铜-8-羟基喹啉络合物极谱吸附波

由于铜—8—羟基喹啉络合物吸附波具有较高的灵敏度而被推荐为国家环保部门的标准分析方法。但由于它的选择性不够好,还不能够将其应用于工业废水等复杂样品的分析。本文于上述体系中加入EDTA或EGTA而使方法的选择性大大提高,并改善了铜低浓度区的线性关系。当有4×10~(-3)MEGTA存在时,至少1000倍Ca~(2+),至少100倍Pb~(2+)、Cd~(2+)不干扰测定。当有10~(-3)MEDTA存在时,则100倍以上的Cd~(2+)、Mn~(2+)、Zn~(2+)、Mg~(2+)、Pb~(2+)等常见离子不干扰测定(铜为0.1ppm)。     

聚L-组氨酸修饰电极方波溶出伏安法同时测定痕量铅和镉

在pH=3.0的NaAc-HAc缓冲液中,用循环伏安法制备聚L-组氨酸修饰玻碳电极,研究Pb2+和Cd2+在修饰电极上的方波阳极溶出伏安特性,建立了方波阳极溶出伏安法测定Pb2+和Cd2+的新方法。在最佳实验条件下,Pb2+和Cd2+的摩尔浓度为5.00×10-8~7.50×10-4 mol/L时与峰电流呈良好的线性关系,Pb2+和Cd2+检出限分别为5.0×10-9、1.0×10-9 mol/L。     

磁性高岭土的制备及对铅离子的吸附

采用共沉淀法制备磁性高岭土,以扫描电子显微镜(SEM)、能量色散X射线光谱(EDX)、红外光谱(FTIR)和X射线衍射(XRD)对其进行表征。分析了吸附剂用量、pH、时间对磁性高岭土吸附Pb~(2+)的影响,并与Fe_3O_4和高岭土的吸附性能进行比较。SEM表明制备的磁性高岭土为大小不均匀的细小颗粒,XRD结果表明磁化后,高岭土的晶体结构改变不大,EDX表明磁化后,Si、Al元素的含量基本不变,O元素含量有所增加,且出现了Fe元素的波峰,FTIR表明磁化后出现了Fe—O的特征吸收峰;吸附实验结果表明在20 min内达到吸附平衡,在Pb~(2+)浓度为5.0 mg·L~(-1)时,去除率达到99.38%。磁性高岭土对Pb~(2+)的吸附性能高于Fe_3O_4和高岭土的吸附性能,Langmuir模型能更好的描述Pb~(2+)在磁性高岭土上的吸附平衡,对Pb~(2+)为优惠吸附。Pb~(2+)的吸附行为更符合拟二级动力学方程,说明Pb~(2+)在磁性高岭土上的吸附过程主要由化学吸附控制。     

改性谷壳生物炭负载磁性Fe去除废水中Pb~(2+)的效果及机制

将谷売生物炭用酸改性后负载磁性Fe_3O_4,得到一种新的吸附材料(BC~Fe)。通过单因素吸附实验,研究了时间、pH、添加量、浓度以及温度等参数对BCTe吸附废水中Pb~(2+)的影响,并对其进行比表面积及傅里叶红外光谱分析,探讨该磁性生物炭对Pb~(2+)的吸附机理。结果表明对Pb~(2+)的吸附能在2 h内基本达到平衡。在Pb~(2+)溶液初始浓度为100mg·L~(-1),pH=5.0温度为25℃,分別添加0.1g和0.15 g的BC-Fe于50 mL Pb~(2+)溶液中,单位质量的BC-Fe对溶液中Pb~(2+)的吸附量分别为40.6 mg·g~(-1)和33.2 mg·g~(-1)去除率分别为81.3%和99.9%。该吸附过程符合拟二级动力学模型,理论平衡吸附量为43.9 mg·g~(-1)。用Langmuir等温吸附方程能够很好地描述其吸附行为;热力学研究表明对Pb~(2+)的吸附过程是自发的吸热过程。     

