Physicochemical properties of potassium carbonate and glycerol mixtures at different molar ratios and temperature

This study was conducted to explore the development of Deep Eutectic Solvents (DES) based on a mixture of Potassium Carbonate and Glycerol as an alternative to conventional organic solvents, which are hazardous, non-biodegradable, and release volatile organic compounds (VOCs). Conventional solvents face issues such as limited solubility for ionic compounds and pose serious environmental and health risks. Therefore, DES is proposed as a more environmentally friendly and safer solution. The objective of this study is to identify the optimum molar ratio and evaluate the effect of temperature on the physicochemical properties of the potassium carbonate-glycerol mixture, namely pH, density, viscosity, and ionic conductivity. In this study, Potassium Carbonate and Glycerol were mixed at molar ratios of 1:10 and 1:16 and stirred at 50°C until a homogeneous solution was formed. The mixtures were analyzed within a temperature range of 30°C to 70°C.
The tests conducted included pH measurement using the Hanna Hi2020 pH meter, hydrogen bonding using FTIR, density using the Attention Force Tensiometer, viscosity using a rotational viscometer, and ionic conductivity using the Eutech CON 2700 conductivity meter. The results showed that both molar ratios of 1:10 and 1:16 formed stable DES solutions. The FTIR spectra confirmed the presence of hydrogen bonding between Glycerol (hydrogen bond donor) and carbonate ions (hydrogen bond acceptor). The pH values for both mixtures remained consistent (~11.5), indicating strong chemical stability. Density and viscosity decreased with increasing temperature due to reduced intermolecular forces, while ionic conductivity increased with temperature, reaching 33.80 mS/cm at 70°C for the 1:10 ratio. The 1:10 ratio demonstrated higher ionic conductivity and thermal stability, while the 1:16 ratio was more fluid and suitable for applications requiring low viscosity. In conclusion, DES based on Potassium Carbonate and Glycerol has potential as a tunable green solvent, suitable for applications such as CO₂ absorption, catalysis, and electrochemical systems. This study contributes to the development of sustainable solvents that are environmentally friendly and safer, aligning with green chemistry principles for research and industrial use.