超声波／零价铁降解对硝基苯胺的试验研究

对在超声波、零价铁和超声波／零价铁(U／Fe^0)等体系中对硝基苯胺的降解规律进行了研究。研究结果表明。对硝基苯胺在超声波作用下，降解规律符合一级反应动力学模型，但超声波对高浓度的对硝基苯胺降解效果较差。在U／Fe^0体系中，超声波和零价铁对降解对硝基苯胺具有协同作用，对硝基苯胺降解速率显著提高。降解机理显示，对硝基苯胺在零价铁表面上发生原电池反应，被还原为对苯二胺，在超声波作用下进一步降解。在U／Fe^0体系中添加Cu^2 ，形成Fe／Cu原电池，可进一步促进对硝基苯胺的降解速率，降解效率优于铸铁屑形成的Fe／C原电池。     

Fe~0/O_2体系降解苯胺废水机理

以苯胺为研究对象,在Fe~0/O_2体系中开展了降解实验。考察了苯胺在Fe~0/O_2体系与单一Fe0体系和单一O2体系下的降解效果,探究了Fe~0/O_2体系中活性氧化物的产生及降解苯胺的可能途径。结果表明:初始浓度为5.1 mg·L~(-1)的苯胺在Fe~0/O_2体系中可完全降解,降解过程存在协同效应,在Fe~0/O_2体系下降解速率常数为单一零价铁体系与单一氧化体系降解速率常数之和的46.15倍;Fe~0/O_2体系中活性氧化物主要有H2O2和·OH等自由基,苯胺在体系中的降解以·OH氧化为主,可能的降解途径为矿化和聚合,并以矿化为主;苯胺降解过程中氮素产物的变化表明降解体系中存在大量含氮有机物等中间产物。     

超声波/零价铁降解对氯苯胺性能及机理研究

在超声波/零价铁体系中考察了溶液初始pH值、浓度对对氯苯胺降解的影响.在pH值为3～11范围内最佳条件为pH=9;初始浓度为0.1、0.2和0.4 mmol/L时的降解率(180 min)分别为83.2%、63.5%和36.1%.对氯苯胺在单纯铁粉、单纯超声波和超声波/零价铁3种体系中降解符合拟一级反应动力学规律,速率常数分别为6.83×10-4、3.95×10-3和1.01×10-2 min-1,增强因子为218%,表明铁粉与超声波对对氯苯胺降解有明显的协同效应.在体系中加入自由基捕捉剂正丁醇能抑制对氯苯胺的降解,证实对氯苯胺降解主要是依靠羟基自由基的氧化作用.     

硝酸根对零价铁去除地下水中六价铬的影响

通过批实验和连续通流的柱模拟实验对比研究了存在NO3-和不存在NO3-条件下零价铁（Fe0）去除Cr（Ⅵ）的反应特征,并对比分析了NO3-对零价铁（Fe0）去除Cr（Ⅵ）的影响。批实验结果表明,在不同初始pH条件下,NO3-的加入均使得零价铁（Fe0）去除Cr（Ⅵ）的速率升高;当初始pH=7时,NO3-的促进作用最强,反应速率是无NO3-条件下的2.1倍。柱实验结果表明,NO3-的加入使得Fe0去除Cr（Ⅵ）的反应分成了3个不同的阶段：高效期（1025 PV）。在高效期,反应中的NO3-表现为对Fe0反应位点的竞争,抑制了Cr（Ⅵ）还原。在后期的2个阶段中,反应中NO3-则呈现明显的促进作用。NO3-的存在使得零价铁（Fe0）柱趋于整体性同步钝化,延长了Fe0柱的运行寿命,并且增加了零价铁（Fe0）柱对Cr（Ⅵ）的去除效率。NO3-对Fe0去除Cr（Ⅵ）反应的促进作用原因是由于NO3-与Fe0反应产生Fe3O4,Fe3O4可以还原Cr（Ⅵ）,并且具有阻滞反应的产物在Fe0表面堆积和促进电子传导作用。     

