中国科学院生态环境研究中心机构知识库
Advanced  
RCEES OpenIR  > 环境水质学国家重点实验室  > 学位论文
题名: C60系列纳米材料对重金属污染物的易化运移作用研究
作者: 袁 玥1
学位类别: 硕士
答辩日期: 2017-06
授予单位: 中国科学院大学
授予地点: 北京
导师: 彭先佳
关键词: 易化运移,重金属,C60系列纳米材料,多孔介质,吸附 ; facilitated transport, heavy metals, C60 series carbon nanomaterials, porous media, adsorption
其他题名: Facilitated transport of heavy metal contaminants byC60 series carbon nanomaterials
学位专业: 环境科学
中文摘要: 碳纳米材料由于其广阔的应用前景被大量关注研究,同时,其环境安全性也成为科学研究的热点。由于碳纳米材料具有高吸附性能和强迁移行为,极有可能对环境中的重金属污染物产生易化运移作用,从而造成危害。因此,研究碳纳米材料对重金属的易化运移作用,是对碳纳米材料环境安全性的重要补充。本研究首先选取C60作为典型碳纳米材料,重点研究了其原始态(C60)、表面络合态(SDBS络合态C60)及表面氧化态(C60(OH)n)三种材料在水环境中的稳定性和迁移行为。其次,深入研究了C60(OH)n纳米颗粒对单组份重金属(Cu2+)和双组分重金属(Cu2+和Cd2+)的易化运移作用。取得的主要研究成果如下: (1)研究了C60、SDBS络合态C60和C60(OH)n三种碳纳米材料在水环境中的稳定性和迁移行为。Zeta电位测试和陈化实验结果显示,两种改性碳纳米材料的稳定性均较C60更强,说明表面络合和表面氧化改性均显著提高碳纳米材料的水环境稳定性。对SDBS络合态C60的聚沉行为研究发现,在近中性pH条件下,络合态C60的临界聚沉浓度为550 mM NaCl。对C60和络合态C60在不同离子强度的穿透曲线的研究结果表明,络合态C60纳米颗粒比C60纳米颗粒具有更高的C/C0峰值,即具有更强的迁移能力。同时,对C60(OH)n在不同孔隙水流速和pH下的穿透曲线的研究结果发现,C60(OH)n也具有很强的水环境迁移行为,C/C0值超过0.95。 (2)由于研究了C60(OH)n分散性好,且具强稳定性和迁移能力,选取其作为研究对象,研究了不同条件下C60(OH)n对单组分重金属Cu2+的易化运移作用。结果发现,在所有考察的条件下,C60(OH)n均表现出对Cu2+具有极强的易化运移作用,且pH和C60(OH)n浓度对易化运移的影响显著。使用了非平衡两区运移模型对Cu2+的穿透曲线进行拟合。拟合结果发现,C60(OH)n纳米颗粒的存在降低了Cu2+在介质中迁移的阻滞系数。通过等温吸附试验和吸附动力学实验考察易化运移作用的机理,结果发现,C60(OH)n纳米颗粒对Cu2+的易化运移作用主要来自于其对Cu2+极强的吸附能力。此外,还发现C60(OH)n的存在可以降低介质对Cu2+的吸附速率,使得介质与Cu2+结合需要更长的时间,因此也使得Cu2+具有充足的运移时间,从而起到易化运移的作用。 (3)研究了介质中预先存在C60(OH)n对Cu2+迁移的影响和C60(OH)n对预污染介质中Cu2+释放的影响。结果发现,当介质中预先存在滞留的C60(OH)n纳米颗粒时,Cu2+的迁移有微弱的提高。这可能是由于滞留在介质表面的C60(OH)n纳米颗粒很容易被重新释放出来并且携带少量 Cu2+迁移。而当向预污染介质中通入C60(OH)n分散液时,C60(OH)n显著提高了Cu2+的释放率,这意味着C60(OH)n纳米颗粒可能会促进污染的扩散,具有很高的环境风险。 (4)研究了C60(OH)n对双组分重金属Cu2+和Cd2+的竞争吸附和易化运移作用。结果发现,单组分吸附时,C60(OH)n纳米颗粒对Cu2+和Cd2+均有很强的吸附能力。而在双组分共存体系中,C60(OH)n对Cd2+的吸附作用则显著下降。Cu2+和Cd2+之间存在竞争吸附效应,Cu2+和Cd2+与C60(OH)n之间发生吸附作用的主要机制可能是离子交换和物理扩散。在惰性介质和反应性介质中,C60(OH)n均对Cu2+产生了较显著的易化运移作用,而对Cd2+的易化运移则不明显。在惰性介质中,Cu2+和Cd2+不仅存在对介质上反应位点的竞争,还存在对C60(OH)n上吸附位点的竞争,两种竞争机制的叠加作用导致Cu2+的易化运移作用较单组分时减弱,而Cd2+的易化运移作用增强。而在反应性介质中,由于对C60(OH)n的竞争吸附导致Cu2+的易化运移作用较单组分时明显下降,但是因为Cd2+在反应性介质中滞留严重,且使用的重金属浓度也不足以在反应性介质中产生竞争现象,Cd2+的迁移并没有受到Cu2+的影响。
英文摘要: Carbon nano materials (CNMs) has attracted a lot of attention due to their extensive potential application. Meanwhile, the environmental safety of CNMs has drawn much attention from worldwide researchers. Due to the fact that CNMs have high adsorption capability and high mobility, the transport of heavy metals will be prone to be facilitated by CNMs. Then the facilitated transport of heavy metals should be an important aspect of the environmental safety of CNMs. In this research, the stability and mobility of C60, SDBS complexed C60 and C60(OH)n in aqueous environment were studied firstly. Then C60(OH)n was used as model CNMs to investigate its impact on the transport of both one-component heavy metal (Cu2+) and two-component heavy metals (Cu2+ and Cd2+). The main conclusions are as follows: (1) The aqueous stability and mobility of C60, SDBS complexed C60 and C60(OH)n were investigated. The results of zeta potential analysis and sedimentation tests showed that the two modified CNMs had higher stability than pristine C60, which means both complexation and surface oxidation could enhance the aqueous stability of CNMs. The study of aggregation kenetics found that SDBS complexed C60 had a critical coagulation concentration (CCC) of 550 mM NaCl. The breakthrough curves of C60 and complexed C60 under different ion strength showed that the complexed C60 had higher C/C0 value, which implies the higher mobility, than C60 nanoparticles. Meanwhile, the breakthrough curves of C60(OH)n under different flow velocity and pH also showed a high aqueous mobiliy of C60(OH)n with a C/C0 value over 0.95. (2) C60(OH)n nanoparticles were chosen, due to its great dipersity as well as its high stability and mobility, to study its facilitated transport of one-component Cu2+. Batch column experiments showed that fullerol particles could function as carrier to facilitate the transport of Cu2+ under all studied conditions, and pH and fullerol concentration played an important role in the facilitated transport. Besides, two-region nonequilibrium transport convective-dispertive equation was employed for fitting the breakthrough curves of Cu2+ and the results showed the existence of C60(OH)n could the retention factor of Cu2+ transport in the porous media. The mechanism of C60(OH)n nanoparticles to facilitate the transport of Cu2+ was mainly due to its much higher adsorption capacity than the porous media. Besides, the existence of C60(OH)n decreased the adsorption kinetics of the porous media for Cu2+, which led to an decreasing chance for Cu2+ to be retained and thus enhanced the transport of Cu2+. (3) With the pre-existence of fullerol nanoparticles in the porous media, the transport of Cu2+ was slightly enhanced instead of being restrained, which may be because the retained fullerol nanoparticles are easily to release from the porous media and then carry the Cu2+ to transport. In addition, when loaded into the pre-contaminated porous media, the fullerol nanoparticles also increased the release of retained Cu2+, which implies a high environmental risk of fullerol nanoparticles. (4) The competitive adsorption and facilitated transport of two-component heavy metal ions Cu2+ and Cd2+ by C60(OH)n nanoparticles were studied. The adsorption isotherms of one-component Cu2+ or Cd2+ on C60(OH)n nanoparticles showed that C60(OH)n had high adsorption ability for both Cu2+ and Cd2+. However, with two-component heavy metal ions, the adsorption capacity for Cd2+ dropped dramatically. The competitive adsorption exsits between Cu2+ and Cd2+, and the main mechanism of the adsorption of C60(OH)n for Cu2+ and Cd2+ could be the combined effect of ion exchange and physical diffusion. In both iner and reactive media, C60(OH)n showed significant facilitation on Cu2+ transport while the facilitation for Cd2+ was not obvious. In the inert media, the competition between Cu2+ and Cd2+ happened not only for the adsorptive sites of C60(OH)n but also for the reactive sites of the porous media. The two competition effects led to a decrease of C60(OH)n-facilitated transport of two-component Cu2+ compared to one-component condition but an increase of C60(OH)n-facilitated transport for Cd2+. However, in the reactive media, the facilitated transport of Cu2+ decreased with Cd2+ existed because of the competition adsorption of C60(OH)n nanoparticles. But because the reactive media showed very high retention ability to heavy metal ions, and the concentration of heavy metals used in this research in not high enough to show competition for the reactive sites of reactive media, the transport of Cd2+ was not affected by the existence of Cu2+.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38738
Appears in Collections:环境水质学国家重点实验室_学位论文

