A hybrid mesoporous CuO@barley straw-derived SiO2 nanocomposite for adsorption and photocatalytic degradation of methylene blue from real wastewater

In this article, we have reported synthesizing a novel mesoporous CuO@barley straw derived SiO2 (CuO@BSS) as a photocatalyst and adsorbent for methylene blue (MB) removal from aqueous media. Silica nanoparticle as a platform was prepared from barley straw, then modified by grafting of CuO nanoparticles. Our strategy represents a significant development in recycling agricultural waste, such as barley straw, offering a cost for effective photocatalyst and adsorbent. The as-prepared CuO@BSS nanocomposite was characterized using FE-SEM, EDX, TEM, XRD, FT-IR, TGA, and N2 adsorption-desorption. The effect of the pH, CuO@BSS dosage, temperature, time, and initial MB-concentration was systematically investigated. Furthermore, isotherm, kinetic and thermodynamic of MB-removal were also studied. The obtained results indicated that MB-photodegradation is a more convenient method in removing MB than the adsorption process onto mesoporous CuO@BSS nanocomposite at pH 10, where 90% and 99% of MB-dye were removed through adsorption and photodegradation techniques, respectively. The calculated values of ∆G°, ∆H°, and ∆So indicate adsorption's spontaneous and endothermic behavior. The prepared CuO@BSS nanocomposite is a promising candidate for removing MB from real water samples even at high MB concentrations or even after multi-reuse cycles.