Growing Pd NPs on cellulose microspheres via in-situ reduction for catalytic decolorization of methylene blue

Dyeing industry highly contributes to environmental pollution and this needs to be addressed on priority. Pd NPs/CMs, a highly efficient and reusable catalyst for methylene blue (MB) decolorization, were fabricated by in-situ reduction method based on the cellulose microspheres (CMs). Pd NPs/CMs were characterized for the structure and catalytic performance by spectroscopic techniques such as SEM, EDS, XRD, IR, XPS, porosity, zeta potential, MS, and UV-visible spectroscopy, which all demonstrated that Pd NPs were distributed on the cellulose microspheres uniformly and exhibited excellent catalytic performances to decolorize a model organic dye MB in the presence of NaBH₄ with catalytic efficiency higher than 99.8%. More importantly, Pd NPs/CMs were proven to show excellent reusability for at least five cycles. Decolorization mechanism of MB, via the destruction of the chromophores (CN and S) of MB, was established with the help of MS combined with IR and XPS. Blank experiments using pure cellulose microspheres were carried out simultaneously to estimate the level of catalytic capacity achieved to Pd NPs/CMs. These materials proved themselves having great potential in large scale applications to treat dye-containing wastewater.