Reprint of “Role of the fluidity of a liquid phase in determining the surface properties of the opposite phase”

Molecular dynamics simulations of the water-CCl4 interface have been done in two different ways. In the first simulation the CCl4 phase has been frozen in an equilibrium configuration, and only the water molecules have been allowed to move, whilst in the other one no such artificial freezing has been done. This way the effect of the fluid-like structure and fluid-like dynamics of the CCl4 phase on the surface properties of the aqueous phase could be investigated separately. Due to the separate thermostatting of the two types of molecules in the simulations all the differences seen between the interfacial properties of water in the two systems can indeed be attributed to the rigid vs. fluid nature of the organic phase, and not to the thermal contact with a phase of zero temperature. The obtained results reveal that the rigidity of the opposite phase introduces an ordering both in the layering structure and orientation of the surface water molecules. The enhanced orientational ordering leads to a stronger lateral hydrogen bonding structure of the molecules within the subsequent molecular layers beneath the surface, and hence also to a slower exchange of the water molecules between the surface and the bulk aqueous phase

Nitrogén-, kén- és foszforatomot tartalmazó koronaéterek szintézise, molekuláris felismerése és alkalmazása = Synthesis, molecular recognition and application of crown ethers containing nitrogen, sulfur and phosphorus atoms

A kereskedelemből könnyen beszerezhető és viszonylag olcsó alapanyagokból kiindulva piridino-, ill. akridino-18-korona-6 éter alapú királis állófázisokat állítottunk elő, és ezeken jó hatásfokkal rezolváltunk racém protonált primer aminokat, aminosavakat és azok származékait HPLC-vel. Akridin egységet tartalmazó enantiomertiszta koronaétereket szintetizáltunk, és potenciametriás mérések alapján kimutattuk, hogy ezek közül az egyik figyelemre méltó enantioszelektivitást mutat a protonált 1-feniletil-amin enantiomerjeival szemben, míg egy másik kiemelkedő szelektivitással komplexálja az ezüst iont. Optikailag aktív monoaza-18-korona-6 étereket állítottunk elő, ezeket különböző fluorofor (BODIPY, akridinon, N-metilakridinon) jelzőegységgel láttuk el, és fotofizikai módszerekkel behatóan tanulmányoztuk ezek komplexképzését királis vegyületek enantiomerjeivel, ill. különböző fémionokkal szemben. Néhány esetben figyelemre méltó szelektivitást mutattunk ki. Akridinon fluoreszcens jelzőegységet tartalmazó bisz(azakoronaéter) típusú makrociklusokat szintetizáltunk, és a két aza-18-korona-6 éter receptor egységet tartalmazóról kimutattuk, hogy az mind 1:1, mind 1:2 ligandum-fémion arányú komplexek kialakítására képes. Könnyen deprotonálható dialkilhidrogén-foszfát, ill. diarilfoszfinsav egységet tartalmazó enantiomertiszta koronaétereket állítottunk elő, és részletesen tanulmányoztuk utóbbi enantioszelektív komplexképzését protonált primer aralkil-aminokkal. | We prepared chiral stationary phases based on pyridino- and acridino-18-crown-6 ethers starting from commercially available and relatively cheap materials, and using them we resolved racemic protonated primary amines, amino acids and their derivatives efficiently by HPLC. We synthetized enantiopure crown ethers containing an acridine unit, and showed by potentiometric measurements that one of them had a reasonable selectivity for the enatiomers of protonated 1-phenylethylamine, and another one complexed silver ion with very high selectivity. We prepared optically active monoaza-18-crown-6 ethers, attached different fluorofor signalling units (BODIPY, acridinon, N-methylacridinon) to them, and using photophysical methods we thoroughly studied their complexation with the enantiomers of different chiral compounds, and several metal ions, respectively. In a few cases these ligands demonstrated remarkable selectivity. We synthetized bis(azacrown ether)s containing an acridinone signalling unit, and we showed that the one having two aza-18-crown-6 ether receptor units is able to form complexes with both 1:1 and 1:2 ligand to metal ion ratios. We prepared enantiopure proton-ionizable crown ethers containing an dialkylhidrogenphosphate or a diarylphosphinic acid unit, and we thoroughly studied the enantioselective complex formation of the latter with protonated primary aralkyl amines

Effects of Pre-ozonation on Membrane Filtration of Oil-in-water Emulsions Using Different Polymeric (PES, PAN, PTFE) Ultrafilter Membranes

Emulsified oily contaminants of wastewaters cannot be eliminated effectively by conventional treatments, but they pose significant risks both to the environment and to human health, therefore their efficient elimination is imperative. Membrane filtration is a promising technique for the effective purification of oil-in-water emulsions; however, the accumulation of hydrophobic contaminants on the membrane surface quickly leads to significant water flux reduction, which is a limiting factor of the economic utilization. In the present comparative study short-term ozonation was investigated as a suitable pre-treatment to achieve lower flux reduction during the separation of micro- or even nanoscale crude oil droplets by ultrafiltration with different membranes. Results confirmed that pre-ozonation modifies the surface charge (zeta-potential) of the oil droplets which resulted in the reduced accumulation of contaminants on the membrane surface and higher fluxes in the case of every investigated ultrafilter membranes: polyethersulfone (PES), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE). Filtration experiments were carried out using ultrapure and model groundwater matrices for a more thorough discussion of achievable advantages, and it was concluded that in the case of low ionic strength the PES membrane provided the highest flux; however, in the case of realistic water matrix (model groundwater) the application of acetone-conditioned PTFE ultrafilter membrane – combined with pre-ozonation – was much more beneficial. Overall, pre-ozonation decreased the total resistance in all cases; however, the reversibility of the measured filtration resistance and flux reduction was strongly dependent on both the matrix and the membrane surface material