Viscosities and Carbon Dioxide Solubilities of Guanidine Carbonate and Malic Acid-Based Eutectic Solvents

Abstract

Carbon capture and storage (CCS) is one of the technologies needed to reduce anthropogenic emissions of CO 2 in the atmosphere. Protic ionic liquids (PILs) are potential nonaqueous solvents that can combine the benefits of ionic liquids (ILs) and deep eutectic solvents (DESs) to make the carbon capture process more sustainable. In the present study, the viscosities of six eutectic-based solvents have been measured within a temperature range of 303.2−330.2 K and have been modeled using a Vogel−Fulcher− Tammann (VFT)-type equation. The results showed that guanidium malate-based eutectic solvents have significantly lower viscosities than most other deep eutectic solvents. Additionally, CO 2 solubilities in three different guanidium-based eutectic solvents have been measured within a temperature range of 313.2−333.2 K and pressures of up to 200 kPa. Henry's law constants of CO 2 in pure solvents were obtained by modeling the solubility in mixed (aqueous) solvents. The values obtained for Henry's law constants of CO 2 in the studied guanidium-based eutectic solvents were found to lie within a range of 1.3−24 MPa. The values of the Gibbs free energy and the dissolution enthalpy and entropy showed that the CO 2 absorption is exothermic, and after CO 2 absorption, the entropy of the systems decreased.

Densities, Viscosities, and Electrical Conductivities of Pure Anhydrous Reline and Its Mixtures with Water in the Temperature Range (293.15 to 338.15) K

“…Nevertheless, deviations of their η(T) values increase systematically from 100δ = 4.9 at 303.15 K to 26 at 353.15 K. What refs 41, 54, 55, 59, and 60 have in common is the use of rotational rheometers and it is interesting to note that the η(T) values of Dietz et al, 55 as well as the data of Barzinjy and Zankana 60 obtained with such an instrument run essentially parallel, whereas the QMC data of the latter group and values of Du et al 59 are roughly parallel to the present η(T) (Figure S5). Why the results of Troter et al 41 and Mirza et al 54 do not follow the trend of the other rheometer measurements is unclear.…”

“…The second striking feature of Figures 4 and S5 is the very different temperature dependence of some of the literature data compared to the present η(T). 41,54,55,59,60 While the values of Troter et al 41 exhibit a larger variation, those of Mirza et al, 54 Dietz et al, 55 Du et al, 59 and Barzinjy and Zankana 60 have a gentler slope (Figure S5). A possible reason for these discrepancies might be the used viscometers [all five groups applied rotational rheometers, ref 60 additionally a quartz crystal microbalance (QCM)] and the associated measurement protocol.…”

“…Figure shows the data for the pure DES, together with literature values obtained with rolling ball ,,, and Ubbelohde viscometers. Results obtained with other types of instruments ,,,,− are displayed in Figure S5.…”

“…References , , , and did not provide information on instrument calibration. However, the equipment used by Dietz et al .…”

Efficient Recovery of End-of-Life NdFeB Permanent Magnets by Selective Leaching with Deep Eutectic Solvents

“…According to this point, we prepared several novel DESs based on guanidine to establish a selective leaching process for the recovery of a NdFeB permanent magnet, aiming to achieve a green recycle process for this critical material. Only few guanidine-based DESs were reported before, and none of them was applied in the separation of metals. − Criteria such as glass transition temperature, decomposition temperature, viscosity, solubility, and separation ratio were adopted to choose proper DESs to recover Nd. Among these nine DESs, GUC–LAC has low viscosity, low glass transition temperature, and high selectivity to dissolve Nd compared to Fe.…”