Synthesis and Characterization of Silver Nanoparticles-Filled and Polyvinyl Alcohol-Grafted Copolymer Composites for Column Adsorption and Photochemical Degradation of p-Nitrophenol

Abstract

Polyvinyl alcohol (PVA), sodium polyacrylate, and polyacrylonitrile are very effective for stabilizing and controlling the size of nanoparticles. Thus, PVA was grafted to the copolymer of acrylonitrile (AN) and acrylic acid/sodium acrylate (AA/NaAA) using N,N′-methylenebisacrylamide comonomer–crosslinker (MBA). Silver nanoparticles (AgNPs) were synthesized in situ in the polymerization mixtures by reduction of AgNO₃ with ascorbic acid. These nanocomposites were characterized and used for the removal and photocatalytic degradation of p-nitrophenol (PNP) from water. Based on the Box–Behnken design of the response surface methodology, the nanocomposite prepared with the AN:NaAA/AA molar ratio/MBA wt.%/PVA wt.% of 5:1/0.5/2 and impregnated with AgNPs of 18–30 nm average size (noted as PVACP5Ag) showed the optimized results. PVACP5Ag showed the equilibrium batch adsorption (q_e, mg/g) of 240.93 from 50 mg/L PNP in water and a q_e of 36.2 in fixed bed adsorption at a feed inlet concentration (mgL⁻¹)/inflow rate (mLmin⁻¹)/bed height (mm) of 50/30/30. The same composite showed a degradation of 96% after 7 min of exposure to sunlight in the presence of NaBH₄ with a first-order rate constant of 0.3 min⁻¹ and 90.3% degradation after 110 min of exposure with a first-order rate constant of 0.01 min⁻¹ without any reducing agent.