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题名: 电化学处理水中无机物、重金属及金属有机络合物研究
作者: 张宝锋
学位类别: 硕士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 赵旭
关键词: 电混凝,电芬顿,砷,Cu-EDTA,工业废水 ; Electrocoagulation, Electro-Fenton, Arsenic, Cu-EDTA, Industrial wastewater
其他题名: Treatment of Inorganic Matters, Heavy Metals and Metal-Organic Complexs in Water by Electrochemisty
学位专业: 环境工程
中文摘要:     电化学技术在水处理过程中日益受到重视,电混凝与电芬顿是电化学水处理技术中研究与应用较多的方法。本论文首先以氟、砷为目标物,研究电混凝对砷与氟的去除效果与过程机制;以油墨废水、煤制油废水、Cu-EDTA络合物为目标,研究阳极电芬顿处理水中有机污染物的效果、主要影响因素与影响机制,并开展了中试研究。
    首先建立了组合电氧化和电混凝反应系统,将其用于去除地下水中的砷和氟污染物.反应系统内,As(III)首先被氧化为  As(V),然后被电混凝过程产生的絮体共沉淀。电化学极板由钛钌网(DSA)和铁电极组成。As(III)氧化发生在 DSA电极表面。同时,铁电极在电感应的作用下会各种氢氧化铁化合物,这些絮体对  As(V)有较强的吸附、共沉淀作用。研究了电氧化-混凝处理 As(III)时的影响因素,发现,Ca2+和 Mg2+可以促进 As的去除;而 Cl−, CO32−, SiO32−, 和 PO43−抑制 As的去除,且  PO43−的抑制能力最强。pH=8.0时 As的去除效率最佳,过高或者过低的  pH均不利于  As的去除。利用傅里叶变换红外光谱研究电氧化-混凝处理 As的絮体,发现,絮体中  As(III)被氧化为 As(V)。
     研究电絮凝同时去除水中的氟和砷污染物时,将形稳阳极与铁电极、铝电极组合,采用电感应的方法,产生铝离子及铝氧化物絮体、铁离子及铁氧化物絮体,对水中的氟离子和砷离子同时进行有效去除。考察了铁极板和铝极板的比例、电流密度、溶液 pH、共存阴阳离子等对氟离子和砷离子去除的影响,并分析了   As(III)的氧化程度,以及铁、铝的溶出对实验效果的影响。结果表明,在初始砷离子浓度为 1.0 mg/L,氟离子浓度为5.0 mg/L,电流为 120.0 mA时,铁板:铝板=1:3时可同时将溶液中的氟和砷去除,使水质达到饮用水水质标准。电混凝过程对 As(III)和 As(V)均具有较高的去除率。  
     针对络合态重金属污染物Cu-EDTA,开展了电芬顿氧化破络 Cu-EDTA,并通过产生的铁絮体以及铁氧化物的絮凝、吸附以及共沉淀等作用协同去除 Cu 离子及 EDTA  的实验研究。结果显示,溶液总有机碳(TOC)值随电流密度的增大、反应时间的延长而降低。当电流密度增大至 31.25 A/m2时,TOC由120.0 mg/L降至  54.7 mg/L,去除率为54.4%,继续增大电流密度至 114.58  A/m2时会降低溶液中  TOC  的去除率。电芬顿处理Cu-EDTA 时,溶液中 EDTA 的去除速率远远大于大于 TOC,电芬顿反应 5.0  分钟时,溶液中 EDTA去除率已达 99.0%。H2O2投量的增加有助于  TOC和  EDTA去除率的提高,在 H2O2投量为  98.8 mmol/L时,电芬顿反应  30 分钟后,TOC去除率达74.2%。初始pH为 3.0时TOC的去除效率最高,而pH过大或过低均不利于  TOC的去除。电芬顿反应初期•OH产量低于电芬顿反应中期,主要原因在于  Fe2+传质速率的影响。
    针对油墨废水,开展了电混凝和电芬顿处理油墨废水的研究。研究发现,油墨废水中  30.0%的有机组分为悬浮性有机物,剩余 70.0%为溶解性有机物。电混凝可有效去除悬浮性有机物,但对溶解性有机物去除效率不佳;电芬顿反应 5.0  分钟有机物的去除率可达76.0%。电化学反应器中铁极板产生的Fe(II)和适量外源投加的H2O2发生芬顿反应,产生活性极高的羟基自由基(OH•),氧化降解水中的有机物,从而促进了 COD的去除。但是,外源 H2O2的过量投加,在反应初期,反而会消耗电芬顿产生的  OH•,阻碍了  COD的去除。电芬顿反应中,COD 去除率随 pH 的升高而降低,溶液中 Fe(II)的浓度取决于溶液的  pH、H2O2投量以及电流密度。利用凝胶色谱仪,紫外分光光度计,傅里叶变换红外光谱技术和三维荧光光谱技术对电混凝和电芬顿过程中有机物的组分和变化进行了研究,发现电芬顿过程中,污水中的部分芳香族有机物和大分子量有机物被氧化为脂肪烃类物质和小分子有机物。
