Cellulose nanofibrils/polyvinyl alcohol gel microspheres loaded with nickel nanoparticles as catalysts to reduce Cr (VI) by formic acid

In this work, banana peel was used as raw material to prepare cellulose nanofibrils; and then, cellulose nanofibrils/polyvinyl alcohol gel microspheres with a 3D network structure were prepared using reversed-phase suspension cross-linking. Nickel nanoparticles were prepared in situ by reducing nickel ions adsorbed in the gel microsphere network with sodium borohydride to obtain a loaded catalyst. The morphology, functional group structure, and surface elemental composition of the gel microspheres were investigated by various characterization tools. The gel microspheres allow excellent dispersion of the nickel nanoparticles and act as a catalytic vessel for the reaction, allowing the nickel nanoparticles to effectively contact the hexavalent chromium and the reducing agent, resulting in the great catalytic ability for the reduction of Cr (VI) by formic acid. Cr (VI) reduction to Cr (III) was in 25 min at room temperature with a rate constant of 0.3294 min⁻¹.