This study investigates the removal of triazines from an aqueous solution using a novel SiO2/CA nanocomposite membrane. The membranes were fabricated with phase inversion by dispersing SiO2 nanoparticles in the CA casting solutions in the range of 0.01–0.1 wt.%. ATR-IR, FESEM, AFM, and contact angle analyses were employed to characterize the prepared membranes. The effect of silica nanoparticles on the performance of membranes was studied through the pure water flux and MgSO4 rejection obtained at an applied pressure of 10 bars. Nanocomposite CA membranes generally showed higher salt rejection and experienced less flux than neat CA membranes, due to morphology changes. In addition, the observed salt rejection tended to enhance as silica loading increased up to a critical concentration. Three triazines (atrazine, propazine, and prometryn) were removed from water by the prepared membranes, and their rejections were compared. The results showed that the triazines rejection was increased by pressure and feed concentration. The effects of the molecules’ properties, including molecular size, hydrophobicity and dipole moment, were studied. The results revealed that the rejection of prometryn with a larger molecular size was always higher than the other two triazines. It was observed that there was a direct relation between dipole moment and triazine rejection, while this relation was not observed in the case of hydrophobicity.

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