Charge storage in concentrated electrolytes gives redox flow batteries (RFBs) a unique edge in grid-scale energy storage. It also creates a unique challenge in the design of organic molecules as alternatives to expensive vanadium salts. Molecules often come in the form of organic salts, and dissolve by ionic bond breakingand ion solvation, which can hardly be interpreted by "like dissolves like." Here we use anthraquinone sulfonate salts as a model system to investigate factors underlying their aqueous solubility. We synthesize fifteen salts, measure their solubilities with UV–vis spectroscopy, and find that the solubility of the same quinone could change by three orders of magnitude with a change in its counter-cation. The same impact can come from the position and number of the sulfonate groups. We explain the results with the differences in the ion solvation energy and the lattice energy, the latter of which is corroborated by single-crystal X-ray diffraction. We also derive a simple method to semi-quantitatively predict the solubility of a quinone sulfonate salt based on that of a common sulfate salt. The work provides a physical-chemical base for understanding the solubilities of organic salts for the design of high capacity electrolytes for aqueous flow batteries.
Safflower seed oil (SSO) is suitable for nutritional and pharmacological applications due to its high content of linoleic acid and polyphenols. The study aims to investigate the quality of SSO extracted using different extraction methods. In this study, solvent extraction (SE), cold pressing (CP), hot pressing (HP), and subcritical fluid extraction (SFE) by dimethyl ether (SDE), n- propane (SPE), and n -butane (SBE) were used to extract oil from SSO. The physicochemical indexes, bioactive compounds, and oxidative stability of SSO were analyzed and compared. In all samples, the main fatty acid found was linoleic acid, ranging from 76.1% to 79.49% of total fatty acids. SE dramatically improved phytosterol content (up to 311.8 mg/100 g) and yield (up to 23.1%) in SSO. The SFE oils had a higher oxidation induction time (4.28–4.38 h) and α-tocopherol content (580.1–643.7 mg/kg) than other oils (0.76–3.22 h and 451.5–511.7 mg/kg, respectively). In SSO samples, phenolics were particularly abundant in SDE oils. Trachelogenin was the most abundant in all samples. Compared to all the other oils, SFE oils had better oxidative stability, with almost the highest yield, and had higher linoleic acid content, phytosterols, and tocopherols. SFE is a promising processing technology in nutrient-rich SSO.