State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Dongsanlu, Erxianqiao, Chengdu 610059, Sichuan, PR China.
State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Dongsanlu, Erxianqiao, Chengdu 610059, Sichuan, PR China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
Environ Int. 2020 Feb;135:105374. doi: 10.1016/j.envint.2019.105374. Epub 2019 Dec 18.
Biochar-based nanocomposites with functional materials provide an excellent prospect in reactivity and stability. Most biochar reported have no reusability upon aging and offer the risk of release of immobilized components after short-term immobilization. To overcome this, we developed nano zero-valent iron (nZVI) impregnated magnetic green tea biochar (nZVI@GTBC) and studied its performance in immobilizing Pb and long-term effectiveness in the soil. The reactive nZVI units were obtained from iron oxide solution by reducing with polyphenol solution (green tea extract) and were successively stabilized by impregnation onto the remaining green tea waste matrix through co-precipitation technique. Finally, the magnetic biochar was developed from the above nZVI impregnated green tea waste through oven drying and slow pyrolysis technique in different temperature range (150-650 °C). The synthesized nZVI@GTBC biochar was characterized and studied by XRD, FTIR, Raman, UV-Vis, TG/DSC, XPS, SEM, and TEM. The nZVI@GTBC obtained with a particle size of 130 nm and surface charge of +2.8 C/m at 450 °C. Moreover, colloidal stability and mobility experiments were considered to explain the transport behavior and stability of bare nZVI and magnetic nZVI@GTBC in the soil. The immobilization of Pb by pristine nZVI, GTBC, and nZVI@GTBC was compared and explained under different soil pH conditions. The bioavailability of Pb content before and after immobilization was investigated through leaching experiments. Further, thirty days of soil incubation were carried out to examine different species of Pb according to the Tessier sequential extraction scheme. The study suggested that nZVI@GTBC enhanced the immobilization efficiency by 19.38% in comparison with pristine nZVI and 57.14% in comparison with bare GTBC biochar.
基于生物炭的纳米复合材料与功能材料相结合，在反应性和稳定性方面提供了广阔的前景。大多数报道的生物炭在老化后没有可重复使用性，并且在短期固定后存在固定化成分释放的风险。为了克服这一问题，我们开发了纳米零价铁（nZVI）浸渍磁性绿茶生物炭（nZVI@GTBC），并研究了其在固定 Pb 方面的性能和在土壤中的长期效果。反应性 nZVI 单元是通过将氧化铁溶液还原为多酚溶液（绿茶提取物）获得的，然后通过共沉淀技术将其稳定浸渍到剩余的绿茶废物基质上。最后，通过在不同温度范围内（150-650°C）对上述负载 nZVI 的绿茶废物进行烘箱干燥和慢速热解技术，开发出磁性生物炭。通过 XRD、FTIR、拉曼、UV-Vis、TG/DSC、XPS、SEM 和 TEM 对合成的 nZVI@GTBC 生物炭进行了表征和研究。在 450°C 下，获得了粒径为 130nm、表面电荷为+2.8C/m 的 nZVI@GTBC。此外，胶体稳定性和迁移实验被认为可以解释 bare nZVI 和磁性 nZVI@GTBC 在土壤中的迁移行为和稳定性。在不同的土壤 pH 条件下，比较和解释了原始 nZVI、GTBC 和 nZVI@GTBC 对 Pb 的固定化作用。通过浸出实验研究了固定化前后 Pb 含量的生物可利用性。进一步，进行了 30 天的土壤培养实验，根据 Tessier 连续提取方案研究了不同形态的 Pb。研究表明，与原始 nZVI 相比，nZVI@GTBC 可将固定化效率提高 19.38%，与裸 GTBC 生物炭相比，可将固定化效率提高 57.14%。
