Arvind Kumar

Microplastics (MPs) are persistent environmental pollutants of growing concern, threatening aquatic ecosystems worldwide. This study examined the influence of different pollution sources on the abundance, types, and polymer composition of MPs in two South African river systems, the uMsunduzi and Swartskop Rivers. Surface water and sediment samples were collected from sites impacted by industrial, wastewater, agricultural, and urban activities. Both rivers showed high MP contamination, with the highest concentrations detected in industrial and agricultural zones. Fibers dominated the particle shapes, while polyethylene (PE) and polypropylene (PP) were the most common polymers, alongside site-specific contaminants such as polytetrafluoroethylene (PTFE). Sediments generally contained higher MP concentrations and smaller particles than surface waters. These findings highlight the role of land use in shaping MP pollution profiles and the need for targeted mitigation strategies to protect freshwater systems.

In the current study, catalytic behaviour of La_0.5Sr_0.5BO₃ (B=Cu, Fe and Ni) perovskite-like catalysts synthesized by sol-gel method were examined in catalytic peroxidation of acrylic acid as a model organic compound and further characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The effect of various parameters such as catalyst dose, H₂O₂/acrylic acid molar ratio, temperature, pH and initial acrylic acid concentration on acrylic acid and COD removal was studied. The maximum acrylic acid and COD removal of 86.79% and 71.57% were observed at optimum operating conditions (e.g., La_0.5Sr_0.5CuO₃ catalyst dose = 600 mg/L, stoichiometric molar ratio of H₂O₂/acrylic acid = 1.5, pH = 3, temperature 65 °C and reaction time = 3 h). The ROS scavenging studies were performed to identify in-situ generated reactive oxidant species, e.g., hydroxyl radicals (^•OH), superoxide radicals (O₂^•־) and singlet oxygen (¹O₂) and treated with their respective quencher during catalytic peroxidation of acrylic acid. Acrylic acid removal kinetics was performed by first order and Langmuir-Hinshelwood kinetic models. The plausible degradation mechanism was proposed based on intermediates identified by GC-MS analysis during catalytic peroxidation of acrylic acid.