三氧化二铁(科研|Journal of Hazardous Materials: 三氧化二铁强化热解修复重质石油污染土壤)

三氧化二铁

导言
针对目前热解技术在修复重质石油污染土壤过程中存在能耗高且对土壤生态功能破坏大等缺点,近日,国际学术期刊Journal of Hazardous Materials在线发表了“Hematite-facilitated Pyrolysis: An Innovative Method for Remediating Soils Contaminated with Heavy Hydrocarbons”。本研究利用廉价易得、绿色环保的三氧化二铁(Fe2O3)作为添加剂对重质石油污染土壤进行强化热解修复,研究结果表明,Fe2O3能够降低反应能量势垒,使重质石油烃能在相对较低的温度下开始裂解,提升了热解效率。该研究由污染场地安全修复技术国家工程实验室中国环境科学研究院分室谷庆宝研究员课题组完成。

▲图片1来源:期刊发表截图
本文的研究背景是基于石油在开采、储运、加工和使用过程中,因渗漏、溢出等原因可能造成严重的土壤污染。其中,重质石油烃作为石油的组成部分,主要是由芳香烃、胶质和沥青质等大分子有机物构成,在土壤环境中即使经过数十年的自然风化作用依然不能降解,给土壤环境和人居安全造成了一定的威胁。热解技术可在300-500 °C将重质石油烃(胶质、沥青质等)热解为可挥发去除的轻质油和无毒害的焦炭类物质,与焚烧技术相比,热解技术应用于修复石油污染土壤可能节省40%-60%的能耗。然而,该技术仍存在能耗高对土壤生态功能破坏大等缺点。
因此,为了进一步降低热解技术修复石油污染土壤的能耗,维持土壤的生态功能,本研究首次采用廉价易得绿色环保的 Fe2O3添加剂对重质石油污染土壤在相对较低的热解温度和相对较短的时间下进行强化热解修复,基于对土壤中污染物的去除效率、土壤理化性质变化及生态功能恢复的分析和表征,揭示了 Fe2O3强化热解修复重质石油污染土壤的机理,为热解技术在我国石油污染土壤中的应用提供理论和技术支持。

研究表明,在热解温度为400 °C、时间为30 min的条件下,相比于传统无添加剂热解修复后的土壤,添加5% Fe2O3强化热解修复后的土壤中总石油烃(TPH)去除率提升了25.5%,其中芳香烃、胶质和沥青质三个重质组分的去除率分别增加了67.8%、52.3%和67.9%,土壤理化性质分析结果表明Fe2O3强化热解修复后土壤持水率显著增加。作者通过SEM-EDX表征发现Fe2O3强化热解修复后土壤表面变黑且出现大量微孔结构,XPS分析结果表明这层黑色且具有大量微孔结构的物质为石墨碳层。作者还发现Fe2O3强化热解修复后土壤中小麦发芽率和生物产量显著提高,甚至优于无污染土壤,表明Fe2O3强化热解技术能够恢复并提升土壤生态功能。

▲图片2来源:期刊发表截图
文章信息
英文标题:
Hematite-facilitated Pyrolysis: An Innovative Method for Remediating Soils Contaminated with Heavy Hydrocarbons
英文摘要:
As a recalcitrant fraction of petroleum, heavy hydrocarbons (including aromatics, resins, and asphaltenes) can remain in contaminated soils even after decades of weathering, thereby causing serious harm to the soil ecosystem and human health. Pyrolysis is a promising technique for remediating petroleum-contaminated soil. However, this technique still presents some drawbacks, such as high energy consumption and damage to soil properties. Therefore, an innovative method using hematite (Fe2O3) for the catalytic pyrolysis of weathered petroleum-contaminated soil was developed in this study. Compared with soil pyrolyzed without Fe2O3 at 400 °C for 30 min, the residual concentrations of aromatics, resins, and asphaltenes in soil pyrolyzed with 5.0% Fe2O3 were reduced by 67.8%, 52.3%, and 67.9%, respectively. After pyrolysis with 5.0% Fe2O3, the water-holding capacity of soil was considerably increased and the soil became darker and rougher. Scanning electron microscopy analysis showed that many small holes occurred on the surface of the pyrolytic soil. X-ray photoelectron spectrometer analysis showed that a thin layer of graphitic C was formed and deposited on the surface of the pyrolytic soil. We also observed that the wheat germination percentage and biomass yield in the soil pyrolyzed with 5.0% Fe2O3 were even higher than those in clean soil.

中国环境科学研究院博士研究生刘钰钦为该论文的第一作者,谷庆宝研究员和马福俊副研究员为论文的共同通讯作者。该研究得到了国家重点研发计划“有机污染场地土壤修复热脱附成套技术与装备(2018YFC1802100)”和国家自然科学基金项目的资助。
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