Green synthesis of Konjac glucomannan templated palladium nanoparticles for catalytic reduction of azo compounds and hexavalent chromium

Abstract

Palladium nanomaterials (PdNPs) have drawn significant attention due to their fascinating catalytic, optical, and electrical properties. PdNPs-catalytic hydrogenation is considered as an efficient way for the remediation of inorganic and organic pollutants. Thus, a simple Konjac glucomannan (KGM) reduced and stabilized PdNPs-catalysts were green synthesized without using any toxic reagents. The maximization of PdNPs production was investigated using a factorial design of experiments, where one variable (precursor ratio, solution pH, reaction time, and temperature) was studied at a time. The surface plasmon resonance (SPR), morphology, crystallinity, particle size distribution, composition spectra, and stability of as-synthesized PdNPs were explored in detail. Results revealed that the particles are mostly in spherical shapes, smaller in size (6.48 ± 2.19 nm) with a narrow distribution, highly crystalline (d–spacing = 0.224 nm), well stabilized (zeta potential = −17.89 mV), and coated by thin KGM layer of cladding. The type of oxidant and temperature-dependent catalytic degradation of six azo dyes and detoxification of hexavalent chromium [Cr (VI)] was studied. The as-synthesized PdNPs-catalyst demonstrate excellent performance in the formic acid (HCOOH)−induced catalytic reduction of such pollutants with the optimum at 45 °C temperature. We are optimistic that the insights on the behavior of reactant adsorption and reaction kinetics revealed in this study could be readily extended to other reaction systems and practically applied to wastewater treatment.