1Imperial College London, London, United Kingdom
2Nanomox Ltd, London, United Kingdom
The Oxidative Ionothermal Synthesis (OIS) method is a metal oxidation process which takes place in aqueous Ionic Liquid (IL) solutions. The use of IL and water mixtures for making nanoparticles via direct oxidation of metals (OIS) can be used to synthesise materials-by-design (as hetero-structures, core-shell structures and composite materials) with physicochemical properties tailored to meet industrial specifications. Additionally, using these solvents in combination with metals could lead to a more cost-effective and environmentally friendly processes for large-scale synthesis of a wide range of nano and micro materials (Mater. Adv., 2020,1, 3597-3604).
The OIS process for inorganic material production uses low temperatures and safe reagents. This contrasts with conventional methods that require high temperatures or the use of dangerous chemicals such as concentrated acids. Moreover, the method is cost-effective and in particular demands less energy than conventional methods, with up to 97% energy savings leading to a significant reduction in CO2 emissions. Furthermore, early indications point to the feasibility of treating impure source materials and mixed streams, including waste streams containing zinc (or other metals) to produce zinc oxide (or other metal oxides). Excitingly, hydrogen is produced as a by-product that can be recovered and used as a chemical or fuel source.
Through the OIS process, zinc oxide can be generated to compete with mass-market production as well as with more finessed technologies, that involve differentiated sizes and morphologies. The latter is notable, as the technique then spans into the advanced zinc oxide manufacturing market, thereby addressing speciality product requirements.
There are low-to-no evaporative losses, and as the reaction does not consume the ionic liquids, this makes recycling the ionic liquid solution viable. This approach can be extended beyond Zn-based nano–micro materials to other metals.
The OIS process has been validated at a lab scale and it is being scaled up using a 2-litre reactor at Imperial College London, followed by 100-litre and 2,400-litre trials at the Materials Processing Institute in Middlesborough (United Kingdom).
A patent has been applied for by Nanomox Ltd with Francisco Malaret, Kyra Campbell and Jason Hallett as named inventors. Method for producing metal and/or metalloid compounds in an ionic liquid GB2009470.2, WO2021260360A1.