The removal of bisphenol A by ultrafiltration

The removal of bisphenol A (BPA) from drinking water by ultrafiltration membrane (UF) using dead-end model was investigated. The experiment was focused on the effect of various factors on removal efficiency with respect to BPA initial concentration, molecular weight cut offs (MWCOs) of membrane, pH, ionic strength and organic matter. The results showed that UF could remove BPA effectively. UF with 2000–10,000 MWCOs removed BPA by over 92%, with initial concentration of BPA ranging from 100 to 600 μg/L. As pH of solution approached to pKa (9.6–11.3) of BPA, BPA removal efficiency dropped significantly. The effect of ionic strength on BPA removal was not found. The influence of humic acid on BPA removal was minor. It can be concluded that adsorption play a significant role in BPA removal in UF process.

In this study, BPA retention with a UF membrane using dead-end filtration was examined. The experiment was focused on the effect of various factors on BPA retention in terms of BPA initial concentration, molecular weight cut offs (MWCOs) of membrane, pH, ionic strength and organic matter. The obtained results are summarized as follows: BPA initial concentration appears to be a minor effect on BPA retention. Although BPA retention was slightly increased with MWCOs decreased, no significant effect of MWCOs on BPA retention was found. In ultrafiltration of 100 μg/L BPA concentrations at 100 kPa pressure, BPA retention with MWCOs of 10 kDa, 6 kDa and 2 kDa were 93.0%, 88.9% and 97.7%, respectively. As pH values closed to pKa value of BPA, BPA retention was substantially decreased from around 92% at 3.95 pH and 6.96 pH to 9.3% at 10.4 pH. BPA retention in the presence of humic acid was favored. The combination of hydrophobic adsorption and competition adsorption for sites appeared to be a major mechanism for BPA retention.