Rejection prediction of isopropylantipyrine and antipyrine by nanofiltration membranes based on the Spiegler–Kedem–Katchalsky model

• Spiegler-Kedem-Katchalsky model was applied to predict rejection of pharmaceuticals.
• The relationship between reflection coefficient and feed concentration was obtained.
• The solute permeability Ps was nearly a constant.

The Spiegler–Kedem–Katchalsky (SKK) model has been used to predict the rejection of isopropylantipyrine (AMT) and antipyrine (ANT) in a cross-flow with NF-W membrane cell at 25 °C. In this model, the mass transfer parameters σ and Ps were obtained using the best-fit method. The permeate flux was determined by pressure and found to be independent on the kinds of solutes. The results indicated that σ = f(Co) substantially improved the fitting of the SKK model but Ps was nearly a constant for the two pharmaceuticals. In addition, the rejections of AMT and ANT at other concentrations and pressures were predicted and the predicted rejection rates were in agreement with the experimental data.