Naproxen removal by CWPO with Fe3O4/multi-walled carbon nanotubes in a fixed-bed reactor

The prepared Fe3O4/multiwalled carbon nanotubes (MWCNTs) in catalytic wet peroxide oxidation (CWPO) is an effective method of removing some pharmaceuticals from water matrices for environmental protection. Therefore, operating parameters (catalyst dose, H2O2 dose, flow rate, pH) of CWPO with the easy-prepared Fe3O4/MWCNT composite were evaluated for the effective NAP removal in an up-flow bed reactor (UFBR). The prepared catalyst was successfully synthesized by a facile coprecipitation method. The highest removals of TOC and NAP by continuous CWPO of NAP aqueous solution (10 mg L−1) were obtained in the experiments with ratios 0.4 g of catalyst load/double H2O2 stoichiometric ratio (78.4% for TOC and 83% for NAP), and 0.2 g of catalyst load/stoichiometric dose (39.1% for TOC and 73.1% for NAP). Both operated at 10 mg L−1 of NAP, 1.7 mL min−1, 50 °C and circumneutral pH. In addition, their high consumption H2O2 efficiency (> 59.6%) and a low concentration of leached iron dissolved (< 0.28 mg L−1) found at 450 min indicated the great catalyst stability. Furthermore, the application of CWPO for different aqueous matrices, the NAP removal from in a surface water sample was almost complete (90.5%) 1260 min TOS while whereas in the hospital wastewater and wastewater treatment plant effluent samples were 64.9% and 58.9%, respectively. Our results demonstrate that continuous CWPO with the easy-prepared Fe3O4/MWCNTs has the potential to be applied as an effective treatment for the rapid removal of NAP from different water matrices.