Combustion synthesis of mesoporous CoAl2O4 for peroxymonosulfate activation to degrade organic pollutants

A mesoporous CoAl2O4 spinel that is highly efficient for the degradation of RhB, MB, MO, and TCH is prepared through a combustion approach. Both SO4•‒ and •OH are present in the CoAl2O4/PMS system, and SO4•‒ is the dominant reactive oxygen species. [Display omitted] A mesoporous cobalt aluminate (CoAl2O4) spinel is synthesized through a combustion method and adopted for the activation of peroxymonosulfate (PMS) to degrade organic pollutants. Multiple characterization procedures are conducted to investigate the morphology and physicochemical properties of the CoAl2O4 spinel. Due to its mesoporous structure, large surface area, and high electrical conductivity, the obtained CoAl2O4 exhibits remarkable catalytic activity for Rhodamine B (RhB) degradation. Its RhB degradation rate is 89.0 and 10.5 times greater than those of Co3O4 and CoAl2O4 spinel prepared by a precipitation method, respectively. Moreover, the mesoporous CoAl2O4 spinel demonstrates a broad operating pH range and excellent recyclability. The influence of several parameters (catalyst amount, PMS concentration, initial pH, and coexisting inorganic anions) on the oxidation of RhB is evaluated. Through quenching tests and electron paramagnetic resonance experiments, sulfate radicals are identified as the predominant reactive species in RhB degradation. This paper provides new insights for the development of efficient, stable, and reusable cobalt-based heterogeneous catalysts and promotes the application of persulfate activation technology for the treatment of refractory organic wastewater.