title: 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.
authors: Department of Civil Engineering, Indian Institute of Technology, Kharagpur 721302, India.
authors: Sandip
authors: S
authors: Saha
authors: Anjali
authors: A
authors: Pal
authors: Subrata
authors: S
authors: Kundu
authors: Soumen
authors: S
authors: Basu
authors: Tarasankar
authors: T
authors: Pal
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000627:Aminophenols / Q000138:chemical synthesis / Q000737:chemistry; D002118:Calcium / Q000737:chemistry*; D002384:Catalysis; D005782:Gels / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009596:Nitrophenols / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D010777:Photochemistry; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000464:Alginates; D000627:Aminophenols; D005782:Gels; D009596:Nitrophenols; D012834:Silver; D006046:Gold; C026729:4-aminophenol; D002118:Calcium; C024836:4-nitrophenol