Search

To develop a greener method to separate phenols from oils, four kinds of halogen-free zwitterions, including 1-(propyl-3-sulfonate)-triethylaminium (TEA-PS), 1-(propyl-3-sulfonate)-tripropylaminium (TPA-PS), 1-(butyl-4-sulfonate)-triethylaminium (TEA-BS) and 1-(butyl-4-sulfonate)-tripropylaminium (TPA-BS), were designed and synthesized to separate phenols from model oils via forming deep eutectic solvents (DESs) based on the formation of hydrogen bonding between OH group on phenol and the oxygen atom on SO 3 − group of the zwitterions. The effects of time, temperature, dosage of zwitterions, initial phenol content, and structure of zwitterions were investigated. The results show that the extraction process can reach equilibrium within 2 min and the extraction efficiency is not sensitive to temperature. The zwitterions separate well phenol from model oils at room temperature, and the minimum phenol contents follow the order: TEA-PS > TPA-PS > TEA-BS > TPA-BS. The minimum phenol content and the maximum extraction efficiency at 25 °C can reach 4.8 g dm −3 and 98.6%, respectively, by using TPA-BS. All the maximum extraction efficiency can be obtained with n zwitterions : n phenol of less than 0.4, which greatly reduces the dosages of extractants. Importantly, these zwitterions can avoid the introduction of halide ion, which can seriously corrode the process equipment. All these zwitterions can be easily regenerated by an anti-solvent method without an obvious mass loss and a decrease in phenol extraction efficiency. Lastly, the extraction mechanism was studied with FT-IR and the freezing points of DESs indicate that the DESs are formed through hydrogen bonding. [ABSTRACT FROM AUTHOR]

The separation of phenolic compounds from oil mixtures is widely used in the chemical industry. In this research, we found that two types of environmentally benign quaternary ammonium-based zwitterions, betaine and l -carnitine, could be used as new extractants for the separation of phenol from model oils by forming deep eutectic solvents (DESs). The effects of extraction time, temperature, mole ratio of zwitterion to phenol and initial phenol content on the efficiency of phenol separation were investigated. The results indicated that betaine and l -carnitine could form DESs with phenol, and the DESs were insoluble in model oils. Phenol in model oils could be extracted with extraction efficiencies up to 94.6% at an l -carnitine:phenol mole ratio of 0.4 (an l -carnitine:phenol mass ratio of 0.68) and 298.2 K. Phenol in DES could be recovered using an anti-solvent, and betaine and l -carnitine could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass, and they were not changed in their structures after reuse. The separation mechanism was investigated using FT-IR, which showed that betaine and l -carnitine formed DESs with phenol through hydrogen bonding. [ABSTRACT FROM AUTHOR]

Phenols are important materials for the organic chemical industry. They mainly come from coal liquefaction oil, coal tar, petroleum and biomass pyrolysis oil, making the separation of phenols from oil mixtures of great commercial value. Two zwitterionic alkaloids, betaine and L-carnitine, biodegradable and environmentally benign ionic compounds, can efficiently separate phenols from oils by forming deep eutectic solvents (DESs). In this work, the phase equilibria of two ternary systems of toluene + phenol + betaine and toluene + phenol + L-carnitine were measured at 25.0 °C, 45.0 °C and 65.0 °C under atmospheric pressure. The phase behaviors of the two ternary systems were studied, which indicated that there were three kinds of phase regions: liquid, liquid-liquid, and liquid-liquid-solid. The separation of phenol from oil mixtures occurs at the latter two phase regions. Effects of temperature, zwitterionic alkaloid type and its dosage on the phase equilibrium were investigated. With decreasing temperature, the distribution and selectivity coefficients increase. L-carnitine shows better performance in separating phenol from oils via forming DES than betaine. [ABSTRACT FROM AUTHOR]

Indole plays a significant role in the production of products such as spices, medicines, and exogenous auxins. Deep eutectic solvents (DESs) formed by indole and quaternary ammonium salts (QASs, including tetraethylammonium chloride-TEAC, tetrapropylammonium chloride-TPAC, triethylmethyl-ammonium chloride-TEMAC) were found and proposed to efficiently extract indole from model wash oil. The effects of time, temperature, mole ratio of QAS to indole and initial indole concentration on the extraction of indole were studied. The results indicate that these QASs can extract indole from wash oil with efficiencies up to 96.7% (TPAC). The extraction process can be finished within 5 min. It is also found that the ultimate concentrations are almost identical for one kind of QAS although their initial concentrations are different, and the indole concentration in model wash oil can be reduced to a very low level of 1.3 g/dm 3 (TPAC). The maximum distribution coefficients of indole are 40.8 for TEAC, 91.9 for TPAC, and 29.5 for TEMAC at the studied conditions, and the extraction ability follows the order of TPAC > TEAC > TEMAC. Moreover, QASs in DESs can be reused without obvious reduction in extraction efficiency. The extraction mechanism was studied by FT-IR, and the results indicate that there is a hydrogen bond between QAS and indole. Finally, a comparison was made between this method and other methods to verify and demonstrate its desirable properties of efficiency and environmentally friendliness. [ABSTRACT FROM AUTHOR]

