RESUMEN

Silver Oxide (Ag2O)-Guar gum nanocomposite was fabricated via a simple sonochemical co-precipitation method. The obtained photocatalyst was characterized with various techniques such as X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy and transmission electron microscopy along with energy dispersion X-ray spectroscopy. The findings have demonstrated that Ag2O nanoparticles are spherical of 5-20 nm and were dispersed on the surface of polysaccharide guar gum to form Ag2O-guar gum nanocomposite. The as-synthesized nanocomposite was enacted as a competent photocatalyst for the reduction of nitrobenzene and oxidation of benzyl alchohol. The conversion efficiency for the reduction of nitrobenzene was 96 % with the addition of sodium borohydride, and the conversion of benzyl alcohol was 98 %. The highly efficient photocatalytic activity was due to the exceedingly dispersed Ag2O-guar gum nanocomposite where effective separation rate of energy driven electron-hole pairs and stronger light absorption occurs. The possible mechanism of the reactions was implicated in understanding the active species involved in the photocatalytic study.

RESUMEN

A heterostructured Schiff base ligand (Benzildiethylenetriamine)-Silver-Guar gum encapsulated nanocomposites was intended to prepare by simple sonication assisted reflux method. Appropriate composition of purified guar gum, Schiff base ligand and silver nitrate were used for the synthesis. The synthesised nanocomposites were characterised by photoluminescence spectrum, UV-vis diffuse reflectance spectrophotometer, Fourier transform infra-red spectroscopy, X-ray diffractometer, scanning electron microscopy and transmission electron microscopy. The crystalline peaks of XRD and FTIR reveals that Schiff base ligand and guar gum forms metal-organic matrix. Morphology studies have confirmed the organic framework structure and metallic silver nanoparticles are embedded on the organic framework. The efficiency of nanocomposites depends on adsorption capacity and silver nanoparticles that are encapsulated thereby increasing the visible light absorption through surface plasma resonance. The nanocomposite was proved to be highly selective in hydrogenation reaction which favoured the formation of aniline from nitrobenzene as single product with short reaction time and 90% conversion.

Asunto(s)

Galactanos/química , Mananos/química , Nanocompuestos/química , Gomas de Plantas/química , Bases de Schiff/química , Plata/química , Compuestos de Anilina/química , Catálisis , Técnicas de Química Sintética , Galactanos/síntesis química , Hidrogenación , Luz , Mananos/síntesis química , Nanocompuestos/ultraestructura , Nanotecnología , Nitrobencenos/química , Gomas de Plantas/síntesis química , Bases de Schiff/síntesis química , Sonicación

RESUMEN

This study presents the synthesis of guar gum-zero valent iron nanocomposites (ZGNC) by a simple ultrasound co-precipitation method. The guar gum, one of the most cost effective due to ease of manufacture by extraction, abundant availability and high export value accounts almost 80% of total production in India. Guar gum, a natural polymer was used as binders in pharmaceutical formulations, and acts as a reducing and capping agent for the synthesis of zero valent iron nanoparticles (ZVI). The physicochemical properties of the ZGNC were characterized by TGA, FTIR, XRD, FESEM, EDS, HRTEM, DLS and XPS. The average particle size was ∼60-70 nm and the guar gum polymer on the ZVI were clearly visible from HRTEM. The XPS of ZGNC clearly confirms the elemental composition of the ZVI, guar gum and FeO. The 0.5 g/L ZGNC when used for the pollutants treatment, 15 ppm ciprofloxacin was adsorbed with a removal efficiency of 94% in 60 min at pH 4.0 whereas it had exhibited catalytic oxidation for 100 ppm methyl orange with an efficiency of 99% in 60 min at pH 7.0.

RESUMEN

In this present study, a facile and green method to synthesize highly stable Fe3O4-guar gum nanocomposite using ultrasound was reported. Thermal gravimetric analysis, fourier transform infrared spectroscopy, X-ray diffractometry, field emission scanning electron microscopy, energy dispersive spectroscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the crystal structure, size and morphology, elemental composition, metal-metal and metal-oxygen bonds of the synthesized nanocomposites. Fe3O4-guar gum nanocomposite with a size of ∼48nm was obtained as from TEM. The physicochemical characterization supports the feasibility of guar gum as an efficient stabilizing agent for the formation of nanocomposite; guar gum acts as a capping agent with a zeta potential value of -34.8 which was found to be beneficial for achieving lower particle size. Guar gum serves as a matrix for both reduction and stabilization of nanocomposite. The HR-TEM and XPS shows that Fe3O4 nanoparticles are encapsulated by the guar gum polymeric networks or Fe3O4-guar gum core-shell structure. The guar gum encapsulated magnetite nanocomposite has performed better in terms of catalytic activity for the liquid phase reduction of p-nitroaniline. The simple catalytic reduction of p-nitroaniline showed an efficiency of 47% and further exceptional improvement of up to 98% reduction within 60min with the addition of sodium borohydride was achieved. The sonochemical synthesis of Fe3O4-guar gum nanocomposite does not require stringent experimental conditions or any toxic agents, and thus, a straightforward, rapid, efficient and green method for the fabrication of highly active catalysts for treating environmental pollutants.