Oxidation remediation of polycyclic aromatic hydrocarbons contaminated soil by microwave combined with biochar activated persulfate

doi:10.11949/0438-1157.20241160

Abstract

Abstract:

Microwave-activated persulfate (PS) oxidative degradation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils has received widespread attention, but its efficient remediation and its effect on acidification of remediated soil became contradictory. Weakly alkaline biochar was introduced in microwave-activated PS remediation of PAH-contaminated soil. The effects of microwave activation power, PS concentration, biochar addition and soil water content on removal efficiency of benzo[a]pyrene (BaP), soil pH and PS residual concentration in the contaminated soil were investigated. The characteristics of the contaminated soil before and after remediation were analyzed, and the degradation pathway and degradation mechanism of BaP in the contaminated soil were speculated. It was shown that at a microwave activation power of 490 W, a PS concentration of 1 mol/L, a biochar addition of 4% and a soil water content of 20%, the BaP removal efficiency in the contaminated soil after remediation for 60 min reached 97.77%, and the pH of the remediated soil was 4.65, with a residual concentration of 0.072 mol/L of PS. Biochar increased removal rate of BaP in contaminated soil and improved the acidity, particle size distribution and toxicity of the remediated soil to a certain extent. During the oxidative remediation process, BaP completely degraded to small-molecule intermediates and ultimately mineralized to CO₂ and H₂O under the co-oxidation of $S O 4 · -$ , ·OH and $· O 2 -$ free radicals and ¹O₂, electron-transferring non-radicals.

Key words: soil remediation, oxidation, activation, persulfate, microwave, biochar, polycyclic aromatic hydrocarbons

摘要：

微波活化过硫酸盐（PS）氧化降解多环芳烃污染土壤技术得到了广泛的关注，但其对污染土壤的高效修复和对修复后土壤酸化影响较难兼顾。在微波活化PS修复多环芳烃污染土壤中引入弱碱性生物炭，探讨了微波活化功率、PS浓度、生物炭添加量和土壤含水率对污染土壤中苯并［a］芘（BaP）去除率、土壤pH和PS残留浓度的影响，分析修复前后污染土壤特性，推测BaP降解路径和降解机理。研究表明，在微波活化功率490 W、PS浓度1 mol/L、生物炭添加量4%和土壤含水率20%条件下，修复60 min后污染土壤中BaP去除率达到97.77%，修复后土壤pH为4.65，PS残留浓度为0.072 mol/L。生物炭提高了污染土壤中BaP去除率，并在一定程度上改善了修复后土壤的酸性、粒径分布和毒性。BaP在 $S O 4 · -$ 、·OH、 $· O 2 -$ 活性氧自由基和¹O₂、电子转移的非自由基的共同氧化作用下降解为小分子中间产物，最终矿化为CO₂和H₂O。

关键词: 土壤修复, 氧化, 活化, 过硫酸盐, 微波, 生物炭, 多环芳烃

CLC Number:

X 53

Lei WU, Zixuan HU, Yuan GAO, Changbo LIU, Husheng CAO, Tiantian LIU, Ruiyu ZHU, Jun ZHOU. Oxidation remediation of polycyclic aromatic hydrocarbons contaminated soil by microwave combined with biochar activated persulfate[J]. CIESC Journal, 2025, 76(7): 3659-3670.

吴雷, 胡紫璇, 高渊, 刘长波, 曹虎生, 刘田田, 朱瑞玉, 周军. 微波联合生物炭活化过硫酸盐氧化修复多环芳烃污染土壤研究[J]. 化工学报, 2025, 76(7): 3659-3670.

Figures/Tables 11

Fig.1 Schematic diagram of microwave combined with biochar activated persulfate oxidative remediation of BaP contaminated soil

Fig.2 Effects of single and combined process on remediation of BaP-contaminated soil

Fig.3 Effects of microwave activation power on remediation of BaP-contaminated soil

Fig.4 Effects of PS concentration on remediation of BaP-contaminated soil

Fig.5 Effects of BC addition on remediation of BaP-contaminated soil

Fig.6 Effects of soil water content on remediation of BaP-contaminated soil

Fig.7 Characteristics of soil before and after oxidative remediation of persulfate by microwave combined with biochar activation

Table 1 Physicochemical properties of BaP contaminated soil before and after remediation

土壤样品	pH	有机质/ （g/kg）	机械组分/%
土壤样品	pH	有机质/ （g/kg）	砂粒	黏粒	粉粒
原始土壤	7.05	32.14±0.02	60.12	23.11	16.77
修复前污染土壤	7.08	29.12±0.03	63.29	21.22	15.49
修复后土壤	4.65	27.22±0.02	60.34	22.43	17.23

Fig.8 Degradation pathways of BaP in microwave combined with biochar activated persulfate oxidative remediation

Fig.9 Toxicity analysis of BaP degradation intermediates

Fig.10 Behavior of free radicals in oxidative remediation of persulfate by microwave combined with biochar activation

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