Adsorptive removal of pharmaceuticals and personal care products from aqueous solutions by chemically treated fly ash

This study investigated the removal efficiency of pharmaceuticals from aqueous solutions supported on chemically treated fly ash. The coal fly ash was supplied by the electric power station in Krakow, Poland. There are plenty of studies showing the utilization of fly ash as a low-cost adsorbent for wastewater containing heavy metals or dyes. Adsorption and immobilization of pharmaceuticals and personal care products on fly ash is a relatively new method but it is a very promising one. In this study, the adsorptive removal of diclofenac, ketoprofen, carbamazepine, bezafibrate, bisphenol A, 17α-ethinyl estradiol and estriol by HCl- and NaOH-treated fly ash was assessed. Chemical treatment of fly ash changed structures of particles and enhanced specific surface areas. HCl-treated fly ash was characterized by the highest BET specific surface area 47.9 m2 g−1 and unburned carbon content 8.1%. Isotherms for all compounds except for 17α-ethinyl estradiol (EE2) and estriol (E3) were linear. Higher linear regression coefficients (R2) obtained for isotherms of EE2 and E3 show that the Freundlich model better describes their sorption. Adsorption coefficients Kd varied between 109.5 (L kg−1) for bisphenol A and 471.5 (L kg−1) for bezafibrate. Freundlich constants (KF) for EE2 and E3 were 62.3 and 119.9 (µg1−1/nL1/nkg−1), respectively. Acid treatment of fly ash increased adsorption of diclofenac, ketoprofen, carbamazepine, bezafibrate and bisphenol A. Comparison of the octanol–water partitioning coefficients (log KOW) with the partitioning coefficients normalized on unburned carbon content (log KUC) revealed similarities but no strong correlation. The increasing of unburned carbon increased sorption of compounds to fly ash.