The stability orders of a number of alkaline earth oxide cluster isomers (MO) , M = Mg, Ca, Sr, Ba and 1 ≤ ≥ 6 have been determined by means of density functional theory studies using the LDA-PWC functional. Among the candidate structures, the hexagonal-ring-based isomers and the slab shapes are found to display similar stabilities. Stacks of hexagonal (MO) 3 rings are found to be the slightly preferred growth strategy among the (MgO) 6 , isomers. In contrast, the slab structures are slightly preferred for the other alkaline metal oxide (MO) 6 clusters. An explanation based on packing and aromaticity arguments has been proposed. This study may have important implications for modeling and understanding the initial growth patterns of small nanostructures of alkaline earth metals.

No abstract

Water pollution is one of the major concerns around the world. Presence of inorganic pollutants such as heavy metals (i.e., Pb2+, Hg2+, Cd2+, As3+, As(V) ions, Cr(VI) ions, Co2+,Cu2+, Ag+, Ni2+, Zn2+, etc.) in water is a severe environmental and public health problem, since the accumulation of these non‐biodegradable heavy metals in human body cause severe diseases. This review systematically summarizes the application of advance nanocomposites based materials for removal of heavy metals from waste water. The review covers the following topics: role of inorganic nanomaterials, polymer based nanocomposites, chitosan based nanocomposites, carbon nanotubes/metal/metal oxide nanocomposites, nanocomposites based on inorganic fillers and graphene/graphene oxide, etc. The goal of this study is to provide the latest and advance analysis as well as references in the area of developing nanotechnology.

The present work deals with the adsorption of acetaldehyde, one of the most harmful volatile organic compounds (VOCs), on the TiO2 anatase nanosurface. The research was undertaken due to environmental concerns, as the TiO2 nanosurface serves as an excellent catalyst for the adsorption and decomposition of VOCs. The chemistry of aldehydes on metal oxides is complex and elaborate, as it can result in a variety of reactions, such as selective oxidation, alcohols disproportionation, etherification and reductive coupling to higher olefins. The structural properties of the various nanosurfaces were first examined and finally adsorption studies were made on the (TiO2)17 cluster, as it shows least reconstruction and offers all kinds of coordination sites for the study. It is found that a myriad of different adsorption products are formed on the TiO2 nanosurface, depending upon the coordination site. The low coordination (3c) sites are highly reactive and form stronger bonds with the acetaldehyde molecule, whereas adsorption at the four coordination site leads to the reconstruction of the nanosurface. Acetaldehyde chemisorbs onto the surface producing zwitterionic four-membered rings, in which the carbonyl C=O bond is considerably weakened, or it adsorbs on the TiO2 surface in a H-bridge bonded form. The most feasible mode of adsorption on the TiO2 nanosurface is found to be methyl hydrogen migration resulting in the formation of [CH2-C(H)O] species, which may further undergo transformation by β-aldolization to yield crotonaldehyde and butane. Other products investigated in this work include oxidation to acetate and reduction to ethoxy species. The results obtained in this work can be of significant help in deciding the fate of reaction of acetaldehyde on the TiO2 nanosurface, and using it for decomposition of acetaldehyde to benign products.

No abstract