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It has been found that sulfur dioxide solubility in organic solvents can be well-correlated by Lewis basicity numbers. Mixtures of sulfur dioxide and solvent (N-methylpyrrolidone (NMP), N,N′-(dimethylpropylene)urea (DMPU) and methyldiethanolamine (MDEA)) have been prepared in a 1:1 mole ratio at low temperatures. The melting points of the mixtures are measured, and the mixtures have been analyzed by infrared, ultraviolet-visible, and nuclear magnetic resonance spectroscopy. The solubility of sulfur dioxide has been measured in NMP and DMPU at 25 °C. At sulfur dioxide concentrations of 0.2-0.6 kPa, the solubility is determined using a continuous stirred tank reactor. The absorption of sulfur dioxide proved to be completely reversible. A model where physical and chemical interactions are incorporated showed good correlation with the experimental results.

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Novel supported membranes based on polyvinyl alcohol (PVA) were developed using two strategies: first, by the modification of the PVA network, via so-called bulk modification, with the formation of the selective layer accomplished through the introduction of fullerenol and/or poly(allylamine hydrochloride), and second, by the functionalization of the surface with successive depositions of multilayered films of polyelectrolytes, such as poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate) on the PVA surface. The membrane surface modifications were characterized by scanning electron microscopy and contact angle measurements. The modified PVA membranes were examined for their dehydration transport properties by the pervaporation of isopropyl alcohol-water (80/20% w/w), which was chosen as a model mixture. Compared with the pristine PVA membrane, the main improvement was a marked increase in permeance. It was found that the surface modifications mainly gave rise to a higher global flux but with a strong reduction in selectivity. Only the combination of both bulk and surface modifications with PEL could significantly increase the flux with a high water content in the permeate (over 98%). Lastly, it should be noted that this study developed a green procedure to prepare innovative membrane layers for dehydration, making use of only water as a working medium.

The so-called Graftfast reaction in water and at room temperature (RT) was applied to graft polyethylene glycol (PEG) at the surface of the microporous zeolitic imidazolate framework ZIF-8 nanoparticles (NPs) using acrylPEG of different chain lengths (480 Da and 5 kDa). In comparison to non-modified ZIF-8 NPs, both chemical and colloidal stabilities of PEGylated ZIF-8 NPs are significantly enhanced in water. A series of colloidal complex fluids by mixing PEG grafted ZIF-8 (i. e. PEG-g-ZIF-8) NPs with different amounts of polyvinylalcohol (PVA) was prepared and characterized by advanced characterization tools such as dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) thereby showing their long-term colloidal stability. Finally, dense and supported mixed matrix membranes were cast from PEG-g-ZIF-8/PVA solutions and have shown high performance in isopropanol (IPA) dehydration by pervaporation. The permeation flux of the supported MMM (i. e. 0.091 kg/(m 2 h) is eleven times higher than that of the pure PVA membrane and these MMMs present a high separation factor (i. e. 7326). These transport properties are presumably due to the molecular sieving effects induced by ZIF-8 and the good interfacial properties of the membrane. The computational exploration of the ZIF-8/PVA and PEG/PVA interfaces provides a microscopic scale explanation for the enhanced compatibility of PVA with the PEGylated MOF when compared to that for the composite based on the bare ZIF-8 as a filler.