不同咪唑基离子液体改性PbO2电极降解苯酚废水

以5种不同结构的咪唑基离子液体为电沉积溶液的添加剂,采用电沉积法制备了改性钛基PbO2电极。通过扫描电子显微镜（SEM）、X射线衍射（XRD）对电极表面形貌、晶体结构进行表征。以苯酚为电催化目标降解物,对不同电极氧化去除苯酚及COD的活性进行考察比较;同时,以水杨酸为捕捉剂,通过高效液相色谱（HPLC）分析技术对不同电极体系中羟自由基（·OH）的生成量进行检测。结果表明,阳离子烷基支链长度及阴离子的改变均会对PbO2电极的表面形貌、结晶取向及电催化活性产生一定影响,且后者的影响作用较前者更为突出。[Emim]Br和[Emim]PF6改性电极的电催化活性比较相近,均明显低于[Emim]BF4改性电极。固定阴离子为BF4-,3种不同烷基支链长度离子液体对PbO2电极活性的改进效果顺序为[Bmim]BF4 > [Emim]BF4 > [Hmim]BF4。此外,不同改性电极对苯酚废水COD去除率的高低与·OH的生成量多少一致,表明苯酚的电化学氧化降解主要是由·OH间接氧化引起的。     

阳极氧化联合电-Fenton氧化深度处理垃圾渗滤液

采用多孔碳素阴极、Ti/SnO2-Sb2O5-IrO2阳极构建电化学氧化系统用于渗滤液的深度处理。研究结果表明,所构建的电化学氧化系统通过阳极氧化和电-Fenton氧化2种机制降解有机污染物;处理过程中阴极表面形成的沉淀物对TOC和COD的衰减也产生了影响。在阴极电位为-1.0 V、Fe2+ 初始浓度为0.5 mmol/L的条件下,电化学处理120 min获得了58% 的TOC去除;处理480 min COD去除率为55%,NH3-N去除率为99%,TN去除率为60%,色度几乎被完全去除。GC-MS分析结果表明,渗滤液中以腐殖质类物质为主的有机化合物被降解为分子量相对较小的有机物,直至完全矿化。联合阳极氧化和电-Fenton氧化机制的电化学处理方法为垃圾渗滤液深度处理提供了新的选择。     

Removal of phenol from aqueous solution by coupling alternating current with biosorption

Environmental Science and Pollution Research - The present research was devoted to water decontamination through the valorization of cellulosic fibers for the preparation of performing biosorbent,...     

Degradation of nitrogen-heterocyclic compounds by anodic oxidation and electro-Fenton methods.

This study describes the degradation of nitrogen-heterocyclic compounds (NHCs) by anodic oxidation and electro-Fenton. Using indole as a model nitrogen-heterocyclic compound, the removal of indole reached 68% and 97% by anodic oxidation and electro-Fenton, respectively, while the decay of TOC was 15% and 38% correspondingly. By the analysis of ultraviolet-visible spectra and liquid chromatography/mass spectrum, the degradation mechanism of indole by electro-Fenton was proposed as hydroxyl oxidation and anodic oxidation. The degradation of other NHCs including quinoline, isoquinoline and pyridine by anodic oxidation and electro-Fenton revealed the same sequence: quinoline approximately equal isoquinoline > indole > pyridine. A significant correlation between ln k (natural logarithm of rate constants) and E(LUMO) (the energy of the lowest unoccupied molecular orbit) was obtained by quantitative structure-activity relationship analysis. Degradation of coking plant wastewater showed the removal of COD and TOC were 42% and 22% respectively after 180 min treatment by electro-Fenton.     

