Adsorption of nonylphenol onto granular activated carbon

The applicability of granular activated carbon (GAC) filtration for the removal of the xeno-estrogenic micropollutant nonylphenol (NP) is evaluated using batch adsorption data. From the obtained adsorption data, it was apparent that with contact times of 4 d and 24 hr and GAC dosages of 1 and 0.1 g L-1 no saturation of the GAC could be obtained with NP total contaminant loadings up to 10 000 mug L-1. Higher NP concentrations could not be applied due to its low water solubility (similar to5 mg L(-)1). The influence of temperature (4 or 28 degreesC) on NP sorption onto GAC was negligible. The results showed that the sorption capacity of GAC for NP was at least 100 mg g(-1) GAC. According to these data it can be concluded that a full-scale GAC filter unit will be sufficient to remove environmentally relevant NP concentrations of 10 mug L-1. Consequently, the existing GAC treatment technology in drinking water treatment should protect the consumer from the intake of the xeno-estrogenic micropollutant NP via drinking water. The sorption capacity of dissolved humic acids (DHA) for NP is considerable at liquid NP concentrations of 10 mug L-1 and the affinity of DHA for GAC is not significant. These observations suggest that interference on removal of NP on GAC, due to the presence of DHA, can be expected at microgram per liter concentrations of NP. They may warrant the removal of humic substances in treatment steps preceding GAC-filtration.