零价铁活化过硫酸钠降解含油废水

将零价铁活化过硫酸钠产生硫酸根自由基的高级氧化技术应用于处理含油废水。研究了过硫酸钠浓度、零价铁投加量、p H值对油降解率的影响,分析了反应过程中S2O2-8和Fe2+的浓度变化。通过投加柠檬酸强化了降解效率,并探讨了油降解的动力学过程。结果表明,零价铁活化产生硫酸根自由基是处理含油废水行之有效的手段。当过硫酸钠浓度119 mg·L~(-1)、Fe0投加量为50 mg·L~(-1)、p H=1.0,反应4 h后油降解率达到79.26%。Fe/Ps体系中,存在不同的主反应过程,其中Fe2+为主要活性物质,其浓度与降解速率正相关。适量投加柠檬酸可以优化控制Fe2+浓度,油降解率可提高20.64%。油降解动力学过程用准一级动力学方程描述。     

Cu/Fe和Ni/Fe双金属处理模拟地下水中的铬

研究了零价铁(Fe0)、Cu/Fe、Ni/Fe双金属作为渗透反应格栅(PRB)反应介质对地下水中六价铬〔Cr(Ⅵ)〕去除性能。采用烧杯批次实验研究了铜负载率、镍负载率、投加量及pH对Cr(Ⅵ)去除效率的影响。采用柱模拟室验考察Fe0、Cu/Fe和Ni/Fe双金属作为PRB反应介质对地下水中的Cr(Ⅵ)去除效果。实验结果显示,相对于Fe0,双金属去除效率显著提高,去除效果可达99.7%,速率也是Fe0单独作用时的2倍。Cu/Fe双金属系统随着铜负载率增加去除效率增加,铜负载率达到10%以后,去除效率不再增加,开始有降低的趋势;Ni/Fe双金属系统呈现相同趋势。Cu/Fe、Ni/Fe投加量越大,对Cr(Ⅵ)去除效果越好,并且酸性条件有利于Cr(Ⅵ)的去除。对于Cr(Ⅵ)的去除,Cu/Fe和Ni/Fe双金属比Fe0更具有长效性,其寿命是Fe0单独作用时的2倍以上。     

球磨硫化零价铁活化过硫酸盐降解水体中有机氯农药

利用球磨技术制备了不同硫铁(S/Fe)摩尔比的硫化零价铁(S-mZVI),并与过硫酸钠(PS)组成复合氧化体系(S-mZVI/PS),用于降解水体中的4,4′-DCBP和β-HCH,探索了制备参数和环境因子对有机氯农药降解效果的影响。结果表明：球磨过程中硫的加入不仅可以实现零价铁的硫化,还能提高零价铁的球磨效率。与球磨零价铁相比,S-mZVI的颗粒分散更均匀,呈不规则球状,且S/Fe摩尔比越大颗粒表面越平滑,更接近于球形。S-mZVI/PS体系较mZVI/PS体系对4,4′-DCBP和β-HCH的催化降解活性更高,且随着S/Fe摩尔比的增大,mZVI的腐蚀速率越高,其对污染物的降解效果越好。当S/Fe摩尔比为0.10、PS/Fe投加量配比为1/2时,4,4′-DCBP和β-HCH的降解效果最好,反应120 min后两者的最终降解率分别为92.4%和93.0%。而且,随着pH的升高,4,4′-DCBP和β-HCH降解效率逐渐降低,但二者最终降解率之间的差异较小。腐殖酸和$ {{\rm{HC}}{{\rm{O}}^ -_3} }$的存在会降低4, 4′-DCBP和β-HCH的降解效率,且随着腐殖酸和${ {\rm{HC}}{{\rm{O}}^ -_3}} $浓度的增加,对其降解效果的抑制作用增强;而$ {{\rm{N}}{{\rm{O}}^ -_3}} $的存在及浓度变化对S-mZVI/PS体系中4,4′-DCBP和β-HCH的降解影响较小。因此,S-mZVI可显著提高PS的活化效率及其对有机氯农药的降解速率,适合用作有机氯农药污染水体的修复。     

