硫化亚铁纳米粒子对土壤和地下水中镉的修复研究

发布时间：2018-04-03 11:27

  本文选题：CMC　切入点：FeS纳米粒子　出处：《太原科技大学》2015年硕士论文

【摘要】：镉是自然界中普遍存在的一种剧毒金属元素,可以通过各种地质因素和人为活动等方式释放到环境中,造成土壤、大气、水体中镉含量超标。镉污染土壤的修复和安全利用已成为国内外的研究热点。有关研究发现硫化亚铁(FeS)可以有效的处理土壤和地下水中的重金属。它来源广泛,呈无定形态,比表面积大,处理效率高,本文利用FeS作为钝化剂来吸附土壤和地下水中的重金属镉,主要做了以下方面的工作:采用绿色无污染的有机聚合物羧甲基纤维素钠(CMC)作为稳定剂制备FeS纳米粒子,并将它用于土壤和水中重金属镉的去除,考虑FeS的量、粒径大小、腐殖酸、常见阴离子等对吸附的影响,结果表明:1、CMC可以使合成的FeS纳米粒子稳定分散,FeS纳米粒子能够长期均匀稳定的分散在一定量的CMC水溶液中,不发生沉淀、团聚;2、当CMC和FeS的摩尔比为0.0010时,CMC-FeS对水中镉的去除效率为87%,吸附过程符合准二级吸附动力学速率方程,吸附等温线与Freundlich模型吻合;3、FeS纳米粒子的粒径随着CMC量的增加而减小,纳米粒子的分散稳定性逐渐增强,但粒子之间的流动性会降低;随着CMC和FeS的摩尔比不断增大,FeS纳米粒子吸附Cd的效率增高,当CMC和FeS摩尔比为0.0010时,FeS纳米粒子吸附Cd的效率达到最高值;当CMC和FeS摩尔比再继续增大时,FeS纳米粒子吸附Cd的效率反而下降;4、腐殖酸可以增强FeS纳米粒子对水中镉的修复。当腐殖酸加入0.13g/L和0.40g/L时,FeS颗粒对水中镉的吸附率分别达到95%和97%;5、FeS可以增大土壤中难溶态Cd的量。FeS纳米粒子浓度分别为0g/L、0.05g/L、0.1g/L、0.2g/L、0.5g/L时,土壤中镉的解吸量分别为63.55μg/L、29.525μg/L、4.54μg/L、0.5075μg/L和0.1135μg/L;与空白实验相比,土壤中难溶态Cd的量分别增加了53.5%、92.9%、99.2%和99.8%;6、有机酸和无机阴离子的加入对FeS固定土壤中的镉的影响很大。甲酸、酒石酸和柠檬酸可以增大土壤中难溶态Cd的量,随着甲酸、酒石酸和柠檬酸浓度的增大,FeS土壤中难溶态Cd的量增大;硫酸根和磷酸二氢根也增大了CMC-FeS对土壤中Cd的固定量。随着硫酸根和磷酸二氢根的浓度增大,土壤中难溶态Cd的量增加;随着硒酸根浓度的增大,CMC-FeS对土壤中Cd的解吸量增大。
[Abstract]:Cadmium is a highly toxic metal element widely existing in nature, which can be released into the environment by various geological factors and human activities, resulting in excessive cadmium content in soil, atmosphere and water body.The remediation and safe utilization of cadmium contaminated soil have become a hot spot at home and abroad.It is found that ferrous sulfide can effectively treat heavy metals in soil and groundwater.In this paper, FeS was used as passivating agent to adsorb heavy metal cadmium in soil and groundwater.The main work of this paper is as follows: FeS nanoparticles were prepared by using green organic polymer, carboxymethyl cellulose sodium, as stabilizer, and used to remove heavy metal cadmium in soil and water, considering the amount and size of FeS.The effects of humic acid and common anions on the adsorption showed that the synthesized FeS nanoparticles could be dispersed steadily and steadily in a certain amount of CMC aqueous solution for a long time without precipitation.When the molar ratio of CMC and FeS is 0.0010, the removal efficiency of CMC-FeS in water is 87. The adsorption process accords with the quasi-second-order adsorption kinetic rate equation, and the particle size of FeS nanoparticles decreases with the increase of CMC content, and the adsorption isotherm coincides with the Freundlich model.The dispersion stability of nanoparticles gradually increased, but the fluidity between particles decreased, and with the increasing of molar ratio of CMC and FeS, the efficiency of CD adsorption by FES nanoparticles increased.When the molar ratio of CMC to FeS is 0.0010, the adsorption efficiency of FES nanoparticles reaches the highest value, and when the molar ratio of CMC and FeS continues to increase, the adsorption efficiency of FES nanoparticles decreases by 4%. Humic acid can enhance the repair of cadmium in water by FeS nanoparticles.褰撹厫娈栭吀鍔犲叆0.13g/L鍜，

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