Techno-Economic Analysis of Recycled Ionic Liquid Solvent Used in a Model Colloidal Platinum Nanoparticle Synthesis

Ionic
liquids have garnered significant attention over the past
20 years as alternatives to conventional volatile organic solvents
because they are non-flammable, have negligible vapor pressures, possess
high thermal and chemical stabilities, and can potentially be recycled.
A more recent use of ionic liquids is their application as a solvent
in the synthesis of colloidal inorganic nanoparticles; however, a
major challenge in the adoption of ionic liquids is that they are
generally more expensive than their traditional organic solvent counterparts.
Herein, we provide insight into how recycling an ionic liquid solvent
affects the product characteristics in a model colloidal platinum
nanoparticle synthesis, the structure of the ionic liquid through
each recycle, and the overall cost of nanoparticle fabrication using
a techno-economic analysis. Using a standard ionic liquid, 1-butyl-3-methylimidazolium
bis­(trifluoromethylsulfonyl)­imide (BMIM-NTf2), as the solvent
for a Pt nanoparticle synthesis, we demonstrate that the ionic liquid
can be recovered and reused through multiple successive reactions
following the initial reaction with virgin, or as-purchased, ionic
liquid. The use of recycled ionic liquid does not cause any degradation
in the product quality or change in nanoparticle morphology. Techno-economic
analysis of this synthesis method revealed that, through ionic liquid
recycling, nanoparticle preparation using BMIM-NTf2 can
achieve a cost that is not only competitive but also potentially lower
than that of the conventional organic solvent, 1-octadecene.