吸附态陈旧性石油重度污染土壤的固相铁Fenton氧化修复技术及机制基础研究

The aged soil heavily contaminated by abandon oil distributes widely in China, which leads to a seriously environmental problem and should be tackled instantly. Therefore, this study is about remediating the aged soil heavily by sorbed oil in abandon oil field. By extraction experiment the analysis of the content and composition of oil and soil organic matter in the aged soil, the partition characteristics between oil and soil as well as the way of computing stoichiometric dosage of H2O2 and iron will be clarfied. Thereafter,the formation of soil surface iron catalyst by the stepwise H2O2 under different conditions, the required conditions and the characterictics of soil surface iron catalyst will be studied. Then, soil surface iron catalyst will be prepared and the oxidation of sorbed TPH in aged soil under different conditions, the required conditions will be studied.In addition, under soil surface iron oxidation conditions, the mechanisms of active species radical generation and direct-oxidation characteristics of sorbed TPH as well as relative factors influencing oxidation will be studied. Furthermore, by the above studies, we will clarify the mechanisms regarding the oxidation of sorbed TPH by the active species radical under soil surface iron oxidation conditions. Finally, we will select an abandon oil field and remediate its aged contaminated soil under soil surface iron oxidation conditions. In this field experiment, the relationship between formation of soil surface iron, the active species radical generation and its following utilization and oxidation of sorbed TPH will be optimized.Then, the operation technique will be developed. Thereafter, by this study, we will further enrich theoretical and technical basis for the in situ remediation of heavyly oil-contaminated aged soil.

我国吸附态陈旧性石油污染土壤面积大、涉及区域广、危害大，是目前亟待解决的重大环境问题。本课题针对退役井场重度石油污染土壤，通过萃取试验，研究陈旧性土壤吸附石油的性质及分配特性，研究建立H2O2和铁理论投量的计算方法；在此基础上，研究低浓度多次投加H2O2形成土壤固相铁的条件；通过土壤固相铁氧化试验，研究土壤固相铁氧化陈旧性吸附油的控制条件；并研究体系水相和固相活性基的生成条件、石油氧化规律以及活性基生成速率与石油氧化率的相关关系，阐明土壤固相铁氧化陈旧性吸附油的作用机制；通过退役井场现场土壤固相铁氧化模拟试验，确定土壤固相铁形成、石油氧化同时实现的Fenton优化控制条件，建立土壤固相铁Fenton氧化操作技术，为我国吸附态陈旧性石油重度污染土壤原位修复方法的进一步完善奠定理论和技术基础。

传统Fenton化学氧化石油污染土壤过程中，现有研究的Fenton体系中羟基自由基（•OH）大多数产生在水相中，土壤吸附的石油要先从土壤固相解析到水相才能被间接氧化，但羟基自由基的寿命极短，会在吸附态石油解析到液相之前，羟基自由基已经消失了，羟基自由基存在时间短限制了陈旧吸附态石油的间接氧化去除，为此本研究尝试在固相产生羟基自由基、陈旧性吸附态石油无需解析直接被氧化去除的研究。主要开展了陈旧性土壤吸附石油的性质及氧化特性研究，土壤固相铁形成技术研究（交联剂筛选；溶解性浓度适宜范围确定；H2O2投加浓度和次数适宜范围确定），土壤固相铁制备及其特性研究（结合状态；赋存状态；分布特征及催化特性研究），土壤固相铁氧化陈旧性吸附油的Fenton方法研究（石油氧化相关的内容），土壤固相铁Fenton氧化陈旧性吸附油的机制研究， 土壤固相铁形成、吸附态石油氧化同时实现的Fenton条件优化及操作技术的建立这六部分内容的试验研究，所有研究内容都按计划进行并且按期完成。其中突出的研究进展和创新性的学术业绩为：.（1）研究发现土壤有机质（SOM）中腐殖酸中的醇、醚或C-O等官能团可以吸附或络合溶解性铁（Fe2+）形成土壤固相铁（Fe-SOM），Fe-SOM可以催化H2O2产生•OH直接氧化吸附态的石油污染物，提高土壤陈旧性吸附石油的氧化效果。（2）壳聚糖（Cs）主要促进固相铁氧化物（Fe-SOM oxides）形成，腐殖酸HA主要促进有机固相铁（Organic Fe-SOM）形成。（3）当固相铁存在时，催化H2O2大幅度提高了土壤中石油的氧化效果。且含量越高，H2O2分解产生羟基自由基的反应速率越快，氧化石油效果越好，与水相羟基自由基间接氧化石油的规律相反，固相铁体系中石油的氧化不受羟基自由基存在时间短的限制。（4）分别比较了固相•OH预氧化和液相•OH预氧化对土著菌的影响，固相铁Fenton体系中•OH强度高，相应TPH的去除率（58%）也明显高于不含Fe-SOM的体系（15.6%）。公开发表相关研究论文21篇，其中SCI收录15篇，EI收录2篇；已申请专利11项，其中7项已获得授权；培养硕士研究生18名。