Mineralization of paracetamol in aqueous medium by anodic oxidation with a boron-doped diamond electrode

The degradation of 100ml of solutions with paracetamol (N-(4-hydroxyphenyl)acetamide) up to 1 g l(-1) in the pH range 2.0-12.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a graphite cathode, both of 3-cm2 area, by applying a current of 100, 300 and 450 mA between 25 and 45 degrees C. Complete mineralization is always achieved due to the great concentration of hydroxyl radical (*OH) generated at the BDD surface, with release of NH4+ and NO3- ions. The mineralization rate is pH-independent, increases with increasing applied current and temperature, but decreases when drug concentration raises from 315 mg l(-1). Reversed-phase chromatography revealed a similar complex paracetamol decay in acid and alkaline media. Ion-exclusion chromatography allowed the detection of oxalic and oxamic acids as ultimate carboxylic acids. When the same solutions have been comparatively treated with a Pt anode, a quite poor mineralization is found because of the production of much lower *OH concentration. Under these conditions, the degradation rate is enhanced in alkaline medium and polymerization of intermediates is favored in concentrated solutions. Paracetamol can be completely destroyed with Pt and its kinetics follows a pseudo-first-order reaction with a constant rate independent of pH.     

Degradation of paracetamol by advance oxidation processes using modified reticulated vitreous carbon electrodes with TiO2 and CuO/TiO2/Al2O3

The degradation of paracetamol in aqueous solutions in the presence of hydrogen peroxide was carried out by photochemistry, electrolysis and photoelectrolysis using modified 100 pores per inch reticulated vitreous carbon electrodes. The electrodes were coated with catalysts such as TiO₂ and CuO/TiO₂/Al₂O₃ by electrophoresis followed by heat treatment. The results of the electrolysis with bare reticulated vitreous carbon electrodes show that 90% paracetamol degradation occurs in 4 h at 1.3 V vs. SCE, forming intermediates such as benzoquinone and carboxylic acids followed by their complete mineralisation. When the electrolysis was carried out with the modified electrodes such as TiO₂/RVC, 90% degradation was achieved in 2 h while with CuO/TiO₂/Al₂O₃/RVC, 98% degradation took only 1 h. The degradation was also carried out in the presence of UV reaching 95% degradation with TiO₂/RVC/UV and 99% with CuO/TiO₂/Al₂O₃/RVC/UV in 1 h. The reactions were followed by spectroscopy UV-Vis, HPLC and total organic carbon analysis. These studies show that the degradation of paracetamol follows a pseudo-first order reaction kinetics.     

红萍净化水产养殖水体的研究

利用红萍(Azolla)对富营养化水产养殖水体进行净化研究。结果表明,红萍能显著增加水体中的DO,增氧幅度随流量在16.88%～70.46%之间变化,随着养殖水体流经的层数增多或者处理的时间延长,红萍对水体的增氧量加大,水中DO最终趋向一个常数值K;同时,红萍对水体中的NH₃-N和TP都有明显的去除效果,NH₃-N去除率随流量在9.86%～38.90%间波动,TP的去除率则随流量的变化在5.80%～38.43%之间波动。可见,红萍是净化水质的良好材料,能有效改善水产养殖水环境。利用红萍净化水体将为解决高密度集约化水产养殖的瓶颈提供新途径,实现水产养殖用水的封闭循环利用。     

臭氧/高锰酸盐预氧化对生物过滤净水效能的影响

比较了臭氧(O3)和高锰酸盐复合药剂(PPC)对水源水预氧化的助凝效果及其对后续陶粒生物过滤净水效能的影响.结果表明,两种预氧化剂投加量均为2 mg/L时,PPC的助凝效果较为明显,浊度和溶解性有机碳(DOC)的去除率分别由未投加氧化剂时的85.7%和24.2%提高到88.3Z和35.2%;O3能够增加沉淀后水的可生化性,使特征紫外吸光度(SUVA)由0.97L/(m·mg)降至0.89 L/(m·mg).PPC预氧化有助于生物过滤对浊度的稳定去除,而O3预氧化则有助于生物过滤对DOC的去除.与O3预氧化相比,PPC预氧化有利于后续生物过滤运行初期对NH4 -N的去除,二者后续生物过滤在前3个月对NH4 -N的平均去除率分别为26.6%和73.1%,运行后期二者NH4 -N去除率接近.当进水NH4 -N大于2.0 mg/L时,DO是其去除的主要限制因素.     

