Adsorption, photodegradation, and selective removal of reactive red 2 dye onto cuprous oxide nanoparticles

Environmentally friendly nanoparticles are often utilized to remediate organic pollutants such as dyes in water bodies. Herein, we describe the adsorption and photocatalytic properties of Cu 2 O nanoparticles (Cu 2 ONPs) for the removal of reactive red 2 dye (RR2) from synthetic dye solutions. Cu 2 ONPs as an adsorbent is synthesized by direct precipitation method using sodium hydroxide with cupric chloride in the existence of ascorbic acid as a reducing agent. Scanning electron microscopy (SEM), X-ray diffraction (XRD), dynamic light scattering (DLS) and Fourier transform infrared (FT-IR) analysis were used to characterize the synthesized Cu 2 ONPs. SEM images show that the average size as-prepared of Cu 2 ONPs was determined to be 62.84 ± 11 nm with a homogenous cubic shape. The zeta potential of NPs was measured to be + 22 ± 5 mV with a hydrodynamic diameter of 147 ± 8 nm, according to DLS results. The nanoparticles exhibit excellent adsorption activity for RR2 solution (10–60 μg cm −3 ) at room temperature and pH 5. The RR2 dye adsorption on nanoparticles in the existence of dark and UV light conditions was investigated. Our results indicate that the removal percentage of adsorption in the dark is around 78% and in the light is about 90%. Adsorption behaviors of the Cu 2 ONPs adsorbent fit well with pseudo-second-order kinetic model and Langmuir isotherm. The Cu 2 ONPs were also found to be highly selective for anionic RR2 over cationic methylene blue dye, allowing facile separation of the two dyes from aqueous solutions of dye mixtures. The results also show that Cu 2 ONPs have good recyclability, indicating that they would be a cost-effective material with a considerable possibility in water treatment. Graphical abstract