Simultaneous adsorption of cobalt ions, azo dye, and imidacloprid pesticide on the magnetic chitosan/activated carbon@UiO-66 bio-nanocomposite: Optimization, mechanisms, regeneration, and application

In this study, the modification of magnetic chitosan/activated carbon bio-nanocomposite (MCS/AC) with UiO-66 MOFs (MCS/AC@UiO-66) was carried out, and the obtained bio-nanocomposite was applied as an efficient adsorbent for the ultrasound-assisted simultaneous adsorption removal of cobalt (II) ions (Co (II)), malachite green (MG) dye, and imidacloprid (IMI) pesticide from aqueous solution. Assessing the possible interaction and optimization of process parameters including pH, sonication time, adsorbent mass and the concentration of adsorbates was carried out by response surface methodology based on central composite design (RSM-CCD). The isotherm experimental data were demonstrated to be great fitted with Langmuir isotherm model, and the maximum capacity values of adsorption in a ternary medium were 44.5 mg g(-1), 62.1 mg g(-1), and 25.2 mg g(-1) for Co (II), MG, and IMI, respectively. A better description of the adsorption process was provided by using pseudo-second-order model, meaning that chemical adsorption controlled the process. In addition, the thermodynamic parameters illustrated that the adsorption of all contaminants occurred spontaneously and endothermically. MCS/AC@UiO-66 demonstrated to be a superb reusable adsorbent with a high adsorption capacity even after four adsorption-desorption cycles for the removal of all contaminants from various real wastewater samples. It was concluded that MCS/AC@UiO-66 with excellent properties, such as eco-friendly, easy synthesis, cost-effectiveness, fast adsorption kinetic, high adsorption efficiency, simple magnetic separation, and excellent reusability, could be considered as a promising candidate to remove a wide range of contaminants from wastewaters.

Automated summary

In this study, a magnetic chitosan/activated carbon bio-nanocomposite was modified with UiO-66 MOFs and used as an adsorbent for the simultaneous removal of cobalt (II) ions, malachite green dye, and imidacloprid pesticide from water. The adsorption process was optimized using response surface methodology, and the adsorption capacity and kinetics were evaluated. The results showed that the modified bio-nanocomposite had excellent adsorption performance and could be reused multiple times.