Structural, Optical, Dielectric and Magnetic Behaviour of Cu1-Xcoxo (X = 0.2-0.10) Nano-Composites and Their Applications in Efficient Removal of Cr (Vi) Ion from Water

Pure and Cu1-xCoxO (x = 2, 4, 6, 8 and 10) nanocomposites capped by polyvinylpyrrolidone (PVP) were synthesized by chemical co-precipitation method. The synthesized nanocomposites were characterized using powder X-ray powder diffraction (XRD), high resolution transmission electron microscope (HRTEM), energy dispersive X-ray (EDX) mapping, energy dispersive X-ray fluorescence (EDXRF), diffused reflectance spectroscopy (DRS), Fourier transfer infrared (FTIR), Brunauer-Emmett-Teller (BET), dielectric and vibrating sample magnetometer (VSM) measurements. HRTEM analysis confirmed the synthesis of small agglomerated and elongated nanoparticles with average crystalline size of ~12-30 nm. The monoclinic structure of synthesized materials was confirmed by XRD and FTIR measurements. The purity and successful incorporation of Co dopant atoms in CuO nanostructured were established from EDX mapping and EDXRF measurements. The optical properties were determined from the analysis of DRS spectra and results showed variable bandgap of ~2.03–2.56 eV. The VSM measurements showed week room temperature ferromagnetism in the form of small hysteresis loops for synthesized nanocomposites tailored by Co2+ ion substitutions and attributed to exchanged interaction between localised d-spins of Co2+ ions and electron/hole charge carriers. The dielectric properties viz. dielectric constants and dielectric losses of synthesized nanocomposites were studied in frequency range ~1 kHz–5 MHz and temperature range ~25 oC–300 oC. The observed variation in dielectric properties with frequency and temperature are attributed to relaxation processes resulting from inter-granular activities and grain boundary effects. The adsorption capacity of the synthesized materials for removal of Cr(VI) ions were evaluated for different initial Cr(VI) ion concentration and adsorbent dose at room temperature. The adsorption data was well fitted using Freundlich and Langmuir isotherm-model. The present experimental results confirm that synthesized Cu1-xCoxO (x = 0, 2, 4, 6, 8 and 10) multifunctional nanocomposites can be a credible candidate for spintronics, optoelectronics and efficient adsorbent for Cr (IV) ions removal from wastewater.