Deposition of Au nanoparticles on PDA-functionalized PVA beads as a recyclable catalyst for degradation of organic pollutants with NaBH4 in aqueous solution

Abstract

A highly active and recyclable catalyst for the deposition of Au nanoparticles on the surface of polydopamine-functionalized poly(vinyl alcohol) macroporous beads was fabricated through the oxidative polymerization of dopamine and in-situ reduction route. The morphology and structure of PVA-PDA@Au beads were characterized using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray power diffraction and N2 adsorption–desorption measurement. The as-prepared PVA-PDA@Au beads combined the advantages of PVA-PDA beads and Au NPs. PVA-PDA@Au beads exhibited enhanced catalytic activity towards the degradation of Rhodamine B (RhB) in the presence of NaBH4 with removal efficiency up to 99.5% in 5 min at an initial RhB concentration of 100 mg/L and a catalyst amount of 0.5 g/L. PVA-PDA@Au beads could be easily separated and recycled from the reaction system by simple filtration, and reused for the degradation of RhB in six consecutive cycles with a conversion of >99%. Moreover, the mechanism for the degradation of RhB by PVA-PDA@Au beads was proposed. In addition, the catalytic ability of PVA-PDA@Au beads was further studied to remove Tetrabromobisphenol A (TBBPA), in which approximately 100% TBBPA (initial concentration of 25 mg/L) was removed within 90 min. In practical application, RhB as a pollutant in river water was degraded rapidly by PVA-PDA@Au beads with removal efficiency higher than 94%. Thus, PVA-PDA@Au beads possessed high catalytic activity, fast reduction rate and good reusability as well as easy separation and simple preparation, endowing this catalyst with potential application prospect in the treatment of wastewater containing organic pollutants.