Green biosynthesized N-doped nickel ferrite chitosan-coated nanocomposite for high photocatalytic degradation of organic pollutants from wastewater

Emerging recalcitrant organic pollutants in wastewater impose a global environmental concern that necessitates creation of novel materials or treatment techniques. Various conventional methods were used for removal of organic pollutants, but photocatalytic mechanism is simply cost-effective and green approach. Herein synthesis of N-doped nickel ferrite chitosan-coated nanocomposite (N-NFC) via co-precipitation method using A. indica plant leaves-extract for degradation of Alizarin-dye (AR) and Metribuzin-herbicide (MTB). Powder X-ray-diffraction peaks and electron-microscopic-analysis verified the semi-crystalline nature of composite with 17.99 nm crystalline size, and spherical morphology showed the successful decoration of chitosan around metal oxide. Surface-area-analysis revealed mesoporous characteristics of N-NFC, with increased surface area (107 m²g^-1) and pore volume (0.0277 cc/g). Superparamagnetic behaviour of N-NFC composite verified by M-H curve of Vibrating-Sample-Magnetometric analysis with saturation magnetization (M_s) value 23.54 emu/g. Higher zeta potential (-45.7 mV) and lower band-gap (2.1 eV) values showed stability and high-photocatalytic-activity of composite. N-NFC exhibited maximum removal of AR (96 %) and MTB (92 %), at 10 mgL^-1 with 20 mg catalyst dose at pH ∼7 under 3 h sunlight-irradiation following 1st order-kinetics and Langmuir-adsorption-isotherm model. Radical trapping results suggested that ^·OH > O₂^· are dominant radical species in photocatalytic degradation of targeted pollutants.