Solubility Enhancement of Hydrophobic Compounds in Aqueous Solutions Using Biobased Solvents as Hydrotropes

Abstract

Improving the aqueous solubility of poorly soluble hydrophobic compounds is a topic of great interest to the pharmaceutical, chemical, and food industries. The poor solubility of these compounds in water poses a challenge in developing sustainable processes for their extraction, separation, and formulation. Therefore, in this study, the use as hydrotropes of biobased solvents such as γ-valerolactone (GVL), Cyrene, ethyl lactate, and alkanediols (1,2-propanediol, 1,5-pentanediol, and 1,6-hexanediol) to improve the solubility of two model compounds (syringic acid and ferulic acid) in water is investigated. The effects of the concentration and structure of biobased solvents on the solubility of phenolic compounds in aqueous solutions at (303.2 ± 0.5) K were studied. The results showed that the aqueous solubility of the phenolic compounds studied typically increased with the log (K OW) of the hydrotrope (1,2-propanediol < Cyrene < 1,5-pentanediol < GVL < ethyl lactate < 1,6-hexanediol) and the hydrophobicity of the solute; the hydrotropic dissolution of phenolic compounds is shown to depend on both the hydrotrope and the solute. This study shows that some biobased solvents, especially GVL, are excellent hydrotropes. Their renewable nature, low price, and low toxicity make these results particularly relevant to the field of extraction and separation of bioactive compounds.

Formation of Ethanolamine-Mediated Surfactant-Free Microemulsions Using Hydrophobic Deep Eutectic Solvents

“…Ideally, solubility enhancement with hydrotrope concentration should attain a sigmoidal curve shape; however, here, all DES-based systems deviate from the sigmoidal shape perhaps because of the presence of specific interactions between ETA with DES. Similar findings have been reported in the literature earlier. − The quantitative trend in water intake depends on the structure of the constituents of the DES. The initial maximum of w o observed for (Thy: DA) lies in the ETA concentration range between 0.9 and 1.5 M; for (Men: DA), it is between 0.8 and 1.6 M; for (Lin: DA), it is between 0.5 and 1.2 M; for (Cit: DA), it is between 0.5 and 1.1 M; and for (Ger: DA), it is between 0.7 and 1.8 M.…”