Removal of fluoxetine by adsorption in a fixed-bed column using a hybrid cryogel based on sodium...

Removal of pharmaceuticals, particularly antidepressants, from aqueous environments using environmentally friendly adsorbents remains a challenge. This study developed a hybrid cryogel composed of sodium acrylate and carboxymethyl chitosan (NaPA-CMCs) through cryogelation and evaluated its effectiveness in removing antidepressants using a fixed-bed column. Fluoxetine (FLX) served as the target contaminant, with citalopram (CIT) and venlafaxine (VEN) used for competitive adsorption tests. The effects of pH, flow rate (Q), bed height (H), and initial concentration (C₀) on breakthrough curves were evaluated. FLX removal reached its highest level of 59.03% at pH = 8.5, H = 0.4 cm, Q = 1.5 mL/min, and C₀ = 10 mg/L. Competitive adsorption showed a higher affinity of FLX for the hybrid cryogel surface (9.98 mg/g) than CIT (4 mg/g) and VEN (2.17 mg/g). The pH_ZPC (7.1) of the hybrid cryogel, the pKa 9.8 of FLX, and the pH of the solutions explain electrostatic interactions between sorption sites and ionized FLX. The Thomas and Yoon-Nelson models fit the experimental adsorption data (R² > 0.97, RMSE < 0.062). Regeneration efficiency decreased to 17.8% by the fourth cycle due to alterations in the functional groups and damage to the porous structure of the cryogel during regeneration cycles. The NaPA-CMCs cryogel, therefore, shows potential for removing antidepressants from water.