Influence of silver nanoparticle deposition on self-assembled thin films of weak polyelectrolytes/TiO2 for bezafibrate photodegradation through central composite experimental design

Abstract

This study evaluated, through a central composite experimental design, the influence of silver nanoparticles (AgNPs) deposition, synthesized at different pH and silver concentration [Ag+], on the photocatalytic efficiency of self-assembled thin films (SATFs) of poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA) and TiO2 over bezafibrate (BZF) drug. The SATFs were produced by dip coating on glass substrates using the layer-by-layer technique and were characterized by ultraviolet and visible absorption spectroscopy, scanning electron microscopy with a field emission gun and energy dispersive spectroscopy. The results revealed that the SATF that represents the optimum point of the central composite design (pH = 7.0 and [Ag+] =0.46 mmol L−1) reduced the initial concentration of BZF by 81.4 %. The presence of AgNPs on the polyelectrolytes/TiO2 thin film was responsible for an increase of 64 % in its photocatalytic efficiency when compared to the film containing only polyelectrolytes and TiO2. Silver is present mostly in the form of nanoparticle agglomerates with sizes under 90 nm. Moreover, the optimized SATF showed no reduction in its photocatalytic efficiency after four reuse cycles. Finally, the data set showed that the SATFs of this work possess a high potential for photo-oxidation, which makes them attractive for domestic and industrial wastewater treatment.