To systematically investigate the influence of preparation conditions on pure water permeability (PWP) and solute removal performance of polyvinyl alcohol (PVA) thin‐film composite (TFC) membrane, fractional factorial design was applied. The considered conditions were related to 3 steps of the TFC preparation, including support membrane preparation, PVA coating, and cross‐linking. The results showed that among the selected factors, polysulfone concentration (polymer of the support membrane), heat curing time (related to cross‐linking condition), and their interaction have the most significant effects on the both permeability and salt rejection. The effects of significant factors interaction on permeability and solute rejection of PVA TFC membrane were discussed. Finally, optimum preparation conditions were calculated by numerical optimization to achieve maximum permeability and solute removal, simultaneously. The prepared membrane at optimum conditions showed PWP of 1.74 L/m2hbar and 96.19% Na2SO4 rejection. It was realized that the prediction of mathematical models at optimum conditions was reliable with absolute average relative error 7.43% and 1.18% for PWP and rejection, respectively.

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