Estimation of Hansen solubility parameters with regularized regression for biomass conversion products: An application of adaptable group contribution

Extraction and Separation of Natural Products from Microalgae and Other Natural Sources Using Liquefied Dimethyl Ether, a Green Solvent: A Review

Microalgae are a sustainable source for the production of biofuels and bioactive compounds. This review discusses significant research on innovative extraction techniques using dimethyl ether (DME) as a green subcritical fluid. DME, which is characterized by its low boiling point and safety as an organic solvent, exhibits remarkable properties that enable high extraction rates of various active compounds, including lipids and bioactive compounds, from high-water-content microalgae without the need for drying. In this review, the superiority of liquefied DME extraction technology for microalgae over conventional methods is discussed in detail. In addition, we elucidate the extraction mechanism of this technology and address its safety for human health and the environment. This review also covers aspects related to extraction equipment, various applications of different extraction processes, and the estimation and trend analysis of the Hansen solubility parameters. In addition, we anticipate a promising trajectory for the expansion of this technology for the extraction of various resources.

Experimental and theoretical estimation of the Hansen solubility parameters of paramylon esters based on the degrees of substitution and chain lengths of their acyl groups

Paramylon is a natural hydrophilic polysaccharide produced in the pyrenoids of euglenoids, and esterification may render paramylon hydrophobic. Esterification imparts not only thermoplasticity, but also potential compatibilities with other polymer resins and fillers. However, the dependence of the compatibility on the structure of the polymer ester has not yet been systematically studied. To estimate the affinities between paramylon esters and hydrophobic organic solvents/resins, the dependences of their Hansen solubility parameters, which are association indices, on the degrees of substitution and chain lengths of the ester groups were investigated. Experimental and theoretical investigations were conducted using the dissolution and Fedors methods, respectively. Esterification decreased the solubility parameter from 49 (paramylon) to approximately 18 MPa1/2 (paramylon esters), indicating that the potential affinities of paramylon esters for hydrophobic organic solvents/polymers increased. A multiple regression analysis was also performed to investigate the effects of acyl chain length and degree of substitution with acyl groups on the solubility parameter. The solubility parameters of the paramylon derivatives were continuously variable from hydrophilic to -phobic. Hence, esterification with various acyl groups may control the hydrophobicities of paramylon esters, enhancing their miscibilities with various hydrophobic organic solvents and resins.