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: 铁、锰基氧化物氧化吸附去除有机砷性能与机制
作者: TISTA PRASAI JOSHI
学位类别: 博士
答辩日期: 2017-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 曲久辉 ; 刘锐平
关键词: 有机砷 ; 吸附剂 ; 吸附 ; 非均相氧化 ; 水处理 ; Aromatic organoarsenic compounds ; Adsorbents ; Adsorption ; Heterogeneous oxidation ; Water treatment
其他题名: Efficiency and mechanisms of iron and manganese based adsorbents for the removal of aromatic organoarsenic compounds
中文摘要:    阿萨酸(p-ASA)、洛克沙砷(ROX)等有机砷化物在家禽饲料中作为添加剂广泛应用。家禽食用的大部分有机砷并未发生化学变化而直接从体内排出并可能导致环境砷污染。当p-ASA、ROX等芳香有机砷化合物排入到环境之后,可能通过多种机制转化为毒性更强、迁移性更强的无机砷。这在一定程度上促进了砷污染的扩散并危及饮用水源安全。探究有机砷去除机制和开发有效的有机砷去除技术对于控制砷污染具有重要意义。本论文围绕上述问题开展系统研究,取得如下主要成果:
    首先,系统研究了铁锰复合氧化物(FMBO)对p-ASA、ROX的吸附性能与机理,并以羟基铁氧化物(FeOOH)和锰氧化物(MnO2)为对照。研究显示,FMBO对p-ASA、ROX的最大吸附容量(Qmax)分别为0.52和0.25 mmol g-1 (pH=7.5)。FeOOH与MnO2显示出较低的吸附容量,对p-ASA的最大吸附容量Qmax, p-ASA分别为0.40和0.33 mmol g-1,对ROX的最大吸附容量Qmax, ROX分别为0.08和0.07 mmol g-1。提高pH值将导致静电斥力增大,从而抑制有机砷的吸附。pH 4.0条件下,FMBO对p-ASA和ROX的Qmax, p-ASA与Qmax, ROX值分别提高至0.79和0.51 mmol g-1。UV-Vis、UPLC-ICP-MS、FTIR和XPS等结果证实,FMBO对p-ASA的优异吸附性能归因于FMBO的非均相氧化以及协同吸附过程,FMBO中的锰氧化物和铁氧化物分别具有很强的氧化能力和吸附能力,从而表现出良好的去除效果。这一机制在ROX去除过程中同样存在。
    其次,为了进一步研究p-ASA去除机理,选择具有相似官能团结构的苯胂酸(PA)、苯胺(aniline)作为对照,深入研究了p-ASA在锰氧化物MnO2表面的形态转化过程与机制。研究发现,pH 4.0条件下,MnO2对p-ASA的吸附容量为0.40 mmol g-1,而对PA和苯胺的吸附容量分别为0.23 mmol g-1和0.68 mmol g-1。FTIR和XPS结果证实反应过程中产生了去质子化的苯胺基团,这有利于p-ASA的非均相氧化。进一步结合UV扫描和UPLC-Q-TOF-MS结果,证实吸附在锰氧化物表面的p-ASA首先发生从p-ASA向MnO2表面的电子传递,并形成p-ASA自由基中间产物;中间产物将进一步发生水解和聚合生成苯醌和azophenylarsonic酸的等主要产物。在此基础上,p-ASA中间产物将进一步开环生成亚砷酸盐(As-III)和砷酸盐(As-V)并伴随着锰离子的溶出释放。上述MnO2氧化以及吸附p-ASA过程是MnO2去除p-ASA的主要机理。
    本研究进一步设计开发了具有真空骨架结构的新型Fe-Mn复合氧化物和立方体Fe(OH)3新型吸附材料,并研究了其对p-ASA的去除性能。研究显示,Fe-Mn复合氧化物和立方体Fe(OH)3对p-ASA的最大吸附容量分别达到1.3 mmol g-1和0.72 mmol g-1 (pH 4.0)。pH值对p-ASA的吸附去除有显著影响,随着pH值提高,p-ASA的吸附容量逐渐降低。与MnO2吸附相似, azophenylarsonic酸的也是Fe-Mn复合氧化物氧化、吸附去除p-ASA过程中的重要中间产物。这些研究成果对于开发针对有机砷的新型吸附材料以及高效有机砷去除控制技术具有重要意义。
英文摘要:     The aromatic organoarsenic compounds such as para arsanilic acid (p-ASA) and roxarsone (ROX) are widely used as feed additives in the poultry. They appear to be excreted with no chemical structural change and tend to environmental release of more toxic inorganic arsenic such as arsenite and arsenate. Aromatic organoarsenic compounds tend to transform into more mobile toxic inorganic arsenic via several processes of abiotic and biotic transformation, and can inadvertently spread toxic inorganic arsenic through the environment to drinking water sources. Thus, understanding the mechanism of organoarsenic compounds removal and the development of effective technologies are of significant urgency. Hence, it is more essential to remove aromatic organoarsenic compounds from the poultry manure to control organoarsenic transform into the environment.
