Selenium Disulfide from Sustainable Resources: An Example of “Redneck” Chemistry with a Pinch of Salt

Abstract

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.