Removal of rhodamine B dye from aqueous solution by electro-Fenton process using iron-doped mesoporous silica as a heterogeneous catalyst.

In the current study, Rhodamine B (RhB) dye was removed by electro-Fenton (EF) process using iron-doped SBA-15 (Fe-SBA-15; SBA: Santa Barbara Amorphous) mesoporous silica as a heterogeneous catalyst. This catalyst was prepared with the help of ferric nitrate nonahydrate as a forerunner by wet impregnation method. Various techniques of characterization such as XRD and N2 adsorption-desorption isotherms were performed to confirm the presence of iron particles in the pores of the catalyst. These characterization methods were also used to examine the morphological properties and textural arrangement of the synthesized material. In the batch study of EF process, 750 mL working volume of RhB dye was taken. Anode and cathode used in the process were graphite electrodes respectively with effective area of 25 cm2 each. To maximise the process efficiency, the effect of initial pH, applied voltage, electrode spacing, the concentration of supporting electrolyte and Fe-SBA-15 dosage were investigated and optimized. The optimum conditions obtained were pH of 2, voltage of 8 V, an electrode spacing of 3 cm and Fe-SBA-15 dosage of 15 mg L-1. At the end of 3 h electrolysis, maximum RhB removal of 97.7% and TOC removal of 35.1% were achieved for 10 mg L-1 RhB concentration. In a batch study with real wastewater, 97% of color and 39% of TOC were removed at optimum conditions. Utilization of EF heterogeneous catalyst Fe-SBA-15 is an alternative technique for the elimination of dyes from solution.

Coplanarity driven fluorescence turn-on sensor for chromium(iii) and its application for bio-imaging.

New benzimidazole and benzothiazole derivatives (S1-S3) derived from thiophene-2,5-dicarboxaldehyde and 5,5'-bipyridyldicarboxaldehyde with NSN/SSS/NN binding sites were tested against various cations and anions. S3 showed selectivity toward copper(ii) ions among other cations under consideration with the colour change to pale yellow from colourless under aqueous medium. In the cases of S1 and S2, no colour change was observed. S1 alone showed selective fluorescence turn on for Cr(iii) ions among other cations. S1 showed sensitivity towards Cr(iii) with fluorescence change with bathochromic shift. The prominent fluorescence change of S1 with Cr(iii) ions was applied to live cell imaging of HeLa cells.

Gd2O3:RE³âº and GdAlO3:RE³âº (RE = Eu, Dy) Phosphor: Synthesis, Characterization and Bioimaging Application.

Citrate based sol­gel method is used to synthesize Gd2O3:RE³âº and GdAlO3:RE³âº (RE = Eu, Dy) phosphors. In the present work, the phosphors are characterized using the techniques like X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). Fluorescence confocal microscopy reveals the potential usage of phosphors in biological medium for biolabeling application. XRD patterns confirm the phase purity of Gd2O3 and GdAlO3. The crystallite size and lattice parameters are estimated from XRD result. FTIR spectra are used to investigate the functional group present in the phosphor. The optical emission properties imply that the emission peak positions on Eu³âº or Dy³âº ion are size and host independent. Finally, RAW 264.7 macrophages cell line is used to test the bioimaging performance of the phosphors.

Effect of Precursors on the Synthesis of CuO Nanoparticles Under Microwave for Photocatalytic Activity Towards Methylene Blue and Rhodamine B Dyes.

Copper oxide nanoparticles have been successfully synthesized by microwave assisted precipitation method. Different precursors like copper chloride, copper nitrate and copper sulphate were used for synthesis of CuO nanoparticles with different shape, size and catalytic activity. Sodium hydroxide acts as a capping agent and ethanol as solvent for the synthesis. The XRD study was conducted to confirm the single phase monoclinic structure of as-synthesized and annealed CuO nano particles. The morphology of the as-synthesized and annealed CuO samples was analyzed by high resolution field emission scanning electron microscope. Fourier transform infrared spectroscopy was done for all the synthesized CuO nanoparticles for functional group characterization. The wide band gap and photocatalytic activity were studied by UV-Visible spectroscopy. The photocatalytic degradation of Methylene blue (MB) and Rhodamine B (RhB) dyes in aqueous solution were investigated under UV light (254 nm). In all the cases annealed samples showed good catalytic activity compared to as-synthesized CuO nanoparticles. The CuO nanoparticles from CuCl2 precursor act as excellent photocatalyst for both MB and RhB compared to CuNO3 and CuSO4.

Synthesis, Characterization and Application of Cobalt Incorporated Mesoporous KIT-6 for the Visible Light Assisted Degradation of Methylene Blue.

