Solvatochromism as a probe to observe the solvent exchange process in a 1-D porous coordination polymer with 1-D solvent accessible channels

A one-dimensional porous coordination polymer possessing pleochroic and solvatochromic properties produces an unexpected double V-shaped discolouration of the crystal upon solvent exchange with acetonitrile and nitromethane. Modelling shows that the origin of this effect is preferential sorption at two faces of the crystal.

Simulating preferential sorption of tartrate on prismatic calcite surfaces

Calculated binding energies of favorable adsorption configurations emphasize the importance of surface charge/energetics, structural match and water layers in mineral–organic interactions.

Analysis of soil organic matter at the solid–water interface by nuclear magnetic resonance spectroscopy

Environmental context Structural and conformational information on organic matter–clay complexes and whole soils was obtained using different NMR methods. The results show that organic matter interactions with clay mineral surfaces determine the accessibility of specific organic matter components at the soil–water interface. This physical conformation may also play a role in soil biogeochemical processes and binding to pollutants in terrestrial environments. Abstract Organic matter (OM)–mineral interactions play an important role in OM preservation, global carbon cycling and contaminant transport. Studies have indicated that preferential sorption of OM is dependent on mineral type and solution conditions. In this study, 1H high resolution–magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy was employed to examine OM chemistry in organo-clay complexes. Dissolved OM from a forest soil, Leonardite humic acid and Peat humic acid were sorbed to Ca2+ enriched kaolinite and montmorillonite. As observed using 1H HR-MAS NMR spectroscopy, kaolinite sorbed mainly long-chain aliphatic compounds such as those from plant cuticles whereas montmorillonite sorbed a mixture of aliphatic components and proteins. These results show the preferential sorption of specific dissolved OM components on clay surfaces. This was tested further using solid-state 13C and 1H HR-MAS NMR analysis of whole soils containing kaolinite and montmorillonite as well as a Peat soil for contrast. The species present at the soil–water interface were mainly aliphatic components, carbohydrates and amino acids. Aromatic constituents were present in the soils (observed by solid-state 13C NMR and by 1H HR-MAS NMR spectroscopy when a more penetrating solvent was used) which signifies that these compounds likely exist in more hydrophobic domains that are buried and surface inaccessible. This study highlights the important role of OM interactions with clay minerals in the preservation of OM in soils and suggests that OM–OM associations may also play a role in the protection of specific OM components in soil.

Removal of Thiophene from Binary Mixtures Using Polyether Block Amide (PEBAX) Film by Pervaporation

Reduction of organosulfurs in gasoline has become an urgent requirement in the world, especially in China. The goal of this work focuses on removal of thiophene from binary mixtures of thiophene and n-heptane by means of pervaporation. The PEBAX homogenous film was prepared by coating. The swelling experiments of film were studied for the affinity of PEBAX film to thiophene. The swelling degree of film increased with increasing thiophene content in the mixtures. The result indicates the PEBAX film had preferential sorption to thiophene rather than n-heptane. Pervaporation experiments were studied for investigating separation properties of the film. The effect of thiophene concentration in feed and operation temperature on separation properties of the film was researched. The results of pervaporation showed that both total and thiophene flux increased with increase of thiophene content in the feed and temperature, but the separation factor deceased with their increase. The activity energy was calculated according to the Arrhenius relationship. This work may offer useful visions into the possibility of the separation of sulfur compounds from gasoline via pervaporation.