Current trends in wastewater pollution are inconsistent with long-term sustainable growth. This is being exacerbated by increases in the presence of emerging wastewater pollutants (EWPs), which existing treatment approaches are often not well-equipped to handle.

Silica-Based adsorbent materials (SBAMs) are one technological solution being investigated as a treatment for a range of environmental pollutants including EWPs. This is because of their desirable material properties, manufacturability, and capacity for surface chemistry modifications – which enable efficient and selective pollutant recovery. Nonethless, the environmental impact (EI) of producing and using SBAMs is still poorly understood.

This work addresses gaps in understanding for the EI associated with SBAM life cycles. This is done using a life cycle assessment (LCA) approach supported by material and energy use estimates developed from a mixture of approaches including literature review (academic and patent), process design modelling, and laboratory experimentation. It culminates in a demonstrative case-study assessing the EI of using SBAMs to recover vegetable oils (an
example source of EWP).

Results of the work report EI estimates for a range of materials used in SBAM manufacture, including: 1) silica substrates, 2) silane coupling agents, 3) surface-modified SBAMs, and 4) associated intermediates (e.g. organic surfactants, silicon metals, and chlorosilanes). Findings suggest that silica precursor choice contributes significantly (e.g. 69 and 100%) to the EI of silica substrates produced commercially. Moreover, for emerging methods, silica precursor choice also drives wider changes in predicted SBAM EIs (e.g. 4 to 92 kg-CO2eq/kg) due to its implications on process design constraints.

Findings suggest that silica precursor choice may be a key factor in reducing the impact of SBAMs produced via emerging methods if they are to compete with commercial manufacturing methods. Similar insights are also provided regarding intermediate materials in SBAM lifecycles (e.g. silica substrates, silane coupling agents, and organic surfactant materials).