Synthesis of malachite@clay nanocomposite for rapid scavenging of cationic and anionic dyes from synthetic wastewater

Synthesis of malachite@clay nanocomposite was successfully carried out for the removal of cationic (Methylene Blue, MB) and anionic dyes (Congo Red, CR) from synthetic wastewater. Nanocomposite was characterized by TEM, SEM, FT-IR, EDS analysis and zeta potential. TEM analysis indicated that the particle diameter of nanocomposite was in the range of 14 to 23 nm. Various important parameters viz. contact time, concentration of dyes, nanocomposite dosage, temperature and solution pH were optimized to achieve maximum adsorption capacity. In the case of MB, removal decreased from 99.82% to 93.67% while for CR, removal decreased from 88.55% to 75.69% on increasing dye concentration from 100 to 450 mg/L. pH study confirmed the higher removal of CR in acidic range while MB removal was higher in alkaline range. Kinetic study revealed the applicability of pseudo-second-order model for the adsorption of both dyes. Negative values of ΔG⁰ for both systems suggested the feasibility of dye removal and support for spontaneous adsorption of CR and MB on nanocomposite. Nanocomposite showed 277.77 and 238.09 mg/g Langmuir adsorption capacity for MB and CR respectively. Desorption of dyes from the dye loaded nanocomposite was easily carried out with acetone. The results indicate that the prepared malachite@clay nanocomposite is an efficient adsorbent with high adsorption capacity for the aforementioned dyes.     

基于空气扩散阴极的过流式反应器产单线态氧降解水中亚甲基蓝

构建了钛基二氧化钌(Ti/RuO₂)阳极耦合空气扩散阴极(ADC)的电化学氧化体系,利用过流式反应器对亚甲基蓝(MB)进行氧化去除。结果表明:ADC阴极在200 mA电流下产生H₂O₂的稳定浓度达到45.33 mg/L,电流效率为65.10%。ADC-RuO₂体系对有机污染物的氧化具有选择性,几乎不能氧化苯甲酸钠,但对亚甲基蓝等染料具有较强的氧化作用。且该体系在叠氮化钠和2,5二甲基呋喃等存在时氧化能力受到显著抑制,证明其主要的活性氧化物为单线态氧(~1O₂)。在停留时间为2 min和电流为200 mA条件下,该体系对0.1 mmol/L MB的去除率达到99%,并且MB浓度降低90%时对应的能耗为0.25 kW·h/m3。     

有机/无机缓蚀剂在模拟混凝土孔隙液中对钢筋缓蚀作用对比研究

目的 检测和评价五种有机/无机缓蚀剂在含3.5％NaCl的模拟混凝土孔隙液(SCP)中对Q235碳钢的缓蚀效果.方法 采用动电位极化曲线和电化学交流阻抗谱(EIS)测试方法 .结果 综合评价后可知,0.0015 mol/L的D-葡萄糖酸钠具有最好的缓蚀效果,浸泡30 d后的Rct可达到282.74×104?·cm2,此...     

硫酸盐和氯离子对厌氧生物过程抑制作用的研究

采用混合式厌氧反应器,以酒槽废水为基质,在厌氧体系中投加不同浓度的ＳＯ－和Ｃｌ－,研究盐离子日加入量和累积量与厌氧体系抑制程度的关系,得出维持厌氧体系正常运行所允许的日加入量（ＳＯ－低于１４４ｍｇ／Ｌ,Ｃｌ低于３１９５ｍｇ／Ｌ）和累积浓度（ＳＯ－低于３００ｍｇ／Ｌ,Ｃｌ－低于２００００ｍｇ／Ｌ）;研究了污泥对ＳＯ－和Ｃｌ－的负荷,在ＳＯ－／ＶＳ浓度为５．５５ｇ／ｋｇ和Ｃｌ－／ＶＳ为５８．６ｇ／ｋｇ时,对厌氧体系无抑制作用。     

Chlorobenzene degradation by electro-heterogeneous catalysis in aqueous solution: intermediates and reaction mechanism

This study was performed to investigate the variables that influence chlorobenzene (CB) degradation in aqueous solution by electro-heterogeneous catalysis.The effects of current density,pH,and electrolyte concentration on CB degradation were determined.The degradation effciency of CB was almost 100% with an initial CB concentration of 50 mg/L,current density 15 mA/cm2,initial pH 10,electrolyte concentration 0.1 mol/L,and temperature 25°C after 90 min of reaction.Under the same conditions,the degradation eff...     