硝酸改性稻秆处理含Pb~(2+)模拟废水

在150 m L溶液中,稻秆用量为5 g,硝酸浓度为10%,稻秆颗粒度为20目,改性温度为80℃,改性时间为3h,制备得到硝酸改性稻秆吸附剂。详细探讨了用该吸附剂处理含Pb~(2+)废水的影响因素:吸附剂用量、Pb~(2+)初始浓度、溶液pH值、吸附时间和吸附温度等对Pb~(2+)吸附率的影响,并进一步通过正交实验及对比实验得出处理200 m L,初始浓度为300mg·L-1的含Pb~(2+)废水的最佳吸附工艺为:吸附剂用量为4 g,pH值为6,吸附时间为3 h,吸附温度为20℃,在此工艺条件下,对Pb~(2+)的吸附率达到94.31%,吸附量为14.15 mg·g~(-1)。     

壳聚糖-纳米铁去除上覆水和底泥中Cr(Ⅵ)、Pb~(2+)、Cd~(2+)的研究

利用具有较好抗氧化性和分散性的壳聚糖-纳米铁(CS-NZVI)颗粒去除上覆水-底泥系统中的Cr(Ⅵ)、Pb~(2+)、Cd~(2+),分析了Cr(Ⅵ)、Pb~(2+)、Cd~(2+)去除的动力学特征,考察了pH和盐度对去除效果的影响。结果表明,CS-NZVI颗粒能够有效去除上覆水及底泥中的Cr(Ⅵ)、Pb~(2+)、Cd~(2+),Cr(Ⅵ)、Pb~(2+)、Cd~(2+)的去除过程满足准一级反应动力学方程;随着pH的升高,上覆水中Cr(Ⅵ)的去除率逐渐降低,而Pb~(2+)、Cd~(2+)去除率逐渐升高,底泥中Cr(Ⅵ)去除率先大幅降低后小幅上升,而Cd~(2+)、Pb~(2+)去除率总体呈降低趋势;高盐度不利于上覆水中Cr(Ⅵ)的去除,但对底泥中Cd~(2+)和Pb~(2+)的去除具有促进作用,对底泥中Cr(Ⅵ)的去除没有明显影响。     

酒石酸强化重金属复合污染模拟土壤电动修复过程及机理分析

为提高电动修复重金属复合污染土壤的效率,通过配制重金属复合污染模拟土壤,构建电动修复实验装置,利用2因素完全随机实验设计研究了酒石酸浓度和时间对重金属去除效果的影响;采用BCR法对土壤金属赋存形态进行了分析表征。结果表明:与对照相比,以酒石酸为电解液显著提高了重金属的去除率;重金属去除率受酒石酸浓度和修复时间影响显著;以0.05 mol·L~(-1)酒石酸为电解液修复120 h后,重金属去除效果最好,重金属总去除率为86.15%,Cu~(2+)、Mn~(2+)、Cd~(2+)、Pb~(2+)、Zn~(2+)的去除率分别为75.67%、98.11%、85.1%、70.75%和90.9%。BCR分析表明,酒石酸有助于提高土壤中弱酸提取态重金属含量,提高了重金属的迁移性能,从而有利于电动修复过程。     

不同热解温度污泥生物炭对Pb~(2+)、Cd~(2+)的吸附特性

采用剩余污泥为原料,分别于300、400、500℃缺氧条件下制备污泥生物炭,利用X射线能谱仪(EDS)、环境扫描电镜(SEM)、红外光谱(FTIR)对其进行表征,并探究不同吸附时间,不同pH和不同Pb~(2+)、Cd~(2+)浓度下污泥生物炭对Pb~(2+)、Cd~(2+)的吸附特性,以期拓展污泥资源化利用途径。结果表明,准二级动力学方程能更好地描述污泥生物炭对Pb~(2+)、Cd~(2+)的吸附过程,约30 h达到平衡,其吸附主要受化学吸附控制。随溶液初始pH的升高,重金属的吸附量呈先增高后降低趋势,在pH 4.5时对Pb~(2+)的吸附量最大,而Cd~(2+)在pH 6.5时最大。在25℃时,低温热解制备的污泥生物炭对Pb~(2+)、Cd~(2+)的吸附量为RC500RC400RC300,RC500的饱和吸附量分别为Pb~(2+)(14.39 mg·g~(-1))Cd~(2+)(1.45 mg·g~(-1)),污泥生物炭对重金属离子的吸附量与其水合离子半径呈负相关。     

