Sorption of Se(IV) from Aqueous Solutions with Subsequent Determination by X-Ray Fluorescence Analysis

An approach to sorptive separation of Se(IV) from solutions on a new S,N-containing sorbent with subsequent determination of the analyte in the sorbent phase by the micro-X-ray fluorescence method is presented. The copolymethylenesulfide-N-alkyl-methylenamine (CMA) sorbent is synthesized using the "snake in the cage" procedure and has proven to be stable in acid solutions. Conditions for quantitative extraction of Se(IV) are determined: sorption in 5 M HCl or 0.05 M HNO3 solutions when heated to 60 degrees C with the time of phase contact of 1 h. The residual selenium content in solution is determined by inductively coupled plasma mass spectrometry (ICP-MS) using the Se-82 isotope. The absence of selenium losses is proved and the mechanism of sorption interaction under these specified conditions is proposed. The method of micro-X-ray fluorescence analysis (micro-XRF) with mapping reveals a uniform distribution of selenium over the sorbent surface. The possibility of determining selenium in the sorbent phase by micro-XRF is shown. When comparing the results with the results of calculations by the method of fundamental parameters, it is shown that, to obtain correct results of XRF determination of selenium in the sorbent phase, it is necessary to use standard samples of sorbates.