Screening Refractory Dye Degradation by Different Advanced Oxidation Processes

Area of Science:

• Environmental Chemistry
• Electrochemistry
• Water Treatment

Background:

• Rhodamine B (RhB) is a persistent organic pollutant found in textile wastewater.
• Effective degradation methods are crucial for mitigating environmental pollution from dyes.

Purpose of the Study:

• To investigate the degradation of Rhodamine B (RhB) using electro-Fenton (EF), anodic oxidation (AO), and a combined EF/AO process.
• To evaluate the influence of operational parameters on degradation efficiency and mineralization.
• To assess the toxicity reduction and mineralization pathways of RhB during electrochemical treatment.

Main Methods:

• Electrochemical degradation using carbon felt cathodes and Ti4O7 or Ti/Pt anodes.
• Optimization of current density and assessment of RhB concentration effects.
• Toxicity assessment using Microtox® bioluminescence inhibition test.
• Mineralization analysis via total organic carbon (TOC) removal.
• Degradation pathway elucidation using high-resolution mass spectrometry.

Main Results:

• Optimal current density for RhB degradation was 30 mA cm⁻², balancing efficiency and energy consumption.
• The combined EF/AO process achieved 90% TOC removal at pH 3, indicating superior mineralization.
• Electrochemical treatment significantly reduced the toxicity of RhB solutions, with EF/AO showing the highest reduction.
• Degradation pathways involved chain oxidation reactions, leading to mineralization into CO2 and H2O.

Conclusions:

• EF, AO, and EF/AO are effective electrochemical methods for Rhodamine B degradation and mineralization.
• The combined EF/AO process offers a promising approach for sustainable and eco-friendly wastewater treatment.
• Optimized electrochemical processes can efficiently remove persistent organic pollutants and reduce their toxicity.