Scholarlink

<p>This study evaluates underwater non-thermal plasma (UNTP) as a reagent-free process for the complete mineralization of oxalic acid, a major chelating agent in nuclear decontamination effluents. Quantitative assessment was based on total organic carbon (TOC) removal and stable carbon isotope tracing with uniformly labeled ¹³C-oxalic acid. TOC and ion chromatography (IC) analyses demonstrated complete mineralization within 60&#xa0;min at ≤ 300 ppm (k = 0.120, 0.100, 0.042&#xa0;min⁻¹; t₉₀ = 19.2, 23.0, 55.0&#xa0;min), whereas at 450 ppm partial mineralization remained (TOC 25.4&#xa0;mg C/L after 60&#xa0;min). At higher concentrations (1000–2000 ppm), TOC removal was restricted to 25–57% with rate constants decreasing to 0.008 and 0.003&#xa0;min⁻¹ (t₉₀ = 288, 767&#xa0;min); at 3000 ppm, reaction nearly stagnated (k = 0.0009&#xa0;min⁻¹; t₉₀ ≈ 2558&#xa0;min). Energy yield peaked at low/intermediate concentrations (0.9–1.3&#xa0;g-C kWh⁻¹; 1.1&#xa0;g-C kWh⁻¹ at 450 ppm) but declined to 0.9, 0.3, and 0.2&#xa0;g-C kWh⁻¹ at 1000, 2000, and 3000 ppm. Mechanistic profiling showed that both glyoxylic and formic acids remained below the method detection limits (LOD) throughout the treatment period, supporting that a predominantly direct mineralization pathway to CO₂ was operative. Critically, ¹³C tracer experiments (300 ppm, 60&#xa0;min) yielded δ¹³C = + 5702‰ (~ 7.0 atom % ¹³C), confirming the presence of substrate-derived carbon in the evolved CO₂. No solids or carbonate byproducts were detected, consistent with a nearly closed carbon balance. Bulk temperatures remained ≤ 40&#xa0;°C under all conditions, confirming non-thermal operation. These findings establish TOC-based kinetics and isotopic evidence of oxalic acid mineralization, define a practical operating window (≤ 2000 ppm), and support UNTP as a sustainable route for treating chelating agents in decontamination effluents.</p> Graphic abstract <p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Mineralization of oxalic acid by underwater non-thermal plasma: TOC removal and 13C isotope tracer

  • 期刊论文

  • 发表日期：

    2026年2月10日

查看全文
  • Ki-baek Shin,
  • Heejae Lee,
  • Geon Woo Yang,
  • Yong Cheol Hong,
  • Daeseok Hong,
  • Kangil Kim,
  • Gyuseong Cho

摘要

This study evaluates underwater non-thermal plasma (UNTP) as a reagent-free process for the complete mineralization of oxalic acid, a major chelating agent in nuclear decontamination effluents. Quantitative assessment was based on total organic carbon (TOC) removal and stable carbon isotope tracing with uniformly labeled ¹³C-oxalic acid. TOC and ion chromatography (IC) analyses demonstrated complete mineralization within 60 min at ≤ 300 ppm (k = 0.120, 0.100, 0.042 min⁻¹; t₉₀ = 19.2, 23.0, 55.0 min), whereas at 450 ppm partial mineralization remained (TOC 25.4 mg C/L after 60 min). At higher concentrations (1000–2000 ppm), TOC removal was restricted to 25–57% with rate constants decreasing to 0.008 and 0.003 min⁻¹ (t₉₀ = 288, 767 min); at 3000 ppm, reaction nearly stagnated (k = 0.0009 min⁻¹; t₉₀ ≈ 2558 min). Energy yield peaked at low/intermediate concentrations (0.9–1.3 g-C kWh⁻¹; 1.1 g-C kWh⁻¹ at 450 ppm) but declined to 0.9, 0.3, and 0.2 g-C kWh⁻¹ at 1000, 2000, and 3000 ppm. Mechanistic profiling showed that both glyoxylic and formic acids remained below the method detection limits (LOD) throughout the treatment period, supporting that a predominantly direct mineralization pathway to CO₂ was operative. Critically, ¹³C tracer experiments (300 ppm, 60 min) yielded δ¹³C = + 5702‰ (~ 7.0 atom % ¹³C), confirming the presence of substrate-derived carbon in the evolved CO₂. No solids or carbonate byproducts were detected, consistent with a nearly closed carbon balance. Bulk temperatures remained ≤ 40 °C under all conditions, confirming non-thermal operation. These findings establish TOC-based kinetics and isotopic evidence of oxalic acid mineralization, define a practical operating window (≤ 2000 ppm), and support UNTP as a sustainable route for treating chelating agents in decontamination effluents.

Graphic abstract