Electrospun nanofibers of polycaprolactone loaded with chitosan/carbon quantum dots composite for adsorptive removal of Cd(II) ions from wastewater: Adsorption, kinetics, thermodynamics, and BOX Behnken design.

The research focused on assessing the improvements in stability and effectiveness regarding the elimination of Cd(II) ions. Specifically, this study involved the development of a novel electrospun nanofibrous membrane composed of chitosan (CS), carbon quantum dots (CQDs), and polycaprolactone (PCL). The membrane's primary application is the elimination of Cd(II) ions, from aqueous solutions. By precisely fine-tuning the electrospinning process parameters, we succeeded in optimizing the membrane. The characterizations performed using FTIR, XRD, XPS, SEM and EDX confirm the successful formation of a robustly crosslinked CS/CQDs/PCL nanofiber membrane. This thorough investigation not only showcases the material's textural characteristics but also underscores its potential for various applications. The examination further analyzed the influence of numerous factors, such as dosage, pH, temperature, and initial concentration, by the adsorption mechanism. The research incorporated equilibrium assessments in conjunction with kinetic evaluations to evaluate the characteristics of adsorption. The results showed that the Langmuir isotherm model well captured the adsorption process and that it complied with pseudo-second-order kinetics values. The fact that metal adsorption rises with temperature indicates that endothermic reactions and spontaneous behavior are both features of the adsorption process. The data suggests that the most effective situations for the elimination of Cd(II) ions in water purification are characterized by a pH level of 6, a amount of 0.02 g of CS/CQDs/PCL per 25 mL, and an adsorption capability measured at 340.05 mg/g precisely for the Cd(II) ions solution. In order to enhance the efficiency of the adsorbent in Cd(II) ions elimination from water, it is crucial to consider multiple significant factors. Systematic trials using the Box-Behnken design and response surface methods, made possible by the Design-Expert software, demonstrated significant improvements in the adsorption efficiency. A thorough assessment of the adsorbent's reusability conducted over five consecutive adsorption and desorption cycles shows a high degree of consistency in its removal efficacy.