Eco-friendly synthesis and characterization of phytogenic zero-valent iron nanoparticles for efficient removal of Cr(VI) from contaminated water

Abstract

Zero-valent iron nanoparticles (ZVIN) are widely synthesized by several methods in the last decades because it offers indisputable advantages to almost every area of expertise, heavy metal ions removal, environmental remediation including for the wastewater treatment. Herein, we report for the first time, the green and eco-friendly synthesis of phytogenic ZVIN using reproducible Catharanthus roseus (CR) flower extract for the removal of heavy metal ions including Cr(VI) by adsorption isotherms. The synthesized stable ZVIN were characterized by UV-visible absorption spectroscopy (UV-vis), Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The FT-IR analysis reveals that the polyphenolic compounds that are present in the CR flower extract may be responsible for the reduction and stabilization of the ZVIN. The XRD and SEM-EDX analyses confirmed the phase, composition of elements and morphology of the ZVIN. The synthesized low-cost and non-toxic ZVIN used for the adsorption removal of Cr(VI) from contaminated water; and the Langmuir and Freundlich adsorption isotherms are used to study the adsorption process by the experimental equilibrium adsorption data. The maximum removal of Cr(VI) (98.28%) was observed using optimal conditions of 1.6 g/L of ZVIN concentration, 10 ppm of Cr(VI) concentration, and pH = 4.3 of the initial solution. The adsorption removal of Cr(VI) using the synthesized ZVIN as follows pseudo-second-order kinetic equation with a corresponding correlation coefficient of (R2 = 0.99).