Electropolymerized poly（Toluidine Blue）-modified carbon felt for highly sensitive amperometric determination of NADH in flow injection analysis

Poly(pheniothiazine) films were prepared on a porous carbon felt (CF) electrode surface by an electrooxidative polymerization of three phenothiazine derivatives (i.e.,Tthionine (TN), Toluidine Blue (TB) and Methylene Blue (MB)) from 0.1 mol/L phosphate buffer solution (pH 7.0). Among the three phenothiazies, the poly(TB) film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form (NADH) at +0.2 V vs. Ag/AgCl. The poly(TB) film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH. The peak currents (peak heights) were almost unchanged, irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min, resulting in the measurement of NADH (ca. 30 samples/hr) at 4.1 mL/min. The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 mol/L (sensitivity: 0.318 A/( mol/L); correlation coefficient: 0.997). The lower detection limit was found to be 0.3 mol/L (S/N = 3).     

柚子皮吸附水溶液中亚甲基蓝的机理研究

为研究柚子皮吸附水溶液中亚甲基蓝（MB）的吸附性能和吸附机理,试验考察了不同条件（如pH,生物材料粒径,染料浓度,吸附时间和温度等）对其吸附效果的影响. 结果显示:染料溶液在弱酸或碱性条件下有利于亚甲基蓝被该生物材料吸附;其粒径对吸附效果影响不大;在30 ℃的条件下,对亚甲基蓝的吸附在1 h左右达到平衡且符合二级动力学方程;在30 ℃及pH为8时的最大吸附量为169.49 mg/g,符合Langmuir方程;该吸附过程为放热反应,最大吸附量随温度的升高而减少. 表明柚子皮吸附亚甲基蓝的过程是以物理吸附为主,可作为染料废水处理材料.      

紫外光强化Fe(Ⅱ)-EDTA活化过硫酸盐降解直接耐酸大红4BS

为探索硫酸根自由基对偶氮染料的降解能力,以直接耐酸大红4BS（下称大红4BS）为模拟污染物,通过UV/Fe（Ⅱ）-EDTA/PDS（PDS为过硫酸钠）体系,探讨了初始c（PDS）、Fe（Ⅱ）/EDTA（摩尔比）、无机盐阴离子等对大红4BS降解的影响.结果表明,大红4BS的脱色率随着初始c（PDS）的增加而增大,当c（PDS）超过15 mmol/L时无显著变化.Fe（Ⅱ）/EDTA比在5:1时效果最好,5 min时使0.038 0 mmol/L大红4BS的脱色率达到93.6%.反应符合二级动力学模型.HCO₃-、Cl-、NO₃-、SO₄2-等无机盐阴离子表现出明显抑制作用,c（无机盐阴离子）在100 mmol/L条件下,脱色率分别降低66.9%、13.2%、12.1%、9.43%.利用紫外可见光谱,依据其结构与特征吸收的关系,初步推测自由基离子对大红4BS降解的途径:苯环最先遭到破坏,随后偶氮键断裂、萘环开裂.研究显示,UV光可有效强化Fe（Ⅱ）-EDTA活化过硫酸盐形成SO₄-·自由基,对偶氮染料具有很好的脱色能力,最佳反应条件[PDS:Fe（Ⅱ）:EDTA（摩尔比）为15:5:1]下,大红4BS在10 min时脱色率高达98.1%.      

