Optimization of carbamazepine removal in O3/UV/H2O2 system using a response surface methodology with central composite design Original Research Article

This study used an ozone/ultraviolet/hydrogen peroxide (O3/UV/H2O2) system to remove carbamazepine (CBZ) from water using a second-order response surface methodology (RSM) experiment with a five-level full-factorial central composite design (CCD) for optimization. The effects of both the primary and secondary interactions of the photocatalytic reaction variables, including O3 concentration (X1), H2O2 concentration (X2), and UV intensity (X3), were examined. The O3 concentration significantly influenced CBZ and total organic carbon (TOC) removal as well as total inorganic nitrogen ion production (T-N) (p < 0.001). However, CBZ, TOC removal, and T-N production were enhanced with increasing O3 and H2O2 concentrations up to certain levels, and further increases in O3 and H2O2 resulted in adverse effects due to hydroxyl radical scavenging by higher oxidant and catalyst concentrations. UV intensity had the most significant effect on T-N production (p < 0.001). Complete removal of CBZ was achieved after 5 min. However, only 34.04% of the TOC and 36.99% of T-N were removed under optimal concentrations, indicating formation of intermediate products during CBZ degradation. The optimal ratio of O3 (mg L− 1): H2O2 (mg L− 1): UV (mW cm− 2) were 0.91:5.52:2.98 for CBZ removal, 0.7:18.93:12.67 for TOC removal, and 0.94: 4.85:9.03 for T-N production, respectively.