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.

Automated summary

In this study, lanthanum-modified kappa-carrageenan/sodium alginate aerogels were synthesized for the first time and used to remove ciprofloxacin hydrochloride pollution. The adsorption capacity of La/kappa-car/SA aerogels on CIP was influenced by the presence of microplastics, while humic acid and heavy metal ions did not have a significant impact on the adsorption.