Preparation of Nickel-Based Bimetallic Catalyst and Its Activation of Persulfate for Degradation of Methyl Orange

In this research, a new catalyst for activating persulfate was developed by loading iron and nickel ions onto powdered activated carbon (PAC) for treating methyl orange, and the preparation process was optimized and characterized. The efficacy of the treatment was evaluated using the Chemical Oxygen Demand (COD) removal rate, which reflects the impact of various process parameters, including catalyst dosage, sodium persulfate dosage, and reaction pH. Finally, the recovery and reuse performance of the catalyst were studied, and the intermediate products were analyzed. The optimal conditions for preparing the activated sodium persulfate catalyst were determined to be as follows: a molar ratio of Fe3+ and Fe2+ to Ni of 4:1, a mass ratio of Fe3O4 to PAC of 1:4, a calcination temperature of 700 °C, and a calcination time of 4 h. This preparation led to an increase in surface porosity and the formation of a hollow structure within the catalyst. The active material on the surface was identified as nickel ferrite, comprising the elements C, O, Fe, and Ni. The magnetic property is beneficial to recycling. With the increase in catalyst and sodium persulfate dosage, the COD removal efficiency of the oxidation system increased first, and then, decreased. The catalyst showed good catalytic performance when the pH value was in the range of 3~11. Furthermore, Gas Chromatography–Mass Spectrometry (GC-MS) analysis indicated the complete oxidation of methyl orange dye molecules in the system. This result highlights the important role of the newly developed catalyst in activating persulfate.