Two series of thin film nanocomposite membranes were fabricated by incorporating montmorillonite (Mt) and modified-Mt (m-Mt) within a poly (vinyl alcohol) (PVA) film on a porous polysulfone (PSf) support membrane. The m-Mt was modified by incorporating of poly (4-styrenesulfonic acid-co-maleic acid) (PSSMA) to produce functionalized clay. The m-Mt showed uniform topographies for the prepared modified thin film nanocomposite membranes (TFN-m). The maleic acid groups around the m-Mt layers promoted good dispersion within the PVA film and prevented agglomeration presenting a procedure to reduce the difficulties encountered in the synthesis ofstate-of-the-art nanocompositemembranes. Thepermeation propertiesofthe membranesamples werestudied for Na2SO4 inorganic salt and the pharmaceuticals cephalexin, amoxicillin and ibuprofen. The higher solute rejection performance of the TFN-m membranes in comparison with thin film nanocomposite membranes incorporated with unmodified clay (TFN) confirmed the enhancement of the compatibility of m-Mt in comparison with Mt. Although the pure water flux (PWF) of TFN membranes increased from 6.8l/m2h for thin film composite (TFC)membraneto 14.4l/m2h,thesalt rejectiondecreased from95.7% to 78.1%.ForTFN-mmembranes PWF increased from 6.8l/m2h to 10.8l/m2h with 92.99% salt rejection. For the pharmaceuticals, TFN-m membranes presented comparable separation rates with TFC membrane, but the rejection values of the TFN membrane decreased considerably. Among pharmaceutical solutes, cephalexin with the lowest hydrophobicity showed rejection rate of 94.05%, 86.36%, 98.8% and 98.16% for TFN-0.4, TFN-0.6, TFN-m0.4 and TFN-m0.4, respectively.

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