超声波/纳米铁协同降解氯代苯酚的试验

通过间歇试验对超声波/纳米铁协同降解氯代苯酚(CPs)废水进行了研究,结果表明,超声波/纳米铁协同对CPs的降解率明显高于单纯超声波和单纯纳米铁的降解率;协同体系、单纯超声波和单纯纳米铁降解CPs均符合准一级反应动力学,协同体系的降解速率较单纯超声波提高了5.1~5.6倍,较单纯纳米铁提高了17.7~21倍,并且比它们的几何迭加值高4倍以上;氯代苯酚降解的准一级速率常数和降解率满足以下规律:PCP>2,4,5-TCP>2,4-DCP>3-CP;探讨了混合废水的降解:在混合废水体系中,结构易裂解的优先降解,然后为浓度高的优先降解。     

Fe0/Fe3O4复合材料同时去除水中多种重金属的效果

零价铁(Fe0)具有中等还原性,可通过还原反应或通过铁腐蚀产物的吸附和共沉淀过程去除水中重金属.但由于铁表面易钝化,导致铁腐蚀反应难以持续,这是限制Fe0应用的关键.因此,本研究通过原位制备零价铁复合体系(Fe0/Fe3O4),并采用批处理和连续流的流化床反应器考察了该复合体系同时去除水中Zn2+、Ni2+和Cr(Ⅵ)...     

零价铁(Fe~0)共存下TiO_2光催化降解特性的研究

针对TiO2光催化反应中易出现电子-空穴对(e--h+)的复合、而Fenton技术又面临铁污泥的问题,向TiO2光催化反应中加入零价铁(Fe0)。通过调节溶液pH,使Fe0缓释Fe2+,且反应之后的pH仍能满足TiO2光催化反应所需。溶液中的Fe2+,一方面能减弱TiO2光催化产生的e--h+的复合,提高TiO2光催化反应的效率;另一方面,在紫外灯照射下也可以起到光Fenton降解作用。研究结果表明,Fe0共存下TiO2光催化对废水的降解率高于单独使用TiO2光催化或光Fenton对废水的降解率。对Fe0共存下TiO2光催化降解废水的褪色率的动力学研究表明,该反应属于三级动力学反应,且其对有机物的降解具有TiO2光催化和光Fenton加合增效的效果。     

Catalytic degradation of chlorothalonil in water using bimetallic iron-based systems

Modified zero valent iron (MZVI) was used to study the transformation of a chlorothalonil (CLT) solution and the variation of the observed degradation rate of the reduction reactions. This was carried out when transition metals e.g. Pd, Cu and Co plated on the surface of micrometric iron particles (< 150 microm) were used as reducing catalytic agents for pesticide removal. Reactions were undertaken under both oxic and anoxic conditions in the presence and the absence of a phosphate buffer solution (PBS). Results of batch studies in nitrogen sparged solutions revealed that incomplete slow dechlorination merely occurred with zero valent iron (ZVI), however, complete rapid dechlorination reactions took place with MZVI especially Fe/Pd. Dechlorination was depicted by studying UV absorbance and MS spectra of CLT and all corresponding by-products. Typical blue shifts (deltalambda = 4-6 nm/chlorine atom) were observed at the same time as chlorine cluster isotopes disappeared. After the plating process, metal loading was controlled by analyzing the remaining metal in the solution by atomic absorption spectroscopy. Experiments showed that CLT degradation mechanism is faster in nitrogen sparged solutions in the absence of PBS. Time needed for complete removal of 2.08 +/- 0.19 microM CLT solution was about 2 h when experiments were conducted with ZVI (t1/2 = 15.0 min) and about 10 min when the reaction was carried out under the same conditions with Fe/Pd 1% (t1/2 = 1.0 min). Degradation rates for all bimetallic systems were determined showing that Pd is the more exciting catalytic transition metal followed by Cu and Co. Furthermore, MZVI method showed obvious advantage to traditional CLT treatment methods.     

