Life cycle environmental impact assessment of cyanate removal in mine tailings wastewater by nano-TiO2/FeCl3 photocatalysis

Abstract

Mitigating the environmental health impact associated with cyanate is one of the key challenges facing local communities and the mining industry. Cyanate and cyanide are often found as co-contaminants in the environment. However, there is a lack of comprehensive research on the life cycle assessment (LCA) of photocatalytic cyanate degradation. This study aims to assess the environmental impacts of cyanate degradation by nano-TiO2/FeCl3 photocatalysis and compare the life cycle impacts of UV-A-, visible-, and solar-driven photocatalysis. The functional unit of the LCA involves “the degradation of 98% cyanate from 1 L wastewater by nano-TiO2/FeCl3.” In the synthesis of TiO2 photocatalysts, the IMPACT 2002+ LCA method reveals that aquatic ecotoxicity, non-renewable energy, terrestrial ecotoxicity, and global warming are the main contributors to total environmental damage through cyanate removal by nano-TiO2/FeCl3 photocatalysis. Ethanol and electricity consumption generates higher environmental impacts than other inputs. The results of endpoint analysis highlight that climate change associated with electricity contributes the greatest environmental impact across the entire photocatalysis life cycle for cyanate removal under all different irradiation sources. This study provides deeper insight into the life cycle environmental hotspots of photocatalytic cyanate degradation by nano-TiO2, potentially enabling mining operators and stakeholders to achieve resource efficiency and cleaner production.