No abstract

A computational study on adsorption and dissociation mechanisms of H2 molecule on ZnO cluster was analysed using Density Functional Theory (DFT) approach in Gaussian 09 software. The stable sites for hydrogen adsorption were inferred from the adsorption energy and bond length. Further investigations such as Mulliken charge, HOMO–LUMO energy gap and intrinsic reaction coordinate (IRC) were performed for the stable adsorption sites. It infers that the (ZnO)6 cluster has the highest binding energy of 1.851[Formula: see text]eV (O-site) and the least binding energy of [Formula: see text]3.865[Formula: see text]eV (O-site), showing most favorable size for both adsorption and dissociation of H2 molecule. The IRC plot clearly shows the dissociation mechanism of hydrogen on the ZnO cluster.

Silica nanoparticles with a surface area of 673.60 m/g and particle size of 8-12 nm were prepared using aerogel process (AP) followed by super critical drying. Zero valent Fe, Co, Pt, and bimetallic Fe/Pt and Fe/Co were loaded using an incipient wetness impregnation technique and subsequent reduction. Scanning electron microscopy-energy dispersive X-ray (SEM-EDX) and transmission electron microscopy-energy dispersive X-ray (TEM-EDX) characterizations indicated fine dispersion of iron on AP-SiO +Fe system. Prepared nanoparticles were evaluated for the adsorptive removal of 2,4,6-trinitrotoluene (TNT) from water. Surface area normalized rate constant values indicated the adsorptive removal potential of prepared nanoparticles to be: AP-SiO + Fe/Co > AP-SiO + Fe > CM (commercial) SiO + Fe > AP-SiO + Co > AP-SiO + Fe/Pt > AP-SiO + Pt. Lower pH helped in accelerating the reactive removal of TNT on zero valent iron loaded silica. AP-SiO + Fe/Co system showed the maximum adsorption potential (74 mg/g) after five cycles.