Girma Gonfa

Effect of imidazolium-based ionic liquids on bacterial growth inhibition investigated via experimental and QSAR modelling studies

Tuning the characteristics of solvents to fit industrial requirements has currently become a major interest in both academic and industrial communities, notably in the field of room temperature ionic liquids (RTILs), which are considered one of the most promising green alternatives to molecular organic solvents. In this work, several sets of imidazolium-based ionic liquids were synthesized, and their toxicities were assessed towards four human pathogens bacteria to investigate how tunability can affect this characteristic. Additionally, the toxicity of particular RTILs bearing an amino acid anion was introduced in this work. EC50 values (50% effective concentration) were established, and significant variations were observed; although all studied ILs displayed an imidazolium moiety, the toxicity values were found to vary between 0.05 mM for the most toxic to 85.57 mM for the least toxic. Linear quantitative structure activity relationship models were then developed using the charge density distribution (σ-profiles) as molecular descriptors, which can yield accuracies as high as 95%.

Benzene and Cyclohexane Separation Using 1-Propanenitrile-3-butylimidazolium Dicyanamide Ionic Liquid

Cyclohexane is mainly produced by catalytic hydrogenation of benzene, and the separation of unreacted benzene is very important process. However, the separation of benzene and cyclohexane mixture is one of the difficult separation processes in petrochemical industry. Presently, extractive distillation is commercially used to separate benzene and cyclohexane using molecular solvents. However, the current process suffers from process complexity and high-energy consumption. In this work, new ionic liquid, 1-propanenitrile-3-butylimidazolium dicyanamide was synthesized and applied for separation benzene and cyclohexane mixture. Some of the thermophysical properties of the ionic liquid were measured. The vapour- liquid equilibrium and relative volatility of the components were determined. The ionic liquid breaks the azeotropic mixture and increased the relative volatility of cyclohexane to benzene.

Separation of Benzene and Cyclohexane with Mixed Solvent Using Extractive Distillation

Isothermal Vapour-liquid equilibrium for cyclohexane (1) + benzene (2) binary system, cyclohexane (1) + benzene (2) dimethylformamide (3) ternary system and cyclohexane (1) + benzene (2) dimethylformamide (3) + cosolvent (4) quaternary systems were obtained. The effects of cosolvents (diethyl glycol, dimethylsulfoxide, N-methylformamide) on the performance of dimethylformamide in benzene-cyclohexane separation were studied. The result shows the selected cosolvents suppress the effectiveness of dimethylformamide. The result also shows that the ratio of cosolvents to dimethylformamide affects the separation factor.

Volumetric properties of binary mixtures of benzene with cyano-based ionic liquids

The objective of this study is to investigate the volumetric properties of the binary mixtures comprised benzene and two ionic liquids, 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and 1-butyl-3-methyl- imidazolium dicyanamide ([BMIM][N(CN)2](. Densities (ρ) and viscosities (μ) of the binary mixtures were measured over a temperature range of 293.15 to 323.15 K and at atmospheric pressure. Excess molar volumes and viscosity deviations were calculated from the experimental densities and viscosities values. The volumetric properties of the mixtures were changed significantly with the change of compositions and temperatures. It was also found that the value of excess molar volume and viscosity deviations were negative (-ve) over the entire range of compositions. The results have been interpreted in terms of molecular interactions of ILs and benzene.

Ionic liquid as a potential solvent for preparation of collagen-alginate-hydroxyapatite beads as bone filler

Abstract In this study, collagen/alginate/hydroxyapatite beads having different proportions were prepared as bone fillers for the restoration of osteological defects. Ionic liquid was used to dissolve the collagen and subsequently the solution was mixed with sodium alginate solution. Hydroxyapatite was added in different proportions, with the rationale to enhance mechanical as well as biological properties. The prepared solutions were given characteristic bead shapes by dropwise addition into calcium chloride solution. The prepared beads were characterized using FTIR, XRD, TGA and SEM analysis. Microhardness testing was used to evaluate the mechanical properties. The prepared beads were investigated for water adsorption behavior to ascertain its ability for body fluid uptake and adjusted accordingly to the bone cavity. Drug loading and subsequently the antibacterial activity was investigated for the prepared beads. The biocompatibility was assessed using the hemolysis testing and cell proliferation assay. The prepared collagen-alginate-HA beads, having biocompatibility and good mechanical properties, have showed an option of promising biologically active bone fillers for bone regeneration.

Development of collagen/PVA composites patches for osteochondral defects using a green processing of ionic liquid

Abstract Osteochondral defects are still a big challenge for the surgeons because of good biocompatibility and higher mechanical strength requiring issues of the implants. In this study, different concentrations of collagen (dissolved in ionic liquid) up to 60% were blended with polyvinyl alcohol to prepare hydrogels of good mechanical strength, with the best biocompatibility and excellent fluid uptake ability. Ionic liquid was used as a green solvent for dissolution of collagen at a higher concentration as compared to other normal solvents. The prepared hydrogels were characterized with Fourier transform infrared spectroscopy (FTIR) which showed the characteristic peaks assigned to collagen and PVA. The surface morphology was investigated using scanning electron microscopy (SEM) which revealed homogeneity of the composite patches. Thermal gravimetric analysis (TGA) performed for samples show good thermal stabilities. Fluid uptake ability showed the massive uptake of fluid by the hydrogels. Biocompatibility was tested using hemolysis and MTT assay. Electrodynamic fatigue testing system was used for evaluating the mechanical properties and measured the tensile strength in the range of 2.4 to 8.5 MPa. The prepared osteochondral patches show good biocompatibility and mechanical properties. Graphical Abstract

Benzene and cyclohexane separation using 1-butyl-3-methylimidazolium thiocyanate

Cyclohexane is mainly produced by catalytic hydrogenation of benzene. Removal of unreacted benzene from the product stream is very important in this process. However, due to their close boiling points and azeotrope formation, it is very difficult to separate cyclohexane and benzene by conventional distillation. Currently, special separation processes such as processes extractive distillation is commercially used for this separation. However, this extractive distillation suffers from process complexity and higher energy consumption due to their low extractive selectivity of molecular entrainers used. The aim of the present work is to investigate the applicability of ionic liquids as entrainer in extractive distillation of benzene and cyclohexane mixture. In this study, we investigated 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) ionic liquid for separation of benzene and cyclohexane by measuring the Vapor Liquid Equilibrium data of the two components in the presence of the ionic liquid. As green and potential environmentally friendly solvents, ionic liquids have attracted increasing attention as alternative conventional entrainers in extractive distillation. Isothermal Vapor Liquid Equilibrium for the benzene + cyclohexane + [BMIM][SCN] ternary system was obtained at 353.15 K using a Head Space Gas Chromatography. The addition of [BMIM][SCN] breaks the benzene-cyclohexane azeotrope and increased the relative volatility cyclohexane to benzene in the mixture. The effect of [BMIM][SCN] on the relative volatility cyclohexane to benzene was studied at various benzene and cyclohexane compositions and solvent to feed ratios. The performance of [BMIM][SCN] was compared with typical conventional solvents, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The results show that the relative volatility of cyclohexane to benzene in the presence of [BMIM][SCN] is higher compared that of DMSO and DMF.