摘要
由于铁盐稳定化修复砷污染土通常不考虑砷价态对毒性和迁移性的影响,导致了修复效果欠佳。针对三价砷污染土提出了预氧化-稳定化协同修复方法,先使用芬顿将三价砷氧化为低迁移性的五价砷,再利用氯化铁将其稳定化。通过合成沉降淋滤试验、生物可利用性、pH测试、连续萃取试验和光谱分析研究了协同修复的稳定化效果和机理。结果表明,与未经处理的污染土相比,1%用量的芬顿和1倍铁砷比的氯化铁进行协同修复的稳定化处理可使浸出浓度降低99.6%,生物可利用性砷的质量分数降低99.4%,修复效率得到提高;芬顿氧化和氯化铁稳定化都使土壤pH降低,但1倍铁砷比下协同修复后的pH为5.82,高于6倍铁砷比下只用氯化铁修复的pH(3.78),由此可一定程度上避免过量使用铁盐造成的土壤酸化;连续萃取试验表明协同修复后更多不稳定态的砷转变为稳定形态;光谱分析发现协同修复可以将土壤中三价砷全部氧化为五价,并通过铁氧化物/氢氧化物吸附和砷酸铁沉淀的形式固定砷。本研究结果可为三价砷污染土修复提供理论和技术支持。
The effect of different arsenic valences on toxicity and mobility was usually not considered in stabilization using ferric salt for remediation of arsenic contaminated soil,resulting in an inefficient treatment.A combined treatment of oxidization-stabilization was proposed aiming at arsenite contaminated soil,which included oxidizing arsenite to low mobile arsenate by Fenton,and subsequently stabilizing arsenate by FeCl_3.Synthetic precipitation leaching procedure(SPLP),bioavailability,pH measurement,sequential extraction procedure,and spectral analysis were carried out to investigate the effect and mechanism of the proposed treatment method.The results showed that compared with the untreated contaminated soil,the leaching concentration was reduced by 99.6%with 1%dosage of Fenton and FeCl_(3)at an iron/arsenic ratio of 1,and the bioavailability As mass fraction was decreased by 99.4%.Soil pH was reduced by both Fenton oxidation and FeCl_(3)stabilization.However,the pH(5.82)after 1%dosage of Fenton and 1-molar-ratio of FeCl_(3)was obviously higher than that treated by 6-molar-ratio of FeCl_3(3.78),indicating that soil acidification caused by the excessive use of FeCl_(3)could be alleviated by the proposed treatment.The sequential extraction procedure results showed that a lot of unstable-state arsenic was converted to stable states by the combined treatment.The spectral analysis revealed that arsenite was converted to arsenate after the combined treatment and was subsequently adsorbed by iron oxide/hydroxide or precipitates as ferric arsenate.This study provides theory and technical support for effective remediation of arsenite contaminated soil.
作者
黄津祥
张文杰
蒋墨翰
李玉岐
HUANG Jinxiang;ZHANG Wenjie;JIANG Mohan;LI Yuqi(School of Mechanics and Engineering Science,Shanghai University,Shanghai 200444,China;School of Architecture Engineering,Taizhou University,Taizhou 318000,China;Shandong Electric Power Engineering Consulting Institute Co.,Ltd.,Jinan 250013,China)
出处
《环境工程学报》
CAS
CSCD
北大核心
2023年第10期3416-3422,共7页
Chinese Journal of Environmental Engineering
基金
国家自然科学基金面上项目(41772300)。
关键词
三价砷污染土
芬顿氧化
协同修复
浸出毒性
价态分析
arsenite contaminated soil
Fenton oxidation
combined remediation
leaching toxicity
valence state analysis
