Sustainable Upcycling of Ferrous Sulfate Waste into Functional Fe(7)S(8) via COS-Mediated Controlled Sulfidation.

COS-mediated process converts 96.6 wt.% of ferrous sulfate waste into high-value Fe(7)S(8), enabling sustainable iron and sulfur recovery with enhanced pore structure.

• Why it matters: Industrial ferrous sulfate waste causes environmental issues and resource loss, and current disposal methods produce low-value products with high energy and reagent demands, highlighting the need for better recycling solutions.
• What they did: A gas-solid strategy using carbonyl sulfide (COS) was developed to transform ferrous sulfate waste into Fe(7)S(8), involving stepwise conversion and controlled sulfidation, validated with real waste samples.
• The result: The process achieves efficient upcycling, producing a material capable of removing gaseous mercury, and offers environmental and resource benefits supported by life-cycle and cost analyses.