Acetaminophen degradation in aqueous solution by the UV-LED-EC/Cl₂ process

ABSTRACT

In this study, electrochemically generated free chlorine (EC/Cl2) was activated by UV irradiation with a light emitting diode (LED) lamp at 275 nm to degrade acetaminophen (AAP, 2 μM) in aqueous solution. The potential at a RuO2-IrO2/Ti plate anode was set at 1.5 V vs. the Ag/AgCl electrode. Chlorine was in situ generated in the presence of Cl杴 at the anode and then it was transformed into various active species such as 晑OH and reactive chlorine species (RCS) under UV-LED irradiation. The degradation of AAP was investigated using batch tests, evaluating the influence of different experimental conditions such as NaCl concentration, phosphate buffer saline concentration, irradiation time and solution pH, keeping constant the UV-LED power and temperature. Results show that AAP could be completely degraded by the hybrid process with a high mineralization ratio (73%), and the degradation process followed a pseudo-first-order kinetics. The value of the Electric Energy per Order (EEO) = 1.272 kWh m杴3 order?, which is lower than the energy consumption of some other UV-based processes for AAP degradation. Adding 1 mM HCO3杴 ions slightly decreased the rate of AAP degradation. Luminescent bacteria experiment revealed that the acute toxicity of the reacted solution could be greatly reduced and the ecological risk was effectively abated. The scavenging assay shows that RCS plays a key role in the AAP degradation. The intermediate products were identified, and possible degradation routes were proposed. The system can advantageously replace conventional UV mercury lamp based ones in the degradation of microorganic pollutants.

GRAPHICAL ABSTRACT

KEYWORDS:

• UV-LED
• acetaminophen
• mineralization
• degradation pathway
• acute toxicity

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author Liu upon reasonable request.

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number 52260005]; Natural Science Foundation of Jiangxi Province [grant number 20212BAB204041]; Key Research Development Program of Jiangxi Province [grant number 20203BBGL73230]; Science & Technology Plan Projects of Education Department of Jiangxi Province [grant number GJJ200617].