(374f) Synthesis and Performance Appraisal of Palladium Nanoparticles Supported on Waste Macadamia Nutshell Biomass for Chromium(VI) Detoxification

Though South Africa boasts the largest production of chromium (Cr), the downside of this is environmental pollution, particularly by highly toxic Cr(VI), a well-known carcinogen. Its status as a global leader in the production of Macadamia nuts and palladium (Pd) affords the addition of Macadamia nutshells (MNS), a waste material in nut production, and palladium, a well-established catalyst, to the country’s pool of resources available for use in the mitigation of Cr(VI) pollution. In this work, Pd nanoparticles (PdNPs) were grown on the surfaces of polyethyleneimine(PEI)-grafted MNS granules by the impregnation tetrachloropalladate ions (PdCl4 2-) and subsequent reduction with hydrazine (Figure 1). The Pd functionalized biomass and its precursors were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. SEM revealed the successive formation of layers of the polymeric scaffolds and PdNPs while FTIR suggested straining of the nanoparticle anchoring functional groups and XRD indicated the formation of Pd with a crystallite size of 4.8 nm. The catalytic efficacy of the supported PdNPs in the reduction of Cr(VI) to less toxic Cr(III) in synthetic wastewater was tested. The reusability of the nanomaterial also evaluated. The supported nanoparticles effectively catalysed the reduction of Cr(VI) and appeared to be a promising catalytic material for the treatment of Cr(VI) contaminated aqueous wastes such as electroplating wastewater using formic acid, a clean reagent that yields environmentally benign carbon dioxide and hydrogen gas as by-products.