Applicability of Ni@ZnO polymer nanocomposite as an adsorbent for removal of methylene blue dye from synthetic wastewater: Batch studies and multilinear regression (MLR) modeling

Abstract

Synthetic organic dye such as methylene blue (MB) is non-biodegradable and highly toxic, released from textile wastewater. This work investigates the applicability of Ni@ZnO polymer nanocomposite for MB removal from the wastewater. To understand their differences before and after MB adsorption, composites’ surface morphology was characterized by various techniques including scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transformation infrared (FT-IR) and UV–Vis spectrophotometer. The adsorption mechanism of target pollutants by the composites was also studied based on isotherm and kinetic models. The correlation between the optimized conditions and the percentage removal was further studied by applying multi linear regression (MLR) model. At the same concentration of 100 mg/L, it was found that under optimized conditions of 1 g/L of adsorbent, pH 7.5, and 190 min of reaction time, about 94% and 98% of MB removal were attained, respectively. In spite of the promising results, treated effluents were still unable to meet the required discharge standards of less than 1 mg/L mandated by local legislation. Furthermore, the MB adsorption by the composite was based on attractive electrostatic interactions. Overall, this study not only provides insights into the adsorption efficiency, but also evaluates the recyclability and stability of the adsorbent, addressing key challenges in practical wastewater treatment. By integrating its novel aspects, this work contributes to a more nuanced understanding of the Ni@ZnO composite’s potential in environmental applications, distinguishing this work from existing literature on MB adsorption.