Ayyakannu Sundaram Ganeshraja

Visible-light-induced photocatalysis and peroxymonosulfate activation over ZnFe2O4 fine nanoparticles for degradation of Orange II

Refractory and non-biodegradable pollutants produced by industries have inevitably brought great threat to human life. Integrating several kinds of advanced oxidation processes (AOPs) into one system has been proposed to be an efficient strategy to remove such pollutants from the environment at low cost. In this study, magnetic zinc ferrite fine nanoparticles, firstly synthesized by a novel soft chemical solution process, showed super reactivity, good reusability and easy separation ability for visible-light-induced Orange II degradation in an integrated ZnFe2O4/PMS (peroxymonosulfate, 2KHSO5·KHSO4·K2SO4, OXONE) aqueous system. Powder X-ray diffraction, transmission electron microscopy, and 57Fe Mossbauer and X-ray photoelectron spectroscopy were employed to characterize the structure and morphology as well as recognize the physicochemical changes of the fine nanoparticles before and after the reaction. The generated oxidizing intermediates during the degradation process were detected by electron paramagnetic resonance spectroscopy and classic quenching experiments, which confirmed that both sulfate radical (SO4˙−) and hydroxyl radical (˙OH) co-existed in the degradation process. The systematic condition experiments further verified the dual functionality of the ZnFe2O4/PMS system, which actively acted as a photocatalyst and a PMS activator for dye molecule oxidation under visible light irradiation. This study proves that photocatalysis and PMS activation for remediation of organic pollutants in water can be easily integrated into one system by using zinc ferrite nanoparticles as an environmentally friendly catalyst.

Facile synthesis of iron oxide coupled and doped titania nanocomposites: tuning of physicochemical and photocatalytic properties

A facile hydrothermal method was firstly employed to synthesize iron oxide coupled and doped titania nanocomposites using an aqueous solution of titanium nitrate. The present nanocomposites exhibit altered compositional, optical, electrical, magnetic and photocatalytic properties with respect to varying dosage of iron in the titania matrix. The architecture of characteristic iron oxide such as Fe2O3 coupled with titania was confirmed by 57Fe Mossbauer spectroscopy and X-ray absorption fine structure spectroscopic measurements. The enhanced photocatalytic activity was demonstrated by comparing with that of pure hematite, anatase TiO2, rutile TiO2 and P25 in the degradation of methylene blue under visible light (λ > 480 nm) irradiation in an aqueous suspension. The strategy presented here gives a promising route towards the development of a metal oxide coupled and doped semiconductor material for applied photocatalysis and related applications.

Effects of structural, optical and ferromagnetic states on the photocatalytic activities of Sn–TiO2 nanocrystals

The structural, electronic, magnetic and photocatalytic properties of Sn doped TiO2 diluted magnetic semiconductor nanoparticles (NPs) prepared by a simple hydrothermal method were systematically investigated by various conventional techniques and 119Sn Mossbauer spectroscopy. Anatase, mixed (anatase–rutile) and rutile phases of Sn–TiO2 NPs were obtained by adding different amounts of SnCl4 into a titanium nitrate aqueous solution. Photocatalytic degradation of methyl orange and phenol derivatives (RPhOH) were studied under visible and UV light irradiation in water, respectively. The photocatalytic activities of prepared NPs were found to be drastically related to the structural, optical and ferromagnetic properties. A significant relationship was observed between the Hammett substitution constants of RPhOH and the photocatalytic activity. Among all the samples, the anatase phase with low Sn content performed with the best photocatalytic and ferromagnetic characteristics at room temperature.

Zinc-modulated Fe-Co Prussian blue analogues with well-controlled morphologies for the efficient sorption of cesium

Prussian blue analogues (PBAs) with tunable compositions and morphologies have demonstrated great potential in many applications. We successfully synthesized a series of KFexZn1−x[Co(CN)6] (FexZn1−x–Co) PBAs with well-controlled compositions and morphologies and used them as adsorbents for the removal of Cs+ ions. The increase of Zn : Fe ratio had a significant influence on the final morphology and improved the sorption capacity for Cs. X-ray diffraction and X-ray absorption fine structure spectra were used to confirm that the Cs+ ions were inserted into the crystal channels rather than simply adsorbed on the surface of the PBAs. Based on the quantitative correlation between the concentration of ions released from the PBAs and the Cs+ ions adsorbed, the mechanism of Cs+ sorption in the FexZn1−x–Co PBAs was studied and a Zn2+-modulated Cs+ sorption model, which illustrated the difference in sorption behavior between the FexZn1−x–Co PBAs, was proposed and confirmed by FTIR spectra, extended X-ray absorption fine structure spectra and 57Fe Mossbauer spectra. The results indicated that the FexZn1−x–Co PBAs are excellent candidates for the removal of radioactive 137Cs from nuclear waste.

