Palladium nanoparticles stabilized on a novel Schiff base modified Unye bentonite: Highly stable, reusable and efficient nanocatalyst for treating wastewater contaminants and inactivating pathogenic microbes

Efficient decoration and characterization of highly catalytic, active Pd nanoparticles (NPs) onto a novel Schiff base modified Unye bentonite (UN-Sch) with high coordination performance of structurally defined 2-pyrro-laldehyde ligands against palladium ions (Pd NPs@UN) have been described. Amine modified UN/Pd NPs were fabricated via a facile multi-step approach without utilizing any additional reducing agents. To check the applicability of the synthesized Pd NPs@UN as highly active nanocatalysts in water and wastewater treatment, the reduction of highly toxic compounds such as 4-nitrophenol (4-NP), hexavalent chromium [Cr(VI)], Rhodamine B (RhB), potassium hexacyanoferrate(IID) (K-3[Fe(CN)(6)]) and conga red (CR) at ambient temperature in eco-friendly media has been investigated. The surface nature of Unye bentonite was altered after modification, leading to notable increase in the catalytic properties. The ensuing Pd NPs@UN demonstrated superior catalytic prowess (100% conversion within a few seconds for the aforementioned pollutants), excellent stability (similar to 4 months) and superior recyclability (similar to 96% yield after seven successive cycles). Notably, the present procedure is a clean and green one in which aqueous sodium borohydride (NaBH4) or formic acid (HCOOH) are used as reducing agents in the absence of any toxic reductants. Moreover, the results showed that Pd NPs@UN was effective against fungi and bacteria.