Selenium Disulfide from Sustainable Resources: An Example of "Redneck" Chemistry with a Pinch of Salt.

Selenium disulfide (often referred to as SeS2) encompasses a family of mixed selenium-sulfide eight-membered rings, traditionally used as an anti-dandruff agent in shampoos. SeS2 can be produced by reacting hydrogen sulfide (H2S) with selenite (SeO32-) under acidic conditions. This chemistry is also possible with natural spring waters that are rich in H2S, thus providing an avenue for the more sustainable, green production of high-quality SeS2 particles from an abundant natural source. The orange material obtained this way consists of small globules with a diameter in the range of 1.1 to 1.2 µm composed of various SexS8-x chalcogen rings. It shows the usual composition and characteristics of a Se-S interchalcogen compound in EDX and Raman spectroscopy. Since the mineral water from Bad Nenndorf is also rich in salts, the leftover brine has been evaporated to yield a selenium-enriched salt mixture similar to table salt. As the water from Bad Nenndorf-in comparison to other bodies of water around the world-is still rather modest in terms of its H2S content, especially when compared with volcanic waters, this approach may be refined further to become economically and ecologically viable, especially as a regional business model for small and medium-sized enterprises.