Measurement and PC-SAFT Modeling of the Solubility of Gallic Acid in Aqueous Mixtures of Deep Eutectic Solvents

Abstract

Deep eutectic solvents have appeared as potential solvents for improving the extraction of polyphenols from vegetable or fruit matrixes. Since gallic acid is abundant in these sources, it is considered as a typical standard for quantifying their total polyphenol content after extraction with solvents. However, there are no extensive studies on the solubility behavior of gallic acid in different solvents or deep eutectic solvents. Thus, in this work, the solubility of gallic acid is measured in pure water; aqueous solutions of different hydrogen bond donors such as ethylene glycol, levulinic acid, and glycerol; and aqueous mixtures of deep eutectic solvents using choline chloride as the hydrogen bond acceptor and ethylene glycol, levulinic acid, and glycerol as the hydrogen bond donors. All of the measurements were performed at 293.15, 303.15, and 313.15 K and at 101.3 kPa and were validated by comparing the solubility of gallic acid in water from the literature. Results suggest that a 50 wt % aqueous solution of deep eutectic solvent based on ethylene glycol or glycerol improves the gallic acid solubility compared with a 50 wt % aqueous solution of its corresponding hydrogen bond donor. The deep eutectic solvent containing levulinic acid acts as the best aqueous mixture for gallic acid dissolution. Nondissolved gallic acid was measured after equilibrium using powder X-ray diffraction, showing that its structure does not change upon mixing with all of the liquid mixtures. All of the solid–liquid equilibrium results were accurately modeled with perturbed-chain statistical associating fluid theory (PC-SAFT).

Assessing the Influence of Betaine-Based Natural Deep Eutectic Systems on Horseradish Peroxidase

“…Nevertheless, NADES addition causes the appearance of enzyme aggregates at high temperatures, as shown in Figure B, which have a known effect against activity due to blocking active sites. , However, water addition does not influence T unfolding of HRP (Figure S2). T unfolding values are in the range of what is reported in the literature, namely in the range between 70 and 85 °C. ,,,, In addition, protein aggregation is observed at temperatures between 80 and 85 °C in the presence of NADES as shown in Figure B and Table S7, which was not observed for the control in PBS buffer.…”

“…T unfolding values are in the range of what is reported in the literature, namely in the range between 70 and 85 °C. 19,20,22,24,25 In addition, protein aggregation is observed at temperatures between 80 and 85 °C in the presence of NADES as shown in Figure 5B and Table S7, which was not observed for the control in PBS buffer.…”

Equilibrium Solubility and Solvent Effect Study of 3-Nitrosalicylic Acid in Different Monosolvents Covering Temperatures from 278.15 to 323.15 K

“…The lower basicity (0.40) and acidity (0.19) of acetonitrile lead to a decrease in the solubility. As an organic acid, the trend of the effect of solvent descriptors on the solubility of 3-nitrosalicylic acid is almost the same as that for the solubility of gallic acid in water …”

“…As an organic acid, the trend of the effect of solvent descriptors on the solubility of 3-nitrosalicylic acid is almost the same as that for the solubility of gallic acid in water. 15 Solvent Effect Analysis. The KAT-LSER model is applied here to analyze the relative contributions of solvent properties to the obtained solubility data of 3-nitrosalicylic acid dissolved in different monosolvents at a temperature of 298.15 K. The density of 3-nitrosalicylic acid (1631.0 kg•m −3 ) is accessible in the SciFinder database.…”

“…To further extend its applications of solubility, some advanced models have been proposed in recent publications. − In this work, we select two empirical equations (Buchowski–Ksiazaczak λ h equation − and Apelblat equation − ) and two traditional activity coefficient models (Wilson model − and NRTL model − ) to correlate the 3-nitrosalicylic acid solubility in the abovementioned monosolvents. Besides, the solvent effect on 3-nitrosalicylic acid solubility is inspected by the Kamlet–Taft linear solvation energy relationships (abbreviated to KAT-LSER). − …”