Synergetic Effect of Ni-CuO Nanocomposites with Activated Carbon Synthesized from Zeamays Bark for the Removal of Methylene Blue Dye

Abstract

In this study, nanomaterial adsorbents including CuO, Ni-CuO, Ni-CuO/activated carbon (AC),
and Ni-CuO/zeamays bark (ZB) were synthesized and evaluated for the removal of methylene
blue (MB) dye from wastewater discharged by Anmol Paper Production PLC. Structural and
surface characterizations were performed using X-ray diffraction (XRD), Fourier-transform
infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and UV-visible
spectroscopy (UV-Vis). XRD analysis confirmed the formation of a monoclinic CuO phase, with
a reduction in crystal size from 34.26 nm (CuO) to 18.06 nm (Ni-CuO/ZB). SEM revealed a
porous, hair-like morphology in Ni-CuO nanocomposites. FTIR spectra indicated the presence
of OH and CO functional groups, enhancing adsorption potential. UV-Vis analysis showed a
bandgap reduction from 3.22 eV (CuO) to 2.10 eV (Ni-CuO/AC) and 1.75 eV (Ni-CuO/ZB),
suggesting improved visible light absorption. Batch adsorption experiments showed that Ni
CuO/ZB achieved the highest MB removal efficiency of 99.03% under optimized conditions: 110
ppm dye concentration, pH 12, 1.0 g adsorbent dosage, and 120 minutes contact time. The
adsorption process conformed to the Freundlich isotherm model and pseudo-second-order
kinetics (R² = 0.99), indicating multilayer adsorption and a chemisorption mechanism. Overall,
the Ni-CuO/ZB nanocomposite demonstrated superior performance, making it a cost-effective
and sustainable candidate for industrial wastewater treatment.