A novel morphological ion imprinted polymers for selective solid phase extraction of Cd(II): Preparation, adsorption properties and binding mechanism to Cd(II)

A Cd(II) ion-imprinted polymers (SOS@Cd(II)-IIPs) with specific recognition property and high adsorption capacity was synthesized on a novel spheres-on-sphere (SOS) particle surface. Then, the obtained SOS@Cd(II)-IIPs were characterized and applied in solid phase extraction (SPE) column for the preconcentration of cadmium in real samples. The affinity constant (K ITC ), reaction enthalpy (ΔH), and entropy (ΔS) of Cd(II) binding to monomers (3-mercaptopropyl trimethoxysilane, MPTMS) were also determined by isothermal titration calorimetry (ITC) to analyse their adsorption mechanism. The coordination binding of Cd(II) to MPTMS was demonstrated as an exothermic process with a high K ITC value of 1.60×10 5  M −1 and an enthalpy value of −9.54 kJ∙mol −1 . The binding reaction was mainly driven by both enthalpy and entropy, and can be completed spontaneously at any temperatures. The SOS@Cd(II)-IIPs synthesized on the SOS particle surface exhibited a maximum adsorption capacity of 41.212 mg∙g −1 for Cd(II). Meanwhile, the SOS@Cd(II)-IIPs also showed a specificity recognition ability for Cd(II) using analogues Cu(II), Pb(II), Cr(II), and Ni(II) as interference. In real samples, SOS@Cd(II)-IIPs based SPE can extract approximately 95–105% of Cd(II) with a RSD of 3.41%–8.12%, indicating that it could have wide application prospects in Cd(II) adsorption and detection.