Mineralization of high concentration of aniline and other organics in wastewater by catalytic ozonation on CaMn2O4

Abstract

Aniline is a widely used toxic organic which is difficult to be biodegraded. In this work, the aniline solution with high concentration (200–1000 mg/L) was treated by catalytic ozonation over CaMn2O4 prepared by sol-gel method. COD removal ratio in CaMn2O4/O3 system reached 90 % within 120 min, which is much higher than other reported systems. This system also showed good performance for the treatment of real aniline wastewater from dyeing mill. The physicochemical properties of fresh and used CaMn2O4 catalysts were characterized by XRD, FT-IR, SEM, TEM and XPS. The effects of catalyst concentration, aniline concentration, ozone rate of flow and initial pH on mineralization were studied and optimized. Hydroxyl radical (·OH) was the major specie for the mineralization of aniline. Intermediates from mineralization of aniline were analyzed by GC–MS. Calcium ions can obviously improve the performance of manganese oxides for catalytic ozonation.