Adsorption kinetics, isotherms and mechanisms of three-component covalent organic polymer/sodium alginate beads for ciprofloxacin removal from aqueous solution

Ciprofloxacin (CIP), an important representative fluoroquinolone antibiotic, has been frequently detected in water sources, thus threatening aquatic organisms and human health. In this work, a porous three-component covalent organic polymer (SLEL-6) was synthesized through multi-component (MC) reaction systems for adsorptive removal of CIP from aqueous solution, followed by an encapsulation process to achieve SLEL-6/sodium alginate (SA) beads with boosted adsorption ability, reusability and recyclability. By virtue of the hierarchical porous natures, functional groups as well as pi-rich skeletons, SLEL-6 and SLEL-6/SA beads could deal with CIP contamination effectively. Moreover, the adsorption isotherms of CIP by SLEL-6 and SLEL-6/SA beads follow the Langmuir model showing high theoretical maximum adsorption capacities of 57.47 and 163.93 mg g(-1), respectively. Furthermore, the plausible mechanisms are proposed according to experimental studies of influencing factors, coupled with characterizations before and after adsorption. This work therefore highlighting the immense potential of COP-based SA composite beads as new-type globular adsorbents for eliminating fluoroquinolones from aqueous solution.