磁性壳聚糖改性硅藻土吸附去除水中的铅离子

采用壳聚糖与Fe_3O_4对硅藻土进行混合改性,制备出一种吸附效果好、且能从液相中磁分离的新型复合吸附剂。通过SEM、XRD、VSM和FTIR等手段对其进行表征,并探究溶液pH、吸附剂投加量以及吸附温度等条件对水溶液中Pb~(2+)吸附效果的影响。结果表明:壳聚糖和Fe_3O_4都能够负载到硅藻土上面。当溶液pH为5、吸附剂投加量为10 g·L~(-1)、初始浓度为10 mg·L~(-1)时,Pb~(2+)去除率可以达到96.4%。吸附过程较好地符合假二级动力学模型和Langmuir吸附等温模型,热力学数据说明该吸附是吸热、自发的过程。     

针铁矿对Pb~(2+)的吸附特征及影响因素研究

通过恒温振荡平衡法研究了Pb~(2+)在针铁矿上的等温吸附和吸附动力学特征,探讨了吸附的影响因素.结果表明:(1)随Pb~(2+)平衡浓度和pH的增大,针铁矿对Pb~(2+)的吸附量逐渐增大.(2)针铁矿对Pb~(2+)的等温吸附可用Freundlich和Langmuir方程较好地拟合.(3)在相同温度和pH下,随离子强度的提高,针铁矿对Pb~(2+)的吸附量增大.(4)在相同离子强度和pH下,针铁矿对Pb~(2+)的吸附量总体随温度升高而增大.针铁矿对Pb~(2+)的吸附是自发进行的吸热反应.(5)针铁矿吸附Pb~(2+)的过程可分为初始的快吸附和随后的慢吸附2个阶段.pH影响吸附反应快慢,随pH增大吸附速率增大;随着pH的增大,达到平衡吸附的时间缩短.吸附动力学方程用Elovich方程拟合最佳.     

Electrochemical study of the fungicide acibenzolar-s-methyl and its voltammetric determination in environmental samples

The electrochemical behavior of new generation fungicide acibenzolar-s-methyl (S-methyl 1,2,3-benzothiadiazole-7-carbothioate, ASM) on the hanging mercury drop electrode (HMDE) was investigated using square wave adsorptive stripping voltammetry. This method of determination is based on the irreversible reduction of ASM at the HMDE. The well-defined ASM peak was observed at ?0.4 V (vs. Ag/AgCl) in BR buffer at pH 2.2. The reduction peak current was proportional to concentration of ASM from 1.0 × 10^?8 to 6.0 × 10^?8 mol L^?1 with detection and quantification limit 3.0 × 10^?9 and 1.0 × 10^?8 mol L^?1, respectively. The applicability of the developed method for analysis of spiked samples of tap water, river water, and soil is illustrated. The effect of adsorption on the mercury electrode was studied in detail using the AC impedance method. Possible interferences with other common pesticides and heavy metal ions were examined. Clarification of the electrode mechanism was made using cyclic voltammetry (CV) technique.     