Highly ordered mesoporous three dimensional la3d cobalt doped KIT-6 (Co-KIT-6) material was synthesized by the simple impregnation method and characterized by various physicochemical techniques such as X-ray diffraction, N2 adsorption-desorption isotherm, diffuse reflectance spectroscopy, Fourier transform infra-red spectroscopy and scanning electron microscopy. Larger pore diameter tuned with a narrow size distribution was observed for prepared Co-KIT-6. A series of Co-KIT-6 with different weight percentages solutions were prepared and the photocatalytic efficacy of the samples for degradation of methylene blue was studied under UV and visible light using UV-visible spectrophotometer. It was found that the catalytic activity depends on the amount of cobalt incorporated into the material. The complete degradation of dye was observed within 50 min. Different amount of catalyst and reaction time was considered for the optimization studies.

Band Gap Tuning of h-MoO3 Nanocrystals for Efficient Visible Light Photocatalytic Activity Against Methylene Blue Dye.

The photocatalytic degradation of methylene blue (MB) dye in aqueous solution was investigated using hexagonal molybdenum oxide (h-MoO3) nanocrystals under visible light irradiation. Chemical precipitation method was utilized to synthesize h-MoO3 and control over the crystal size, shape and distribution were characterized by using HNO3 and HCl as precipitating reagents. The photocatalysts were examined through X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectrum (EDX) for structural, functional, surface morphology and elemental analysis, respectively. The XRD results revealed that the samples were in single phase hexagonal crystal structure. XRD peak broadening analysis was used for crystallite size and strain estimation. The particles were anisotropic in nature and showed one dimensional (1-D) rod structure with hexagonal cross section. Further, the crystal phase stability, optical absorption and emission properties were studied by thermo gravimetric analysis (TGA), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) measurements, respectively. The photocatalytic results demonstrated that the photocatalytic activity of h-MoO3 synthesized using HCl was improved, in comparison to that of HNO3 utilized h-MoO3 sample.

Preparation of h-MoO3 and α-MoO3 nanocrystals: comparative study on photocatalytic degradation of methylene blue under visible light irradiation.

A detailed study on visible light photocatalytic degradation of methylene blue (MB) has been investigated in aqueous heterogeneous media containing hexagonal phase molybdenum oxide (h-MoO3) nanocrystals (NCs) which was identified as a new material for visible light driven photocatalysis. A simple and template-free solution based chemical precipitation method was employed to synthesize h-MoO3 NCs by reacting ammonium heptamolybdate tetrahydrate (AHM) with nitric acid. The formation and growth mechanism of h-MoO3 microstructures was explained. In addition, by annealing the h-MoO3 sample, the phase stability of hexagonal was retained up to 410 °C and showed an irreversible phase transition from hexagonal (h-MoO3) to highly stable orthorhombic phase (α-MoO3). Finally, the photocatalytic activities of h-MoO3 and α-MoO3 samples were evaluated using the degradation of MB, representing an organic pollutant of dye wastewater. The effects of various experimental parameters such as catalyst loading, initial dye concentration, light intensity, and operating temperature were analyzed for the degradation of MB. The results demonstrated that the efficiency of visible light assisted MB degradation using h-MoO3 NCs can be effectively enhanced by catalyst loading, light intensity, and operating temperature. However, the efficiency declined with the increase in initial dye concentration. Optimum conditions for higher photocatalytic performance were recognized as a catalyst loading of 100 mg L(-1), a dye concentration of 12 mg L(-1), a light intensity of 350 mW cm(-2), and an operating temperature of 45 °C.

Highly selective response of bipyridyl-incorporated acetyelene dye for zinc acetate.

In this paper, we prepared bpy-modified acetylene dye 2 that contains 2,2'-bipyridine moiety in the center with symmetrically substituted flexible derivatives at both ends. Upon exposure toward various metal salts, 2 revealed a highly selective optical response to Zn(2+) with AcO(-) as a counteranion, which is evidenced by large red shift and significant enhancement in emission intensity. Such a peculiar response to single zinc compound, as far as we are aware, has not been reported elsewhere. Compound 2 will find important usefulness in chemo-sensor application due to its highly selective binding to zinc acetate.

Synthesis and characterization of porous shell-like nano hydroxyapatite using cetrimide as template.

Macromolecules of various surfactants and polymers are being used to prepare nano hydroxyapatites (HAp) of varied morphology. Here we report the successful preparation of shell-like nano HAp spheres with fine morphology, uniform size around 200 nm, and stoichiometry ratio 1.7 with 56% nano- (<5 nm) and 44% mesoporosity using the surfactant tetradecyltrimethylammonium bromide (Cetrimide), which was not reported earlier. The critical micelle concentration (CMC) of Cetrimide was calculated as 3.88 mM at room temperature, and based on that, the other parameters of the experiment were determined. The experiment was conducted at ambient temperature and normal pressure without any temperature control, which was considered a crucial parameter in the earlier works. Thus, this method is suitable to bulk production of HAp. All the inspections confirm the successful preparation of shell-like nano HAp spheres that are suitable for biomedical applications.