Acacia Gum Hydrogels Embedding the In Situ Prepared Silver Nanoparticles; Synthesis, Characterization, and Catalytic Application

Abstract

Hydrogels of Acacia gum (AG) were synthesized in the reverse micelle core of sodium bis (2-ethylhexyl) sulfosuccinate (AOT) in gasoline medium. The as synthesized hydrogels were used as template to prepare Silver nanoparticle (AgNPs) in situ via the reduction mechanism of NaBH4. The successful synthesis of bare hydrogels and AgNPs loaded nanocomposite hydrogels (AG–Ag hydrogels) were characterized through Fourier Transform Infrared spectroscopy, Thermal gravimetric analysis, Differential Scanning Calorimetry, Scanning Electron Microscopy, energy dispersive X-ray spectroscopy and Transmission Electron Microscopy, and Atomic Absorption Spectroscopy (AAS). Different feeds of the as fabricated GA-Ag hydrogels were used to catalyze the well-known reactions of 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), and Methyl Orange (MO) reduction in aqueous medium at ambient physical conditions. Remarkably, 1000 mg/L of AG–Ag hydrogels with reduced 4-NP and 2-NP into its counterparts, 4-aminophenol and 2-aminophenol in 24 min and 15 min, respectively at room temperature. Similarly, 1000 mg/L of AG–Ag hydrogels reduced MO completely within 25 min. The aforementioned catalytic reactions followed pseudo first order rate kinetics, and it was found that the value of rate constant (kapp) increased by increasing the catalyst amount which, thereby confirms the high conversion rate of the reactants. Schematic illustration of fabrication and catalytic action of AgNPs grown inside the pre-synthesized AG Hydrogel matrices.