Preparation of polymer functionalized layered double hydroxide through mussel-inspired chemistry and Kabachnik-Fields reaction for highly efficient adsorption

A novel method for the fabrication of phosphorylated layered double hydroxide (LDH) based adsorbents was proposed, in which polydopamine and a-amino phosphonate chains were anchored onto the pristine LDH nanosheets by a combinatorial procedure of mussel-inspired chemistry and Kabachnik-Fields (KF) reaction. The modified LDH adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Various adsorption conditions, including contact time, pH, Cu2+ concentrations, and solution temperature was further investigated. Kinetics results revealed that the pseudo-second-order model can provide a better depiction of adsorption data. The modified LDH exhibited a better adsorption capacity towards Cu2+ owing to the introduction of oxygen-containing groups. Adsorption isotherms showed that the adsorption data can be well represented by the Langmuir isotherm model. The maximum adsorption capacity was calculated to be 105.44 mg g(-1). Thermodynamic results indicated that the adsorption features of Cu2+ on phosphorylated LDH nanocomposites were spontaneous and endothermic. The electrostatic attraction was proposed as the dominant adsorption mechanism. In summary, this work not only brings about a discovery of surface modification of LDH-based materials via an effective and versatile combinatorial method, but also provides new avenues to architecturally construct various multifunctional hybrid materials for many high-value applications, such as advanced oxidation technology, oxygen reduction reaction, photocatalyst, supercapacitor.