Liu Yanan, Deng Siyu, Chen Lulu, Zhang Ai, Suttiruengwong Supakij, Sun Zhuyu
College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China.
Chemosphere. 2022 Jun;297:134145. doi: 10.1016/j.chemosphere.2022.134145. Epub 2022 Feb 28.
Non-thermal plasma (NTP) technology is an emerging advanced oxidation process, which has shown excellent performances in soil organic pollution remediation. Dissolved organic matter (DOM) is one of the most important components in soil, however, investigations on the structural and compositional changes of DOM during NTP process are lacking. Therefore, in the present study, we systematically investigated the soil DOM changes under different discharge voltages, atmospheres or soils with different moisture contents. The results indicated that after NTP treatment, substantial soil organic matters were released and dissolved in water. For instance, the DOC value of DOM increased dramatically from 21.1 to 197.3 mg L after being discharged for 120 min under the discharge voltage of 80 V. The UV-Vis characterization results indicated the significant increase of hydrophilicity, and decreases of aromaticity and molecular weight for soil DOM during the initial discharge period. However, long time discharge resulted in slight recovery of aromaticity and hydrophobicity, possibly due to the dehydration and re-condensation of small molecules. EEM-FRI results indicated that the total fluorescence intensity of DOM decreased obviously, indicating the destruction of fluorescent dissolved organic matter (FDOM). While the proportions of humic-like and microbial byproduct-like substances increased, indicating that those substances were more recalcitrant under NTP treatment compared with fulvic acid-like and aromatic protein-like substances. Four fluorescence components were identified by PARAFAC, and microbial and terrestrial humic-like substances were more difficult to degrade compared to other humic-like substances and fulvic acid-like substances. Additionally, discharge voltage and atmosphere had great influences on DOM changes, while the impact of soil moisture content was not significant. Overall, this study provided insights into the DOM changes during NTP process, which is valuable for more comprehensive evaluation of the NTP technique application in practical soil remediation.
非热等离子体（NTP）技术是一种新兴的高级氧化工艺，在土壤有机污染修复方面表现出优异性能。溶解有机物（DOM）是土壤中最重要的成分之一，然而，关于NTP处理过程中DOM结构和组成变化的研究尚缺。因此，在本研究中，我们系统地研究了不同放电电压、气氛或不同含水量土壤条件下土壤DOM的变化。结果表明，NTP处理后，大量土壤有机物被释放并溶解于水中。例如，在80V放电电压下放电120min后，DOM的DOC值从21.1急剧增加到197.3mg/L。紫外-可见光谱表征结果表明，在初始放电阶段，土壤DOM的亲水性显著增加，芳香性和分子量降低。然而，长时间放电导致芳香性和疏水性略有恢复，这可能是由于小分子的脱水和再缩合。EEM-FRI结果表明，DOM的总荧光强度明显降低，表明荧光溶解有机物（FDOM）被破坏。而类腐殖质和微生物副产物类物质的比例增加，表明与类富里酸和芳香蛋白类物质相比，这些物质在NTP处理下更难降解。通过PARAFAC识别出四种荧光组分，与其他类腐殖质和类富里酸物质相比，微生物和陆地类腐殖质物质更难降解。此外，放电电压和气氛对DOM变化有很大影响，而土壤含水量的影响不显著。总体而言，本研究深入了解了NTP处理过程中DOM的变化，这对于更全面评估NTP技术在实际土壤修复中的应用具有重要价值。
