Mesoporous waste-extracted SiO2–Al2O3-supported Ni and Ni–H3PW12O40 nano-catalysts for photo-degradation of methyl orange dye under UV irradiation

Abstract

Rather than looking at wastes as “unwanted materials,” this study considers their potential positive value and explores the production of waste-based catalysts. Herein, mesoporous SiO₂–Al₂O₃ was prepared from both rice husk (source for silica) and waste aluminum foils using isophthalic acid as a textural modifier. X-ray diffraction and BET surface analyses of the as-prepared aluminosilicate demonstrated an amorphous structure with an average pore radius of 5.4 nm. The FTIR spectrum revealed the existence of SiO₂–Al₂O₃ interaction. To produce an efficient photocatalyst, Ni nanoparticles were subsequently loaded onto the aluminosilicate surface by reduction of NiCl₂ using hydrazine. Another catalyst, namely Ni–H₃PW₁₂O₄₀/aluminosilicate, with strong Brønsted acid sites was also prepared by impregnating the support with an aqueous solution of H₃PW₁₂O₄₀. TEM images of the as-prepared materials show that the aluminosilicate particles are slab-like, and the loading of Ni and H₃O₄₀PW₁₂ has conserved the morphology of the mesoporous support due to metal–metal interaction. The prepared catalysts were then employed in the purification of water throughout the photocatalytic degradation of methyl orange (MO) dye. The maximum MO adsorption on the surface of the prepared materials was first determined in the absence of UV radiation (dark). The photoactivity of the three materials under the effect of UV irradiation was then detected. The Ni/aluminosilicate catalyst exhibits highest rate of MO removal among the employed materials. A maximum removal of 86% was obtained after an irradiation time of 180 min using the catalyst at a dose of 3 g L⁻¹.