A resorcinarene based chelating agent for selective cloud point extraction of Pb2+ ions in water: Synthesis, structural characterization and analytical applications

Using a sulfonate-functionalized C-iso-butyl-calix[4]resorcinarene as chelating agent, the method of cloud point extraction could be used to extract Pb2+ with high efficiency and selectivity from mixed metal solution. The method of cloud point extraction combined with inductively coupled plasma atomic emission spectrometry (ICP-OES) can be used for the determination of lead in water samples, which showed low detection limit, high recovery rate and good precision. [Display omitted] A sulfonate-functionalized C-iso-butyl-calix[4]resorcinarene was synthesized by the sulfomethylation reaction from calix[4]resorcinarene with formaldehyde solution and sodium sulfite. Sulfonatomethylated calix[4]resorcinarene (C4RS) adopts a symmetrical bowl-shaped conformation in solution and has four methylene sulfonate groups with flexible structure, which provide the possibility of trapping specific metal ions. C4RS is an excellentmetal chelating agent and recognizer with good water solubility in the surfactant solution. It is worth noting that C4RS shows selectivity of the Pb2+ ion over a variety of other competing metal ions such as Cr3+, Ag+, Cu2+, Co2+, Ni2+, Mn2+, Mg2+, Sb3+ and Cd2+. Using C4RS and Trtion X-114 as chelating and extractant agent, respectively, the procedure of cloud point extraction (CPE) could extract Pb2+ ion with high efficiency and selectivity. The method of CPE combined with inductively coupled plasma atomic emission spectrometry (ICP-OES) showed low detection limit of 0.0006 mg L-1, high recovery rate and acceptable precision, and could apply to the determination of lead in the tap water and lake water.