A voltammetric screening method to determine ronidazole in bovine meat

Abstract

An original voltammetric screening method, employing glassy carbon electrode (GCE) with the differential-pulse voltammetry technique (DPV), has been developed to determine residues of the anti-parasitic agent Ronidazole (RNZ) in bovine meat. By using cyclic voltammetry (CV), it has been demonstrated that an irreversible cathodic process occurs at approximately ?0.740?V (vs. Ag|AgCl, KCl 3?mol L^?1) in a 0.100?mol L^?1 phosphate buffer at pH 6.5 as supporting electrolyte. Furthermore, the behavior of RNZ in CV indicates the occurrence of a diffusion mass transfer process to the working electrode surface. The RNZ reduction mechanism was proposed as a 6-electron transfer, similar to Metronidazole under the same pH range. Quantification of RNZ and method validation were then carried out by DPV. The relative standard deviation (RSD) were 3.21% for intraday precision of 10 consecutive repetitions and 6.78% for interday precision after five analysis. Limits of detection and quantification were also obtained, and the values were 0.107 and 0.358?mg kg^?1, respectively. The recovery percentage for three different concentrations of RNZ in the bovine meat matrix ranged between 98.1% and 100.3%. The method proved to be efficient for screening RNZ in bovine meat.     

EDTA强化电动力学修复重金属复合污染土壤

在自制的电动力学装置中,研究多种重金属复合污染土壤的电动力学修复,通过在阴极添加络合剂EDTA来提高修复效率。实验结果表明,EDTA的引入提高了修复过程中的电流值,且EDTA与重金属的络合提高了污染物向电极液的迁移效率,从而强化了电动力学修复效果。在设定的浓度(0、0.01、0.02、0.05和0.1 mol/L)中,0.1 mol/L的EDTA具有最佳的修复效率。在此实验条件下,污染土壤中的总铜、总铅和总镉的去除率分别为90.2%、68.1%和95.1%。电动力学修复后,对土壤重金属进行化学形态分析,发现电动力学修复显著改变了土壤重金属存在形态,修复后土壤中的铜、铅、镉主要以较稳定的有机态和残余态形式存在,显著降低了对周边生物和环境的毒害。     

烟气脱硫过程锰催化氧化亚硫酸钙的研究

利用直径280 mm、高320 mm的间歇式搅拌槽,在MnSO4加入浓度为0～0.05 mol/L的情况下,对亚硫酸钙悬浮液进行了催化氧化实验研究.实验结果表明,锰离子的加入会改变亚硫酸钙的氧化机理及氧化过程,表现为终点氧化率和氧化速率的变化.当Mn2 浓度为0.05 mol/L时,亚硫酸钙的终点氧化率比未加入Mn2 时高30%;此外,与非催化反应过程相比,Mn2 的加入能使亚硫酸钙在一个更宽的浓度范围内(0.02～0.073 mol/L)和一个更宽的时间范围内(20～100 min)均保持较高的氧化速率水平.     

Direct electrochemical detection of glyphosate at carbon paste electrode and its determination in samples of milk,orange juice,and agricultural formulation

Abstract

This paper describes a simple, inexpensive, highly sensitive, selective, and efficient electrochemical method to determine glyphosate (GLY) in samples of milk, orange juice, and agricultural formulation. The oxidation reaction on the electrode surface was electrochemically characterised by cyclic voltammetry (CV) and square wave voltammetry (SWV). The investigation of GLY at carbon paste electrode revealed a non-reversible oxidation peak at +0.95 V versus Ag/AgCl, which was used for electrochemical detection of GLY. The operating parameters (pH, frequency, step potential, and amplitude) were optimised in relation to the peak current intensity, and a calibration curve was set up in a concentration range of 4.40?×?10^?8–2.80?×?10^?6 mol L^?1, with a detection limit of 2?×?10^?9 mol L^?1. After calibration curve was plotted, the developed procedure was applied to determine GLY in previously contaminated samples: milk and orange juice, and in a commercial formulation, obtaining recovery values between 98.31% and 103.75%. These results show that the proposed method can be used for GLY quantification in different samples with high sensitivity, specificity, stability, and reproducibility.     

