A tubular ceramic membrane coated with TiO-P25 for radial addition of HO towards AMX removal from synthetic solutions and secondary urban wastewater.

This work aims to integrate several hydrogen peroxide (HO) activation mechanisms, photolysis (UVC irradiation), chemical electron transfer (TiO-P25 photocatalysis), and reaction with TiO-P25 in dark conditions, for reactive oxygen species (ROS) generation towards the removal of contaminants of emerging concern (CECs), in a single unit operated in continuous-flow mode. An HO stock solution is fed by the lumen side of a tubular ceramic membrane, delivering the oxidant to the (i) catalyst immobilized in the membrane shell-side and (ii) annular reaction zone (ARZ, space between membrane shell-side and outer quartz tube) where CECs contaminated water flows with a helix trajectory, being activated by UV light provided by four lamps placed symmetrically around the reactor. First, the effect of several parameters in the removal of a CEC target molecule, amoxicillin (AMX), was evaluated using a synthetic solution ([AMX] = 2.0 mg L): (i) light source (UVA or UVC radiation), (ii) HO dose, (iii) HO injection method (radial permeation vs. upstream injection), and (iv) number of TiO-P25 layers deposited on the membrane. The UVC/HO/TiO system with radial addition of HO (20 mg L) and 9-TiO-P25 layers provided the highest AMX removal efficiency (72.2 ± 0.5%) with a UV fluence of 45 mJ cm (residence time of 4.6 s), due to the synergic effect of four mechanisms: (i) AMX photolysis, (ii) HO photocleavage, (iii) TiO-P25 photoactivation, and (iv) chemical reactions between HO and TiO-P25. The urban wastewater matrix showed a negative effect on AMX removal (~44%) due to the presence of ROS scavengers and light-filtering species.