engleski

Viscosity and pH determination of choline chloride based deep eutectic solvents containing amides

Given the use of large amounts of volatile and flammable organic solvents in industry, rapid development of green and sustainable technologies, as well as environmentally friendly solvents is required. Deep eutectic solvents (DESs) are a promising alternative to traditional solvents due to their suitable characteristics such as non- toxicity, thermal stability, easy preparation, biodegradability and price. DESs are generally based on mixtures of cheap and available components, nontoxic quaternary ammonium salts (usually choline chloride) with natural products (amides, sugars, alcohols, sugar alcohols, polyols and organic acids) as HBD. Since there is a possibility of tailoring their physicochemical properties making them appropriate for use in different processes, it is important to characterize the solvents well, especially physicochemical properties. For the measurement of physicochemical properties (viscosity and pH), five choline chloride based solvents with different urea derivatives and acetamide were prepared and characterized. The effects of water addition and temperature on these physicochemical properties were also evaluated. The measured physicochemical properties were provided in temperature range from 30 to 80 °C with different water contents in range 10-50 % (v/v). The high viscosities of DESs can present a problem, especially in extraction and energy consumption needed for stirring and pumping, but luckily, the viscosity can be easily adjusted by obtaining higher temperatures or adding appropriate amount of water. For the DESs used in this study, the viscosity decreased in the following order: choline chloride:1, 3 dimethlyurea (1:2)>choline chloride:thiourea (1:2)>choline chloride:acetamide (1:2)>choline chloride:urea (1:2)>choline chloride: N-methlyurea (1:3). Increase of temperature and water content of DESs is followed by pH decreasing in all DESs except solvent with thiourea. pH values were in the range 9.30 – 7.20, 9.13 – 6.87, 7.59 – 5.08, 4.47 – 5.81 and 8.23 – 6.70 for N-methylurea, urea, acetamide, thiourea and 1, 3-dimethyurea, respectively.

deep eutectic solvents ; choline chloride ; viscosity ; pH

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