Health Protection Using Clay Minerals: A Case Study Based on the Removal of BPA and BPS from Water

Anthropogenic activity releases hazardous contaminants and pollutants that are not removed fully by water treatments. Among such pollutants, bisphenol-A (BPA) and bisphenol-S (BPS) are included in a series of Endocrine Disruptive Compounds, which may cause disruption due to hormone blockage or mimicking. Thus, even though those pollutants are not considered lethal, they are hazardous to health due to their similarity to 17β-estradiol, and they have been shown to cause developmental malformation in Zebrafish and breast and prostate tumors in rodents. Both BPA and BPS have been found in water sources at concentrations >30 μg L–1 and since water treatment plants are ineffective at removing them, their concentration is constantly increasing. The purpose of the present study, using a collection of experiments performed by B.Sc. and M.Sc. students, was to apply clay-based materials to the removal of such health hazards from water. Specifically adapted modified clays as neutral organoclays can optimize the interaction between pollutants and the matrix to achieve efficient adsorption. Such an approach is very effective for relatively insoluble pollutants such as BPA, but less so for the more soluble BPS. On the other hand, BPS can be photodegraded catalytically using raw clay or TiO2-impregnated clay. At low catalyst concentration, the modified clay was as effective as a commercial TiO2 catalyst, whereas combining it with H2O2 yielded considerably better results. In summary, clay minerals offer solutions for the removal of health-hazardous pollutants from water, based on different procedures and mechanisms. The versality of clay minerals allows 'tailoring' specifically adapted materials that might improve their efficiency based on such very specific pollutant-matrix interactions.