Effect of plant concentration on the green synthesis of Nickel Ferrite (NiFe2O4) nanoparticles for the photodegradation of methylene blue (MB) dye and Sulfamethoxazole pharmaceutical pollutant from wastewater

The increasing presence of hazardous organic pollutants, including dyes and antibiotics, highlights the need for environmentally friendly and sustainable photocatalysts for pollutant degradation. In this study, nickel ferrite (NiFe 2 O 4 ) nanoparticles were synthesized using Sutherlandia frutescens plant extract through a green hydrothermal method. The plant extract’s biomolecules operate as natural capping and reducing agents, providing an eco-friendly synthesis approach. Different extract masses (5 g, 10 g, and 20 g) were used to investigate how plant extract concentrations influence the structural and photocatalytic properties of NiFe 2 O 4 nanoparticles. XRD confirmed the synthesis of a crystallite spinel NiFe 2 O 4 nanoparticles, with crystallite sizes measured from the ranges of 41–52 nm. Among the samples, the 10 g S. frutescens -NiFe 2 O 4 displayed uniform distribution and reduced agglomeration of particles. It also exhibited the smallest crystallite size and enhanced surface area. Photodegradation of MB dye achieved 89% efficiency in 60 min, following pseudo-first-order kinetics. After five cycles, reusability tests confirmed high stability with 78% efficiency. Experiments using radical trapping revealed that holes (h + ) were the predominant reactive species responsible for dye removal. SMX degradation achieved a 58% efficiency in 120 min. Thus, these results demonstrate that S. frutescens -derived NiFe 2 O 4 is a promising, eco-friendly photocatalyst for wastewater treatment applications.