Reactive Blue 19 dye removal by UV-LED/chlorine advanced oxidation process

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Advanced Oxidation Processes

Background:

• Dye contamination in wastewater poses environmental challenges.
• Advanced Oxidation Processes (AOPs) show promise for degrading stable organic pollutants.
• Reactive Blue 19 (RB19) is a common, persistent dye found in textile effluents.

Purpose of the Study:

• To evaluate the efficacy of UV-LED/chlorine as an AOP for RB19 dye removal.
• To investigate the influence of operational parameters on dye degradation.
• To compare the UV-LED/chlorine process with UV-LED irradiation and chlorination alone.

Main Methods:

• Experimental study of UV-LED irradiation, UV-LED/chlorine, and chlorination for RB19 removal.
• Optimization of parameters: pH, chlorine concentration, dye concentration, and reaction time.
• Kinetic analysis and radical scavenging assays to elucidate degradation mechanisms.
• Assessment of anion interference and synergistic effects.

Main Results:

• UV-LED/chlorine achieved >99% RB19 removal under optimized conditions (pH 5, 300 μM chlorine, 20 mg L^-1 RB19) with a rate constant of 17.1 × 10^-2 min^-1.
• UV-LED irradiation alone was ineffective; chlorination alone yielded 64.7% removal.
• Hydroxyl radicals (OH^•) were the primary reactive species, contributing 67.23% to RB19 degradation.
• A synergy index of 5.0 indicated a significant enhancement by combining UV-LED and chlorine.
• Optimized UV-LED/chlorine process removed 98% of Chemical Oxygen Demand (COD) and showed promise for textile wastewater treatment (30.9% COD removal).

Conclusions:

• The UV-LED/chlorine process is a highly efficient AOP for removing RB19 dye and reducing COD in wastewater.
• Hydroxyl radicals play a dominant role in the degradation mechanism.
• The combined process exhibits a strong synergistic effect, outperforming individual methods.
• This technology offers a viable solution for treating dye-contaminated industrial effluents.