Carbothermal reduction for preparing nZVI/BC to extract uranium: Insight into the iron species dependent uranium adsorption behavior
Carbothermal reduction for preparing nZVI/BC to extract uranium: Insight into the iron species dependent uranium adsorption behavior
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DOI：
10.1016/j.jclepro.2019.117873
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发表时间：
2019-12
影响因子：
11.1
通讯作者：
Huimin Zhang;Y. Ruan;Aiping Liang;K. Shih;Zenghui Diao;M. Su;Li’an Hou;Di-yun Chen;Hui Lu;L. Kong
中科院分区：
文献类型：
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作者：
Huimin Zhang;Y. Ruan;Aiping Liang;K. Shih;Zenghui Diao;M. Su;Li’an Hou;Di-yun Chen;Hui Lu;L. Kong
目前，中国产生了大量的含铀废水，需要经过有效的处理才能排放。铀在ZVI上的固定化引起了国内外研究人员的广泛关注。表面氧化和团聚限制了纳米零价铁(NZVI)修复铀污染的效率。本工作采用绿色碳热还原法制备了环境友好的生物炭负载ZVI(nZVI/BC)。研究了废水中铀在nZVI/Cs、氧化态nZVI/Cs和Fe3O4上的固定化行为。铁盐在70 0 °C时转化为氧化铁，在三氯化铁和硝酸铁的存在下进一步还原为nZVI，这是淀粉在80 0和90 0 °C碳化的结果。碳化温度和铁源对铀的吸附能力不同，这取决于铁物种的转化。纳米片状FeCl/C(1：4~90 0)和纳米FeN/C(1：4~90 0)对U(VI)的最大吸附容量分别为34.82和55.14 mg/g，对C-Fe3O4的去除效率高于C-Fe3O4。吸附U(VI)后的nZVI/Cs的扫描电子显微镜图谱和XPS分析表明，U(VI)的固定是同时吸附和还原的结果。
Currently, a lot of uranium containing wastewater was generated in China, which required efficient treatment before being discharged. Immobilization of uranium on ZVI has attracted many concerns from researchers in the world wide. Surface oxidation and agglomeration limited the efficiency of nano zero-valent iron (nZVI) in remediation of uranium pollution. In this work, a green carbothermal reduction process was conducted to prepare environmental friendly biochar-supported ZVI (nZVI/BC). Immobilization behavior of uranium on nZVI/Cs, oxidized nZVI/Cs and Fe3O4from wastewater were investigated. The iron salt was converted into iron oxides at 700 °C, further being reduced into nZVI in the presence of ferric chloride and ferric nitrate being carbonization of starch at 800 and 900 °C. The uranium adsorption capacities were different from the carbonization temperature and iron sources, which depended on the transformation of iron species. The maximum adsorption capacities of nano-flake FeCl/C (1:4–900) and nanoparticles FeN/C (1:4–900) for U(VI) were 34.82 and 55.14 mg/g. The removal efficiencies of FeCl/C (1:4–900) and nanoparticles FeN/C (1:4–900) were higher than that of 44% for C–Fe3O4. The SEM-mapping and XPS analysis of nZVI/Cs after U(VI) adsorption indicated that the immobilization of U(VI) was ascribed to simultaneous adsorption and reduction.