    1. The interactions of p-ASA and ROX with ferric and manganese binary oxide (FMBO) was investigated to study their adsorption efficiency and mechanism, whereas ferric oxide (FeOOH), and manganese oxide (MnO2) were also studied for the comparison. The maximum adsorption capacities (Qmax) of FMBO towards p-ASA and ROX were found to be 0.52 and 0.25 mmol g-1 (pH=7.5). FeOOH and MnO2 showed lower adsorption capability, the corresponsive Qmax, p-ASA were 0.40 and 0.33 mmol g-1 and Qmax, ROX were 0.08 and 0.07 mmol g-1, respectively. The lowered pH improved the adsorption onto the adsorbents owing to the decreased repulsive forces; and Qmax, p-ASA and Qmax, ROX onto FMBO increased to 0.79 and 0.51 mmol g-1 at pH 4.0. Based on combined results of UV-Vis spectra, UPLC-ICP-MS, FTIR, and XPS, the synergistic effect of heterogeneous oxidation and adsorption was demonstrated to be the main mechanism for the efficient removal of p-ASA by FMBO. Manganese oxide demonstrated significant oxidation of p-ASA, while adsorption process was mainly achieved by ferric oxide. This effect also involves in the adsorption of ROX onto FMBO.
    2. To gain insight into the transformation mechanisms, how the process of p-ASA transformation works in detail on the surface of MnO2 was investigated by comparing it with phenylarsonic acid (PA) and aniline, which have similar chemical configuration. In compare to the values of 0.23 mmol g-1 and 0.68 mmol g-1 for PA and aniline, the maximum adsorption capacity was determined to be 0.40 mmol g-1 for p-ASA at pH 4.0. The results of FTIR and XPS spectra supported the presence of a protonated amine, resulting in a suitable condition for the oxidation of p-ASA. Based on the combined results of UV-Vis spectra and UPLC-Q-TOF-MS, confirmed that the adsorbed p-ASA was first oxidized through the transfer of one electron from p-ASA on MnO2 surface to form a p-ASA radical intermediate, which through further hydrolysis and coupling led to formation of benzoquinone and azophenylarsonic acid, which was identified as a major intermediate product. After that, p-ASA radical intermediate was cleaved to form arsenite (As III), and then further oxidized into arsenate (As V) with the release of manganese (Mn) into solution, indicating a heterogeneous oxidation process.
    3. Fe-Mn framework and cubic Fe(OH)3 was used as a promising novel adsorbents for the removal of p-ASA. The maximum adsorption capacity for p-ASA on Fe-Mn framework and cubic Fe(OH)3 was determined to be 1.3 mmol g-1 and 0.72 mmol g-1 at pH 4.0, respectively. Although p-ASA adsorption decreased gradually with increasing pH indicating that removal was strongly pH dependent. Azophenylarsonic acid was identified as an oxidation intermediate product of p-ASA after adsorption on Fe-Mn framework. The novel adsorbent Fe-Mn framework showed good adsorption performance towards p-ASA. The obtained results gain insight into the potential applicability of Fe-Mn framework for the removal of p-ASA.
    This study is relevant to drinking water science and technology because it demonstrates how iron and manganese based (Fe-Mn) adsorbents were applied for the treatment of organoarsenic compounds in water in different condition. Therefore, from an engineering point of view, Fe-Mn based adsorbents can be practically applied as promising adsorbents in treatment system for the removal of organoarsenic in water.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38597
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
TISTA PRASAI JOSHI--铁、锰基氧化物氧化吸附去除有机砷性能与机制.pdf(5615KB)学位论文--限制开放 联系获取全文

Recommended Citation:
TISTA PRASAI JOSHI. 铁、锰基氧化物氧化吸附去除有机砷性能与机制[D]. 北京. 中国科学院研究生院. 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
[TISTA PRASAI JOSHI]'s Articles
CSDL cross search
Similar articles in CSDL Cross Search
[TISTA PRASAI JOSHI]‘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