生物炭改性高庙子膨润土对铕(Ⅲ)的吸附特性

Adsorption Property of Eu(Ⅲ) on Bentonite Modified by Biochar

摘要:

针对作为我国核废料处置库缓冲/回填材料——高庙子（GMZ）膨润土——在长期运营条件下的缓冲性能衰减问题，利用梧桐叶为碳源制备生物炭改性GMZ膨润土，通过微观表征和批次吸附试验，研究了其结构和对Eu(Ⅲ)的吸附性能，进一步探讨了复合材料的作用机理.结果表明，生物炭改性GMZ膨润土中的官能团出现次甲基（—CH），说明有机官能团嫁接成功，层间距进一步增大，蒙脱石表面的细小颗粒在改性后变大.在吸附性能方面，随着固液比和接触时间的增加，吸附率提高；随着pH值、离子强度的增加，吸附率降低；生物炭改性GMZ膨润土对Eu(Ⅲ)的吸附等温线符合Langmuir模型和准二级动力学模型，最大理论吸附量为32.36 mg?g-1.

关键词:生物炭; 膨润土; 吸附; Eu(Ⅲ)

Abstract:

Aimed at the buffer performance degradation problem of GMZ bentonite, which is the cushioning backfill material of China’s nuclear waste repository in longterm operation, the biochar modified GMZ bentonite was prepared by using the leaves of Davidia involucrata as carbon source. The microstructure and adsorption performance of Eu(Ⅲ) were studied by microscopic characterization and batch adsorption experiments. The mechanism of the composite was further discussed. The results showed that methine (—CH) appeared in the functional group of biochar modified GMZ bentonite, indicating the fact that the organic light energy group grafting was successful; the interlayer spacing was further increased, and the fine particles on the surface of montmorillonite became larger after modification. In terms of adsorption performance, with the increase of solidliquid ratio and contact time, the adsorption rate increases while with the increase of pH value and ionic strength, the adsorption rate decreases. The adsorption isotherm of biocarbon modified GMZ bentonite to Eu(Ⅲ). The Langmuir model and the quasi-secondary kinetic model have a maximum theoretical adsorption capacity of 32.36 mg?g-1.

Key words:biochar; bentonite; adsorption; Eu(Ⅲ)