Cloud Point Extraction Method for Separation and Pre-concentration of Molybdenum and Zirconium Using Mixture of Surfactants from Natural Waters and their Determination by Spectrophotometry

A simple and environmentally friendly technique, cloud point extraction (CPE), has been developed to analyse Molybdenum (Mo(VI)) and Zirconium (Zr(IV)) in water samples using spectrophotometry. This method involves the use of a surfactant mixture composed of Triton X-114 (TX-114) and cetyltrimethylammonium bromide (CTAB). In this approach, Mo(VI) and Zr(IV) metal ions are complexed with Pyrogallol red (PR) and Chrome Azurol S (CAS), respectively. The metal complexes of Mo(VI) and Zr(IV) are heated to reach the cloud point temperature and extracted into the micellar phase. Several parameters, such as pH, ligand concentrations, surfactant concentrations (TX-114 & CTAB), equilibration temperature, and equilibration time, were optimized to enhance the efficiency of the extraction process. Using the optimized conditions, linear calibration graphs were established over the concentration ranges of 1.23 - 37.0 mu g L-1 for Mo(VI) and 8.05 - 112.78 mu g L-1 for Zr(IV). The detection limits for Mo(VI) and Zr(IV) were determined to be 1.24 ng mL-1 and 9.92 ng mL-1, respectively. The applicability of this method was successfully demonstrated in the analysis of Mo(VI) and Zr(IV) concentrations in river water and coastal waters, with recovery rates falling within the range of 87% to 101%