Fabrication of Magnetic Nanoparticles Integrated Carbon Matrix from Chrysopogon zizanioides Roots: Strong Dye Adsorption and Persulphate Assisted Photodegradation

Abstract

Activated carbon with magnetic nanoparticles was prepared from the roots of Chrysopogon zizanioides by impregnating the biomass with Fe³⁺ followed by carbonization in a muffle furnace. To assist the carbonization process, Zn²⁺ ions were also taken along with ferric ions during impregnation. The pH_ZPC, density of surface functional groups, surface acidity constants and advanced characterizations like FT-IR, N₂ adsorption-desorption isotherms, SEM with EDAX, DLS, XRD and VSM analysis were carried out. The adsorption and natural sunlight induced photooxidation of two cationic dyes, namely, methylene blue and rhodamine B in presence of potassium persulphate were studied by varying parameters like time, dye concentration, pH of the dye solution, amount of magnetic activated carbon and concentration of persulphate ions. The adsorption capacities of methylene blue and rhodamine B were found to be 5.97 and 0.96 mg/g, respectively. Photocatalytic oxidation of the dyes was very rapid in the presence of persulphate with the observed rate constants being 5.3 × 10^–3 min^–1 for methylene blue and 13.0 × 10^–3 min^–1 for rhodamine B. The magnetic activated carbon is found to be effective even after five successive degradation experiments.