纳米TiO2光催化氧化去除水中痕量双氯芬酸的研究

以TiCl4为前驱体,采用水解法经不同温度煅烧制备了具有不同理化性能的纳米TiO2光催化剂。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、物理吸附仪、紫外—可见光漫反射吸收光谱(UV-Vis DRS)等手段对纳米TiO2的晶相结构、粒径、孔径分布以及禁带宽度等进行了表征。以蒸馏水配制的双氯芬酸溶液为目标物,进行了纳米TiO2光催化氧化去除双氯芬酸的活性测试,研究了纳米TiO2的理化性能与光催化氧化活性之间的关系。结果表明,经400℃煅烧制得的纳米TiO2样品具有最高的光催化氧化活性,其在紫外光照射60min下对双氯芬酸的去除率为98%左右,比单独紫外光照射高出85百分点。纳米TiO2光催化氧化去除双氯芬酸的反应近似一级反应动力学模型,其中经400℃煅烧制得的纳米TiO2光催化氧化去除双氯芬酸的表观反应速率常数为0.054 54min-1,是普通商用TiO2的2倍左右,与德国Degussa P-25TiO2的光催化氧化活性最相近。     

有毒难降解有机物高级氧化电催化电极

在电催化电极的作用下 ,电化学反应和化学催化作用结合 ,导致有机分子的电催化降解。在分析中 ,综述了电催化高级氧化电极研究现状 ,阐述与评价了过渡金属涂层电极、金属氧化物涂层电极、含掺杂半导体涂层电极、金刚石膜电极、三维电极等几个主要方面的研究成果 ,并对今后工作的重点提出了一些意见。     

紫外波长对UV/Cl2高级氧化去除水中有机物的影响

为明确紫外波长对UV/Cl2高级氧化体系的影响,使用中心波长分别为267、275和286 nm的发光二极管LED作为光源,探究Cl2光解动力学、UV/Cl2体系自由基生成、对模式化合物溶液以及天然水、再生水TOC的去除。结果表明：在中性或酸性体系中,267 nm最接近HClO最大吸收波长237 nm,吸光度和量子产率均较大,羟基自由基产生水平较高,有机物去除效果较好;在碱性体系中,286 nm最接近ClO-最大吸收波长292 nm,尽管量子产率较小,但吸光度很大,有机物去除效果较好;由于水杨酸在292 nm附近有较强的竞争吸收,使用UV286去除水杨酸效果被削弱。应用UV/Cl2技术选择波长时需要考虑吸光度、量子产率、竞争吸收等因素;对于弱碱性天然水或再生水,采用波长为292 nm的紫外光一般可获得较优处理效果。     

掺杂锰矿粉的PbO2复合电极的制备与应用

采用高压塑片法制备了纯PbO2电极及掺杂锰矿粉的PbO2复合电极,通过扫描电镜、加速寿命测试对电极性能进行了考察,并探讨了用PbO2复合电极对弱酸性桃红BS溶液进行的电催化降解机制和工艺条件.结果表明.PbO2复合电极的使用寿命是纯PbO2电极的3.3倍;在所考察的范围内,随着电流密度的增大,染料转化率和COD去除率均随之增加-当电流密度由70mA/cm2增加到90 mA/cm2时,染料转化率和COD去除率增加趋势减缓;溶液pH对染料降解有影响,弱酸性桃红BS溶液在强酸和强碱条件下的降解效果较好,pH在3.98～7.99时,染料转化率和COD去除率变化不大;染料转化率和COD去除率均随着电解时间呈递增关系,3.0 h后上升趋势逐渐减缓;支持电解质为NaCl时,能使染料转化率迅速提高,但其COD去除率不是很高;支持电解质为KNO3时,能显著提高弱酸性桃红BS溶液的COD去除率,0.5 h时COD去除率达到83%以上.另外,通过加入羟自由基清除剂叔丁醇的研究表明,在弱酸性桃红BS的降解过程中,有羟自由基产生并参与了催化降解反应.     

