Novel Synthesis of Cu@ZnO and Ag@ZnO Nanocomposite via Green Method: A Comparative Study for Ultra-Rapid Catalytic and Recyclable Effects

A Facile Synthesis and Properties of Graphene Oxide-Titanium Dioxide-Iron Oxide as Fenton Catalyst

Textile industries discharge wastewater in huge amount that contains several toxic contaminants, especially organic dyes. Organic dyes present in wastewater have many adverse effects on environment as well as on living organisms including human beings. The generation of a nanocomposite to trap the toxic organic dyes from wastewater is highly recommended. Herein, we report the preparation of graphene-iron-titanium oxide (GFT) nanocomposite using simple, practical, and cost-effective protocol. The prepared tri-nanocomposite was successfully recognized by employing several analytical techniques. Morphology of the prepared nanocomposites was assessed by SEM coupled with EDS (energy dispersive spectroscopy). HRTEM was used to measure the size of the nanocomposites with shape and morphology. The UV-visible absorption spectra of the nanocomposites were recorded by a UV-visible spectrophotometer. Finally, the crystal structures of the nanocomposites were confirmed by XRD. Moreover, we proposed a plausible mechanism to demonstrate the catalytic activity of GFT oxide nanocomposite for the degradation auramine (AM) dye via a heterogeneous Fenton process.

Ag@ZnO/MWCNT ternary nanocomposite as an active and stable catalyst for the 4-nitrophenol reduction in water

The nitroaromatic compounds, known as organic pollutants, have arising attention due to their carcinogenic character, highly dangerous to human health. In this work, the Ag@ZnO/MWCNT ternary nanocomposite synthesized via conjugation of sonochemical and solvothermal treatments manifests high performance in the reduction of 4-nitrophenol in the aqueous media (TOF value of 246 min^-1μmol metal^-1). The incorporation of MWCNT onto the nanocomposite structure favored the reusing of the catalysts even after eight consecutive catalytic runs without catalysts cleaning nor product removal. Obtained samples were characterized by XRD, TEM, UV-vis, Raman and FTIR spectroscopies. It was found that ultrasonic treatment at relatively moderate conditions leads to functionalization of MWCNT, the appearance of C=C and OH groups and change of electronic properties of Ag@ZnO/MWCNT composite which provide its stable material dispersion in aqueous solution and high catalytic performance in the 4-nitrophenol reduction. This technique may be effectively applied for the functionalization of carbon including materials for their usage in an aqueous media.

Formation of Single-Walled Carbon Nanotube-Ruthenium Nanoparticles in Ethanol upon Microwave Radiation

In this work, an environmentally friendly microwave method was employed to rapidly synthesize a single-walled carbon nanotube-Ru nanoparticle (SWCNT-Ru) catalyst utilizing ethanol as the reducing agent. In general, the SWCNT-Ru nanoparticle catalyst facilitated the degradation of Congo red dye solutions, of both low and high concentrations, within eight minutes at room temperature, and possessed great recoverability and reusability properties. High-resolution transmission electron microscopy (HR-TEM) analysis of the SWCNT-Ru nanoparticle catalyst, which was synthesized with 0.05 wt. % RuCl₃ in ethanol, revealed highly dispersed Ru nanoparticles of the averaged size of 2.0 nm ± 0.5 nm onto the single-walled carbon nanotube bundles. Raman spectroscopy analysis indicated that there was no alteration to the nanotube structural framework upon the formation of the Ru nanoparticles. UV-Visible spectroscopy analysis indicated that the electronic properties of both smaller and larger diameters of SWCNTs were altered upon the coordination of the Ru nanoparticles. In addition, studies showed that when using ethanol as a reducing agent, concentrations of the RuCl₃ salt must remain below 0.10 wt. % to facilitate the production of Ru nanoparticles with efficient catalytic properties.