Files in This Item:
File Name/ File Size Content Type Version Access License
袁玥--C60系列纳米材料对重金属污染物的易化运移作用研究.pdf(5523KB)学位论文--限制开放 联系获取全文

作者单位: 1.中国科学院生态环境研究中心

Recommended Citation:
袁 玥. C60系列纳米材料对重金属污染物的易化运移作用研究[D]. 北京. 中国科学院大学. 2017.
Service
Recommend this item
Sava as my favorate item
Show this item's statistics
Export Endnote File
Google Scholar
Similar articles in Google Scholar
[袁 玥]'s Articles
CSDL cross search
Similar articles in CSDL Cross Search
[袁 玥]‘s Articles
Related Copyright Policies
Null
Social Bookmarking
Add to CiteULike Add to Connotea Add to Del.icio.us Add to Digg Add to Reddit
所有评论 (0)
暂无评论
 
评注功能仅针对注册用户开放,请您登录
您对该条目有什么异议,请填写以下表单,管理员会尽快联系您。
内 容:
Email:  *
单位:
验证码:   刷新
您在IR的使用过程中有什么好的想法或者建议可以反馈给我们。
标 题:
 *
内 容:
Email:  *
验证码:   刷新

Items in IR are protected by copyright, with all rights reserved, unless otherwise indicated.

 

 

Valid XHTML 1.0!
Copyright © 2007-2018  中国科学院生态环境研究中心 - Feedback
Powered by CSpace