Lanthanum modification κ-carrageenan/sodium alginate dual-network aerogels for efficient adsorption of ciprofloxacin hydrochloride

Ciprofloxacin hydrochloride (CIP) is a kind of typical antibiotic, which would cause a potential hazard to natural water if discharged in a large amount. In this study, lanthanum-modified kappa-carrageenan/sodium alginate aerogels (La/kappa-car/SA) were successfully synthesized for the first time by the sol-gel method. And the removal of CIP from aqueous solutions was investigated using La/kappa-car/SA aerogels. The results showed that the adsorption followed the pseudo-second-order kinetic model and the Langmuir-Freundlich isotherm model. The adsorption equilibrium time was about 16 h and the maximum adsorption capacity was 179.97 mg g(-1). Coexisting microplastics had a synergistic effect with La/kappa-car/SA, thereby promoting the adsorption capacity on CIP. Humic acid and heavy metal ions had no significant effect on the adsorption of La/kappa-car/SA aerogels, whereas the ionic strength and strong acid/alkaline environment would inhibit the adsorption of CIP. Using HCl solution (pH = 2) as eluent, the desorption rate of CIP could reach 98% within 80 min. The breakthrough time of dynamic adsorption was positively correlated with the mass of adsorbent, and the dynamic adsorption curve was in accordance with the Yoon-Nelson model. Ciprofloxacin hydrochloride be removed by La/kappa-car/SA aerogels successfully through a mixed mechanism of electrostatic interaction, pi-pi electron donor-acceptor interaction, hydrogen bonding, and hydrophobic interaction. As a result, La/kappa-car/SA aerogels can serve as a kind of novel adsorbent that effectively reduces CIP pollution due to its availability, efficiency, stability, and no secondary pollution. (C) 2021 The Authors. Published by Elsevier B.V.