3D-macroporous chitosan-based scaffolds with in situ formed Pd and Pt nanoparticles for nitrophenol reduction. (15th July 2018)

• Record Type: Journal Article
• Authors: Berillo, Dmitriy; Cundy, Andrew
• Is Part Of: Carbohydrate polymers. Volume 192(2018)
• Page Start: 166
• Page End: 175
• Publication Date: 2018-07-15
• Subjects: Macroporous cryogels -- Chitosan -- Palladium nanoparticles -- Platinum nanoparticles -- Nitrophenol -- Catalysis; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2018.03.038
• Languages: English
• ISSNs: 0144-8617

Abstract

Graphical abstract: Highlights: Preparation of macroporous materials with in-situ formed Pd or Pt nanoparticles. Reduction of palladium or platinum complexes by glutaraldehyde. Physicochemical properties of cryogels based on chitosan and Pd or Pt nanoparticles. Catalytic activity of in-situ formed Pd or Pt nanoparticles for reduction of nitrophenol. Kinetic rates of nitrophenol reduction, turnover number and turnover frequency of immobilized nanoparticles. Abstract: 3D-macroporous chitosan-based scaffolds (cryogels) were produced via growth of metal-polymer coordinated complexes and electrostatic interactions between oppositely charged groups of chitosan and metal ions under subzero temperatures. A mechanism of reduction of noble metal complexes inside the cryogel walls by glutaraldehyde is proposed, which produces discrete and dispersed noble metal nanoparticles. 3D-macroporous scaffolds prepared under different conditions were characterised using TGA, FTIR, nitrogen adsorption, SEM, EDX and TEM, and the distribution of platinum nanoparticles (PtNPs) and palladium nanoparticles (PdNPs) in the material assessed. The catalytic activity of the in situ synthesised PdNPs, at 2.6, 12.5 and 21.0 μg total mass, respectively, was studied utilising a model system of 4-nitrophenol reduction. The kinetics of the reaction under different conditions (temperature, concentration of catalyst) were examined, and a decrease of catalytic activity was not observed over 17 treatment cycles. Increasing the temperature of the catalytic reaction from 10 to 22 and 35 °C by PdNPs supported within the cryogel increased the kinetic rate by 44 and 126%, respectively. Turnover number and turnover frequency of the PdNPs catalysts at room temperature were in the range 0.20–0.53 h −1 . The conversion degree of 4-nitrophenol at room temperature reached 98.9% (21.0 μg PdNPs). Significantly less mass of palladium nanoparticles (by 30–40 times) was needed compared to published data to obtain comparable rates of reduction of 4-nitrophenol.