Carbonate-activated hydrogen peroxide oxidation process for azo dye decolorization: Process, kinetics, and mechanisms

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies

Background:

• Advanced oxidation processes (AOPs) are crucial for industrial wastewater treatment.
• Highly alkaline wastewaters pose challenges for conventional treatment methods.

Purpose of the Study:

• To investigate the efficacy of the carbonate-activated hydrogen peroxide (CAP) oxidation process for removing organic pollutants from highly alkaline wastewater.
• To evaluate the performance of CAP using acid orange 7 (AO7) as a model pollutant.

Main Methods:

• Systematic evaluation of parameters influencing AO7 decolorization by CAP.
• Identification of active species using scavenger experiments and electron spin resonance (ESR).
• Analysis of AO7 degradation products to propose transformation pathways.

Main Results:

• CAP demonstrated superior AO7 decolorization compared to bicarbonate-activated hydrogen peroxide.
• Decolorization efficiency increased significantly with carbonate and hydrogen peroxide concentrations.
• Trace Co(II) addition enhanced AO7 removal.
• Superoxide and carbonate radicals were identified as key reactive species.

Conclusions:

• The CAP oxidation process is effective for treating highly alkaline wastewater containing organic pollutants like AO7.
• Optimized conditions and Co(II) catalysis enhance CAP efficiency.
• Understanding radical species and degradation pathways informs process optimization.