超声强化Fe0去除阳离子红GTL的研究

采用US/Fe0系统去除阳离子红GTL,考察了pH值、Fe0用量、超声功率及活性炭、H2O2、盐分添加对阳离子红GTL去除率的影响,利用紫外-可见吸收光谱变化查明阳离子红GTL在不同条件下的去除差异性,利用SEM解析铁的形态与染料去除的相关性。结果表明： pH≥5.0时超声和Fe0具有协同效应,Fe0用量2 g/L,pH=7.0,超声功率135 W,阳离子红GTL去除率达到96.07%;一定量的活性炭、H2O2、盐分添加会加速染料去除,US加速Fe0反应速度,但不改变染料降解机理,添加活性炭能够彻底降解阳离子红GTL,添加H2O2提供的氧化环境抑制苯胺类化合物生成;铁的形态及与染料的接触是影响染料去除效果的重要原因。     

Simultaneous adsorption and degradation of γ-HCH by nZVI/Cu bimetallic nanoparticles with activated carbon support

Cu amended zero valent iron bimetallic nanoparticles were synthesized by doping Cu on the surface of iron. They were incorporated with granular activated carbon (AC) to prepare supported particles (AC-Fe⁰-Cu), which were used to remove γ-HCH. Cu on the surface of iron enhanced the dechlorination activity of Fe⁰. The dechlorination rate constant (k_obs) increased with the Cu loading on the surface of iron and the maximum was achieved with 6.073% Cu. AC as a support was effective for increasing the dispersion of the nanoparticles and avoiding the agglomeration of the metallic nanoparticles. The simultaneous adsorption of γ-HCH on AC accelerated the degradation rate of γ-HCH by the bimetals. After reaction for 165 min, around 99% of γ-HCH was removed by the solids of AC-Fe⁰-Cu. In addition, AC could adsorb the degradation products. The degradation of γ-HCH was mainly through dehydrochlorination and dichloroelmination based on the intermediate products detected by GC/MS.     

超声波和零价铁联用对氯代苯酚脱氯降解作用的研究

采用超声波和零价铁联用对氯代有机物3氯苯酚(CP)、2,4-二氯苯酚(DCP)和2,4,6-三氯苯酚(TCP)模拟废水进行了脱氯处理研究。以单因素法, 考察了铁粉初始投加量、溶液的初始浓度、超声波功率和溶液的pH值等因素对氯代酚降解的影响,并探讨了降解反应动力学。结果表明,超声波和零价铁联用对氯酚具有显著的降解效果,当水样初始浓度为25 mg/L,溶液pH呈弱酸性,超声波功率为200 W时,氯代酚的脱氯效率达到最大值。降解反应符合准一级反应,CP、DCP和TCP的反应速率常数分别0.0613 h^-1、0.374 h^-1和0.197 h^-1。     

Simultaneous oxidation of EDTA and reduction of metal ions in mixed Cu(II)/Fe(III)-EDTA system by TiO2 photocatalysis

Both the photooxidation of EDTA and the photoreduction of metal ions in metal-EDTA systems were investigated. EDTA oxidation by TiO(2) photocatalysis occurred sequentially as Cu(II)-EDTA>Cu(II)/Fe(III)-EDTA>Fe(III)-EDTA. For Cu(II)-EDTA, EDTA was completely decomposed after only 60min of irradiation. The rate of EDTA decomposition was directly correlated with the initial Cu(II) concentration in the case of a mixed Cu(II)/Fe(III)-EDTA system. The metal ions in a single metal-EDTA complex were removed following significant decomposition of EDTA. For a mixed Cu(II)/Fe(III)-EDTA system, however, no copper was removed whereas almost all of the iron was removed. The iron and copper species deposited on the TiO(2) surface were identified via EPR and XPS as mixed FeO/Fe(3)O(4) and Cu(0)/Cu(2)O, respectively.     

