The aim of this research is to study the effect high concentrations salts, pressure and temperature on performance RO membrane with time. Four different (Na2CO3) (5000, 15000, 25000 35000) ppm various pressures such as (1, 3 5) bars at temperatures feed solution (i.e., 25, 35 45) ◦C were used in work. It was found that, concentration salt increase, rejection decrease. While membranes increases ...