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BACKGROUND Ionic liquids (IL) are an interesting solvent choice for specific industrial applications since physicochemical properties can be fine-tuned by modifying the substituent groups or the cation/anion pair. Hydrophobic ILs are considered green solvents and known to be good absorbents for hydrophobic organic compounds. Given their physicochemical properties an industrial application of such compounds is conceivable. Classical physicochemical properties such as density, viscosity and surface tension have a strong influence on the fluid dynamics; they were therefore measured and determined. RESULTS The density, viscosity and surface tension of 23 hydrophobic ILs were measured at room temperature. These compounds are potential candidates for the absorption and biodegradation of volatile organic compounds (VOCs) in a two-phase partitioning bioreactor. The thermal expansion coefficient, molecular volume, standard molar entropy and lattice energy were determined for each IL using empirical and semi-empirical equations based on the density values. Viscosity values were correlated by the Arrhenius equation. Then, the surface excess enthalpy and surface excess entropy were determined from the surface tension values. CONCLUSION The influence of the presence of different functional moieties (unsaturated bonding, oxygenated and cyanide) and the side chain length in the physicochemical properties of these hydrophobic ILs was discussed, since their presence affected directly the density, viscosity and surface tension. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Four silicone oils ( PolyDiMethylSiloxane, PDMS) of different viscosities, namely 5, 20, 50, and 100 mPa s were characterized to select the most suitable polymer for the biological treatment of toluene. The PDMS volatilities and the partition coefficients of toluene between air and PDMS were investigated. Toluene biodegradation tests were also carried out to assess the absence of toxicity of the considered PDMS vis-a-vis the microorganisms. RESULTS PDMS 20, 50 and 100 had negligible volatilities at 25 °C and 35 °C, whereas PDMS 5 was volatile even at 25 °C. The results indicate that the amount of VOCs emitted by PDMS increased with the temperature according to a logarithmic law. The partition coefficient of toluene between air and the four PDMS were similar (H = 2.9 Pa m3 mol−1) indicating that the affinity between toluene and PDMS was identical whatever their viscosity. Moreover, biodegradation tests allowed the conclusion that the four PDMS tested are not toxic for microorganisms. CONCLUSION PDMS 20, 50 and 100 were suitable at 25 °C for the biological treatment of toluene. Since all these PDMS were satisfactory at 25 °C, it could make sense to select the least viscous oil for use in the process, i.e. PDMS 20. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Studies on the degradation and mineralization of tetracycline by means of the electro-Fenton process are lacking in the available literature. Its relevance as a pre-treatment prior to a biological process for the removal of tetracycline was therefore examined. RESULTS Degradation followed pseudo-first-order kinetics and the optimal operating conditions were: 0.1 mmol L-1 catalyst (Fe2+) concentration, 300 mA applied current intensity and 25 mg L-1 tetracycline, leading to total degradation within only 5 min and a mineralization yield of 89 % after 6 h electrolysis. Biodegradability tests were realized with 100 mg L-1 tetracycline; BOD5/ COD ratio increased from 0.02 to 0.56 after 6 h electrolysis, showing the relevance of the electro-Fenton pre-treatment. However, to keep a significant residual organic content, 2 to 4 h electrolysis time may be more relevant, leading to BOD5/ COD ratio and mineralization yields of 0.33-0.44 and 46-72%, respectively. CONCLUSION Activated sludge cultures of pretreated and non-pretreated tetracycline solutions were carried out for 3 weeks. The overall TOC removal increased from 28% for the non-pretreated tetracycline to 68 and 86% after 2 and 4 h electrolysis, confirming the efficiency of the proposed combined process. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]