocellulose at temperatures above 170 ◦C without using GVL. The microwave temperature and seaweed type played a dominating role in the mass closure balances leading to >95 % identified compound.</p