Investigation Of The Critical Behavior In Ionic Solution Containing [C_nmim]~+

Critical behaviors in five ionic solutions were investigated in this study. Those five ionic solutions include:{x1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6])+(1-x)1-butanol},{x [C8mim][PF6]+(1-x)2-butanol},{x [C8mim][PF6]+(1-x) tert-butanol},{x1-octyl-3-methylimidazolium tetrafluoroborate ([C8mim][BF4)+(1-x)1-pentanol}, and{x [C8mim][BF4]+(1-x)1-heptanol}. The critical compositions xc and the critical temperatures Tc of five ionic solutions were determined respectively. The (T-n) coexistence curves (the plots of T against the refractive index) were obtained by measuring the the refractive indexes in two coexisting phases at various temperatures for the five ionic solutions. The (T-n) coexistence curves were converted to the (T-x) coexistence curves (the plots of T against the mole fraction) by the "Standard Curve" method, and the (T-φ) coexistence curves (the plots of T against the volume fraction) were further obtained. The critical exponent β, the critical coefficients B and B1of coexistence curves for five ionic solutions were calculated, which confimed that all the five ionic solutions belong to the3D-Ising universality.The (T-x) coexistence curves were converted to the (T-p) coexistence curves (the plots of T against the reduced density of the solution) and the (T-px2) coexistence curves (the plots of T against the reduced partial molar density). The asymmetric behaviors of the coexistence curves for the five ionic solutions were analyzed by the complete scaling theory and the asymmetric coefficients a1and a3were determined.