In this article, dicationic ionic liquids (DILs), including N , N , N , N ′, N ′, N ′-hexaethyl-ethane-1,2-diammonium dibromide (HEDBr), N , N , N , N ′, N ′, N ′-hexaethyl-propane-1,3-diammonium dibromide (HPDBr) and N , N , N , N ′, N ′, N ′-hexaethyl-butane-1,4-diammonium dibromide (HBDBr), were designed and used to extract phenolic compounds from model oil and coal tar oil. The effects of stirring time, temperature, DIL:phenol mole ratio, and initial phenol concentration on the extraction of phenol were studied. It is found that the DIL:phenol mole ratio is only around 0.3 when the highest extraction efficiency of phenol is obtained. The extraction process completes within 5 min at room temperature, and the extraction efficiency is not dependent on temperature. Also, the ultimate phenol concentration remains constant despite the difference in initial phenol concentrations. Of these DILs, HPDBr shows the lowest ultimate phenol concentration of 3.9 g/dm 3 , and the extraction efficiency of phenol can reach as high as 97.0%. These DILs can be regenerated by anti-solvent method and reused several times without significant reduction in extraction efficiency. In addition, HPDBr was demonstrated to extract phenolic compounds from real coal tar oil, and its extraction efficiency of phenolic compounds is 92.7%. The mechanism, analyzed by FT-IR, shows that there is a hydrogen bond between phenol and DIL. [ABSTRACT FROM AUTHOR]

Forming deep eutectic solvents (DESs) by quaternary ammonium salts (QASs) and phenolic compounds to extract phenolic compounds from oil mixtures is effective. However, a small amount of neutral oil is entrained in the DESs. In this work, we proposed an anti-extraction method to remove the neutral oil entrained in DESs. Low-carbon alkanes (LCAs, including n -hexane, cyclohexane, and n -nonane) were added to model DESs to remove neutral oil. We found that the LCAs could effectively remove neutral oil entrained in the DESs. Of the three LCAs, n -hexane showed the best performance, and the removal rate of neutral oil could reach as high as 92.2%. The separation process could complete within 15 min, and the removal rate of neutral oil did not change significantly with temperature. In addition, n -hexane could effectively remove neutral oils in DESs formed by real coal tar and choline chloride. The neutral oil content in the phenolic compound product decreased to only 1.9 wt%, which greatly improves the purity of the phenolic compound product. [ABSTRACT FROM AUTHOR]

Phenolic compounds (such as phenol, cresol sand xylenol), which are basic materials for the organic chemical industry, are mainly produced from coal liquefaction oil, coal tar, petroleum, and biomass pyrolysis oil. It has been reported that the separation of phenols from oil with forming deep eutectic solvents based on quaternary ammonium salt (QAS) is an efficient and environmentally friendly method. However, the phase equilibrium of QAS + phenol + oil mixtures has not been reported in the literature. In this work, the phase equilibrium for separating phenol from model oil with 2-hydroxy- N , N , N -trimethyl-ethanaminium chloride (ChCl), N , N , N -triethyl-ethanaminium chloride (TEAC), and N , N , N -trimethyl- methanaminium chloride (TMAC) was studied. Phase equilibria of three ternary systems of toluene + phenol + QAS were measured at 25.0, 40.0 and 65.0 °C, and phase behaviors of the ternary systems were studied. Effects of temperature, type and dosage of QAS on the equilibrium were investigated. The results show that low temperatures are beneficial to extraction of phenol and the phenol removal efficiency decreases with increasing temperature. Among the QASs, TEAC has the strongest ability to separate phenol, but the concentration of toluene entrained in the DES phase is the largest. Only TMAC is dissolved in the oil phase to a small extant, which can cause the loss of extractant. ChCl not only has high phenol removal efficiency, but also causes a small concentration of toluene entrained in the DES phase, which shows that ChCl is an efficient and environmentally friendly extractant. [ABSTRACT FROM AUTHOR]

Phase equilibria of the binary systems of high pressure CO 2 + deep eutectic solvents (DESs) formed by quaternary ammonium salts (QASs, including 2-hydroxy- N , N , N -trimethyl-ethanaminium chloride, ChCl; N , N , N -trimethyl-methanaminium chloride, TMAC; and N , N , N -triethyl-ethanaminium chloride, TEAC) and phenol were measured at temperatures from 313.15 K to 333.15 K, pressures from 1.71 MPa to 13.3 MPa and mole ratios of phenol to QAS from 2.00 to 4.00. It has been found that two-phase equilibrium exists at all the studied conditions. The solubility of phenol in the CO 2 phase and the solubility of CO 2 in the DES phase at different pressures, temperatures, mole ratios of phenol to QAS have been obtained. Both the solubility of phenol in the CO 2 phase and the solubility of CO 2 in the DES phase formed by ChCl and phenol shows the largest, while those in the DES phase formed by TEAC and phenol shows the smallest. This work provides phase equilibrium data for phenol extraction and QAS regeneration. [ABSTRACT FROM AUTHOR]