Reduction of hexavalent chromium with colloidal and supported palladium nanocatalysts

The Cr(VI) pollutants are known to cause serious harm to the environment and human health. Chemical reduction is one of the efficient methods to eliminate the Cr(VI) pollutants. We synthesized polyvinylpyrrolidone-stabilized palladium (PVP-Pd) colloidal nanoparticles to catalytically reduce Cr(VI). The PVP-Pd colloidal nanocatalysts were active on the complete reduction of Cr(VI) to Cr(III) with a rate of 22.2 molCr/(molPd min) or a turn-over frequency (TOF) of 1,329 h−1 at pH 4.0 and 45 °C. Magnetic Fe3O4 support was used for recycling the palladium nanocatalysts. The as-prepared Pd–Fe3O4 catalyst was easy to be separated from the reaction system by simply applying an external magnet and it exhibited efficient and stable reduction performance even after eight recycles.