过硫酸钾去除水中的TCE

以地水中的氯代烃污染物三氯乙烯(TCE)为目标污染物,以过硫酸钾溶液为氧化剂,探讨了不同条件下过硫酸钾对TCE的去除效果。实验结果表明,在40℃,过硫酸钾初始浓度为2.43 g/L条件下,反应2 h后,TCE的去除率就可达到96.8%;过硫酸钾对TCE的去除符合一级反应动力学方程,速率常数(K)为1.3364 h-1,半衰期(t1/2)为0.51 h;过硫酸钾对TCE的去除速率在pH为中性附近时最大,其后无论pH升高或降低去除速率均减小;受温度和pH影响较明显,并且反应温度越高,受pH的影响越明显;随离子强度的增加而减小;反应活化能为119.6 kJ/mol;过硫酸钾溶于水生成过硫酸根离子(S2O28-),S2O28-会进一步生成硫酸根自由基(SO4-.),在碱性条件下,SO4-.与OH-反应会进一步生成羟基自由基(.OH)。过硫酸钾对于TCE的去除主要源自SO4-.和.OH的强氧化性。     

柠檬酸强化纳米零价铁活化过硫酸钠体系降解水溶液中的三氯乙烯

采用螯合剂柠檬酸(CA)强化纳米零价铁(nZVI),活化过硫酸钠(PS)体系,降解水溶液中的三氯乙烯(TCE),分别考察了PS、CA、nZVI投加量、溶液初始pH和无机阴离子对TCE降解效果的影响,确定了在TCE降解过程中起主导作用的活性氧自由基,并验证了PS/nZVI/CA体系降解实际地下水中TCE的效果。结果表明:投加适量的CA可以明显提高PS/nZVI体系对TCE的降解效果,但当CA浓度过高时,TCE降解反而受到抑制,过量或不足的PS、nZVI均会降低TCE的降解率;当溶液初始pH为3～9时,PS/nZVI/CA体系可有效降解TCE;溶液中存在的Cl–和HCO_3~-会抑制TCE的降解,其中HCO_3~-的抑制作用大于Cl–;自由基清除实验和电子顺磁共振实验表明PS/nZVI/CA体系中产生了HO·、SO_4~-·和O _2~-·活性氧自由基,其中HO·、SO_4~-·对TCE降解起主导作用;CA的加入有利于实际地下水中TCE的降解,PS/nZVI/CA体系相比PS/nZVI体系,更适应实际地下水中各种水质条件的冲击,具有实际应用前景。     

工业废铁屑活化过硫酸盐降解水中环丙沙星的研究

为了有效降解水中的喹诺酮类抗生素环丙沙星(CPFX),降低处理成本,利用工业废铁屑(IWFe)活化过硫酸盐(PS)降解CPFX,探索了IWFe的粒径、反应体系初始pH、PS/CPFX(质量比)对CPFX降解效果的影响,并且研究了反应动力学、自由基的生成以及使用前后IWFe的变化。结果表明,IWFe+PS体系对CPFX的去除率超过90%,随着IWFe粒径的变小和PS/CPFX的增大,CPFX的去除率增加。在中性条件下,CPFX的去除率最大。IWFe的表面氧化物主要为Fe_3O_4和α-FeOOH,其中Fe~(2+)可活化PS产生·SO_4~-和·OH,·SO_4~-和·OH对CPFX的去除率的贡献分别为47.7%和21.9%。使用后,IWFe上Fe~(2+)的减少低于Fe~(3+)的增加,表明IWFe内核的Fe~0也参与了PS的活化。本研究提供了一种高效、低成本的有机废水处理方法,对实际工程具有一定的参考价值。     

新型过硫酸盐活化技术降解有机污染物的研究进展

在利用过硫酸盐氧化降解有机污染物过程中,以过硫酸盐活化所产生强氧化性的硫酸根自由基至为关键,综述了近来过硫酸盐的新型活化技术,其中以零价金属材料,含铁矿石,含铁复合材料,活性炭及含碳复合材料,含醌结构有机物活化为主线展开。通过介绍各种活化机理以及相应活化技术在降解有机污染物的研究,继而提高过硫酸盐降解有机污染物的潜在研究与应用价值。     

pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene

The ability of free ferrous ion activated persulfate (S₂O₈²⁻) to generate sulfate radicals (SO₄⁻) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO₄⁻ with excess Fe²⁺ and a quick conversion of Fe²⁺ to Fe³⁺. This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe³⁺ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe³⁺ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe³⁺ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S₂O₈²⁻ and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe³⁺ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe³⁺ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.     

