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

This study used an ozone/ultraviolet/hydrogen peroxide (O-3/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 O-3 concentration (Xj), H2O2 concentration (X-2). and UV intensity (X-3), were examined. The O-3 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 O-3 and H2O2 concentrations up to certain levels, and further increases in O-3 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 O-3 (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. (C) 2011 Elsevier BM. All rights reserved.