The effect of deterioration of nanofiltration membrane on retention of pharmaceuticals

The retention of 8 acidic and 2 neutral pharmaceuticals in nanofiltration (NF) was investigated by a loose NF membrane and a tight NF membrane. The retention change due to the exposure to chlorine was studied. The retention of pharmaceuticals was affected by the electric repulsion effect in addition to the size exclusion effect. In the case of the loose NF membrane, the retention of pharmaceuticals was more sensitive to the exposure to chlorine than salt retention because both the decrease in electric repulsion effect and the increase in pore size affected the permeation of pharmaceuticals. On the other hand, in the case of the tight NF membrane, the retention of acidic pharmaceuticals were maintained at higher range at neutral pH range even after exposure to chlorine, though the increase in the pore size was obvious judging from the decrease in the retention of pharmaceuticals in the acidic solution environment.

The retention of 8 acidic and 2 neutral pharmaceuticals were investigated by a loose NF and a tight NF membranes and the retention change due to the exposure to chlorine was studied. The retention of pharmaceuticals was affected by the electric repulsion effect in addition to the size exclusion effect. The retention of acidic pharmaceuticals by the loose NF membrane was increased with increase in solution pH, as can be explained by the dissociation to ions of the pharmaceuticals. The retention of the pharmaceuticals by the tight NF membrane was kept high regardless of a species of the pharmaceuticals at all pH range. In the case of the loose type NF membrane, the retention of pharmaceuticals was more sensitive to the exposure to chlorine than salt retention because both the decrease in electric repulsion effect and the increase in pore size affected the permeation of pharmaceuticals. On the other hand, in the case of the tight NF membrane, the retention of acidic pharmaceuticals were maintained at higher range at neutral pH range even after exposure to chlorine, though the increase in the pore size was obvious judging from the decrease in the retention of pharmaceuticals in the acidic solution environment.