Speciation analysis of inorganic selenium in wastewater using a highly selective cellulose-based adsorbent via liquid electrode plasma optical emission spectrometry.

Speciation of selenium (Se) is typically carried out using a sophisticated technique such as ICP-MS after preconcentration using an adsorbent; however, the separation and preconcentration of inorganic Se has not been realized in the solutions containing high concentrations of SO. A dithiocarbamate-modified cellulose (DMC) was used in this study for the selective extraction and preconcentration of inorganic Se in wastewater, with a portable liquid electrode plasma-optical emission spectrometry (LEP-OES) being employed for quantification. DMC was found to selectively and quantitatively adsorb selenite (Se) over a wide range of pH (1.0-8.0); however, less than 3.0% of selenate (Se) was adsorbed in a pH range of 3.0-11. Quantitative extraction of Se was achieved even in the presence of 3.5 mol L SO. The maximum sample volume from which 10 mg of DMC could quantitatively extract Se was found to be 500 mL. KOH (0.60 mL, 1.5 mol L) was found to quantitatively desorb Se retained on the adsorbent and yielded an enrichment factor of 833. The recovery of Se species from synthetic flue-gas desulfurization wastewater containing Se and Se at concentrations of 5.0 µmol L was 96.2 ± 1.8% and 105.8 ± 1.8%, respectively.