Exploration of Reactive Black 5 Dye Desorption from Composite Hydrogel Beads-Adsorbent Reusability, Kinetic and Equilibrium Isotherms

A low-cost adsorbent was prepared by using cherry stones powder and chitosan and used to retain Reactive Black 5 dye from aqueous solution. Then, the spent material was submitted to a regeneration process. Five different eluents (water, sodium hydroxide, hydrochloric acid, sodium chloride and ethanol) were tested. Among them, sodium hydroxide was selected for an advanced investigation. Values of three working conditions, namely the eluent volume, its concentration and the desorption temperature, were optimized by Response Surface Methodology-Box-Behnken Design. In the established settings (NaOH volume: 30 mL, NaOH concentration: 1.5 M, working temperature: 40 degrees C), three successive cycles of adsorption/desorption were conducted. The analysis performed by Scanning Electron Microscopy and by Fourier Transform Infrared Spectroscopy revealed the evolution of the adsorbent throughout the dye elution from the material. Pseudo-second-order kinetic model and Freundlich equilibrium isotherm were able to accurately describe the desorption process. Based on the acquired results, our outcomes sustain the suitability of the synthesized material as dye adsorbent and the possibility of efficaciously recycling and reusing it.

Automated summary

A low-cost adsorbent made of cherry stones powder and chitosan was used to remove Reactive Black 5 dye from water. The spent material was regenerated using sodium hydroxide as the eluent. Response Surface Methodology-Box-Behnken Design was used to optimize the eluent volume, concentration, and desorption temperature. The findings support the suitability of the synthesized material as a dye adsorbent and its potential for efficient recycling and reuse.