Study on CuO/Al₂O₃ catalytic ozone treatment of acid red B solution

Abstract

A CuO/Al2O3 catalyst was prepared using the impregnation method. The catalytic activity of CuO/Al2O3 for the ozonation of acid red B (ARB) in aqueous solution was studied, the chemical oxygen demand (COD) removal rate was an indicator for catalytic activity evaluation. The effects of initial ARB concentration, solution pH, and different oxidative degradation systems on oxidative degradation of ARB solution were studied. The CuO/Al2O3 catalyst was characterized using X‐ray diffractometry (XRD), N2 adsorption desorption test, X‐ray photoelectron spectroscopy (XPS), and zero‐point charge (pHzpc). The results show that copper species on the carrier were in the form of CuO and highly dispersed on the carrier. CuO can increase the alkalinity of the Al2O3 surface, and the CuO/Al2O3 catalyst facilitates the decomposition of O3 into ·OH, which was beneficial for the catalytic O3 oxidation degradation reaction. With the increase of the initial concentration of simulated wastewater, the CuO/Al2O3 catalytic reaction still has a high COD removal rate. Alkaline solution was of benefit to catalyze the degradation of ARB solution. When the ARB solution pH = 8.93, the degradation reaction was carried out for 40 min, the COD removal rate reached 83.2%. The degradation reaction was dominated by the hydroxyl radical (·OH) reaction.

The Adsorption of Ozone on the Solid Catalyst Surface and the Catalytic Reaction Mechanism for Organic Components

“…For example, Cr 2 O 3 , an n-type semiconductor, had higher activity than CeO 2 did, which was a ptype semiconductor. Furthermore, the catalytic activities of Cu and Ag oxides were reported in the following order: [20] Cu < Cu 2 O ðp-typeÞ < CuO ðn-typeÞ Ag < Ag 2 O ðp-typeÞ < AgO ðn-typeÞ Qian's [21] and Xu's [22] group studied the decomposition of acid red B solution and Acid Orange 7 by ozone under the catalysis of CuO/Al 2 O 3 , respectively. In decomposition of Acid Orange 7, Al 3 + , and Cu 2 + in CuAl 2 O 4 , which was prepared by a conventional citric acid complexation method, performed a synergistic function: the former acted as a reservoir of surfaceactive sites such as hydroxyl groups and Lewis acid sites, and the later made the electron transfer with ozone possible to enhance the efficiency of radical generation.…”

“…Qian's [21] and Xu's [22] group studied the decomposition of acid red B solution and Acid Orange 7 by ozone under the catalysis of CuO/Al 2 O 3 , respectively. In decomposition of Acid Orange 7, Al 3+ , and Cu 2+ in CuAl 2 O 4 , which was prepared by a conventional citric acid complexation method, performed a synergistic function: the former acted as a reservoir of surface‐active sites such as hydroxyl groups and Lewis acid sites, and the later made the electron transfer with ozone possible to enhance the efficiency of radical generation [22] …”