Efficient Reusable Gold-Mesoporous Silica Nanocatalysts for Aromatic Nitro Reduction: Role of Phenolic Chelating Ligands on Immobilizing Gold Nanoparticles and Catalytic Activity

Developing heterogeneous metal nanocatalysts is highly desirable since the catalyst can be easily separated and reused for several times. In this manuscript, we have immobilized gold nanoparticles (AuNPs) on the surface of mesoporous silica (SiO[Formula: see text] using simple amino acid-based phenolic chelating molecules and utilized as highly reusable catalyst for nitroarene reduction. The synthesized nanocomposites (Au@SiO2-1 and Au@SiO2-2) have been unambiguously confirmed using powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), high resolution-transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Interestingly, Au@SiO2-1 exhibited highly enhanced 4-nitrophenol reduction that was studied using absorption spectroscopy. Further catalytic activity of Au@SiO2-1 was also explored for 2-nitroaninline and 4-nitroaniline. The reusable studies demonstrated that the catalyst did not show significant change in the activity up to ten cycles. After catalytic reactions studies confirmed the strong attachment of AuNPs on the SiO2 matrix.

Silver doped SnO2 Nanostructures for Photocatalytic Water Splitting and Catalytic Nitrophenol Reduction

Driven by the quest of renewable and clean energy sources, researchers all around the globe are seeking solutions to replace the non-renewable fossil fuels to meet the ever-increasing energy supply...

Immobilization of Ag(0) nanoparticles on quaternary ammonium functionalized polyacrylonitrile fiber as a highly active catalyst for 4-nitrophenol reduction

Ag(0) nanoparticles were immobilized on various pyridine salt, imidazole salt and quaternary ammonium functionalized polyacrylonitrile fibers (PANFs) to prepare Ag(0)-immobilized fiber catalysts.

Sulfidation of Zero-valent Iron Nanoparticles for Environmental Remediation

<p>The ability of nano-sized zero-valent iron (nZVI) to remove environmental contaminants, from heavy metals to polyhalogenated hydrocarbons, has been well established. However, the reactivity of nZVI towards contaminants is hampered due to competing for side reactions with oxygen and water. Sulfidemodified nZVI (S-nZVI) has become a viable option as S-nZVI has been shown to reduce organic compounds such as trichloroethylene faster than nZVI while also maintaining an increased resistance to oxidation by water. The Fulton group has established that nZVI supported on a naturally occurring microsilicate (Microsilica600, or “misi”), from a Rotorua geothermal deposit, is capable of removing nitrates from water. This material, or nZVI@misi, minimises the potential bioaccumulation path that nZVI has, and is easier to handle than unsupported nZVI. This research investigated the effect of sulfidation of nZVI@misi (or S-nZVI@misi) on the reactivity towards the degradation of a variety of different potential contaminants. S-nZVI@misi was synthesised using sodium thiosulfate for sulfidation. Increasing the concentration of the reagent and sulfidation time from 3 hours to 24 hours resulted in high percentages of sulfur-to-iron (S/Fe) for each material. This increase in S/Fe had a significant impact on the removal of cadmium and chromium as with higher the percentage of S/Fe, the faster the removal of these species occurred. Compared to pristine nZVI@misi, S-nZVI@misi was significantly faster at removing both cadmium and chromium. However, sulfidation of nZVI@misi proved to reduce the rate of 4-nitrophenol reduction and prevent nitrate reduction from occurring. Experimental analysis also showed that cadmium removal was faster with S-nZVI supported by FeOOH-coated microsilica, compared to material supported by un-coated microsilica. Therefore, we have synthesised supported S-nZVI that quickly removes cadmium and chromium from solution compared to standard supported nZVI.</p>

Sulfidation of Zero-valent Iron Nanoparticles for Environmental Remediation

<p>The ability of nano-sized zero-valent iron (nZVI) to remove environmental contaminants, from heavy metals to polyhalogenated hydrocarbons, has been well established. However, the reactivity of nZVI towards contaminants is hampered due to competing for side reactions with oxygen and water. Sulfidemodified nZVI (S-nZVI) has become a viable option as S-nZVI has been shown to reduce organic compounds such as trichloroethylene faster than nZVI while also maintaining an increased resistance to oxidation by water. The Fulton group has established that nZVI supported on a naturally occurring microsilicate (Microsilica600, or “misi”), from a Rotorua geothermal deposit, is capable of removing nitrates from water. This material, or nZVI@misi, minimises the potential bioaccumulation path that nZVI has, and is easier to handle than unsupported nZVI. This research investigated the effect of sulfidation of nZVI@misi (or S-nZVI@misi) on the reactivity towards the degradation of a variety of different potential contaminants. S-nZVI@misi was synthesised using sodium thiosulfate for sulfidation. Increasing the concentration of the reagent and sulfidation time from 3 hours to 24 hours resulted in high percentages of sulfur-to-iron (S/Fe) for each material. This increase in S/Fe had a significant impact on the removal of cadmium and chromium as with higher the percentage of S/Fe, the faster the removal of these species occurred. Compared to pristine nZVI@misi, S-nZVI@misi was significantly faster at removing both cadmium and chromium. However, sulfidation of nZVI@misi proved to reduce the rate of 4-nitrophenol reduction and prevent nitrate reduction from occurring. Experimental analysis also showed that cadmium removal was faster with S-nZVI supported by FeOOH-coated microsilica, compared to material supported by un-coated microsilica. Therefore, we have synthesised supported S-nZVI that quickly removes cadmium and chromium from solution compared to standard supported nZVI.</p>