Engineering of silver nanoparticle fabricated poly (N-isopropylacrylamide-co-acrylic acid) microgels for rapid catalytic reduction of nitrobenzene

Ahmed

et al. 2016

Applied Organom Chemis

Self Cite

109

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 NaBH4 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.

Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Catalytic reduction of 4‐nitrophenol using silver nanoparticles‐engineered poly(N‐isopropylacrylamide‐co‐acrylamide) hybrid microgels

Ahmed

et al. 2016

Applied Organom Chemis

Self Cite

109

“…The maximum reduction of CR was found to be 95% at a permeation rate of 947 Lm −2 h −1 . Although, different metal nanoparticle (MNp) catalysts have been reported for CR reduction, naked MNps possess high surface energy due to which they coagulate rapidly and lose their catalytic activity . Various stabilizing systems like micelles, dendrimers, and microgels have been reported to prevent the aggregation and coagulation of MNps as well as to prolong their life span.…”

Section: Introductionmentioning

confidence: 99%

Silver Nanoparticles Engineered Polystyrene‐Poly(N‐isopropylmethacrylamide‐acrylic acid) Core Shell Hybrid Polymer Microgels for Catalytic Reduction of Congo Red

Naseem

Macro Chemistry & Physics

et al. 2018

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Polystyrene‐poly(N‐isopropylmethacrylamide‐acrylic acid) [pSty‐p(NIpmam‐AC)] core shell microgels loaded with silver nanoparticles (NPs) as a recyclable catalyst for rapid reduction of Congo Red (CR) dye in aqueous medium is reported for the first time. Catalytic activity of Ag‐pSty‐p(NIpmam‐AC) core shell composite microgels is measured by adopting the reduction of CR as a benchmark reaction. Restriction of Ag NPs in single layered p(NIpmam‐AC) shell of Ag‐pSty‐p(NIpmam‐AC) core shell composite microgels enhances the diffusion of reactants to access the Ag NPs, surface during reaction with respect to previously reported core shell and homogenous composite microgels, and thus enhances the rate of CR reduction. The solid nonresponsive pSty core induces easy recyclability in core shell composite microgel catalysts. The effect of different reaction parameters such as amount of catalyst, concentration of NaBH4 and CR on the reaction completion time for CR reduction, as well as on the value of apparent rate constant (kapp), is also studied by keeping all other parameters constant, separately. Reduction efficiency of Ag‐pSty‐p(NIpmam‐AC) catalyst is also measured under different reaction conditions for the reduction of CR. A slight decrease in the percentage activity of Ag‐pSty‐p(NIpmam‐AC) catalyst is observed for up to four cycles for CR reduction. The reported Ag‐pSty‐p(NIpmam‐AC) composite microgel catalysts can be used to degrade other pollutants.

Core‐shell microgel stabilized silver nanoparticles for catalytic reduction of aryl nitro compounds

Naseem

et al. 2020

Applied Organom Chemis

Silver nanoparticles loaded into shell of poly (styrene‐N‐isopropylmethacrylamide‐co‐acrylic acid) core shell [P (SNA‐CS)] gel particles were synthesized and analyzed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis) and dynamic light scattering (DLS). Catalytic activity of Ag@P (SNA‐CS) particles was investigated by reducing p‐nitroaniline (p‐NA) into p‐aminoaniline (p‐AA) in the presence of sodium borohydride (NaBH4) reductant. Molecules of the substrate adsorbed on the surface of silver nanoparticles interact with borohydride ions (BH4−) to form p‐AA. Other nitroarenes like o‐nitroaniline (o‐NA), p‐nitrophenol (p‐NP) o‐nitrophenol (o‐NP), 2,4‐dinitrophenol(2,4‐DNP) were also reduced into their corresponding aryl amines using Ag@P (SNA‐CS) composite microgels as catalyst. Reported catalyst efficiently reduced the nitro aromatic compounds individually as well as simultaneously at ambient temperature. Effect of different reaction conditions (catalyst dose, concentration of NaBH4 and concentration of p‐NA) on reaction completion time, value of apparent rate constant (kapp) and reduction efficiency of the catalyst for reduction of p‐NA was also demonstrated. Ag@P (SNA‐CS) catalyst was found to be able to retain activity up to four cycles.