Optimization of variables for cadmium and copper removal using magnetic nanocomposite

This study aims to investigate cadmium and copper ultrasound-assisted removal efficiency on a laboratory scale using a cobalt ferrite/activated carbon (COF/AC) composite as an adsorbent. For this purpose, the effect of four independent variables (i.e., composite amount, pH, heavy metal concentrations, and ultrasound radiation time) on the performance of the cadmium and copper removal was investigated. The COF/AC composite was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and vibrating-sample magnetometer (VSM). The SEM and XRD techniques showed the successful synthesis of the COF/AC composite. The COF/AC composite has a surface area of 659.4 m² g⁻¹, an average diameter of 3.6 nm, and a pore volume of 0.482 cm³ g⁻¹. In this study, R² ˃ 0.99 and Adj-R² ˃ 0.98 for both analytes signify a high agreement between the obtained laboratory data and the model-predicted data. The analysis results for heavy metal removal revealed the following optimal conditions: the composite content of 0.22 g, ultrasound radiation time of 22 min, concentration of 19 mg L⁻¹, and pH of 5. Under optimal conditions, the maximum removal efficiency reached 93.46% and 97.45% for cadmium and copper, respectively. The COF/AC composite reuse results showed no significant decrease in removal efficiency up to 4 times of use during the adsorption and desorption process. Analysis of real samples showed that the removal rates of cadmium and copper were 89.62% and 96.37%, respectively.