Polystyrene-supported triazoles for metal ions extraction: Synthesis and evaluation

- Engineered polymers were readily prepared from azidomethyl polystyrene using “click chemistry”.
- Chelating moeties were easily introduced as triazoles by selecting series of substituted alkynes.
- Metal chelating properties were compared with those of natural clays (raw and purified).
- Natural clays were more efficient for metal uptake for the five studied cations but not highly selective.
- Triazole bearing polymers were less efficient but for one polymer which was also selective for cadmium ion.

In order to prepare substituted polymers bearing functional groups to chelate metals for their application in extraction and/or depollution applications, Merrifield polymer was transformed into the known azidomethyl polystyrene. Click-chemistry based on copper (I)-catalyzed Huisgen's reaction was then used to form polymer-grafted 1,4-triazoles using a variety of synthesized substituted alkynes. These polymer-supported triazoles were then used to extract metals (Cd, Fe, Mg, Ni and Co) from aqueous solutions. A comparative study of metal extractions by these supported triazoles was made between the starting azidomethyl polystyrene and two natural clays taken from the Gafsa area (South-West Tunisia). Raw and purified clays from two Gafsa sites were found to extract metals quite well with almost no selectivity, except for lower fixations of cadmium and magnesium. The synthesized polymers were found to extract all metals with lower efficiencies than the clays. However, one of the polymer-supported triazole was found to extract selectively cadmium with a high efficiency, reaching the levels of the natural clays.

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