Simple and low cost dithizone-functionalized polymer membranes as a tool for mercury preconcentration and monitoring in aqueous bodies. Preliminary results using X-ray absorption near-edge structure (XANES)

Here the effectiveness of cation selective membranes, produced for divalent mercury (Hg2+) preconcetration from aqueous bodies, is examined. To this end, the behavior of PVC-based membranes, functionalized with dithizone for mercury complexation, is examined by means of Energy Dispersive X-ray Fluorescence (EDXRF) and total reflection - X-ray absorption near-edge structure (TXRF–XANES) techniques. In our previous works, we successfully immobilized dithizone on PVC-based thin film substrates, creating novel Hg-selective membranes, and identified the optimal experimental parameters affecting mercury sorption from water samples. Nonetheless, the question remains, to what extent dithizone is responsible for mercury complexation on the membrane surface, or it just improves the membrane’s active surface area thus simply improving the adsorptive effect. Using the EDXRF technique it appears that membranes functionalized with dithizone has a much higher efficiency (by up to threefold) in preconcetrating mercury from water matrices, compared to the non-functionalized membranes. Then, the membranes were also examined by means of TXRF–XANES and it was identified that indeed mercury-dithizone complex is produced on the membrane surface, which is responsible for the much higher mercury sorption, compared to the non-functionalized membranes. Also, the XANES mercury-dithizone spectrum is presented. Given polymer membrane simple manufacturing procedure and their low cost this study works towards establishing a new method for very low concentration mercury analysis (sub-ppb levels) as well as mercury collection from aqueous bodies, provided that the membranes are produced and used in large-scale routine works.