功能型纳米LDHs协同矿渣固结Cr(VI)性能与机理研究

Chromium containing hazardous wastes contain a large amount of water-soluble Cr(VI), which is carcinogenic and mainly exists as Na2CrO4. It poses a serious threat to human health and ecological environment. The immobilization efficiency of Cr(VI) by traditional cement is low due to the lack of chemical fixation. In responsible of this problem, the blast furnace slag is used as the main immobilization material for its potential cementitious and reducing properties. Three types of nano-LDHs, with different functions, namely chemical binding, reducing detoxification and physical fixation, are introduced to achieve efficient immobilization of Cr(VI). The starting point of this project is the potential activation. The activation mechanism, immobilization mechanism and the main factors are discussed. On this basis, the effects of composition and structure of functional nano-LDHs on the immobilization capacity are studied. Meanwhile, the hydration and hardening properties are also investigated. Then the efficacy and mechanism of functional nano-LDHs to enhance the immobilization of Cr(VI) by slag are verified. Finally, the corrosion resistance of Na2CrO4-LDHs-slag pastes in the simulated acid rain, underground sulfate attack and landfill leachate environment are evaluated. The leaching mechanism of Cr(VI) and Cr(III) during the corrosion process is also analyzed in order to evaluate the safety and stability. The research outcomes will provide theoretical basis and technical support for the harmless disposal of Cr(VI) containing hazardous wastes.

含铬危险废物中含有大量水溶性致癌物Cr(VI)，其主要以Na2CrO4形式存在，严重威胁人体健康和生态环境。传统水泥对Cr(VI)缺乏有效的化学结合作用，固结效率较低。针对该问题，本项目拟以矿渣为主要固结材料，利用其潜在胶凝性和还原性，并通过引入能发挥化学结合、还原解毒和物理固封功能的纳米LDHs（层状双氢氧化物），实现Cr(VI)的高效固结处置。以Na2CrO4对矿渣活性的潜在激发作用为切入点，探明激发机理、固结机制及其主要影响因素。在此基础上，研究功能型纳米LDHs组成、结构对其固结能力及固结体水化硬化性能的影响，探明LDHs提升矿渣固结Cr(VI)的效率与机理。研究模拟酸雨、硫酸盐和填埋场渗滤液环境中Na2CrO4-LDHs-矿渣固结体的抗侵蚀能力，分析Cr(VI)和Cr(III)的溶出机理，评价固结体的长期安全稳定性，为含Cr(VI)危险废物的无害化处置提供理论基础和技术支持。

含铬危险废物中含有大量水溶性致癌物Cr(VI)，严重威胁人体健康和生态环境，传统水泥对其缺乏有效的化学结合作用。在传统固化技术基础上，开发高效、环保的Cr(VI)固化材料，对于保护我国生态环境和保障人民身体健康具有重要的现实意义。本项目从水溶性Na2CrO4的化学性质出发，以碱激发原理为基础，首先研究了Na2CrO4作用下高炉矿渣的水化行为，揭示了水溶性Cr(VI)对矿渣活性的激发作用；其次，基于层状双金属氢氧化物（LDHs）的组成可调控性和结构记忆效应，制备了具有化学结合作用和还原作用的LDHs材料，分析了其吸附Cr(VI)的能力及其影响因素，明确了LDHs组成与其吸附Cr(VI)能力的关系；在此基础上，利用LDHs材料具有的碱性及记忆效应，将其与矿渣复合，研究了LDHs材料对矿渣水化、硬化性能及Cr(VI)浸出浓度的影响，提出了LDHs复合矿渣固化Cr(VI)的新体系；最后，评估了新体系在硫酸盐以及模拟垃圾填埋场渗滤液等侵蚀环境中的长期稳定性能。研究成果可为含Cr(VI)危险废物的无害化处置提供理论基础和技术支持。