Stover ash - extracted mixed oxides surface-doped with Ni for photo-degradation of water organic pollutants

Abstract

ABSTRACT The mesoporous catalytic composite material was prepared from both stover ash (as a source of mixed oxides) and treated rice straw with very low residue on ignition (as a pore-capping agent). X-ray diffraction and BET surface analyses of the as-prepared mesoporous mixed oxides (MMO) exhibited a partially crystalline structure with an average pore diameter of 16.4 nm. To modify the optical properties, Ni nanoparticles were loaded onto the MMO surface via the reduction with hydrazine. Both MMO and the modified material, namely Ni-MMO, were investigated by HR-TEM, IR, X-ray diffraction, BET surface analyses, XPS, PL spectra, and UV-Visible reflectance measurements. In a good agreement, all tests confirmed that Ni nanoparticles interacted with oxides on the surface with restructuring and a new potential crystal system. XPS revealed that Ni generates surface oxygen vacancies (SOV) which induced sub-band levels to stabilise e-/h* pairs. Ni-MMO with low PL intensity showed a high photocatalytic activity in degradation of Rhodamine B dye with a maximum of 99.1% after 180 min under visible irradiation and catalyst dose of 1 g L−1. The reusability test for Ni-MMO exhibits the catalyst stability in four consecutive cycles.