The gas-photocatalytic degradation of trichloroethylene without water

The photocatalytic degradation of gaseous trichloroethylene (TCE) without water has been studied. The degradation products were determined to be CO₂, HCl and Cl₂, and the reaction stoichiometry, was described as

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. The degradation rate was found to be linear with 0.16 power of the illumination intensity. When the TCE concentration was low (10¹⁴ mol L⁻¹ or a little more), its degradation rate model could be considered as first order kinetics. A mechanism of valence band hole oxidation was proposed.     

Fenton试剂和活化过硫酸钠氧化降解土壤中的二氯酚和三氯酚

氯酚类物质（chlorophenols, CPs）在环境介质中广泛存在且具有很强环境毒性。为探究化学氧化修复场地氯酚类污染的可行性,通过室内实验、模拟搅拌实验、现场中试,开展应用Fenton试剂和活化过硫酸钠氧化降解土壤CPs的研究。结果表明,化学氧化可有效降解土壤中的CPs,在氧化剂用量和CPs总量摩尔比为15:1时,CaO活化Na2S2O8能高效降解土壤中的二氯酚（2,4-DCP）和三氯酚（2,4,6-TCP）,室内实验和现场中试的去除率均达90%以上,处理后的2,4-DCP和2,4,6-TCP浓度均低于《展览会用地土壤环境质量评价标准》（HJ 350-2007）A类标准限值。Fenton试剂在室内实验中降解率达90%以上,但现场中试对2,4-DCP和2,4,6-TCP的降解率仅为66.1%、23.8%,处理后2,4-DCP浓度仍超过A类标准限值1倍以上。此外,在修复过程中,约70%的2,4-DCP、2,4,6-TCP会向液相转移,因此,需要关注修复系统引入水后污染物向液相中的转移可能造成的二次污染。研究结果可为氯酚类污染土壤的修复提供新思路,并为实际工程应用提供理论依据。     

Enhanced degradation of bisphenol S by persulfate activated with sulfide-modified nanoscale zero-valent iron

Environmental Science and Pollution Research - Sulfide-modified nanoscale zero-valent iron (S-nZVI) has been considered an efficient material to remove heavy metals and organic contaminants. The...     

Synergistic adsorption and advanced oxidation activated by persulfate for degradation of tetracycline hydrochloride using iron-modified spent bleaching earth carbon

At present, tetracycline hydrochloride (TCH) is a widely used antibiotic, and is often detected in water, posing a serious harm to human and ecological health. In this study, spent bleaching earth (SBE) was pyrolyzed to obtain spent bleaching earth carbon (SBE@C) and the nano Fe⁰/SBE@C prepared after zero-valent iron loading was adopted to remove TCH in water for the first time. The combination of nano Fe⁰/SBE@C and PS, the strong adsorption of SBE@C coupled with the oxidation of free radicals could achieve TCH efficient removal. The effects of nano Fe⁰ load, nano Fe⁰/SBE@C dosage, solution initial pH, and PS/TCH molar ratio on TCH removal efficiency in nano Fe⁰/SBE@C?+?PS system were studied. The results indicate that the optimal reaction conditions are 5% nano Fe⁰ load, 0.2 g/L nano Fe⁰/SBE@C dosage, initial pH of 3, PS/TCH molar ratio of 100:1. Under these conditions, TCH removal efficiency could reach 91%. Meanwhile, response surface methodology (RSM) was applied to predict optimal value of reaction conditions. The removal efficiency corresponding to the predicted optimal conditions was consistent with the actual removal efficiency obtained from the experiment. Moreover, six reaction systems were tested, and TCH removal efficiency in the SBE@C?+?PS system was 22.6%. When nano Fe⁰ was loaded on SBE@C, TCH removal efficiency in Fe⁰/SBE@C?+?PS system increased to 78.2%, in which TCH was first adsorbed on the surface of nano Fe⁰/SBE@C, and then was degraded by the oxidation of SO₄^?? and ?OH. Totally, the nano Fe⁰/SBE@C?+?PS system displayed excellent TCH removal efficiency, good stability and reusability, exhibiting a promise toward TCH removal.

