Spectral Fingerprint Investigation in the near Infra-Red to Distinguish Harmful Ethylene Glycol from Isopropanol in a Microchannel

Ethylene glycol (EG) and isopropanol (ISO) are among the major toxic alcohols that pose a risk to human health. However, it is important to distinguish them, since EG is more prone to cause renal failure, and can thus be more dangerous when ingested than ISO. Analysis of alcohols such as isopropanol and ethylene glycol generally can be performed with a complex chromatographic method. Here, we present an optical method based on absorption spectroscopy, performed remotely on EG-ISO mixtures filling a microchannel. Mixtures of ethylene glycol in isopropanol at different volume concentrations were analyzed in a contactless manner in a rectangular-section glass micro-capillary provided with integrated reflectors. Fiber-coupled broadband light in the wavelength range 1.3–1.7 µm crossed the microchannel multiple times before being directed towards an optical spectrum analyzer. The induced zig-zag path increased the fluid–light interaction length and enhanced the effect of optical absorption. A sophisticated theoretical model was developed and the results of our simulations were in very good agreement with the results of the experimental spectral measurements. Moreover, from the acquired data, we retrieved a responsivity parameter, defined as power ratio at two wavelengths, that is linearly related to the EG concentration in the alcoholic mixtures.

Separation of the Mixture 2-Propanol + Water by Heterogeneous Azeotropic Distillation with Isooctane as an Entrainer

Advanced processes, which are alternatives to ordinary distillation, are essential to dehydrate azeotropic alcoholic mixtures for biofuel production. In that regard, this work focuses on the analysis of heterogeneous azeotropic distillation for the separation of a 2-propanol + water mixture in order to recover the alcohol with a sufficiently low water content. By comparing the performances of various entrainers on the basis of ternary maps, isooctane was selected for further process analysis. An advantage it poses is related to the fact that traces of it within the recovered dehydrated alcohol are highly welcome with a view to its subsequent use as a fuel. Aspen Plus® V11 software was employed for the simulation of the process, thus filling the gap existing in the literature due to the lack of studies on the process analysis of the heterogeneous azeotropic distillation of the 2-propanol + water system using isooctane as an entrainer.

Preferential Solvation of 4-Carboxyl-2, 6-Dinitrophenylazohydroxynaphthalenes in Mixed Hydroxylic Solvents

Background: The applications of a group of 4-carboxyl-2,6-dintrophenylazohydroxynaphathalenes, AZ-01 to 04, as colourants, chemosensors or synthetic intermediates have been limited by their solubility.Aim: To investigate the effect of solvent mixture composition on the solubility, solution thermodynamics and position of equilibrium processes of the dyes.Method: The UV-visible spectral patterns of the dyes in binary mixtures including Methanol:Water, Ethanol:Water, Methanol:Ethanol, Methanol:Propan-1-ol, Methanol:Propan-2-ol, Propan-1-ol:Water and Propan-2-ol:Water were acquired. The type and quantitative estimation of solute-solvent interactions at play were determined by fitting spectral patterns to solvent parameters using multilinear regression.Results: Preferential solvation was detected by the non-ideality of the plots of E12 as against the mole fractions of co-solvent in all binary mixtures. In pure solvents, the spectral shifts of AZ-01, 03 and 04, which exist predominantly in the hydrazone form, were affected by polarity of solvent milieu while solvent basicity and acidity, in that order, were the significant parameters for AZ-02. In aqueous alcoholic mixtures, solvent polarity was contributory, although to different degrees, to the observed spectral data of the four dyes. However, solvent acidity and basicity were the primary determinants of spectral shifts observed with AZ-04 and AZ-03 respectively. Spectra-structure relationships identified the formation of the charged hydrazone tautomer which requires stabilisation by polar solvent milieu as responsible for the observed trend. In addition, interactions between new aggregated solvent-solvent species and the propionic acid substituent present in AZ-03 contributed to its spectral shifts.Conclusion: The solvatochromic properties of the phenylazonaphthalene series in binary mixtures have been successfully studied.

Diffusion in multicomponent aqueous alcoholic mixtures

The Fick diffusion coefficient matrix of the highly associating quaternary mixture water + methanol + ethanol + 2-propanol as well as its ternary and binary subsystems is analyzed with molecular dynamics simulation techniques. Three of the ternary subsystems are studied in this sense for the first time. The predictive capability of the employed force fields, which were sampled with the Green–Kubo formalism and Kirkwood–Buff integration, is confirmed by comparison with experimental literature data on vapor-liquid equilibrium, shear viscosity and Fick diffusion coefficient, wherever possible. A thorough analysis of the finite size effects on the simulative calculation of diffusion coefficients of multicomponent systems is carried out. Moreover, the dependence of the Fick diffusion coefficient matrix on the velocity reference frame and component order is analyzed. Their influence is found to be less significant for the main matrix elements, reaching a maximum variation of 19%. The large differences found for the cross elements upon variation of the reference frame hinder a straightforward interpretation of the Fick diffusion coefficient matrix with respect to the presence of diffusive coupling effects.

Antimicrobial Activity of Myrtus communis L., Cinnamomum verum and Eugenia caryophyllata Alcoholic Mixtures

Background and Objective: With the significant increase in the prevalence of infectious diseases and the development of drug resistance by human pathogenic bacteria, there is a continuous need to discover new antimicrobial compounds from plants. Methods: Four extracts of wild Myrtus communis L. berries (myrtle berries) were prepared with the addition of Cinnamomum verum and Eugenia caryophyllata. The extracts were screened in vitro for their antimicrobial activities using agar-well diffusion method against Escherichia coli, Staphylococcus aureus, Enterobacter cloacae, Listeria monocytogenes, Pseudomonas aeruginosa and Proteus mirabilis cultures. Results: The inhibition zones ranged from 12 to 22 mm. The MICs values of extracts lies between the ranges of 30 to 100 mg/ml. Of the extracts studied, the most active ones were those obtained from the myrtle berries:cloves, myrtle berries:cinnamon:cloves with the highest inhibition zones 22 mm and 17mm against S. aureus and L. monocytogenes at 50 mg/ml and 80 mg/ml, respectively. None of the extracts was active against E. coli and P. mirabilis. Conclusion: The present investigations have exposed that the myrtle berries:cloves, myrtle berries: cinnamon:cloves extracts could be used in traditional medicine as natural antimicrobial agents in treatment the bacterial infections.

Alcohol induced gelation of TEMPO-oxidized cellulose nanofibril dispersions

Alcohol-induced gelation of partially oxidised cellulose nanofibrils (OCNFs): nanoscale (SAXS) and macroscale (rheology) insights into OCNF self-assembly in aqueous-alcoholic mixtures.