Bis(1,10-phenanthrolin-1-ium) tetra-chlorido-zincate monohydrate.

In the crystal structure of the title compound, (C12H9N2)2[ZnCl4]·H2O, the two independent 1,10-phenanthrolinium cations are bridged by the water molecule and the tetrahedral tetrachloridozincate anion via N—H⋯O, O—H⋯Cl and N—H⋯Cl hydrogen bonds, forming chains along [100]. The chains are linked via C—H⋯Cl hydrogen bonds and a number of π–π interactions [centroid–centroid distances vary from 3.5594 (14) to 3.7057 (13) Å], forming a three-dimensional network. In each 1,10-phenanthrolinium cation, there is a short N—H⋯N interaction.

cis-Bromido(methyl­amine)­bis­(propane-1,3-di­amine)­cobalt(III) dibromide

In the title compound, [CoBr(CH5N)(C3H10N2)2]Br2, the cobaltIII ion has a distorted octahedral coordination environment and is surrounded by four N atoms in the equatorial plane, with an additional N atom and the Br atom occupying the axial positions. In the crystal, the complex cation and the two counter anions are linked via N—H⋯Br and C—H⋯Br hydrogen bonds, forming a three-dimensional network.

Enhanced Photocatalytic Response of N Doped Niobium Titanates Prepared by Ion Exchange Process

Herein we report the homogeneous and effective substitution of O by N in the layered titanates. The resultant materials HTiNbO5-xNx (350°C, 30 min) unveiled extraordinary band-to-band excitation and increased absorption intensity (induced by oxygen vacancies). Upward shift of valence band maximum by N 2p states is confirmed by photoelectron spectroscopy and is concluded as the source of band-to-band visible light excitation. The electrons generated upon visible light excitation in the conduction band of HTiNbO5-xNx (350°C, 30 min) had strong reduction ability, reducing O2 into active O2•- radicals during photocatalysis. These findings are the clear evidence for the substantial role of doped N in achieving band-to-band visible-light photon excitation in layered titanates. The new physical insights into substitutional N in layered titanates with hydrogen bond (weak bond energy) gained here may have important implications for developing other efficient visible light photocatalysts by nonmetal doping.

catena-Poly[[[bis­(1H-imidazole-κN3)zinc(II)]-μ2-imidazol-1-ido-κ2N:N′] nitrate]

The title compound, {[Zn(C3H3N2)(C3H4N2)2]NO3}n, is a one-dimensional coordination polymer along [01-1] with the ZnII atom coordinating to four imidazole/imidazolide rings. The ZnII atom has a regular tetrahedral geometry with the planes of the two monodentate imidazole rings inclined to one another by 87.94 (17)°, while the planes of the bridging imidazolide rings are inclined to one another by 39.06 (17)°. In the crystal, the chains are linked via bifurcated N—H⋯(O,O) hydrogen bonds, forming sheets parallel to (001). These two-dimensional networks are linked via C—H⋯O hydrogen bonds and a C—H⋯π interaction, forming a three-dimensional structure.

Crystal structure of trans-aqua­(perchlorato-κO)bis­(propane-1,3-di­amine-κ2N,N′)copper(II) perchlorate

In the title compound, the CuII atom has a distorted octahedral coordination sphere coordinated by the N atoms of two propane-1,3-diamine ligands in the equatorial plane. The axial positions are occupied by a water O atom and an O atom of a disordered perchlorate anion [occupancy ratio 0.631 (9):369 (9)].

trans-Diamminedichloridobis(1H-imidazole-κN3)nickel(II)

The whole molecule of the title compound, [NiCl2(C3H4N2)2(NH3)2], is generated by inversion symmetry. The NiII ion, which is located on an inversion center, has a distorted octahedral coordination environment and is surrounded by two ammine N atoms and two Cl atoms in the equatorial plane, with two N atoms of two imidazole groups occupying the axial positions. The imidazole ring makes a dihedral angle of 81.78 (18)° with the Ni/N/Cl equatorial plane. In the crystal, molecules are linked via N—H⋯Cl hydrogen bonds and C—H⋯π interactions, forming a three-dimensional network.