The associating lattice gas in the presence of interacting solutes.

We have investigated the phase diagram of a statistical model for hydrogen-bonding solutions for polar solutes. The structured solvent is represented by an associating lattice gas, which presents anomalous density and liquid-liquid coexistence. Polar solute particles and solvent particles interact attractively, while the solvent-solvent interaction is made directional through bonding arms, which mimic hydrogen bonds. The model behavior is obtained via Monte Carlo simulations in the grandcanonical ensemble, for different sets of parameters. For small solute chemical potential and weak attraction between solute and solvent particles, addition of solute yields a shift in the transition lines of the pure solvent. This is the scenario explored by different authors, in the pursuit of stabilizing the water liquid-liquid coexistence line. However, as we show, in the case of larger solute chemical potentials, or of stronger solute-solvent attractions, new phases may arise. [ABSTRACT FROM AUTHOR]