Degradation of anti-inflammatory drug ketoprofen by electro-oxidation: comparison of electro-Fenton and anodic oxidation processes

The electrochemical degradation of the nonsteroidal anti-inflammatory drug ketoprofen in tap water has been studied using electro-Fenton (EF) and anodic oxidation (AO) processes with platinium (Pt) and boron-doped diamond (BDD) anodes and carbon felt cathode. Fast degradation of the parent drug molecule and its degradation intermediates leading to complete mineralization was achieved by BDD/carbon felt, Pt/carbon felt, and AO with BDD anode. The obtained results showed that oxidative degradation rate of ketoprofen and mineralization of its aqueous solution increased by increasing applied current. Degradation kinetics fitted well to a pseudo-first-order reaction. Absolute rate constant of the oxidation of ketoprofen by electrochemically generated hydroxyl radicals was determined to be (2.8?±?0.1)?×?10⁹ M^?1 s^?1 by using competition kinetic method. Several reaction intermediates such as 3-hydroxybenzoic acid, pyrogallol, catechol, benzophenone, benzoic acid, and hydroquinone were identified by high-performance liquid chromatography (HPLC) analyses. The formation, identification, and evolution of short-chain aliphatic carboxylic acids like formic, acetic, oxalic, glycolic, and glyoxylic acids were monitored with ion exclusion chromatography. Based on the identified aromatic/cyclic intermediates and carboxylic acids as end products before mineralization, a plausible mineralization pathway was proposed. The evolution of the toxicity during treatments was also monitored using Microtox method, showing a faster detoxification with higher applied current values.     

紫外线-氯联合高级氧化体系降解水中的萘普生

采用高级氧化(advanced oxidation processes, AOPs)技术去除水体中的药物及个人护理品(PPCPs)污染物,选取PPCPs中的典型物质萘普生(NPX)为研究对象,探讨了其在UV/氯体系中的降解特性。结果表明：在UV/氯体系中,NPX的降解遵循拟一级动力学模型。氯剂量越高,溶液pH越低,越有利于NPX的降解;不同水基质种类对UV/氯工艺降解NPX的效果有不同影响,HCO3-和HA的存在抑制了NPX的降解,而Cl-的存在明显促进了NPX的降解。UV/氯工艺是一种行之有效的处理PPCPs的技术,但与直接氯氧化相比,UV/氯工艺会有生成更多消毒副产物的风险,需要在实际应用中加以注意。     

二氧化氯-接触催化氧化联合去除水中铁和锰

为了解决水体中铁锰季节性超标的问题,提出一种既能够减少化学试剂的使用又能有效去除铁锰的经济有效的方法。研究了单一方法(二氧化氯氧化法、接触催化氧化法)及两者联合对铁锰的去除效果,提出用二氧化氯氧化-锰砂过滤联合方法解决。研究表明,用ClO2氧化去除水中Fe2+的反应先发生、速率较快且效果较好,而与Mn2+反应则较慢并且不能完全转化为沉淀。单纯接触催化氧化法需要较长时间,过滤层才能达到稳定且较好的处理效果,培养过程中其除锰效果并不理想。两者联合时,利用过滤层的吸附作用去除部分铁锰,减少了氧化剂的使用。初期3个柱的除Mn2+效果都比较好,去除率均大于80%;然而采用石英砂或纤维束滤料的滤柱去除Mn2+的效果随时间变差,但采用锰砂的除锰效果在实验期间始终维持在较高水平。     

负载型纳米TiO2光催化降解水中微量溶解性间二甲苯

以高压汞灯为光源 ,采用浸涂 -烧结法制备的负载型纳米TiO2 作为光催化剂 ,通过对水中微量溶解性间二甲苯的光催化氧化过程的研究表明 ,初始浓度在 6 .6 8— 17.36mg/L的范围内 ,间二甲苯的光催化反应遵循表观一级反应动力学规律 ,反应的表观速率常数随溶液初始浓度的增大而减小 ,半衰期则随初始浓度的增大而增加 ,经 1.5h反应后 ,溶液中间二甲苯的去除率从 17.36mg/L的 5 4 .4 4 %增加到 6 .6 8mg/L的 75 .90 %。     

Electrochemical degradation of Acid Blue and Basic Brown dyes on Pb/PbO2 electrode in the presence of different conductive electrolyte and effect of various operating factors

