Some call them sol­vents of the future, oth­ers call them green sol­vents and then there are few who also label them as design­er solvents…

But what exact­ly are ion­ic liquids ?

Sim­ply put, ion­ic liq­uids are salts in the liq­uid state, hav­ing melt­ing point close to or below room tem­per­a­ture. Salt – as in table salt ? No. In chem­istry, salt is anoth­er name for an ion­ic com­pound that is formed from a neu­tral­iza­tion reac­tion between an acid and a base. NaCl is a salt and so is CuSO4. Salts com­pose of anions (neg­a­tive­ly charged atoms) and cations (pos­i­tive­ly charged atoms). These anions and cations can either be inor­gan­ic, organ­ic, monoatom­ic or poly­atom­ic and are held togeth­er by elec­tro­sta­t­ic forces in an ion­ic bond. Reit­er­at­ing, salts that exist as liq­uid at near-ambi­ent tem­per­a­ture are called ion­ic liq­uids. Aren’t salts sup­posed to exist in sol­id state under nor­mal room tem­per­a­ture ? Yes, but not all. That’s why a clear dis­tinc­tion is made in this case, specif­i­cal­ly includ­ing those salts that exist as liq­uid at room tem­per­a­ture. To clear any con­fu­sions : NaCl is a salt but it is not an ion­ic liq­uid. TriPh­enyl­ButylPhos­pho­ni­um Iodide is a salt and as well as an ion­ic liq­uid.

Indus­tri­al Appli­ca­tions of Ion­ic Liquids

Ion­ic liq­uids are used in pletho­ra of indus­tri­al appli­ca­tions, serv­ing dif­fer­ent pur­pos­es. The most com­mon of these appli­ca­tions are list­ed below :

As het­eroge­nous and homoge­nous catalysts

Cer­tain ion­ic liq­uids can dis­solve cat­a­lysts and at the same time they can also be immis­ci­ble with the process’s reac­tants and prod­ucts. This prop­er­ty allows them to be used as het­eroge­nous as well as homoge­nous cat­a­lysts in indus­tri­al process­es.

As absorbents of car­bon dioxide

Ion­ic liq­uids can absorb car­bon diox­ide. This makes their deploy­ment ide­al in indus­tri­al set­tings to help reduce car­bon diox­ide emis­sions. It’s one of the rea­sons why ion­ic liq­uids are called green sol­vents. Fur­ther­more, their inert­ness to ion­iz­ing radi­a­tions is cur­rent­ly being looked into to poten­tial­ly chan­nel their use to treat high-lev­­el nuclear waste.

As met­al ions purifier

Indus­tries dis­charge con­t­a­m­i­nat­ed and pol­lut­ed water in rivers and oceans. Among the dif­fer­ent types of pol­lu­tants found in these con­t­a­m­i­nat­ed dis­charges, cad­mi­um and mer­cury car­ry seri­ous risks to the ecosys­tem. Ion­ic liq­uids can absorb these met­al ions and ensure that water bod­ies do not get con­t­a­m­i­nat­ed. Well, this wraps up our dis­cus­sion about what are ion­ic liq­uids and how they are being used in dif­fer­ent indus­tri­al process­es. If you want to learn more about ion­ic liq­uids, here is a bonus read for you…