Micro-nano structure nanofibrous p-sulfonatocalix[8]arene complex membranes for highly efficient and selective adsorption of lanthanum(iii) ions in aqueous solution

In this study, micro-nano structured p-sulfonatocalix[8]arene (calix8) complex membranes prepared by electrostatic adsorbing anionic calix8 onto the cationic nanofibrous mats with micro-nano structure were utilized as an affinity membrane for the selective adsorption of lanthanum(iii) ions, where the cationic nanofibrous mats were fabricated by wet-electrospinning technique from polyacrylonitrile (PAN) solution with the aid of pore-forming agent poly(vinyl pyrrolidone) (PVP) and followed by the amination with diethylene triamine (DETA). The as-prepared nanofibrous calix8 complex membranes were subject to selective adsorption of La(iii) ions in aqueous solution and showed very high adsorption capacity and selectivity for La³⁺ from other metal ions such as Fe³⁺, Al³⁺, Cu²⁺, Ca²⁺, Mg²⁺ and K⁺. The resultant membranes adsorbed with La(iii) ions could be desorbed and regenerated successfully without significantly affecting their adsorption capacity. The adsorption data at equilibrium were well fitted to Langmuir isotherm equation with a maximum adsorption capacity of 155.1 mg g^-1 for La(iii) ions. Furthermore, the possible adsorption mechanism of La(iii) ions onto the calix8 membrane was discussed based on the FTIR and XPS data. This study demonstrated a facile route for highly efficient and selective separation of lanthanide ions from aqueous solutions.