Hydrolysis of Congo red in subcritical water in the presence of CeO2/ZSM5 catalyst

The heterogeneous catalyst of CeO 2 /ZSM5 was applied to hydrolyze Congo red in subcritical water for the first time in the present study. The hydrolysis rate of Congo red could be significantly accelerated by introducing only 5 mg of 5% CeO 2 /ZSM5. The Congo red could be completely hydrolyzed at 220°C for 2 min—a reaction temperature 40°C lower than in the absence of 5% CeO 2 /ZSM5. In addition, the 5% CeO 2 /ZSM5 could be recycled for another run, and its Congo red hydrolysis efficiency and surface morphology showed no obvious change after 3 runs of recycling. The hydrolysis kinetics of Congo red in subcritical water could be well expressed by the Weibull model. The activation energy for hydrolysis of Congo red in subcritical water in the presence of 5% CeO 2 /ZSM5 (104.8 kJ mol –1 ) was much lower than in the absence of 5% CeO 2 /ZSM5 (155.9 kJ mol –1 ). The frequency factors were calculated to be 8.1 × 10 9 and 1.9 × 10 14 min –1 in the presence and absence of 5% CeO 2 /ZSM5, respectively. With these excellent properties, 5% CeO 2 /ZSM5 may prove to be an advantageous catalyst for the hydrolysis of Congo red in textile wastewater, in subcritical water.