     

石墨烯复合活性碳纤维气体扩散电极对甲基橙的降解性能

采用超声-浸渍法制备石墨烯(GO)复合活性碳纤维(ACF)气体扩散电极,对其微观形貌、表面元素及表面官能团等进行表征,通过甲基橙批量降解处理实验阐述阴极双氧水产生性能与机理。结果表明,制备条件GO与聚四氟乙烯分散液(PTFE)质量比为1:4、GO浆液中无水乙醇添加量100 mL、煅烧温度360 ℃、煅烧时间10 min得到的电极性能最优,GO/ACF较ACF在45 min电催化反应甲基橙降解率提升了21.11%,双氧水最终的质量浓度提高了4.65倍,GO/ACF对甲基橙的最终降解率为100.0%,扫描电子显微镜微观形貌表征结果表明,石墨烯可均匀负载于活性碳纤维表面,X-射线光电子能谱、傅里叶变幻红外光谱仪、循环伏安及电化学阻抗测试结果表明,石墨烯复合增加了电极表面C＝O官能团含量,电极电阻减小了40.06%,有利于产生H₂O₂。对初始电压、电解质浓度影响降解因素进行了优化,使用10次后GO/ACF对甲基橙降解率仍保持在100.0%、甲基橙废水COD去除率仅下降了4.45%,表明GO/ACF具有较高循环稳定性。以上研究结果可为印染废水电催化高效脱色处理与有机污染物氧化降解提供理论依据与技术借鉴。     

泥浆系统中Fe2+活化过碳酸钠降解三氯乙烯

主要探究泥浆系统中Fe2+活化过碳酸钠(SPC)降解三氯乙烯(TCE)的效果。通过批次实验研究土壤对TCE的吸附作用,并考察泥浆系统中SPC和Fe2+投加量对TCE去除效果的影响。结果表明,土壤对TCE具有一定的吸附作用;泥浆系统中,土壤含有的有机质越多,TCE去除效果越低;当SPC/TCE摩尔比为5/1~20/1时,SPC投加量对TCE去除影响不明显,TCE去除效果随Fe2+投加量增大而提高。当水土质量比为30/1,TCE初始浓度为20 mg/L时,SPC/Fe2+/TCE最优摩尔比为10/30/1,此时TCE最终去除率达到97.5%。综上所述,Fe2+活化过碳酸钠降解三氯乙烯快速高效,为应用于实际场地修复提供有效的理论依据。     

钴金属-有机骨架活化过硫酸钠降解废水中的盐酸土霉素

采用新制备的钴金属-有机骨架(Co-MOF)和过硫酸钠(PS)分别作为催化剂和氧化剂,并通过Co-MOF活化PS降解废水中的盐酸土霉素,考察Co-MOF浓度、PS浓度、pH及温度对降解盐酸土霉素的影响。SEM、TEM、XRD及XPS等结果证明,Co-MOF成功地被合成。降解实验结果表明,与单独的Co-MOF、PS相比,Co-MOF/PS的降解性能有大幅度的提高。当pH=5、温度30 ℃、Co-MOF为200 mg·L⁻¹以及PS为2 000 mg·L⁻¹时,5 min后对20 mg·L⁻¹盐酸土霉素的降解率最高达到97.1%。在催化剂的重复使用实验中,Co-MOF第4次运行对盐酸土霉素的降解率由97.1%(第1次)降低至82.1%,这表明Co-MOF材料可以重复利用降解盐酸土霉素。Co-MOF降解盐酸土霉素实验反应前后的XRD和XPS数据表明Co-MOF具备良好的稳定性。以上研究结果可为新型高效降解体系的开发及其在水环境污染控制领域的应用提供参考。     