Electrocatalytic degradation of Acid Blue and Basic Brown dyes from simulated wastewater on lead dioxide anode was investigated in different conductive electrolytes. It was shown that complete degradation of these dyes is dependent primarily on type and concentration of the conductive electrolyte. The highest electrocatalytic activity was achieved in the presence of NaCl (2g/l) and could be attributed to indirect oxidation of the investigated dyes by the electrogenerated hypochlorite ions formed from the chloride oxidation. In addition, contribution from direct oxidation could also be possible via reaction of these organic compounds with the electrogenerated hydroxyl radicals adsorbed on the lead dioxide surface. In the presence of NaOH, the electrocatalytic activity of the employed anode was not comparable to that in NaCl due primarily to the absence of chloride. This indicates that dyes degradation in NaOH occurs exclusively via direct electrochemical process. However, in H2SO4, the electrode performance was poor due partially to the absence of chloride from the conductive solution. The possibility of electrode poisoning as a result of growth of adherent film on the anode surface or production of stable intermediates not easily further oxidized by direct electrolysis in H2SO4 might also be accountable for the poor performance observed in this conductive electrolyte. Optimizing the conditions that ensure effective electrochemical degradation of Acid Blue and Basic Brown dyes on lead dioxide electrode necessitates the control of all the operating factors.     

纳米SiO2对Pb2+污染水源水混凝过程的影响

随着纳米材料的广泛应用,越来越多的纳米材料会泄露到水环境中,但目前关于纳米材料对混凝过程的影响还缺乏充分的研究。针对不同浊度,不同纳米SiO2浓度,不同pH以及腐殖酸对混凝去除Pb2+的影响进行了一系列的研究。结果表明,在低投加量(40 mg/L) 条件下,Pb2+的去除率受浊度影响较大,然而在高投加量(80 mg/L) 条件下,Pb2+的去除率受浊度的影响反而较小,且随着浊度从15.0 NTU增加到90.0 NTU,Pb2+的去除率从70.172%下降到63.925%。当浊度为45.0 NTU,投加量为40 mg/L时,铅离子的去除率在 SiO2投加量达到0.8 mg/L时达到最高(92.34%)。由于在低浊度条件下絮体形成不充分,以至于生成的絮体对SiO2的吸附去除率较低,所以吸附在SiO2表面的Pb2+会悬浮在溶液体系中,造成Pb2+去除率的下降。随着pH的升高,Pb2+去除率呈先升高后降低的趋势,且在偏碱性条件下达到最高。pH对Pb2+去除率的影响主要体现在其对纳米SiO2表面电荷的影响,SiO2表面负电荷增多可有效提高Pb2+的去除率,说明纳米SiO2的吸附作用在去除Pb2+的过程中起重要的作用。在高混凝剂投加量(80.0 mg/L)下腐殖酸对Pb2+的去除有促进作用,且当腐殖酸存在时,SiO2的含量对Pb2+的去除率无明显影响。     

Heterogeneous photocatalytic oxidation of organics for air purification by near UV irradiated titanium dioxide

The photocatalytic degradation of high concentrations of various organic pollutants (acetone, 2-propanol and toluene) in dry and humid air streams was carried out using a specially designed photoreactor based on the UV-TiO2 principle. The influence of several parameters which control the destruction efficiency (flow rate, initial contaminant and water vapour concentration, temperature and light intensity) has been studied. The conversion was maximal at room temperature, low flow rates and low initial contaminant concentrations. The presence of water in the inlet stream strongly affected the performance of the catalyst. The primary oxidation product of 2-propanol was acetone.     

Photocatalytic oxidation of xenobiotics in water with immobilized TIO2 on agitator

Abstract

A novel photocatalytic oxidation reactor, using Degussa P‐25 T_iO₂ as a stationary phase with a thickness of 1.5–2.0 um on the blades of agitator, was developed to study the photocatalytic oxidation of xenobiotics. Particularly in this device, separation of photocatalyst from the purified water after oxidation reaction was not necessary, and no other aeration equipment was required to supply oxygen. To examine the efficiency of this device, photocatalytic degradation of xenobiotic organics such as carbofuran was studied as an example. Results indicated that carbofuran could be degraded completely with mineralization efficiency of 20 % after 6 hours of oxidation under the imposed conditions. The mineralization rate of carbofuran was found to follow the pseudo‐first order reaction kinetics. Moreover, the rate constant of mineralization was found to be proportional to T_iO₂ film area and the square root of UV light intensity. These results implied the mineralization efficiency of carbofuran could be improved through increasing T_iO₂ film area and UV light intensity. Accordingly, this novel device showed potential application for degrading xenobiotics in water.