Abstract
The retention of 10 pharmaceuticals by 5 types of nanofiltration membranes was examined experimentally. The retention of acidic pharmaceuticals was dependent on the pH of the solution, while that of neutral pharmaceuticals was not affected by pH. The retention was low in the case of lower pH where the acidic pharmaceuticals were neutral solutes, while the retention was high at higher pH where they were negative ions. The retention was a function of the size of solutes in the low pH region where the sieving effect was dominant rather than the electrochemical effect. The retention by a tight membrane was high regardless of the solute size of the pharmaceuticals and of solution pH.
