Fabrication and adsorption mechanism of chitosan/Zr-MOF (UiO-66) composite foams for efficient removal of ketoprofen from aqueous solution

Abstract

• The ultralight porous chitosan/(UiO-66) foams (CSF@UiO-66) were synthesized. • CSF@UiO-66 foam testified lightweight, good flexibility and high stability. • CSF@UiO-66 foam could efficiently remove ketoprofen (KTP) from water. • DFT calculations were applied to reveal the adsorption mechanism. Porous chitosan/Zr-MOF (UiO-66) composite foams (CSF@UiO-66) were facilely prepared by grafting UiO-66 into polymerized chitosan using epichlorohydrin as the linking agent. The flexible foams with high loadings of UiO-66 exhibited low density (15.0 ∼ 23.4 mg/cm 3 ) and superior liquid–solid separation performance. The hierarchical pores and abundant functional groups contributed to the effective removal of ketoprofen (KPF) from water by the composite foams, achieving a maximum adsorption capacity of 209.7 mg/g at pH 4, outperforming most reported adsorbents. Batch adsorption experiments demonstrated that the adsorption of KPF could be described by the Langmuir isotherm and pseudo-second-order kinetic model. Importantly, the composite foams showed excellent performance even in the presence of some ions and good reusability for engineering applications. Furthermore, density functional theory (DFT) calculations revealed that the adsorption mechanism between the composite foams and KPF could be attributed to hydrogen bonding and π-π interaction. In essence, this work provides an innovative strategy for the fabrication of a blocky composite foam with high loadings of MOF for efficient adsorptive removal of KPF in liquids, which can overcome the disadvantages of agglomeration due to small particle size and poor stability of MOFs.