Utilizing Reclaimed Petroleum Waste to Synthesize Water-Soluble Polysulfides for Selective Heavy Metal Binding and Detection

Abstract

Many industrial processes produce waste with toxic and precious metal pollutants. Current remediation strategies lack the selectivity needed to effectively eliminate heavy metals. Thus, materials are needed to effectively treat waste streams and contaminated waterways. Sulfur is well known for its ability to selectively bind heavy metals. Additionally, excess sulfur is produced on large scales during petroleum refinement making it inexpensive and abundant. Inverse vulcanization enables surplus sulfur to be repurposed into high sulfur content materials without the need for solvents. These polysulfides have demonstrated many beneficial applications including heavy metal binding. However, they are plagued by low solubility and dominated by hydrophobic monomers. Here, elemental sulfur and charged monomers, including diallyl dimethylammonium chloride (DADMAC), were combined for the first time in a one-step reaction forming water-soluble polysulfides. The water solubility allows for complete interaction of dissolved metal ions with the polymer, rather than surface-level interaction as is the case for traditional inverse vulcanized polymers. Additionally, the charged polysulfides exhibit enhanced solubility in organic solvents, making solution-based characterization such as NMR more accurate. Poly­(S-DADMAC) has demonstrated selective binding to gold and silver inducing the formation of a macromolecular complex that precipitates from solution. Additionally, these polymers interact with other heavy metals including lead and copper demonstrating a visible color change at low concentrations that may be used to detect the presence of these metals in wastewater. The low cost, ease of preparation, and scalability make these polysulfides practical as well as functional.

A comparison of adhesive polysulfides initiated by garlic essential oil and elemental sulfur to create recyclable adhesives

“…8 This method expanded rapidly due to the synthetic ease, scalable synthesis, and adherence to many of the principles of green chemistry due to sulfur acting as the solvent, initiator, and monomer, yielding high atom economy and limiting waste production. 9 Inverse vulcanization has been used to create materials for a wide range of applications including cathodes, 8,10,11 infrared optics, [12][13][14] and water purification, [15][16][17][18][19][20][21] among others. [22][23][24][25][26][27][28] In a prior report we described the first adhesives formed by inverse vulcanization by combining elemental sulfur with garlic essential oil (GEO).…”

Modelling mercury sorption of a polysulfide coating made from sulfur and limonene

“…8,10 Additionally, there has been a resurgence in methods to make polymers from sulfur, [11][12][13][14][15] which has created many opportunities for using these low-cost and scalable polymers in mercury and heavy metal remediation. 8,[16][17][18][19][20][21][22][23][24][25][26][27] In this study, we investigated one of these sulfur polymers made by direct copolymerisation of elemental sulfur with the renewable terpene limonene. Our lab first reported the synthesis and use of this material in mercury remediation in 2015, 28,29 describing its advantageous features.…”

“…8,10 Additionally, there has been a resurgence in methods to make polymers from sulfur, 11–15 which has created many opportunities for using these low-cost and scalable polymers in mercury and heavy metal remediation. 8,16–27…”

Modelling mercury sorption of a polysulfide coating made from sulfur and limonene

“…7,9 Additionally, there has been a resurgence in methods to make polymers from sulfur, [10][11][12][13][14] which has created many opportunities for using these low-cost and scalable polymers in mercury and heavy metal remediation. 7,[15][16][17][18][19][20][21][22][23][24][25][26] In this study, we investigated one of these sulfur polymers made by direct copolymerisation of elemental sulfur with the renewable terpene limonene. Our lab first reported the synthesis and use of this material in mercury remediation in 2015, 27,28 describing its advantageous features.…”