氯离子活化过氧乙酸对罗丹明B的降解性能及机理研究

为解决传统H₂O₂(过氧化氢)体系对高盐特性染料废水去除效率低的问题,筛选合适的氧化剂迫在眉睫. PAA(过氧乙酸)因具备氧化还原电位较高、裂解所需键能较低、对pH适应范围更广等优点具有巨大的应用潜力. 因此,采用高浓度梯度Cl-活化PAA用于去除RhB(罗丹明B),通过对比不同体系的降解效果、控制Cl-浓度和PAA投加量等反应条件,探究Cl-/PAA体系降解RhB的催化性能及反应机理. 结果表明:①Cl-/PAA体系对RhB的氧化能力远高于Cl-/H₂O₂体系,并且RhB降解过程符合拟一级反应动力学模型,提高氧化剂PAA的投加量和催化剂Cl-的浓度、降低初始RhB浓度均有利于目标污染物的去除. ②在初始RhB浓度为10 mg/L、PAA投加量为2.0 mmol/L、Cl-浓度为400 mmol/L后续处理条件下,10 min内RhB的降解率达到96.2%. ③pH对RhB的降解影响微弱, Fe3+促进了RhB的降解,K+对降解过程轻微抑制,NO₂-、CO₃2-、HCO₃-则表现出非常显著的抑制作用,脱色率分别降低了70.8%、83.8%和90.8%,而Mn2+、SO₄2-对RhB降解无显著影响. ④RhB在超纯水、自来水及反渗透水不同水源中的降解率无明显变化,具有良好的应用前景;结合自由基捕获试验及电子自旋共振证明,Cl-/PAA体系中产生的乙酰氧基、乙酰过氧基及单线态氧是在RhB降解中起主导作用的活性物质. 研究显示,Cl-活化PAA对去除罗丹明B具有较高的催化活性,通过模拟实际废水证明Cl-/PAA是一种可行的高级氧化技术.      

导数示波极谱法测定农药中的三氯乙醛

本文报导用导数示波极谱法直接测定农药中微量三氯乙醛的方法。实验结果表明,三氯乙醛在0.010mol/L NH_4Cl、5.00×10~(-4)mol/L EDTA和2.00×10~(-6)mol/L四乙基溴化铵组成的底液中,于滴汞电极上产生灵敏的峰电流。峰电位为-1.55V(Vs·S·C·E·)。检测下限为3.00×10~(-7)mol/L;浓度在3.00×10~(-7)～1.00×10~(-3)mol/L范围内与峰电流呈良好的线性关系。     

脉冲电化学氧化降解亚甲基蓝

为改善传统电化学氧化的缺陷,将脉冲式供电引入到电化学氧化中,利用Ti/PbO₂-PVDF电极,对亚甲基蓝（MB）模拟染料废水进行电化学氧化降解处理,分析初始浓度、脉冲电压、脉冲频率、占空比和NaCl浓度等因素对降解效果的影响.结果表明,当MB初始浓度为100mg/L,脉冲电压为5.5V,脉冲频率为1500Hz,占空比为50%,NaCl浓度为0.01mol/L时,降解效果最好.在相同条件下,比较脉冲与直流两种供电模式下的电化学氧化效果.结果表明脉冲模式下,90min内MB脱色率、COD去除率及电流效率分别为100%、94.5%和60.1%,均高于直流模式;脉冲模式下能耗为0.013kWh/gCOD,远小于直流模式的0.107kWh/gCOD.上述结果表明脉冲供电模式相比于直流供电模式具有明显优势.     

热处理富钙凹凸棒黏土吸附磷的影响因素

以800℃热处理富钙凹凸棒黏土（记为NCAP800）为研究对象,通过批处理试验和动态试验研究了不同因素（pH、竞争离子、柠檬酸）对NCAP800吸附磷的能力的影响.结果表明:酸性条件对磷的吸附能力无影响,碱性条件（pH>9）对NCAP800的磷吸附具有一定的抑制作用,pH对NCAP800磷吸附能力的影响主要通过改变黏土矿物中可交换钙、镁含量与矿物表面Zeta电位.阴离子中HCO₃-对磷的抑制作用较为显著,尤其当ρ（HCO₃-）为5~20 mg/L时抑制作用最为显著,其次是SO₄2-,NO₃-和Cl-对磷的吸附无抑制作用.HCO₃-和SO₄2-抢夺钙的结合位点,从而降低了NCAP800对磷的吸附能力.低浓度（c为0~5 mmol/L）的柠檬酸对磷的吸附抑制作用较弱,高浓度（c为5~50 mmol/L）的柠檬酸对磷的抑制作用较为显著,柠檬酸对磷的抑制机制同样是通过竞争NCAP800表面的磷吸附位点.研究显示,NCAP800在碱性条件下对磷具有较好的吸附作用,HCO₃-和SO₄2-及高浓度柠檬酸均会抑制NCAP800对磷的吸附.      

