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The separation of nitrogen dioxide (NO2) from the gas mixture with nitrogen (N2) by selective adsorption and diffusion in three Zeolitic Imidazolate Frameworks (ZIFs) is examined by Gibbs Ensemble Monte Carlo (GEMC) and Molecular Dynamics (MD) computer simulations at 373 K, which is a temperature that can be found in the exhaust gases of combustion engines and furnaces. This temperature ensures that the chemical equilibrium reaction between NO2 and N2O4 can be neglected since at this temperature almost only NO2 exists. At 373 K, the membrane selectivity of NO2 over N2 is predicted to be about 4.2 (ZIF-90), 5.2 (ZIF-8), and 10.6 (ZIF-78). In addition, it is shown that N2O4 can be neither adsorbed nor diffuses inside these ZIF materials, which makes these ZIFs a promising materials for separation by membranes. Due to molecular sieving, only N2 and NO2 can pass the ZIF membranes.

The silver nanoparticles (AgNPs) complexed with curcumin (CUR) extracted from turmeric (TMR) were synthesized and applied for a simple and rapid colorimetric technique for Pb2+ detection. The results reveal that our low-cost and rapid AgNPs-CUR sensor is highly selective for Pb2+ ions with the detection limit of 13.6 µM (2.8 mg.L−1) and can be applied for real water samples. Not only the observed absorption spectrum and the solution color can reveal the contamination of Pb2+ in the sample, but also an orange floccules precipitate can be clearly observed by naked-eye within 20 min. In addition, the results obtained from DFT calculation agree well with the experiments. Density functional theory (DFT), at the M06 level with mixed basis set of 6-31G(d) and def2-tzvp, was applied to propose the binding mechanism of AgNPs with CUR and AgNPs-CUR with Pb2+. Calculated binding energies of the compound of AgNPs with CUR and the AgNPs-CUR with Pb2+ are −145.8 and −361.4 kcal mol−1, respectively, indicating that the AgNPs-CUR is strongly interact with Pb2+ ions through formation of highly stable Pb2+AgNPs-CUR complexes indicating the stable aggregative phenomena which agrees well with FTIR spectrum.

Cationic (Malachite Green) and anionic dyes (Indigo carmine) removal by cross-linked chitosan (CSglu) beads has been investigated using experimental and computational approaches. The experimental investigations of the adsorption isotherm, kinetics, and thermodynamics information correlated well with computational studies in term of structures and binding energies (ΔEB). Cross-linked chitosan adsorb Malachite Green better than Indigo carmine using Langmuir adsorption isotherm. The CSglu beads in frozen dried form showed highly adsorption capacity (714.29 mg.g−1) for malachite green (MG) but they are not favorable for indigo carmine (IND). In order to probe the atomistic-level detail between these two dyes and CSglu, molecular dynamics simulations (MDs) have been applied to determine detailed analysis of binding site of the complexes. MG is more preferable to bind with CSglu than IND due to its complementary of the molecular electrostatic potential (MEP) to the CSglu surface. The quantum calculations using density functional theory (DFT) with different levels and basis set super position error (BSSE) were used to calculate ΔEB and to effectively predict the adsorption capabilities of cationic and anionic dyes by cross-linked chitosan.

The permeation of methane molecules through the silicalite-1 surfaces with and without silanol groups has been studied by nonequilibrium molecular dynamics computer simulations. A newly fitted intermolecular potential between the methane molecules and the silanol is used. A control volume provides a nearly stationary gas phase close to the membrane. The nonequilibrium process of filling the (initially empty) membrane with methane molecules until saturation is considered, and the surface permeability has been evaluated. It turns out to be strongly influenced by the presence of silanol groups. Additionally it was found that for a large part of the loading process the particle stream into the zeolite membrane was nearly independent upon the deviation from equilibrium. This means that far from equilibrium the decay of this deviation does not follow an exponential law.

The adsorption of nucleobase-analog anticancer drugs (fluorouracil, thioguanine, and mercaptopurine) on a graphene flake (C54H18) was investigated by shifting the site at which adsorption occurs from one end of the sheet to the other end. The counterpoise-corrected M06-2X/cc-pVDZ binding energies revealed that the binding stability decreases in the sequence thioguanine > mercaptopurine > fluorouracil. We found that adsorption near the middle of the sheet is more favorable than adsorption near the edge due to the edge effect. This edge effect is stronger for the adsorption of thioguanine or mercaptopurine than for fluorouracil adsorption. However, the edge effect reduces the binding energy of the drug to the flake by only a small amount