Polymers blended peanuts activated carbon composite hydrogels fabricated Ag NPs as dip-catalyst for industrial dyes discoloration in aqueous medium

Abstract

Hydrogels are three-dimensional superabsorbent polymers with many biomedical, medicinal, and environmental applications. Single and double-networks carboxymethyl cellulose (CMC) and polyacrylamide (PAA) composites hydrogels were synthesized through freeze-thawing process, using formaldehyde. The CMC or PAA single and double networks were prepared by blending them separately with activated carbon (AC), and was designated as CMC-AC, PAA-AC, and PAA-CMC-AC. The Ag ions adsorbed by these hydrogels were chemically reduced with NaBH4 to zero-valent Ag nanoparticles (Ag NPs). The Ag NPs supported hydrogels were used as a dip-catalyst for the discoloration of dyes in the presence of NaBH4. It was observed that the experimental data is well-fitted in the zeroth order kinetics. For instance, the PAA-AC@Ag NPs indicated the highest rate constant of 2.9 × 10−1 and 4.2 × 10−1 min−1 Congo red (CR) and methyl orange (MO) dyes discoloration. The other hydrogels supported Ag NPs also exhibited strong catalyst activity, but PAA@Ag displayed the highest catalyst activity among the series. The FESEM images of the Ag NPs supported hydrogels suggesting some range of self-assemblies, and EDS gives elemental purity. FTIR and Raman spectroscopy indicated various functional groups of the catalysts. Similarly, the crystallite size and %crystallinity was calculated from XRD.