Microgels stabilized selenium nanoparticles: An efficient photocatalyst for dye degradation

Abstract

We developed selenium nanoparticle (Se-NP)-embedded poly-N-isopropylacrylamide (PNIPAM) hybrid microgel (nano-SeHMG) for the photodegradation of victoria blue (VB) dye in an aqueous medium. PNIPAM microgels were prepared by free radical precipitation polymerization, and Se-NPs were formed inside the polymer network using in situ reduction of selenous acid with NaBH₄. Surface characterization of bare Se-NPs, pure PNIPAM, and nano-SeHMG was conducted. Controlled-size Se-NPs, averaging 31 ± 4.8 nm, were embedded within the microgels, providing stability against agglomeration and resulting in a large surface area. Nano-SeHMG achieved 98 % degradation of VB dye in 80 min, compared to 23 % and 68 % degradation with pure PNIPAM and bare Se-NPs, respectively, under the same conditions. The photocatalytic reduction of VB followed pseudo-first-order kinetics with an apparent rate constant of 7.33 × 10^-3 min^-1. Factors such as contact time, catalyst dosage, initial dye concentration, temperature, and pH significantly influenced the catalytic performance of nano-SeHMG. The thermo-responsive behavior of microgels allowed tunable catalytic activity by adjusting the system temperature. The photocatalyst demonstrated excellent recyclability, making it a cost-effective material for dye degradation. Hybrid microgel-based photocatalysts offer a novel approach in designing smart materials for wastewater treatment.