    煤制油废水广泛存在于煤制油工艺中。在实验内,使用 1.0 L 的反应器,利用阳极电芬顿与 NaClO氧化处理煤制油废水。在阳极电芬顿过程中,氧化剂 H2O2的投量为 6.0‰,COD值可从进水的5500.0 mg/L 降至出水时的 2200.0  mg/L,与此同时,NH4-N含量从530.0 mg/L升高至  550.0 mg/L,色度由反应前的 55.0升高至  1790.0,这是因为阳极电芬顿反应之后,产生的大量 Fe(II)和 Fe(III)和水中残留的有机物鳌合、络合,从而使色度急剧增加。大量的 Fe(II)和 Fe(III)的存在会阻碍后续的生化反应,因此投加  NaClO氧化剂于阳极电芬顿出水中,以破络合金属有机物。NaClO氧化工艺的最佳效果为:COD,NH4-N,色度和浊度去除率分别为 11.0%、89.0%、94.0%、98.0%。反应过程中 95 %的铁-有机物络合物被破络合,从而使 Fe(III)顺利沉淀。
英文摘要:      Environmental electrochemistry  is the  electrochemical theory  and method  applied  in the field of   environmental protection.Electrocoagulation and    anode    electric    fenton electrochemical    technology    of    environmental    electrochemistry    is    widely    used    in environmental protection. In this experiment, with the target of fluorine, arsenic and chromium,the   treatment  effect   of   removal   of   inorganic   matter  and   heavy   metals   in  water   by electrocoagulation and chemical reductant-electric flocculation were studied; with the target of plugboard wastewater and  coal oil wastewater,  the effects of  removal of organic contaminant by the anode fenton technology were studied.
     An  electrochemical  reactor was  built  and  used  to  remove  arsenite from  water.  In  this reactor,  arsenite can  be  oxidized  into  arsenate, which  was  removed  by electro-coagulation process simultaneously.  The reactor mainly included  dimension stable anode  (DSA) and iron plate electrode. Thus, the  arsenic was removed by  coagulation process. Influencing factors on the removal  of arsenite  were investigated.  It is found  that Ca2+  and Mg2+  ions promoted  the removal  of  arsenite.  However,   Cl−,  CO32−,  SiO32−,  and  PO43−   ions  inhibited  the  arsenic removal. And, it is observed that  the inhibition effect was the largest in  the presence of PO43−. Furthermore,  it is  observed that  the  removal efficiency  of  arsenate is  the largest  in  the pH value of  8. Increase or  decrease of  pH value did  not benefit  to the arsenite  removal. Fourier transform  infrared spectra  were  used  to  analyze the  floc  particles,  it is  suggested  that  the removal mechanism of As(III)  in this system seems to be  oxidative of As(III) to As(V) and to be removed by adsorption/complexation with metal hydroxides generated in the process.
