Amir Hossein Behroozi, Arghavan Mirahsani, Pascale Champagne, E. Hosseini Koupaie
Ibuprofen (IBP) is a pharmaceutical commonly released into water, where it poses environmental risks. Effective treatments must be developed to remove IBP from water. In this study, protonated epichlorohydrin-crosslinked chitosan beads (PECBs) were synthesized and characterized for the adsorption of IBP from aqueous solutions. Chitosan, a non-toxic and biodegradable biopolymer, was crosslinked with epichlorohydrin to improve acid stability (mass retention of 98 %), which also reduced the equilibrium water content (20 %) and created a mesoporous structure (2–12 nm) favorable for adsorption. Optimal adsorption conditions were achieved at neutral pH and 1.00 g IBP/L concentration, with a maximum adsorption capacity of 232 mg IBP/g PECB and followed by the Langmuir model (sum of squared error ( SSE) = 104, coefficient of determination ( R 2 ) = 0.998). Adsorption kinetics data showed a rapid initial adsorption phase (<60 min) followed by a slower approach to equilibrium at 12 h. Adsorption kinetics were best fitted by the Avrami model ( SSE = 1.90, R 2 = 0.999), indicating a mixed adsorption process involving both physical and chemical interactions. The strong fit of this kinetic model suggests that chemisorption contributes considerably to the overall rate of adsorption, whereas electrostatic attraction governs the extent of adsorption under specific pH conditions. At pH > pK a (4.9), the negatively charged IBP molecules interact electrostatically with the protonated amino groups on PECBs, whereas at pH < pK a , hydrogen bonding becomes more prominent due to the neutral form of IBP. PECBs retained ~85 % of their adsorption capacity after four reuse cycles, indicating a potential for reusability. Leaching tests revealed no detectable release of potentially toxic epichlorohydrin into the water. These findings suggest that PECBs are effective adsorbents for removing anionic contaminants, such as IBP, from aqueous environments.