Photochemical Green Synthesis of Calcium-Alginate-Stabilized Ag and Au Nanoparticles and Their Catalytic Application to 4-Nitrophenol Reduction

Abstract

Silver and gold nanoparticles have been grown on calcium alginate gel beads using a green photochemical approach. The gel served as both a reductant and a stabilizer. The nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), energy dispersive X-ray (EDS), and selected area electron diffraction (SAED) analyses. The particles are spherical, crystalline, and the size ranges for both Ag and Au nanoparticles are <10 nm. It is noticed from the sorption experiment that the loading of gold on calcium alginate beads is much more compared to that of Ag. The effectiveness of the as-prepared dried alginate-stabilized Ag and Au nanoparticles as a solid phase heterogeneous catalyst has been evaluated, for the first time, on the well-known 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of excess borohydride. The reduction was very efficient and followed zero-order kinetics for both Ag and Au nanocomposites. The effects of borohydride, initial 4-NP concentration, and catalyst dose were evaluated. The catalyst efficiency was examined on the basis of turnover frequency (TOF) and recyclability. The catalytic efficiency of alginate-based Ag catalyst was much more compared to that of the Au catalyst. The as-prepared new solid-phase biopolymer-based catalysts are very efficient, stable, easy to prepare, eco-friendly, and cost-effective, and they have the potential for industrial applications.

A Brief Review on Nanoparticles: Types of Platforms, Biological Synthesis and Applications

“…Ag Intracellular Reduction [55] Fungi Fusariumoxysporum Ag Extracellular Reduction [56] Fusariumoxysporum Pt Extracellular Reduction [56] Fusariumoxysporum Au Intracellular Reduction [57] Aspergillusfumigatus Ag Extracellular Reduction [29] Verticillium sp. Au Intracellular Reduction [44] Plants Aspergillus avus Ag Extracellular Reduction [58] Acalyphaindica leaf extract Ag Extracellular Reduction [59] Medicagosativa seed exudate Ag Extracellular Reduction [60] Cymbopogon exuosus extract Au Extracellular Reduction [61] Live Alfalfa plants Au11 Intracellular - [62] Magnolia kobus leaf broth Ag Extracellular Reduction [63] Figure 2. Biological synthesis of nanoparticles and their applications [64] .…”

Catalytic Activity of BiVO4-graphene Nanocomposites for the Reduction of Nitrophenols and the Photocatalytic Degradation of Organic Dyes

“…1 Aromatic nitro compounds represented by nitrophenols and synthetic dyes are major water pollution sources, owing to their solubility, and biological and chemical stability in water. [2][3][4][5] Aminophenol is an important intermediate in the synthesis of analgesic and antipyretic drugs such as phenacetin, acetanilide and acetaminophen. 6 A reducing agent, aminophenol is also utilized as a photographic developer and as an anticorrosion lubricant in fuels.…”

Generation of alginate gel particles with AuNPs layers by polydimethylsiloxan template

“…1 According to their special optical, catalytic, and electrical natures, gold nanoparticles could be used in labeling, delivery, heating, and sensing, and have a great advantage for applications in biochemistry, cell biology, and medicine. 2 There have been numerous reports on utilization of AuNPs in tumor-targeting drug delivery, 3,4 biomolecular detection, 5,6 and medical diagnostics.…”

“…7 Alginate has been used as stabilizer, 8,9 but there were few report on biopolymer used as immobilization matrix for the metal ions such as Au 3+ . 1,10 The biopolymer matrix for the synthesis of gold nanoparticles shows great potential in biomedical applications. Alginate acid is a kind of biopolymer, which containing 1,4-linkeda-D-mannuronic and L-guluronic acid residues arranged randomly along the chain.…”

“…Alginate acid is a kind of biopolymer, which containing 1,4-linkeda-D-mannuronic and L-guluronic acid residues arranged randomly along the chain. 1 Based on its low cost and naturally occurring property, alginate gel has been widely used in food industry, biology, chemistry, and medicine. For example, this hydrogel might function as capsule for living organisms or drugs.…”