Photocatalytic Performance of Ag/Humic Acid Magnetic Nanoparticles for Degradation of Methylene Blue in Aqueous Medium.

The contamination of water as a result of the discharge of organic dyes from industrial facilities that process pharmaceuticals, textile fabrics, leather, and petrochemicals, is a significant concern. The water quality of the aquatic environment is mostly impacted by pigments, even in small amounts less than 1 mgL^-1 (Sharma et al. 2021). Methylene blue which is considered as mutagenic, toxic, and non-biodegradable, was selected as a model in this study to represent the azo-dye class. The undesired effects of dye contamination can be eliminated through the sustainable and eco-friendly remediation procedure of photocatalytic degradation. The properties and efficiency of the catalytic reaction are significantly influenced by the morphology of the catalyst. Mott Schottky measurements and chronoamperometry were employed to elucidate the electronic properties of a composite silver humic acid magnetic nanoparticle (Ag/HA MNP) with a core-shell structure. The nanoparticle was subsequently employed in the photocatalytic degradation of methylene blue. The indirect band gap energy was calculated as 1.82 eV by employing Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-DRS). The optimal parameters established in the study were used to maintain the effective photocatalytic degradation of methylene blue in an aqueous medium. Optimization studies for photocatalytic degradation of model dye-MB showed that the optimum degradation percentage (42%) was achieved rapidly in a short time period of 30 min with 0.06 g MNP in 10 mgL^-1 solution. The first-order rate constant was determined to be 4.4 × 10^-2s^-1. This study contributes to the literature by proposing Ag/HA magnetic nanoparticles which were synthesized and installed for the first time as a catalyst for the photodegradation of methylene blue in aqueous medium.