Egg Shell Modified with β-Cyclodextrin, as Green Adsorbent for Dyes from Synthetic Wastewater

In this research, egg shell (ESh) nanoparticles modified by glycine/β-cyclodextrin (ESh/Gly/βCD) and ethylenediamine/β-cyclodextrin (ESh/NH₂/βCD) were synthesized and used to remove crystal violet (CV), and malachite green (MG) dyes from synthetic wastewater. Different analytical techniques were used for characterization of prepared samples. The results indicated that ESh/Gly/βCD and ESh/NH₂/βCD have high adsorption efficiency for organic dyes such as other adsorbents. The kinetic studies exhibited that the research follows the pseudo-second-order kinetic model. Also, because the procedure follows the Freundlich and Elwich model, the surface adsorption process takes place on heterogeneous surfaces. According to the Weber–Morris kinetic model, intraparticle diffusion is a two-step and gradual process. Furthermore, the maximum adsorption capacity of CV, and MG dyes over ESh/Gly/βCD was calculated 94.58 and 103.09 mg/g, and onto ESh/NH₂/βCD was found to 101.19 and 101.55 mg/g, respectively. Moreover, the calculated thermodynamic parameters indicated that the adsorption method is endothermic in the first stage and exothermic in the second stage. Methanol was chosen as the adsorbents washing solvent for the recovery and reuse of nanoadsorbents and in the sixth consecutive adsorption–desorption process, the removal percentage of CV and MG dyes by ESh/Gly/βCD was 80 and 84%, respectively, and by ESh/NH₂/βCD was 84% and 90%, respectively. Finally, the ESh/Gly/βCD and ESh/NH₂/βCD nanoparticles can be considered as new nanosupports for the removal of various dyes from industrial wastewater.