生物炭对土壤中六价铬和莠去津的吸附锁定作用研究

发布时间：2018-06-24 23:15

本文选题：生物炭 + 六价铬　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：生物炭应用在土壤中具有温室气体减排、改善土壤性质、丰富土壤微生物群落等作用,同时对污染物有较好吸附效果,能有效控制其迁移作用。本文着重考察生物炭对污染物的吸附能力,以六价铬和莠去津作为目标污染物,研究生物炭在土壤环境中对六价铬和莠去津的吸附锁定效果,并将生物炭酸化来提高对莠去津的吸附能力,探讨酸化后生物炭吸附能力提升的原因。本文通过土柱淋滤实验,研究土壤中添加生物炭后对Cr(VI)的迁移影响,特别是对其进行模拟酸雨淋滤实验,进一步研究含生物炭的土壤对Cr(VI)的锁定效果。结果表明,仅施加1%的生物炭,就能大幅度提高土壤系统固定Cr(VI)的能力,小粒径生物炭对Cr(VI)的吸附固定能力更加明显,在一定条件下是大粒径的固定吸附量的3倍,在酸雨淋滤作用下也不易解吸。关于酸化前后生物炭对莠去津的吸附效果实验,实验结论说明酸化能够提高生物炭对莠去津的吸附能力。酸化前后的生物炭都可以用Freundlich方程进行拟合,温度对吸附能力有显著的影响,随着温度的升高,吸附量也随之提高,酸化前生物炭符合Elovich动力学方程,而酸化后生物炭符合准二级动力学方程。酸化后的生物炭对莠去津具有更好的吸附能力,是由于酸化增加了生物炭的表面积和孔径、孔容等,使得生物炭具有更多的吸附位点和更强的范德华力,同时也改变了生物炭的表面电性,与莠去津之间产生强烈的静电吸引。将生物炭添加进土壤中,可以提高土壤系统对莠去津的吸附固定效果,随着生物炭添加量的增加,吸附固定效果增加。在土壤培养试验中,生物炭没有出现解吸,表现了很好的吸附稳定性。实验证明土壤的含水量对酸化后的生物炭吸附莠去津的能力有明显的影响,当土壤长期处于高含水量状态时,酸化后生物炭的吸附能力有所下降。综上所述,生物炭在土壤中对六价铬、莠去津都有很好的吸附固定作用,可以有效的降低两者的迁移性,特别是将生物炭酸化后,能够更好的提升对莠去津的吸附能力,酸化后的生物炭在我国北方的旱田土壤中应用能够达到比较好的吸附效果,实验结果对不同类型的污染土壤治理有很好的实际参考价值。
[Abstract]:Biochar can reduce greenhouse gas emissions, improve soil properties, enrich soil microbial communities, and have good adsorption effect on pollutants, which can effectively control their migration. In this paper, the adsorption ability of biochar to pollutants was investigated. The adsorption and locking effect of biochar on hexavalent chromium and atrazine in soil environment was studied with hexavalent chromium and atrazine as the target pollutants. The adsorption ability of atrazine was improved by acidification of biochar, and the reason for the increase of adsorption ability of biochar after acidification was discussed. In this paper, the effects of biochar on Cr (VI) migration in soil were studied by soil column leaching experiment, especially the simulated acid rain leaching experiment, and the locking effect of biochar containing soil on Cr (VI) was further studied. The results showed that the ability of Cr (VI) fixation in soil system could be greatly improved by adding only 1% biochar. The adsorption and fixation capacity of small diameter biochar on Cr (VI) was more obvious than that of large diameter biochar under certain conditions, and the adsorption capacity of Cr (VI) was 3 times as much as that of large particle size. It is not easy to desorption under acid rain leaching. As to the adsorption effect of atrazine on biochar before and after acidification, the experimental results show that acidification can improve the adsorption ability of atrazine to biochar. The biochar before and after acidification can be fitted by Freundlich equation. Temperature has a significant effect on the adsorption capacity. With the increase of temperature, the adsorption capacity increases, and the biochar before acidification accords with Elovich kinetic equation. The acidified biochar accords with the quasi-second-order kinetic equation. The acidated biochar has better adsorption ability to atrazine because acidification increases the surface area, pore size and pore volume of biochar, which makes biochar have more adsorption sites and stronger van der Waals force. At the same time, it also changed the surface electrical properties of biochar, and produced strong electrostatic attraction between atrazine and biochar. The adsorption and fixation effect of atrazine could be improved by adding biochar into the soil, and with the increase of biochar addition, the adsorption and fixation effect of atrazine could be increased. In soil culture experiment, no desorption of biochar was observed, which showed good adsorption stability. The results showed that the soil moisture content had a significant effect on the adsorption ability of atrazine by acidified biochar, and when the soil was in high water content for a long time, the adsorption capacity of biochar decreased after acidification. To sum up, biochar has a good adsorption and fixation effect on hexavalent chromium and atrazine in soil, which can effectively reduce the migration of both, especially after acidification of biochar, it can improve the adsorption capacity of atrazine. The application of acidified biochar in dry soil of northern China can achieve better adsorption effect. The experimental results have a good practical reference value for the treatment of different types of contaminated soil.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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