Greening Pathways for Synthetic Talc Production Based on the Supercritical Hydrothermal Flow Process

Abstract

Recent efforts in chemistry have led to development of a fast and continuous process for the production of synthetic talc in a supercritical hydrothermal reactor. This attractive process compatible with industrial requirements leads to advantageous physicochemical characteristics including submicrometer size, hydrophilicity, and high chemical and mineralogical purity. In addition, the high speed of the process and moderate reaction conditions have potential advantages from a viewpoint of the impacts on the environment. To verify environmental advantages and seize further opportunities to improve environmental performance, the current study evaluates the new process using the life cycle assessment (LCA) methodology. A cradle-to-gate assessment considers the production of synthetic talc from different magnesium and reagent acid precursors at different concentrations. The findings suggest high impacts of precursors (65−94%, depending on their concentration) and low impacts of process energy and water. Substituting magnesium acetate with magnesium sulfate could reduce greenhouse gases from 4.8 to 2.6 kgCO 2 and cumulative energy use from 86 to 34 MJ per 1 kg of synthetic talc. Discussion draws on previous LCA studies on the supercritical hydrothermal process and applications of synthetic talc considering its environmental performance and characteristics in comparison to the conventional (natural) talc.

Geoinspired syntheses of materials and nanomaterials

“…Recently, the cradle-to-gate environmental LCA analysis related to the SHFS of talc was evaluated by Glogic et al 154 At the maximal reagents' concentration yielding 76 g L À1 of talc, the precursors account for 94% of the impacts. In particular, sodium metasilicate, employed as the silicon source, contributes solely to 40-60% of the total impacts, depending on the synthesis reaction.…”

Life Cycle Assessment of Magnetite Production Using Microfluidic Devices: Moving from the Laboratory to Industrial Scale

“…24 Several studies have demonstrated that there is an avenue to evaluate their environmental performance through the life cycle assessment (LCA) methodology. 25,26 The LCA methodology has been widely used to assess the environmental sustainability of new products and emerging technologies in the early stages. 27 In particular, this methodology has been used in different fields that involve nanomaterials such as photovoltaic systems, 28 soil remediation, 29 water remediation, 30 lithium-ion batteries using silicon nanotubes for electric vehicles, 31 and biogas production.…”

“…However, the scaling-up of emerging technologies from the laboratory to the industrial scale involves various challenges, including adaptability to other materials, complex manufacturing and operating processes, and determining their environmental impact . Several studies have demonstrated that there is an avenue to evaluate their environmental performance through the life cycle assessment (LCA) methodology. , …”

In Situ Dispersion of Lignin in Polypropylene via Supercritical CO2 Extrusion Foaming: Effects of Lignin on Cell Nucleation and Foam Compression Properties

“…Although these inorganic fillers are in general not costly, they may cause some environmental and health concerns. For instance, for talc, raw material extraction often involves mining activities that destroy or pollute natural habitats [9]. Furthermore, naturally occurring talc is often contaminated with asbestos, a known carcinogen, raising some concerns about the occupational health of the workers who handle these fillers [10].…”

“…Recently synthetic inorganic nanoparticles, such as molecular-sieve [12] and talc nanoflakes [13,14], and lightweight synthetic polymers, such as fluoroelastomers [15] and polydimethylsiloxane (PDMS) [16], have also been demonstrated as efficient nucleating agents for scCO 2 foaming of PP. Nevertheless, the syntheses of these nanomaterials all involve relatively expensive chemical processes or non-eco-friendly chemicals [9,17].…”