Co-adsorption and Co-removal of Cu(II), Ciprofloxacin, and Norfloxacin from Water by a Modified Three-Component...

Organic pollutants and heavy metal ions (HMIs) are widely present in water systems. They often coexist in the environment and form more complex forms of pollution through complexation, thereby posing a serious threat to human health and the ecological environment. We successfully synthesized a three-component covalent organic framework (TpBD-SO₃H/OH) and functionalized it through the introduction of diethylenetriaminepentaacetic acid (DTPA). Eventually, a covalent organic framework material with dual DTPA/sulfonic acid functionalities (TpBD-SO₃H/OH-DTPA) was obtained. Subsequently, this material was applied to the co-adsorption and removal of ciprofloxacin (CIP), norfloxacin (NOR), and Cu(II). The experimental results demonstrated that the maximum adsorption capacities of TpBD-SO₃H/OH-DTPA for CIP, NOR, and Cu(II) were 424.5, 392.4, and 513.7 mg g^-1, respectively. In addition, we systematically carried out adsorption experiments and characterization analyses, and based on density functional theory (DFT), theoretical calculations were conducted on the minimum repeating unit of TpBD-SO₃H/OH-DTPA and its possible adsorption configurations. The influence of the addition sequence of pollutants on the adsorption behavior was deeply explored, thereby verifying the specific adsorption mechanism of pollutants on the surface of the adsorbent. TpBD-SO₃H/OH-DTPA can maintain stable adsorption performance under different environmental factors and can maintain the stability of the adsorption effect after five adsorption-desorption cycles. This study provides useful insights into the co-adsorption behavior of a modified covalent organic framework.