热脱附可有效去除污染场地土壤结合残留态PAHs  

Effective removal of residual PAHs in soil from contaminated site by thermal desorption

作　　者：冯潞 宋静[2,3] 郝国辉 余海波[2] 唐伟[2] 晏井春 陈星[5] 洪欣 FENG Lu;SONG Jing;HAO Guohui;YU Haibo;TANG Wei;YAN Jingchun;CHEN Xing;HONG Xin(School of Resources and Environmental Engineering,Anhui University,Hefei 230601,China;Institute of Soil Science,Chinese Academy of Sciences,Nanjing 211135,China;University of Chinese Academy of Sciences,Nanjing 211135,China;Jiangsu Agricultural Products Quality Inspection and Testing Centre,Nanjing 210013,China;China Construction Eighth Engineering Division Crop.,Ltd.,Shanghai 200122,China)

机构地区：[1]安徽大学资源与环境工程学院,合肥230601 [2]中国科学院南京土壤研究所,南京211135 [3]中国科学院大学南京学院,南京211135 [4]江苏省农产品质量检验测试中心,南京210013 [5]中国建筑第八工程局有限公司,上海200122

出　　处：《环境工程学报》2024年第12期3623-3632,共10页Chinese Journal of Environmental Engineering

基　　金：国家重点研发计划资助项目(2021YFC1809201)。

摘　　要：工业污染场地土壤中的多环芳烃(PAHs)经长时间老化后,由于土壤有机质的吸附等作用会形成不可萃取的结合残留态PAHs,其仍可能具有生物有效性。因此,PAHs污染土壤修复时需要考虑对结合残留态PAHs的去除效果。选用安徽某焦化场地长期自然老化的PAHs污染土壤,采用烘箱模拟不同脱附温度(150、200、250、300、400、500℃)和停留时间(30、60、90 min),旨在探究热脱附对结合残留态PAHs(尤其是高环PAHs)的去除效果及可能去除机制。研究结果表明:1)热脱附可有效去除污染场地土壤中可提取态和结合残留态PAHs。在300℃、30 min条件下,可提取态和结合残留态PAHs去除率分别为99.6%、99.3%,结合残留态苯并[a]芘未检出。2)热脱附会导致土壤有机质质量分数下降。在250℃,以上时腐殖质组分胡敏素开始被去除并伴随胡敏酸生成,胡敏酸和富里酸在400℃以上时质量分数显著下降,直至未检出。3)综合分析,热脱附去除结合残留态PAHs的机制可能是土壤中胡敏素受热分解破坏了胡敏素对结合残留态PAHs的吸附作用,导致结合残留态PAHs解吸并在高温条件下被去除。该研究结果可为多环芳烃污染土壤热脱附工艺设计和修复后土壤安全性评估提供科学依据。Polycyclic aromatic hydrocarbons(PAHs)in soils at contaminated industrial sites form nonextractable bound residues after long-term ageing due to adsorption by soil organic matter,etc.The bound residual PAHs may still be bioavailable.Therefore,the removal of bound PAHs needs to be considered in the remediation of PAHs-contaminated soils.Naturally aged PAHs-contaminated soil from a coking site in Anhui Province was selected and different desorption temperatures(150,200,250,300,400,500°C)and residence times(30,60,90 min)were simulated in an oven.The purpose of the study was to investigate the effect of thermal desorption on the removal of bound residue PAHs(especially high molecular weight PAHs)and the possible removal mechanism.The results showed that:1)Thermal desorption was effective in removing extractable and bound PAHs from the contaminated soil,and the removal rates of extractable and bound PAHs were 99.6%and 99.3%,respectively,at 300℃for 30 min,and the bound benzo[a]pyrene was not detected.2)Thermal desorption leaded to a decrease in soil organic matter content.Humin started to be removed and was accompanied by the formation of humic acid above 250℃,and the content of humic acid and fulvic acid decreased significantly above 400℃until they were no longer detectable.3)The removal of bound residual PAHs by thermal desorption is likely due to the thermal decomposition of humin in soil,which destroys the adsorption of bound residual PAHs on humin,leading to the desorption of bound residual PAHs and their removal at high temperatures.The study provides a scientific basis for the design of the thermal desorption of PAH-contaminated soil and the assessment of the safety of remediated soils.

关 键 词：多环芳烃 污染场地 结合残留态 热脱附 土壤有机质 

分 类 号：X53[环境科学与工程—环境工程]