     Furthermore, in order to  removal fluoride and arsenic ions simultaneously, combination  of DSA electrode  with  aluminum  electrodes and  iron  electrodes  were  used. Aluminum  oxide flocs  and  iron  oxide  flocs  were  produced  and  can  remove  fluoride  ion  and  arsenic  ions effectively.  Effects of  ratio  of  the  iron plate  and  aluminum  plate, the  current  density,  pH,coexisted  cation-anions on  the removal  of  fluoride and  arsenic ions  were  investigated. The results showed  that  arsenic in  the  initial ion  concentration of  1.0  mg/L, fluoride  ion in  the concentration of 5.0  mg/L can be simultaneously  removed within 40 min  with 120.0 mA and the ratio of iron to aluminum of 1:3. Meantime, both of the removal of As(III)  and As(V) were efficient.
     Research  was carried  out  in view  of the  complexing  state of  heavy metal  pollutants  of Cu-EDTA. Cu-EDTA  was oxidized  by electro-Fenton process,  and Cu  and EDTA ions  were removed  by flocculation,  adsorption  and coprecipitation  of  iron oxide  etc  together. Results shew that  the removal  rate of  TOC value increased  with the  addition of  current density  and reaction. When the current density increased to 31.25 A/m2, TOC fell from 120.0 mg/L to 54.7 mg/L, removal rate of TOC was 54.4%. When the current density increased to 114.58 A/m2, he removal rate  of TOC  would reduce  in the solution.  Cu-EDTA was  treated by electro-Fenton process, EDTA removal  rate was  much greater than  the TOC in  the solution.  At 5.0 mins  of electro-Fenton  reaction,  EDTA removal  rate  had  reached  to 99.0%.  The  increase  of  H2O2 dosage helped  to improve  the removal rate  of TOC  and EDTA. When  the H2O2  dosage was 98.8 mmol/L,  after 30 mins  of electro-Fenton reaction,  TOC removal rate  was 74.2%. When the initial  pH  was 3.0,  TOC removal  efficiency was  highest,  oversize or  undersize pH  was detrimental  to the  TOC  removal.  At the  early  Fenton  reaction, concentration  of •OH  was lower, while  in the  middle of  electro-Fenton process,  concentration of •OH was  higher, the reason was mainly due to the effects of Fe2+ mass transfer rate.
     The    treatment   of    the    plugboard    wastewater   was    performed  by an optimal electrocoagulation  and  electro-Fenton.  The   organic  components  with  suspended  fractions accounting  for  30.0%  COD  were preferably  removed  via  electrocoagulation  at  initial  5.0 min.In contrast, the removal efficiency was increased to 76.0%  with the addition of H2O2. The electrogenerated Fe2+ reacts with H2O2 and leads to the generation of OH, which is responsible for the higher  COD removal.However, overdosage H2O2  will consume •OH generated  in the electro-Fenton  process  and   lead  to  the  low  COD  removal.The   COD  removal  efficiency decreased with the increased pH. The concentration of Fe2+ ions was dependent on the solution pH, H2O2  dosage and  current  density. The  changes of  organic characteristics  in coagulation and oxidation  process were differenced  and evaluated using  gel permeation  chromatography,fluorescence excitation–emission scans and Fourier transform infrared spectroscopy. A laboratory-scale anode-Fenton (AF) followed by NaClO oxidation at a volume of  1.0 L was  used to  treat  coal-into-oil  wastewater. In  the  AF process,  COD  can  be removed  from 5500.0 mg/L to 2200.0 mg/L at the H2O2 dosage of 6.0% scale anode-Fenton (AF) followed to 550mg/L, and  chromaticity raised  a lot  from 55.0  to 1790.0  because of Fe-organic  complex produced by AF process. So NaClO was  added into water to eliminate the complex in order to precipitate iron.  Maximum removal  AFeficiencies of  11.0%, 89.0%, 94.0%  and 98.0%  were obtained for COD, NH4-N, chromaticity and turbidity, respectively.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/37043
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Recommended Citation:
张宝锋. 电化学处理水中无机物、重金属及金属有机络合物研究[D]. 北京. 中国科学院研究生院. 2016.
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