Preparation and characterization of a nanoclay/PVA/PSf nanocomposite membrane for removal of pharmaceuticals from water

Abstract 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 of state-of-the-art nanocomposite membranes. The permeation properties of the membrane samples were studied 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 6.8 l/m2 h for thin film composite (TFC) membrane to 14.4 l/m2 h, the salt rejection decreased from 95.7% to 78.1%. For TFN-m membranes PWF increased from 6.8 l/m2 h to 10.8 l/m2 h 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.