Environmental assessment of a bottom-up hydrolytic synthesis of TiO2 nanoparticles

Abstract

A green metrics evaluation of the bottom-up hydrolytic sol–gel synthesis of titanium dioxide (TiO₂) nanoparticles has been performed by following two different approaches, namely, EATOS software and LCA methodology. Indeed, the importance of engineered nanomaterials is increasing worldwide in many high-technological applications. Due to the as yet completely un-established environment and human health impact of nano-sized materials, the possibility of at least choosing a greener synthetic strategy through an accurate comparison of detailed environmental assessments will soon be of absolute importance in both the small and large scale production of these advanced inorganic materials. The present LCA study has been carried out following an ecodesign approach, in order to limit the environmental impacts and protect human health. The results of LCA analysis suggest that the highest environmental impact is mainly due to energy and the titanium isopropoxide precursor used in the synthesis process. Concurrently, software EATOS has been employed to calculate the environmental parameters that account for the environmental and social costs related to all the chemicals involved in the analyzed synthesis. As the EATOS approach is based purely on synthetic chemical mechanism considerations, thus neglecting any energy contributions, and its results cannot be directly compared to those arising from LCA analysis. However, similar and comparable outcomes are obtained by simply neglecting the energy contributions, broadening the application fields of the combined EATOS-LCA approach to the inorganic synthesis of engineered nanomaterials, highlighting the great potential of their synergy.