Highly efficient visible light-driven Ag/AgBr/ZnO composite photocatalyst for degrading Rhodamine B

Sertraline hydrochloride (designated as sertraline from now on) is an antidepressive drug with unpleasant effects in the gastric tract. Therefore, improved means of delivery allowing for a more controlled and efficient release were looked for. Two different porous materials, montmorillonite-K10 and MCM-41, were chosen as hosts. The drug was intercalated in the interlayer spacing of the clay by cation exchange and was loaded inside the MCM-41 channels by pore volume impregnation means. Spectroscopic evidence (UV/vis, FTIR, powder X-ray diffraction (XRD) and 13 C CP/MAS and 29 Si CP/MAS and MAS solid-state NMR), as well as elemental analysis, complemented by DFT calculations, demonstrated the presence of sertraline in the composite materials. The release processes were monitored under in vitro conditions using a simulated body fluid. The release profile from the clay is fast, indicating that a concentration peak is reached in a short period of time, while the release profile from MCM is slower but lasts longer. These differences are discussed on the basis of different therapeutic indications for both materials. 2006 Elsevier B.V. All rights reserved.

Research paper Loading and delivery of sertraline using inorganic micro and mesoporous materials

A novel carbon nanotubes modified Bi12O17Cl2 composite (CNTs/Bi12O17Cl2) was prepared via hydrothermal method. The chemical structures, morphologies, optical properties of the synthesized samples were revealed by XRD, XPS, SEM, TEM, BET and UV-vis DRS measurements. The photocatalytic activity of the CNTs/Bi12O17Cl2 composite was evaluated with degradation reaction of rhodamine B (RhB) under visible light. CNTs/Bi12O17Cl2 exhibited improved photocatalytic activity in comparison with pure Bi12O17Cl2, and kept favorable stability and recyclability in the reaction. The relatively high photocatalytic activity of CNTs/Bi12O17Cl2 resulted from the enhanced separation efficiency of photo-induced charges, which were revealed by the photoluminescence spectra and transient photocurrent measurements. CNTs loaded at the surface of Bi12O17Cl2 sheets acted as electron carriers to efficiently transfer the photoinduced electrons, namely to promote the separation of photoinduced electrons and holes, thus improving the photocatalytic activity of the composite materials. At last, a possible photocatalytic reaction mechanism over the CNTs/Bi12O17Cl2 composite was proposed based on the results of trapping experiment, ESR measurements and the band energy analysis.

Enhanced photocatalytic activity of Bi12O17Cl2 nano-sheets via surface modification of carbon nanotubes as electron carriers.

Nickel-doped tin dioxide (NDT) microspheres with various doping levels were prepared by hydrothermal synthesis and characterized by using X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive spectroscopy analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-vis absorption spectroscopy. The formation mechanism of NDT microspheres was discussed. All samples prepared with different Sn/Ni ratios shows higher photocatalytic activity than that of pure SnO2 and pure NiO under visible light irradiation (λ > 420 nm). The photocatalytic activity is closely related to the composition of as-prepared photocatalysts. It is noted that the NDT microspheres with the doping content of 33.3 mol% exhibit the highest photoactivity. Moreover, this catalyst showed improved stability, and the activity did not weaken significantly after four recycles. The higher activity of NDT microspheres may be attributed to the combined effect of its demonstrated doping levels and appropriate band gap. And the doping of Ni2+ may facilitate the generation of electron and hole pairs and inhibit their recombination rate by acting as temporary trapping sites of photoinduced electrons.

Synthesis and characterization of Ni doped SnO2 microspheres with enhanced visible-light photocatalytic activity

Photocatalytic activity of TiO2 (anatase) is appreciably enhanced by substitutional doping of Mo in anatase lattice, in conjunction with the incorporation of nanostructured MoO3 within the parent anatase lattice. The photocatalyst material was characterized in detail using X-ray diffraction, Raman spectroscopy, diffuse reflectance (DR-UV–Vis spectroscopy), X-ray photoelectron spectroscopy, and electron microscopy. Photocatalysis experiments were conducted using a model rhodamine-B (Rh–B) dye reaction using both UV and visible irradiation sources. The observed trends in the case of visible irradiative source can be summarized as follows: Mo-1 < Mo-2 < Mo-5 ≫ Mo-10. Attempts were made to isolate the structural factors that control photochemical behavior of these Mo–TiO2 photocatalysts and to correlate photocatalytic activity with different structural aspects like oxidation state, band gap, surface species, etc. Mechanistic insights were acquired from ex situ 1H NMR studies showing different intermediates an...

Effect of Mo-Incorporation in the TiO2 Lattice: A Mechanistic Basis for Photocatalytic Dye Degradation

MCM-41 based materials were prepared with immobilized Mo II and Mo VI active sites based on [MoI 2 (CO) 3 ] and [MoO 2 Cl 2 ] cores, respectively, using a 2-aminopyridine glycidyloxypropyl derivative as anchoring ligand. Suitable characterization by powder X-ray diffraction, FTIR and, 13 C and 29 Si solid state NMR spectroscopy was accomplished. All new materials were successfully used in photodegradation experiments of rhodamine B under aerobic conditions. Control experiments using neat MCM-41 and direct photolysis of rhodamine B were also carried out. All experiments were run without any external source of oxygen other than air. Photocatalytic results show that the presence of Mo and its oxidation state is not innocent in this process. In addition, Mo catalysts act most probably by quenching rhodamine B excited state leading to extended degradation of the dye, through secondary photochemistry, beyond a simple de-ethylation process. Density functional theory (DFT) results corroborate with this showing that when rhodamine B is in excited state the xanthene moiety bond orders change.

Photocatalytic degradation of rhodamine B using Mo heterogeneous catalysts under aerobic conditions

Nano flowers of a new polymeric lead(II) complex containing the azide anions, [Pb(baea)(N3)·(N3)]
 n
 (“baea” is the abbreviation of bis(2-aminoethyl)amine), has been synthesized by a sonochemical method. The new nano-structure was characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, elemental analyses, and IR spectroscopy. Single crystalline material was obtained using a heat gradient applied to a solution of the reagents. Single-crystal X-ray diffraction analyses show that the coordination number for PbII ions is five, PbN5 and hold hemidirected coordination geometry. To the best of our knowledge, the 1D coordination polymer interact with each other via supramolecular and weak Pb···N interactions to create 2D supramolecular frameworks.

Mohammad Safi Shalamzari

Papers

Photocatalytic degradation of rhodamine B using Mo heterogeneous catalysts under aerobic conditions

Synthesis and Characterization of the New Nano Flowers Lead(II) Coordination Polymer with Hemidirected Coordination Sphere