Fe-AC微电解活化过硫酸盐降解直接耐酸大红4BS

为快速脱色降解偶氮类染料,同时解决零价铁活化效率低、易被氧化的问题,以直接耐酸大红4BS（大红4BS）为模拟废水污染物,通过Fe-AC/PDS（铁碳微电解活化过硫酸钠）反应体系对大红4BS进行脱色降解。对影响大红4BS降解的几种因素如Fe：AC（铁碳质量比）、PDS浓度、初始pH等进行探究。结果表明,大红4BS脱色率在Fe：AC=3：1时高达94.7%。增大PDS浓度能明显促进反应进行,但超过5 mmol·L-1时,对体系影响不大。初始溶液pH对Fe-AC/PDS体系降解大红4BS作用显著,在酸性和中性（pH=3.02、4.67、7.32）时,大红4BS的脱色率分别高达98.8%、96.2%、94.7%,但在碱性（pH=9.38、10.78）条件下,其脱色率只有24.5%、18.7%。无机盐阴离子对Fe-AC/PDS体系降解大红4BS有抑制作用,而阳离子对其产生促进作用。自由基俘获实验表明Fe-AC/PDS体系降解大红4BS并不仅仅只是自由基的氧化反应,还存在其他复杂反应,继而对Fe-AC/PDS体系降解大红4BS的机理进行探讨。     

Degradation of propyl paraben by activated persulfate using iron-containing magnetic carbon xerogels: investigation of water matrix and process synergy effects

An advanced oxidation process comprising an iron-containing magnetic carbon xerogel (CX/Fe) and persulfate was tested for the degradation of propyl paraben (PP), a contaminant of emerging concern, in various water matrices. Moreover, the effect of 20 kHz ultrasound or light irradiation on process performance was evaluated. The pseudo-first order degradation rate of PP was found to increase with increasing SPS concentration (25–500 mg/L) and decreasing PP concentration (1690–420 μg/L) and solution pH (9–3). Furthermore, the effect of water matrix on kinetics was detrimental depending on the complexity (i.e., wastewater, river water, bottled water) and the concentration of matrix constituents (i.e., humic acid, chloride, bicarbonate). The simultaneous use of CX/Fe and ultrasound as persulfate activators resulted in a synergistic effect, with the level of synergy (between 35 and 50%) depending on the water matrix. Conversely, coupling CX/Fe with simulated solar or UVA irradiation resulted in a cumulative effect in experiments performed in ultrapure water.     

磁性还原氧化石墨烯负载Fe0对罗丹明B的类芬顿降解

合成了磁性还原氧化石墨烯负载零价纳米铁材料（Fe0-MF-RGO）,并在双氧水（H2O2）的作用下构成类芬顿试剂用于对罗丹明B（RhB）的吸附-催化降解。通过正交实验研究了pH值、Fe0-MF-RGO用量、RhB初始浓度、温度和H2O2浓度5个影响因素。在15 ℃、pH值为7.0、Fe0-MF-RGO投加量1.0 g·L-1、RhB初始浓度为50 mg·L-1以及H2O2浓度为0.8 mmol·L-1的条件下,150 min后模拟废水中RhB的去除率达到98.17%,经5次循环使用后去除率为72.97%。     

Biosorption and biodegradation of trichloroethylene by acclimated activated sludge

The biosorprion and biodegradation of trichloroethylene (TCE) was investigated. The experimental results showed that at 25°C the adsorption equilibrium of TCE at concentrations from 10 mg/L to 200 mg/L could be described by the Freundlich isotherm. Adsorption could complete within 15 min. Results indicated that glucose could serve as a co-substrate and enhance TCE biodegradation through co-metabolism. The TCE biodegradation conformed to the first-order reaction kinetic, and the rate constant was 0.3212 day⁻¹ at 25°C. In addition, results also indicated that TCE could serve as the sole substrate and be biodegraded under aerobic condition. No intermediate products such as DCE and VC were accumulated during the degradation.     

