3.3.5. Refractive Index (*nD*) Measurement

An ATAGO RX-5000 Alpha Digital Refractometer (Tokyo, Japan) with a measuring accuracy of ±4.10−<sup>5</sup> was used to determine the refractive index values of the PILs. The measurement was done in a temperature range of 293.15 to 333.15 K. The instrument was also calibrated by using standard organic solvents provided by the supplier. In addition, a commercial imidazolium IL was also used while conducting the validation test and the result was compared with the values available from the literature [50].
