Degradation of acetaminophen with ferrous/copperoxide activate persulfate: Synergism of iron and copper

To enhance the advanced oxidation process based on persulfate, CuO was introduced into the Fe2+/PS system to achieve a synergistic effect between Fe and Cu. Results showed that Fe2+ was able to adsorb onto the CuO surface to form Fe(II) and further reduced Cu(II) into Cu(I), which can further release into the solution to participate in oxidation reactions. In this case, SO4·- can be generated via Fe2+ and Cu+ reactions with PS and ·OH from Cu+ reaction with dissolved oxygen (DO). The degradation efficiency of APAP was studied under the optimal condition (initial pH 6.5, PS = 0.8 g L-1, Fe2+ = 0.7 mM, CuO = 0.3 g L-1), and the results indicated that the Fe2+/CuO/PS system can achieve a higher degradation rate of APAP (92% within 90 min) rather than Fe2+/PS and CuO/PS system (79% and 10%). Quenching experiment was performed to verify the active radicals in the Fe2+/CuO/PS system. Sulfate and hydroxyl radicals were generated in the Fe2+/CuO/PS system. Besides, some critical factors, such as Fe2+ concentration, catalyst dosage, PS concentration, initial pH (buffers and nonbuffers), and dissolved oxygen were evaluated in bath experiments. Results indicated that dissolved oxygen was essential in the Fe2+/CuO/PS system. APAP degradation experiments were conducted in surface water, and the intermediates were detected via GC-MS. The results indicated that the Fe2+/CuO/PS system is effective in the treatment of APAP in natural waters.