Mesoporous spongy Ni–Co oxides@wheat straw-derived SiO₂ for adsorption and photocatalytic degradation of methylene blue pollutants

The exploitation and employment of agricultural waste in polluted water treatment are one of the most important cost-effective approaches. Therefore, a novel mesoporous spongy adsorbent/photocatalyst was successfully synthesised through the grafting of nickel and cobalt oxides nanocomposites with wheat straw-derived SiO₂ (WSS). Nickel and cobalt oxides were added to enhance the functionality of wheat straw-derived SiO₂. This synthesis methodology presents a simplistic, cost-effective, and eco-approachable alternative to getting an adsorbent and photocatalyst for the adsorption and photocatalytic degradation of methylene blue (MB) pollutants from wastewater. The modified wheat straw-derived SiO₂ (MWSS) was characterised via XRD, SEM, EDX, TGA, FTIR, and nitrogen adsorption. Molecular dynamics computational calculations were performed to comprehend the ability of methylene blue to adjust the MWSS surface. The adsorption and photodegradation trials were performed to optimise the pH, contact time, initial MB concentration, and temperature parameters. The optimum removal conditions were as follows: pH 10, dose 50 mg, contact time 45 min, temperature 25 ± 2 °C, and UV lamp (70 W) for photocatalytic degradation process. The obtained data indicated that the mesoporous MWSS adsorbent/photocatalyst provided efficient adsorption capability (79%), significant photocatalytic performance (93%), and higher solidity during reusability as well. Furthermore, kinetics and isotherm models were checked to explain the MB removal mechanism using mesoporous spongy MWSS. This study suggests an efficient composite that contributes to getting rid of the MB pollutants from wastewater.