哌啶清洁生产工艺条件的研究

研究了有机电催化还原的方法生产哌啶的清洁生产工艺,探讨了电极种类、吡啶初始浓度、电流密度、电解质溶液浓度及添加剂的加入等条件对哌啶的收率和电流效率的影响。结果表明,采用RaneyNi板式电极,吡啶初始浓度为0．2～0．3mol／L,电流密度为20-80A／dm^2,常温下在0．5mol／L的NaOH水溶液中进行电还原反应,可获得90％以上的哌啶收率和80％以上电流效率。该清洁生产工艺具有产率高、纯度高,生产条件温和,节能高效等优点。     

硅烷化改性沸石对重金属离子的吸附性能

制得一种用于重金属废水处理的新型硅烷化改性沸石吸附剂,成本低、效果显著且稳定。通过对改性沸石表征,分析了改性对沸石结构的影响。结果表明,改性一定程度降低了原沸石的晶体特征,但基本上保持了其结构组成;硅烷化改性成功地在沸石上接枝了氨基。对硅烷化沸石的特性研究,得出硅烷化沸石对Ni2+、Cu2+、Zn2+和Pb2+吸附最佳投加量为1、1、1.6和0.6 g/L,且此时对4种离子的去除率也较好;吸附动力学研究得出,其吸附过程可用二级动力学方程较好地拟合;吸附达到平衡时,4种金属离子的平衡吸附量分别为11.23、17.41、15.45和59.42 mg/g;硅烷化沸石对金属离子的吸附行为更符合Langmuir模型,为化学吸附;在酸性条件下(pH=2～6),硅烷化沸石仍保持一定的吸附能力,具有一定的耐酸性。     

The solid-solution partitioning of heavy metals (Cu,Zn, Cd,Pb) in upland soils of England and Wales

Ninety-eight surface soils were sampled from the uplands of England and Wales, and analysed for loss-on-ignition (LOI), and total and dissolved base cations, Al, Fe, and trace heavy metals (Cu, Zn, Cd, Pb). The samples covered wide ranges of pH (3.4-8.3) and LOI (9-98%). Soil metal contents measured by extraction with 0.43 mol l-1 HNO3 and 0.1 mol l-1 EDTA were very similar, and generally lower than values obtained by extraction with a mixture of concentrated nitric and perchloric acids. Total heavy metal concentrations in soil solution depend positively upon soil metal content and [DOC], and negatively upon pH and LOI, values of r2 ranging from 0.39 (Cu) to 0.81 (Pb). Stronger correlations (r2=0.76-0.95) were obtained by multiple regression analysis involving free metal ion (Cu2+, Zn2+, Cd2+, Pb2+) concentrations calculated with the equilibrium speciation model WHAM/Model VI. The free metal ion concentrations depend positively upon MHNO3 and negatively upon pH and LOI. The data were also analysed by using WHAM/Model VI to describe solid-solution interactions as well as solution speciation; this involved calibrating each soil sample by adjusting the content of "active" humic matter to match the observed soil pH. The calibrated model provided fair predictions of total heavy metal concentrations in soil solution, and predicted free metal ion concentrations were in reasonable agreement with the values obtained from solution-only speciation calculations.     

微电解-生物法处理含铬电镀废水的研究

采用微电解生物法组合工艺处理含铬电镀废水,在实验过程中,电镀废水中的重金属离子通过微电解法预处理可去除90%以上,剩余部分被后续工艺的微生物功能菌去除。实验结果表明对Cr6+含量为50mg/L,Cu2+含量为15mg/L,Ni2+含量为10mg/L的废水,经处理后,重金属离子的净化率达999%,且无二次污染。     

含重金属水处理污泥的固化和浸出毒性研究

工业危险固体废物在进行安全填埋前需要进行固化稳定处理。针对电镀厂和皮革厂含重金属的水处理污泥 ,用不同比例的水泥、粉煤灰进行固化稳定处理。考虑酸雨环境 ,浸出实验采用TCLP标准。电镀厂污泥单独固化时 ,其浸出液中铜离子浓度由 78 0mg/L下降到 1 5mg/L ;镍离子浓度由 2 2 4 5mg/L下降到 2 2 2mg/L ,高于危险废物允许进入填埋区 15mg/L的控制限值。电镀厂污泥与皮革厂污泥混合后固化 ,浸出液毒性明显降低。铜离子的浸出浓度降低到1 98mg/L ,镍离子降低到 4 10mg/L ,总铬降低到 0 4 0mg/L ,各项指标均低于国家危险废物允许进入填埋区的控制限值 ,可安全填埋。