Elemental sulfur is produced as a byproduct of the oil refining industry. Although this sulfur has its applications, its rate of consumption falls far short of its rate of production. This excess has prompted an exploration into novel sulfur-based materials, notably, polymers formed by inverse vulcanization. Like sulfur, these polymers tend to be completely insoluble in water, placing severe limitations on its utility. This work explores the properties of the first water-soluble polymer produced by inverse vulcanization. Polymer structure was confirmed by H NMR and further characterized by DSC and GPC. Sulfur selectively adsorbs some toxic heavy metal ions according to the hard-soft acid-base theory. The charged monomer, diallyldimethylammonium chloride (DADM) grants the polymer solubility, thereby maximizing its interaction with aqueous metal ions. The reagents are polymerized for 6 hours in an oil bath at 160 °C, dissolved, then filtered. Poly(S-DADM) with 30, 50, and 70% by weight sulfur were created and tested for solubility. The p(S50%-DADM50%) was also tested with a variety of metal salts in aqueous solution at high concentrations to check for precipitation. Silver, lead, and cadmium were given particular focus, using sodium, calcium, and iron ions as controls to qualitatively determine selectivity. The salt solutions which showed precipitation were also measured quantitatively by atomic absorption spectroscopy to determine the metal binding capacity of the polymer. The selectivity, economy, and simplicity of p(S-DADM) has an advantage over current non-specific filtration methods by binding selectively to certain heavy metal ion contaminants.

Selective precipitation of toxic metal ions by charged polysulfide p(S-DADM)

ACS Spring Meeting 2021

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