A research team at Flinders University in Australia has “developed an inexpensive, non-toxic polymer that can absorb hazardous mercury compounds out of water and soil.” The secret ingredient of the polymer is a colorless liquid hydrocarbon that is extracted from the peel of citrus fruits such as lemons, limes and oranges. The process to extract limonene, which gives citrus fruits their smell, includes centrifugal separation and steam distillation.
According to a paper published in the journal Angewandte Chemie International Edition, limonene is combined with an equal mass of molten sulfur and synthesized to form a sulfur-limonene polysulfide compound. The two-phase mixture becomes a single, dark red phase upon reaction. The mixture turns a bright yellow in the presence of mercury.