铜基生物炭活化过硫酸钠处理废水中EDTA-Cu

为实现废水中EDTA-Cu的快速破络和去除,以铜基生物炭(CuO@BC)为催化材料活化过硫酸钠(PS),探究了EDTA-Cu、TOC和铜的去除效率及影响因素,初步揭示了催化机理。结果表明,CuO@BC-PS体系能够在60 min时有效去除97.1%的EDTA-Cu和69.6%的TOC,并且通过沉淀去除62.2%的铜。氧化铜(CuO)是提高复合材料催化作用的关键因素,降解反应体系中自由基作用不大,非自由基途径活化PS是降解EDTA-Cu的主要原因。以上研究结果可为络合态重金属污染废水的高级氧化处理提供参考。     

过渡金属离子活化过硫酸盐去除土壤中的芘

比较研究了Fe2+、Co2+和Ag+活化Na2S2O8及KHSO5对土壤中芘的氧化降解效果,并对上述反应过程进行动力学研究及芘降解产物成分分析。在土水质量比为1：5,氧化剂和过渡金属离子添加摩尔比为10：1,30℃恒温水浴磁力搅拌及反应时间5~120 min条件下开展了系列实验。结果表明,3种离子中Fe2+活化Na2S2O8氧化降解芘的去除效果最优,反应120 min后芘去除率为93.4%;Co2+是活化KHSO5的最佳过渡金属离子,反应5 min后芘去除率达94.5%,在反应120 min后芘去除率增高至97.0%。此外,降解动力学拟合结果表明Fe2+、Co2+和Ag+活化Na2S2O8和KHSO5降解芘的过程符合准一级反应动力学,且土壤中绝大部分芘可被活化过硫酸盐体系氧化降解。     

热活化过硫酸盐对双酚A的降解及其机理

研究了热活化过硫酸盐对双酚A的氧化降解效能及机理,探讨了温度,反应物初始浓度,pH值,阴离子和腐殖酸对双酚A降解的影响。结果表明:在实验范围内,双酚A的降解率随温度和过硫酸钠初始浓度的升高而增加;双酚A在酸性条件下的降解率比在中性和碱性条件下要高;阴离子的存在会抑制溶液中双酚A的降解,抑制作用依次为SO42- >Cl- >NO3-;加入腐殖酸后,双酚A的降解受到抑制。双酚A的降解中间产物主要为对苯二酚、对异-丙烯基苯酚、2-甲基-2,3-二氢苯并呋喃和3-甲基-2,3-二氢苯并呋喃。     

Fe(Ⅱ)活化过硫酸钠去除水中三氯生

采用Fe2+活化过硫酸钠（SPS）对水中三氯生（TCS）的去除进行了研究,考察了Fe2+、SPS的投加量、TCS初始浓度、pH值和腐殖酸（HA）等对TCS去除的影响,GC-MS鉴定识别了降解产物。结果表明Fe2+活化SPS工艺能有效去除TCS,2,4-二氯苯酚（2,4-DCP）为其主要降解产物,SPS浓度为1.0 mmol·L-1,Fe2+的投加量为0.4 mmol·L-1时,初始浓度为460 μg·L-1的TCS 2 min后去除率可达93.87％,TCS慢速反应阶段的降解符合一级反应动力学方程,其动力学常数K=0.140 min-1。TCS的去除随Fe2+浓度的增加先增大后减小,高浓度的Fe2+不利于2,4-DCP的降解,适量提高SPS浓度有利于TCS的去除和2,4-DCP的降解,TCS去除随初始浓度增大而降低,酸性环境有利于TCS的去除,腐殖酸对TCS的去除具有抑制作用,低浓度腐殖酸不利于2,4-DCP的降解。