A Simple Approach to Achieve Self-Buffering Protic Ionic Liquid-Water Mixtures

Ionic liquid (IL)-water mixtures have drawn increasing attention in a range of applications ranging from chemical synthesis and separation to bioscience and energy applications. The acid-basic nature of ILs is often an important property to be considered when selecting and designing ILs. Herein, we evaluated this IL property by correlating the stoichiometry of a protic IL and pH of IL-water mixtures. We then developed a simple method to achieve self-buffering protic IL-water mixtures by titrating buffering agents. The rule of buffering protic IL-water mixtures was proposed to be linearly related to pIL ion concentration and correlated with ionicity. Through this approach, self-buffering capability can be achieved in protic IL-water mixtures without significantly changing the ion concentration.