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Catalytic reduction of 4‐nitrophenol using silver nanoparticles‐engineered poly( N ‐isopropylacrylamide‐ co ‐acrylamide) hybrid microgels
Author(s) -
Begum Robina,
Farooqi Zahoor H.,
Ahmed Ejaz,
Naseem Khalida,
Ashraf Sania,
Sharif Ahsan,
Rehan Rida
Publication year - 2017
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.3563
Subject(s) - silver nanoparticle , dispersity , chemistry , poly(n isopropylacrylamide) , catalysis , thermogravimetric analysis , aqueous solution , reaction rate constant , nanoparticle , chemical engineering , polymerization , polymer , polymer chemistry , fourier transform infrared spectroscopy , dynamic light scattering , nuclear chemistry , copolymer , organic chemistry , kinetics , physics , quantum mechanics , engineering
Nearly monodisperse poly( N ‐isopropylacrylamide‐ co ‐acrylamide) [P(NIPAM‐co‐AAm)] microgels were synthesized using precipitation polymerization in aqueous medium. These microgels were used as microreactors to fabricate silver nanoparticles by chemical reduction of silver ions inside the polymer network. The pure and hybrid microgels were characterized using Fourier transform infrared and UV–visible spectroscopies, dynamic light scattering, X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry and transmission electron microscopy . Results revealed that spherical silver nanoparticles having diameter of 10–20 nm were successfully fabricated in the poly( N ‐isopropylacrylamide‐ co ‐acrylamide) microgels with hydrodynamic diameter of 250 ± 50 nm. The uniformly loaded silver nanoparticles were found to be stable for long time due to donor–acceptor interaction between amide groups of polymer network and silver nanoparticles. Catalytic activity of the hybrid system was tested by choosing the catalytic reduction of 4‐nitrophenol as a model reaction under various conditions of catalyst dose and concentration of NaBH 4 at room temperature in aqueous medium to explore the catalytic process. The progress of the reaction was monitored using UV–visible spectrophotometry. The pseudo first‐order kinetic model was employed to evaluate the apparent rate constant of the reaction. It was found that the apparent rate constant increased with increasing catalyst dose due to an increase of surface area as a result of an increase in the number of nanoparticles.