Stabilized Ag nanoparticles loaded smart poly(chitosan-N-isopropylacrylamide-methacrylic acid) hybrid microgels for catalytic reduction of nitroarenes

Nitroarenes (NAs) are one of the most toxic pollutants in the water which cannot easily be eliminated. This challenge can be resolved with conversion of NAs into less toxic aryl amines (AAs) rapidly in the presence of a suitable catalyst. Therefore, poly(chitosan-N-isopropylacrylamide-methacrylic acid) P(ChS-NIPAM-MAA) P(ChNM) microgels were synthesized by microwave irradiations which were then fabricated with silver (Ag) nanoparticles (NPs) by in-situ reduction method and characterized with TEM, XRD, DLS, FTIR, and SEM techniques. The Ag-P(ChNM) hybrid microgels showed pH and temperature responsive behavior along with long time stability. The catalytic efficiency of Ag-P(ChNM) was evaluated for the reduction of 4-nitroaniline (4NiA) under different conditions such as concentration of NaBH4, temperature, content of Ag-P(ChNM), and 4NiA concentration. The Ag-P(ChNM) successfully converted different NAs into their corresponding AAs catalytically with high yields. The highest yield was obtained for 4-nitrophenol (4NiP) (99%) and the lowest for 2,4-dinitrophenylhydrazine (2,4DNiPH) (71%). Electron-withdrawing group containing derivatives of NAs rapidly reduced into AAs than electron-donating substituents. They exhibited excellent catalytic efficiency, stability, recyclability, and maintained their catalytic efficiency over multiple cycles. © 2024 Elsevier B.V.