# Study on the treatment of methyl orange contaminated water by activated carbon fiber/copper oxide as persulfate activator under microwave irradiation

## TL;DR

This study uses a microwave and a copper oxide-activated carbon fiber catalyst to efficiently remove methyl orange from water.

## Contribution

An innovative microwave-assisted heterogeneous catalytic oxidation process using ACF/CuO and persulfate is proposed for azo dye degradation.

## Key findings

- Methyl orange removal reached nearly 100% under optimized microwave and catalyst conditions.
- COD and TOC removal rates were 89.65% and 72.36%, respectively.
- Degradation pathway involves breaking double bonds and forming water and carbon dioxide as final products.

## Abstract

To effectively treat refractory azo dye wastewater, microwave advanced catalytic oxidation technology was adopted to degrade the model pollutant methyl orange using activated carbon fiber (ACF)/CuO as the catalyst and potassium persulfate (K2S2O8) as the oxidant. The optimized experimental parameters and the degradation pathway of methyl orange were determined. The results showed that when the microwave power was 500 W, the irradiation time was 2 min, the dosage of potassium persulfate was 0.6 g/L, and the dosage of ACF/CuO was 10 g/L, the removal rate of methyl orange solution was close to 100%, the COD removal rate was 89.65%, and the TOC removal rate was 72.36%. Mechanism analysis indicated that the double bond was broken to generate acid and p-nitrophenol, which were gradually degraded to benzene and phenol under the oxidation of sulfate radical. Subsequently, the benzene and phenol underwent chain cleavage to form maleic anhydride, and part of the benzene, phenol, and the generated maleic anhydride were ultimately degraded to water and carbon dioxide.

A combinative strategy involving microwave and heterogeneous catalysis based on ACF/CuO/K2S2O8 was innovatively applied to remove methyl orange contaminated water.

Methyl orange, COD and TOC removal efficiency in the combinative process were achieved to 100%, 89.65% and 72.36%, respectively.

Double bonds in methyl orange were broken to generate acid and p-nitrophenol, and they gradually degraded into benzene and phenol by oxidation of sulfate radicals. Water and carbon dioxide are the final degradation products.