We presented a simple and efficient method for making a polymer–metal nanocomposite using various amounts of cobalt ferrite magnetic nanoparticles (CoFe2O4 MNp) with sulfonated waste polystyrene (SWPS) and utilized for Calcon dye degradation. The MNp was encapsulated with SWPS to avoid agglomeration and maintain its smaller size. ATR-FTIR, Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM), high-resolution transmittance electron microscopy (HR-TEM), atomic force microscopy (AFM) and solid UV were used to analyze the produced polymeric magnetic nanoparticles (SWPS/MNp). As the MNp loading increases, the average particle size decreases. For Calcon dye degradation, SWPS/MNp (20 wt%) was utilized with a smaller average particle size, and the structural changes were detected using a UV-Vis spectrophotometer. As a result, the Calcon dye’s characteristic absorbance peak at 515 nm was red-shifted to 536 and 565 nm after 5 min, resulting in a color shift from dark brown to light blue that could be seen with the naked eye. A strong linear correlation was found between the red-shifted absorbance and the concentration of dye solution over the range of 10–100 ppm under optimal conditions. The proposed dye degradation process is simple, efficient, and environmentally friendly and has been successfully used to purify organic azo-dye-containing water.

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The effect of non-magnetic core wire diameter and conductivity on giant magnetoimpedance (GMI) in composite wires has been investigated. Microstructure, magnetic and magnetoimpedance (MI) properties of a Permalloy (Ni 80 Fe 20 ) films electrodeposited on Cu, Ag and Nichrome wires have been investigated. Present results show that the magnitude of MI varies (from 611% to 31%) with both core-wire diameter (0.1 mm to 1.17 mm) and conductivity. Maximum MI (∼700%) and sensitivity (∼40%/Oe) is observed at 50 kHz for the NiFe film deposited on 100 μm Ag wire. The frequency (f max ) at which maximum in MI is observed depends on the effective conductivity of the wire. Further, from the model calculation we have shown that the skin depth (δ) at f max increases with the increase in core wire diameter of the composite wire and this in turn related to GMI. Therefore, from the present study we conclude that the MI parameters, such as, field sensitivity, MI and f max can also be tuned by choosing a suitable core-wire. These observations are in agreement with the results obtained from the numerical simulations.

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