Fe-loaded superfine powdered activated carbon prepared by ball milling for synergistic adsorption and persulfate activation to remove aqueous carbamazepine.

The massive use of personal medicines makes them widely enter the aquatic environments and cause pollution, drawing a great deal of attention over the last few years. In this study, a novel nano Fe-loaded superfine powdered activated carbon (Fe@SPAC) was prepared via a simple ball milling method. Fe@SPAC showed a rapid and effective removal for aqueous carbamazepine (CBZ) via the process of synergistic adsorption and persulfate (PDS) activation. The removal efficiency of CBZ (30 mg L) could be up to 96% by Fe@SPAC (0.05 g L) with the presence of PDS (2 mM), and the maximum pseudo-first-order rate constant was 0.12 min. The performance of Fe@SPAC was superior to other reported iron-bearing activator materials, and its dosage was much lower. Fe@SPAC was also effective to remove other typical drug pollutants and had excellent reusability in five cycles. The loaded Fe could activate PDS to generate OH and SO, which played the major role for CBZ removal. It is interesting that carbon base of Fe@SPAC could also activate PDS via surface defects, making the minor contribution to CBZ degradation. Besides, Fe@SPAC showed rapid and high adsorption for CBZ due to the superfine particle diameter, partially contributing to CBZ removal. Finally, the possible break sites of CBZ and its degradation pathway were proposed based on DFT theoretical calculation and product identification. Fe@SPAC would be a promising material for the removal of drug pollutants, and this study may help understand the mechanisms of synergistic adsorption and persulfate activation by carbon composite material.