Degradation of roxarsone in UV-based advanced oxidation processes: A comparative study
Lu Chen1, Hongchao Li1, Jieshu Qian1
1Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, Nanjing 210094, China.
Journal of Hazardous Materials
|November 23, 2020
Summary
This study investigated UV-based advanced oxidation processes (AOPs) for degrading the organoarsenical roxarsone (ROX). UV/hydrogen peroxide showed the highest ROX removal, while UV/peroxydisulfate best reduced total organic carbon.
Area of Science:
- Environmental Chemistry
- Water Treatment Technologies
- Advanced Oxidation Processes
Background:
- Organoarsenicals like roxarsone (ROX) present significant environmental and health risks.
- Effective degradation methods for ROX are crucial for mitigating its ecological impact.
Purpose of the Study:
- To comparatively investigate the degradation of ROX using UV-based advanced oxidation processes (AOPs).
- To evaluate UV/hydrogen peroxide (UV/H2O2), UV/peroxydisulfate (UV/PDS), and UV/peroxymonosulfate (PMS) for ROX removal and arsenic speciation.
Main Methods:
- Comparative analysis of UV/H2O2, UV/PDS, and UV/PMS processes for ROX degradation.
- Determination of second-order rate constants for ROX with hydroxyl and sulfate radicals.
- Investigation of kinetic models, oxidant dosage, pH, and water matrix effects (humic acid, bicarbonate).
- Analysis of arsenic speciation changes during degradation.
Main Results:
- ROX removal efficiency order at pH 7.0: UV/H2O2 > UV/PDS > UV/PMS.
- UV/PDS demonstrated the highest efficiency in reducing total organic carbon (TOC).
- Degradation followed pseudo-first-order kinetics, with rate constants increasing with oxidant dosage.
- pH had limited effect except for UV/PMS at pH 11.0; humic acid and bicarbonate inhibited degradation.
- Arsenic in ROX was primarily converted to As(V) across all tested AOPs.
Conclusions:
- UV/H2O2 and UV/PDS are effective AOPs for ROX degradation and TOC reduction.
- Understanding reaction kinetics and influencing factors is key for optimizing ROX removal.
- These findings offer valuable insights for treating ROX-contaminated water using UV-based AOPs.
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