Repurposing Industrial By-products For Remediation

By combining by-products from the petrochemical and citrus industries, chemists have created a polysulfide that can remove certain toxic metals from water and soil. The material is made simply by mixing equal masses of sulfur and (+)-limonene without any solvent. Both sulfur and limonene are produced in abundance, with the petroleum refining process churning out more than 60 million tons of sulfur annually and the citrus industry extracting 70,000 tons of limonene from orange zest each year. Justin M. Chalker of Flinders University spearheaded work on the by-product-derived material. The polysulfide can be processed into a functional coating or molded into a solid form capable of removing toxic palladium(II) and mercury(II) salts from soil and water (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201508708). When the material binds to a sufficient amount of mercury, it undergoes a color change from brown to yellow. This feature could be used to monitor the lifetime of remediation devices made from the polysulfide.