Spectroscopic studies of dye-surfactant interactions with the co-existence of heavy metal ions for foam fractionation

The interaction between a cationic dye Methylene Blue (MB) and an anionic surfactant sodium dodecyl sulfate (SDS) with the presence of Cd²⁺ was investigated spectrophotometrically in a certain concentration range. The spectrophotometric measurements of dye-metal ion-surfactant system were carried out. The results indicated that the SDS concentration had a significant influence on the dye spectrum, while the addition of Cd²⁺ hardly caused change of the maximum value of absorbance. According to this observation, we concluded that electrostatic and hydrophobic interaction between dye and surfactant occurred up to a certain level, and the homo-ions Cd²⁺ almost exerted no effect on the dye-surfactant complexation, establishing a theoretical foundation for simultaneous removal of organic dye and heavy metal using foam fractionation. Meanwhile, the effects of their interaction on foam performance were investigated. The results showed that the addition of Cd²⁺ favored the tendency to ameliorate foam properties just contrary to MB. The feasibility of foam separation for dye and heavy metal removal from simulated wastewater was also confirmed using a continuous foam fractionator. In the simultaneous removal process, with the initial SDS concentration ranging from 0.5 to 5.0 mmol/L, the maximum removal efficiencies of MB and Cd²⁺ were obtained as 99.69% and 99.61%, respectively. The enrichment ratios were reduced from 24.34 to 7.65 for MB and from 22.01 to 3.35 for Cd²⁺.     

铅污染对菱幼苗SOD、POD及叶细胞亚显微结构的影响

不同浓度Pb2+溶液处理菱(Trapa bicornis Osbeck)幼苗后,考察了菱幼苗的超氧化物歧化酶(SOD)、过氧化物酶(POD)以及叶细胞亚显微结构出现的变化,并初步探讨了Pb2+的毒性机理.结果表明,SOD的活性与铅离子浓度(5~20mg/L)表现出明显的剂量-效应关系, Pb2+浓度愈大,毒害程度愈深.POD活性在较低浓度(5,10mg/L)作用下,持续升高;在较高浓度(15,20mg/L)下,其活性出现先上升后下降的趋势.电子显微镜观察发现,在20mg/L Pb2+溶液处理7d后,叶细胞的叶绿体基粒数目减少,基粒片层解体,叶绿体双层膜断裂;线粒体、高尔基体、内质网等解体消失;细胞核的染色质与核质遭到破坏,核膜破裂.同样处理条件的叶片组织总DNA电泳显示,DNA完全断裂呈现弥散状,提示Pb2+毒害所致细胞死亡有别于细胞程序性死亡. Pb2+对菱的毒害是多途径综合作用的结果.     

地下环境中Fe2+对硝基苯的还原衰减作用模拟研究

研究了地下环境中的Fe2+对硝基苯(NB)的还原衰减作用,模拟了Fe2+还原硝基苯的过程及不同硬度、CO32-、SO42-、NO3-、Cl-等地下水化学组成对反应的影响,目的是阐明Fe2+还原硝基苯的机制及水化学组成对反应影响的原因.结果表明,在温度为10℃、pH为6.8的条件下,Fe2+和硝基苯浓度皆对其还原衰减有影...     

Solar photocatalytic decomposition of two azo dyes on multi-walled carbon nanotubes (MWCNTs)/TiO2 composites

Multi-walled carbon nanotubes (MWCNTs)/TiO₂ composite photocatalysts with high photoactivity were prepared by sol-gel process and further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and UV-vis absorption spectra. Compared to pure TiO₂, the combination of MWCNTs with titania could cause a significant absorption shift toward the visible region. The photocatalytic performances of the MWCNTs/TiO₂ composite catalysts were evaluated for the decomposition of Reactive light yellow K-6G (K-6G) and Mordant black 7 (MB 7) azo dyes solution under solar light irradiation. The results showed that the addition of MWCNTs enhanced the adsorption and photocatalytic activity of TiO₂ for the degradation of azo dyes K-6G and MB 7. The effect of MWCNTs content, catalyst dosage, pH, and initial dye concentration were examined as operational parameters. The kinetics of photocatalytic degradation of two dyes was found to follow a pseudo-first-order rate law. The photocatalyst was used for seven cycles with photocatalytic degradation efficiency still higher than 98%. A plausible mechanism is also proposed and discussed on the basis of experimental results.     

