  Effect of ionic solute on a near-critical binary aqueous mixture confined
between charged walls with different adsorption preferences is considered
within a simple density functional theory. For the near-critical system
containing small amount of ions a Landau-type functional is derived based on
the assumption that the correlation, $\xi$, and the Debye screening length,
$\kappa^{-1}$, are both much larger than the molecular size. The corresponding
approximate Euler-Lagrange equations aresolved analytically for ions insoluble
in the organic solvent. Nontrivial concentration profile of the solvent is
found near the charged hydrophobic wall as a result of the competition between
the short-range attraction of the organic solvent and the electrostatic
attraction of the hydrated ions. Excess of water may be present near the
hydrophobic surface for some range of the surface charge and $\xi\kappa$. As a
result, the effective potential between the hydrophilic and the hydrophobic
surface can be repulsive far from the critical point, then attractive and again
repulsive when the critical temperature is approached, in agreement with the
recent experiment [Nellen at.al., Soft Matter {\bf 7}, 5360 (2011)].
