QSPR modeling of selectivity at infinite dilution of ionic liquids

PTDC/EQU-EQU/30060/2017 UIDB/50006/2020 UIDP/50006/2020The intelligent choice of extractants and entrainers can improve current mixture separation techniques allowing better efficiency and sustainability of chemical processes that are both used in industry and laboratory practice. The most promising approach is a straightforward comparison of selectivity at infinite dilution between potential candidates. However, selectivity at infinite dilution values are rarely available for most compounds so a theoretical estimation is highly desired. In this study, we suggest a Quantitative Structure–Property Relationship (QSPR) approach to the modelling of the selectivity at infinite dilution of ionic liquids. Additionally, auxiliary models were developed to overcome the potential bias from big activity coefficient at infinite dilution from the solute. Data from SelinfDB database was used as training and internal validation sets in QSPR model development. External validation was done with the data from literature. The selection of the best models was done using decision functions that aim to diminish bias in prediction of the data points associated with the underrepresented ionic liquids or extreme temperatures. The best models were used for the virtual screening for potential azeotrope breakers of aniline + n-dodecane mixture. The subject of screening was a combinatorial library of ionic liquids, created based on the previously unused combinations of cations and anions from SelinfDB and the test set extractants. Both selectivity at infinite dilution and auxiliary models show good performance in the validation. Our models’ predictions were compared to the ones of the COSMO-RS, where applicable, displaying smaller prediction error. The best ionic liquid to extract aniline from n-dodecane was suggested.publishersversionpublishe

CO 2 + Methanol + Glycerol: Multiphase behaviour

The phase behaviour of the system CO2 + methanol + glycerol has been studied at low concentrations of this tri-alcohol. The synthetic method was implemented in a visual sapphire cell. New phase diagrams were obtained at temperatures of 313.15 and 333.15 K. Different methanol/glycerol molar ratios of 113, 50 and 30 were considered and its influence on phase behaviour accounted for. Pressures were varied from 6.03 to 11.44 MPa. A specific experiment is reported, starting from an initial volume of 4 mL of liquid mixture methanol + glycerol (methanol/glycerol molar ratio 30), where, with a stepwise addition of CO2, diverse fluid phase phenomena were detected, such as VLE, Critical Point, VLLE, VLLLE, LLE and LE

Solubility of CO2 in glycerol at high pressures

The solubility of CO2 in liquid glycerol was measured at the temperatures of 353.2 K, 393.2 K and 423.2 K, and pressures up to 32 MPa. The static synthetic method was used in a variable-volume view cell. The solubility of CO2 in glycerol was enhanced by pressure increase and by temperature decrease. When compared with reported values for alcohols with the same chain length, the solubility increased in the following order: glycerol < 1,2-propylene glycol < 1-propanol < 2-propanol

Tetramethylguanidine-based gels and colloids of cellulose

Novel and stable gels of cellulose were produced. These gels are prepared at room temperature by com-bination of cellulose and tetramethylguanidine (TMG) in different ratios (1:1, 1:2, 1:3 in equivalents ofalcohol groups of cellulose per number of molecules of TMG). Detailed NMR, SEM, rheological and XRDstudies of these gels were carried out. The concentration of cellulose in the gel, temperature, frequency ofoscillation and shear rate were used as variables in order to understand the fundamentals and optimizeoperational conditions, considering their possible use as matrices for CO2capture. Cellulose recoveryfrom a specific gel was performed using ethanol as precipitating agent, leading to a lower crystallinity,which permits to consider this polymer in further studies associated to physical/chemical modificationof celluloseinfo:eu-repo/semantics/publishedVersio