初夏渤海湾营养盐结构特征及其限制状况分析

根据2016年初夏渤海湾营养盐、叶绿素a和相关水文参数等数据,利用浮游植物吸收营养盐最低阈值和化学计量关系作为判断依据对渤海湾营养盐限制状况进行分析.结果表明：受陆地径流和渤海中部冷水输入的影响,初夏渤海湾在近岸、中部和湾口呈现三个明显的温盐特征海区.溶解无机氮（DIN）和活性硅酸盐（SiO₃^2--Si）受陆源输入影响,呈现近岸高湾口低的特征;DIN平均浓度为（7.67±6.48）μmol/L,SiO₃^2--Si平均浓度为（5.44±3.01）μmol/L,在湾口表层,DIN含量较低仅为（2.21±2.94）μmol/L,其中50%站点含量低于阈值（1μmol/L）,58.3%的站点存在DIN限制.而活性磷酸盐（PO₄^3--P）受陆源输入和浮游植物吸收储存作用等因素影响,呈现西部和曹妃甸外近海高中部较低的分布特征,平均浓度为（0.07±0.07）μmol/L,近岸受陆源氮磷输入总量差异影响,表层存在磷潜在限制比例达100%,而中部表层受浮游植物消耗吸收的影响,PO₄^3--P含量较低,仅为（0.02±0.02）μmol/L （未检出设为0）,其中近74.3%的水样含量低于阈值（0.03μmol/L）,磷限制状况严重.随着渤海湾氮磷营养盐陆源输入总量差距不断扩大,磷限制状况必将会进一步发展.     

批次培养条件下三角褐指藻对不同磷胁迫压力及恢复的响应

采用批次培养,设置5个PO₄-P浓度（0 μmol/L,0.566 μmol/L,2.26 μmol/L,9.05 μmol/L,36.2 μmol/L）进行实验,并从第9 d开始进行2 d恢复实验,研究三角褐指藻在不同磷胁迫压力及恢复下的响应。测定参数包括PS Ⅱ的最大光能转化效率（Fv/Fm）、PS Ⅱ的实际光能转化效率Y（Ⅱ）、光合电子传递效率（ETR）及藻密度。结果发现:磷胁迫对藻密度、Fv/Fm、Y（Ⅱ）和ETR有显著影响。恢复实验中,Fv/Fm、Y（Ⅱ）、ETR等恢复速率与起始所受磷胁迫程度以及再添加的磷浓度呈正相关。与藻密度相比,Fv/Fm、Y（Ⅱ）、ETR等荧光参数可以在12 h内产生更显著的变化。本实验表明,在严重的磷胁迫条件下,磷的输入可以造成藻类的补偿生长;在小时尺度上叶绿素荧光参数随磷胁迫程度可以迅速做出响应。     

碱度和浊度对混凝去除磺胺甲唑与土霉素的影响

为研究不同碱度和浊度下抗生素SMZ(磺胺甲唑)和OTC(土霉素)的混凝去除特征,选择PAC(聚合氯化铝)为混凝剂,并分别以碳酸氢钠、高岭土调节碱度〔以ρ(CaCO₃)计〕和浊度进行混凝模拟试验. 结果表明:当浊度为10 NTU时,SMZ和OTC的混凝去除率随着c(PAC)(以Al3+计)的增加而增加;在碱度为100 mg/L、c(PAC)为0.35×10-3 mol/L时,浊度对抗生素的去除有一定的影响但不显著,对SMZ去除的影响大于OTC. c(PAC)为0 mol/L时,高岭土对目标抗生素的吸附去除率较低,表明对抗生素去除起主要作用的是PAC. 碱度对SMZ和OTC的混凝去除率影响显著,这种影响是通过同时影响PAC的水解产物形态和抗生素总电荷而发挥作用的. 碱度为0 mg/L时,SMZ与OTC的混凝去除率分别为6.79%、-3.42%;碱度为25、100 mg/L时,SMZ与OTC的混凝去除率明显增加,并且当c(PAC)<0.3×10-3 mol/L时,低碱度(25 mg/L)下抗生素的混凝去除率优于高碱度(100 mg/L),而当c(PAC)>0.3×10-3 mol/L时则相反. 研究显示,碱度和浊度对混凝去除抗生素均有明显影响,但碱度对混凝去除抗生素的影响大于浊度.      

高盐度环境下某污水处理厂AAO生化系统微生物群落变化分析

为研究高盐度环境下AAO生化系统的活性污泥优势微生物,利用高通量测序技术对不同时期污泥进行微生物结构进行分析.结果表明:p(Cl-)从1000 mg/L上升到5000 mg/L的过程中,微生物群落结构发生明显变化.持久型OTUs占总序列90.59％,其中Proteobacteria(变形菌门)相对丰度始终在40％以上,...