浒苔基生物炭对污染疏浚物中重金属的盖帽修复研究

Dredging as an important measure to maintain the water depth of port and navigation, a large number of digged dredged materials has become a reservoir of various types of pollutants due to human activities. In order to prevent marine environment pollution, contaminated dredged materials must be restrictively disposed before dumping. Due to the missing of related technologies, the actual management of contaminated dredged materials is still in absence in China. Capping remediation is to cover the contaminated dredged materials in seafloor with cleaning materials to control the migration and diffusion of pollutants, which has successful cases in abroad. Biochar has a strong adsorption capacity for heavy metals due to the porous structure and abundant oxygen-containing functional groups on the surface. It is widely used in soil remediation, but less involved in the remediation of dredged materials. Biochar yield obtained from Enteromorpha hydrothermal liquefaction is 10-30%. Therefore its application to the remediation of heavy metals in contaminated dredged materials has important research and application value. This subject intends to carry out simulation study of Enteromorpha-based biochar for capping remediation of heavy metals-contaminated dredged materials in the laboratory to reveal the blocking effect and adsorption mechanism of capping layer. The results could accumulate basic data and scientific basis for the capping remediation of contaminated dredged materials, and provide technical support for the comprehensive treatment of contaminated dredged materials in China.

疏浚作为维护港口水深和通航的重要措施，挖出的大量疏浚物受人类活动影响显著，已成为各类污染物的蓄积库。为避免产生新的环境问题，污染疏浚物必须经过限制性海上处置方可倾倒。由于相关技术的研究空白，我国对污染疏浚物的实际管理工作还处于缺位状态。盖帽修复是将污染疏浚物在海底用清洁材料覆盖以控制污染物的迁移扩散，在国际上已有成功案例。生物炭因多孔结构和表面丰富含氧官能团对重金属有较强吸附能力，在土壤修复方面应用较广泛，但在疏浚物的修复研究领域涉及较少。浒苔水热法获得的生物炭产率达10-30%，将其应用到污染疏浚物的重金属修复中具有重要研究和应用价值。本课题拟在实验室开展浒苔基生物炭掺杂粘土对污染疏浚物盖帽修复的模拟研究，揭示盖帽层对疏浚物中重金属迁移的阻滞效应和吸附机制。研究结果可为污染疏浚物的盖帽修复积累基础数据和科学依据，同时为我国污染疏浚物的综合治理提供技术支撑。

浒苔基生物炭对污染疏浚物的重金属修复具有重要研究和应用价值。本课题利用限氧热解法制备浒苔基生物炭，并开展特性分析，将其应用到对海水中典型重金属的吸附研究中，探讨其吸附规律，在此基础上，开展浒苔基生物炭对污染疏浚物盖帽修复的模拟研究，揭示盖帽层对疏浚物中重金属迁移的阻滞效应和吸附机制。主要研究结果为：1）实验制备的浒苔生物炭是一种具有吸附潜力的材料，浒苔基生物炭有良好的空隙结构，表面富含有机官能团。2）将优化后的浒苔生物炭应用到对海水中重金属的吸附中，发现其吸附海水中铜和铅在60 min内即可达到平衡，最大去除率分别为91%和54%；浒苔生物炭对海水中重金属的吸附满足Langmuir等温吸附式，对铜和铅的饱和吸附量分别为254和98 mg/Kg。3）盖帽实验表明，上覆水中重金属浓度随着盖帽厚度的增加而降低，Cu、Pb和Cd的盖帽效率分别为83.5%、53.9%和76.4%。4）盖帽实验对疏浚物中Cu有一定的固化效果，对Pb的固化效果不明显，可能增加污染疏浚物中不稳定态Cd的释放。浒苔生物炭的盖帽法对污染疏浚物重金属释放的阻滞效应可能主要基于机械屏障及物理/化学吸附作用。