Comparison of Cytotoxicity and Photocatalytic Properties of Iron Vanadate Nanoparticles with Commercial Catalysts: For the Degradation of Microplastics and Bacterial Inactivation Application

Microplastics (MPs) and the development of associated antibiotic-resistant bacteria are of serious concern. Conventional water treatment methodologies do not sufficiently address the issue of MPs and MPs-attached bacteria. The photocatalytic process is a promising technique that utilizes solar light to generate HO^● radicals for the degradation of MPs and inactivation of microorganisms. In this work, the iron-vanadate (FeVO₄, IVAN) nanoparticles prepared by the coprecipitation and a subsequent freeze-drying technique were tested for their cytotoxicity and photocatalytic activity in the degradation of MPs and inactivation of bacteria. Cytotoxicity of the prepared IVAN catalyst showed moderate toxicity levels at a concentration of 12.5 μg/mL. Photocatalytic degradation of catalysts evaluated using attenuated total reflection infrared (ATR-IR) spectroscopy revealed the overall highest increase in the carbonyl index (CI) and peroxyl index (PI) for the IVAN nanoparticles compared with commercial catalysts. The scavenging experiments confirmed that HO^● and O₂ ^●- were the potential main reactive oxygen species produced during the photocatalytic process using IVAN. Furthermore, nuclear magnetic resonance (NMR) spectra proved an oxidative degradation of polystyrene (PS) MPs. Apparently, leaching of Fe and V ions closer to the acceptable toxicity levels was detected by using inductively coupled plasma optical emission spectrometry (ICP-OES). Interestingly, IVAN exhibited inhibition of the <i>Staphylococcus aureus</i> USA300 biofilm in both dark and light conditions. Therefore, our investigation of IVAN and commercial photocatalysts could give insights into the preparation of efficient catalysts for treating MPs and bacteria in water.