Aryl diazonium-modified olive waste: A low cost support for the immobilization of nanocatalysts

There is a world demand for biobased materials in many areas of (nano) science and (nano) technology. In particular, one can benefit from the abundant agricultural waste residues to design high performance materials provided this is achieved through smart surface chemical processes. In this context, olive pit particles were modified with in situ generated aryl diazonium salts in organic medium to provide new functional materials. Various chemical functionalities were successfully anchored onto the olive pit surfaces, namely thiol (-SH), amine (-NH2) and carboxylic acid (-COOH) moities. The as-modified olive pits served for the immobilization of gold and silver metal nanoparticles (Au and Ag NPs) and selected olive pit/NP hybrids were evaluated as catalysts. Surface composition and morphology of the pristine, grafted and nanoparticle-decorated olive pit particles were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The hybrid materials were found to catalyse remarkably well the reduction of 4-nitrophenol to 4-aminophenol, taken as an example.