Abstract
Mercury pollution threatens human health across the globe. From artisanal and small-scale gold mining alone, more than 15 million people are exposed to this neurotoxic metal. In this practice, mercury is used intentionally to extract gold from ore. The amalgam formed is then burned to recover the gold, releasing the mercury into the atmosphere. Mercury rich mine tailings are also dumped directly into soil and waterways, resulting in a staggering 800 tons of mercury pollution each year due to this type of gold mining. These gold mines are located primarily in developing nations, so cost effective methods for capturing the associated mercury pollution are urgently needed. This study features the synthesis of polymers made from sulfur and cooking oil and their use in sequestering mercury from air, water and soil. The polymers were prepared in a single, economical step by heating elemental sulfur at 180 ºC in the presence of unsaturated cooking oils such as canola oil. The resulting cross-linking provides a rubber product that can be used directly to capture mercury pollution, including the remediation of mercury-laden water and soil — the types of pollution encountered in artisanal gold mining. Neither the polymer nor the polymer bound to mercury were toxic to human cells, so the polysulfide is promising as a tool for in situ remediation of mercury contaminated mine tailings and soil. Because sulfur is a by-product of petroleum refining and spent cooking oils from the food industry are suitable starting materials, these mercury-capturing materials can be synthesized entirely from waste. This study is therefore an advance in waste valorisation and environmental chemistry.