零价铁耦合芬顿氧化法处理TNT红水

采用零价铁耦合芬顿氧化法处理TNT红水,研究了初始pH、零价铁投加量、过氧化氢（H2O2）投加量及温度对红水中总有机碳（TOC）去除效果的影响,同时进行了TOC去除过程中反应动力学的探讨。结果表明,零价铁耦合芬顿氧化体系可有效降解TNT红水中的2,4-二硝基甲苯-3-磺酸钠和2,4-二硝基甲苯-5-磺酸钠。在初始pH为2,温度为20 ℃的条件下,加入1.5 g·L-1零价铁反应1 h后,再加入100 mL·L-1H2O2反应4 h,红水中二硝基甲苯磺酸盐浓度从500 mg·L-1降至0 mg·L-1,去除率为100%,TOC浓度从150 mg·L-1降至30 mg·L-1,去除率达到80%。反应中TOC的降解过程遵循拟二级反应动力学方程。零价铁耦合芬顿氧化法可以作为TNT红水的有效处理途径。     

腐殖酸和铁对阿特拉津光降解影响的研究

为考察除草剂在水体中的自净性能,对模拟太阳光(λ> 290 nm)下腐殖酸和铁元素对阿特拉津的光化学降解进行了研究。结果表明,单独辐照阿特拉津几乎不降解。在分别加入3、5和10 mg/L的腐殖酸时,阿特拉津的降解率分别为34.36 %、40.74%和15.66 %;在Fe(Ⅲ)投加量从0.01 mmol/L增加到0.2 mmol/L时,阿特拉津的降解率从24.36 %增加到34.97 %。而在当腐殖酸与铁共存时,阿特拉津降解率则进一步提高。紫外可见光谱和荧光光谱均表明,腐殖酸-铁络合物的形成及其光化学作用,促进了阿特拉津的降解。     

零价铁修复受三氯乙烯污染地下水的实验研究

通过批实验和柱实验研究了三氯乙烯（TCE）初始浓度、四氯乙烯(PCE)等对零价铁去除三氯乙烯的影响,并建立了三氯乙烯降解的反应动力学方程。结果表明：（1）零价铁对TCE具有较好的降解效果,反应符合准一级反应动力学方程,表观反应速率常数随TCE浓度的增加而减小;（2）在铁粉充足的条件下,TCE初始浓度对降解效果影响不显著,且TCE去除率皆可达到90%以上;（3）PCE的存在抑制了TCE的脱氯反应。PCE和TCE共存时,TCE的最大去除率仅为64.2%;TCE脱氯反应的表观反应速率明显降低,反应半衰期由TCE单独存在时的6.8～9.7 h增大到66 h～346.5 h。     

Regeneration of iron for trichloroethylene reduction by Shewanella alga BrY

Zero valent iron (ZVI), the primary reactive material in several permeable reactive barriers, is often oxidized to ferrous or ferric iron, resulting in decreased reactivity with time. Iron reducing bacteria can reconvert the ferric iron to its ferrous form, prolonging the reduction of chlorinated organic contaminants. In this study, the reduction of Fe(II,III) oxide and Fe(III) oxide by a strain of iron reducing bacteria of the group Shewanella alga BrY(S. alga BrY) was observed in both aqueous and solid phases. S. alga BrY preferentially reduced dissolved ferric iron over the solid ferric iron. In the presence of iron oxide the Fe(II) ions reduced by S. alga BrY efficiently reduced trichloroethylene (TCE). On the other hand, Fe(II) produced by S. alga BrY covered the reactive surfaces of ZVI iron filings and inhibited the reduction of TCE by ZVI. The formation of precipitates on the iron oxide or Fe0 surface was confirmed by scanning electron microscopy. The results suggest that iron-reducing bacteria in the oxidized Fe0 barriers can enhance the removal rate of chlorinated organic compounds and influence on the long-term performance of Fe0 reactive barriers.