PH-controlled solid-phase enrichment of Mn(II): confirmation of the structure of the extracted ternary Mn(II) complex by single crystal X-ray structure analysis

Abstract

Trace-level (μg g−1) selective separation of Mn(II) from other associated metal ions have been carried out by impregnating equimolar mixture of pyridine-2, 6-dimethanol (PDM) and thiocyanate ion on silica. The sorbent showed maximum Mn(II) sorption capacity (1.23 mmol g–1) at pH 5.0. Mn(II) was completely eluted by 8.5 mL 1.0 mol L−1 HNO3 from 1.0g sorbent and subsequently measured with flame atomic absorption spectrometer (FAAS).The structure of the extracted Mn(II) complex was established by Fourier transform infrared red spectra and confirmed by single crystal X-ray structure analysis. Thermogravimetric analysis (TGA) shows the stability of the isolated Mn(II) complex at the extraction temperature. Three sigma detection limit (N = 10) of the method was 0.6 μg mL−1 with a relative standard deviation of 0.1% (N = 10). The method has a pre-concentration factor of 105. Marginal interference from Cu2+ has been masked with NH4SCN. The developed method has been tested for trace-level separation and estimation of Mn(II) in spiked water samples.