Simultaneous Determination of Lead,Copper, and Mercury Free from Macromolecule Contaminants by Square Wave Stripping Voltammetry

Abstract

A novel approach for the voltammetric determination of Pb²⁺, Cu²⁺, and Hg²⁺ in the presence of macromolecule contaminants was developed. An Au nanoparticles array was directly electrodeposited onto the gold electrode surface followed by a further modification of a mercaptoethanesulfonate (MES) monolayer. Square wave stripping voltammetry (SWSV) of Pb²⁺, Cu²⁺, and Hg²⁺ was performed on the doubly modified electrode. The electrodeposited gold nanoparticles provided a significantly improved sensitivity. Simultaneously, the MES monolayer efficiently prevented the macromolecules accessing the electrode surface. Compared with the bare gold electrode, the doubly modified electrode has the ability to detect metal ions in the presence of macromolecule contaminants, even when their concentration reach 100 ppm. Under the optimal conditions, the detection limits of 0.16, 0.15, and 0.14 ppb for Pb²⁺, Cu²⁺, and Hg²⁺ were obtained, respectively. The calibration graphs were linear in the concentration range of 1–100 ppb. The results of the analysis of a real metallurgy wastewater sample were reported. The electrode system has a great potential for the direct determination of trace metals in the complex environment and biological samples.     

活化过硫酸盐原位化学氧化修复有机污染土壤和地下水

原位化学氧化 （ISCO）是近些年来国内外较为推崇的一种土壤和地下水修复技术。过硫酸盐（PS,S₂O₈^2-）具有易运输、较稳定、易溶于水和易传质等性质,能很好地适应ISCO的发展要求。它在光、热、过渡金属离子、强氧化剂和强碱性环境等活化条件下,能产生强氧化性的硫酸根自由基SO₄^·-,适用于氧化降解各种有机污染物。本文在分析活化过硫酸盐（activated persulfate,APS）氧化机理的基础上,综述了不同方式活化过硫酸盐原位修复有机污染土壤和地下水及APS协同、联用技术的应用,并就值得深入研究的问题和热点趋势进行了展望。     

A new gas chromatography/mass spectrometry method for the simultaneous analysis of target and non-target organic contaminants in waters

In this study we developed a GC–MS method for the analysis of priority pollutants, personal care products (PCPs) and other emerging contaminants in waters using large volume injection with backflushing. Analyses are performed in the SIM/scan mode, so that in addition to the targeted organic contaminants, this method allows the simultaneous screening of non-target compounds. The scan data are analysed using Deconvolution Reporting Software (DRS) which screens the results for 934 organic contaminants. Deconvolution helps identify contaminants that are buried in the chromatogram by co-extracted materials and significantly reduces chromatographic resolution requirements, allowing shorter analysis times. All compounds have locked retention times and we can continually update and extend the mass spectral library including new compounds. Linearity and limits of detection in SIM and full-scan mode were studied. Method detection limits (MDLs) in effluent wastewater ranged in most of the cases from 1 to 36 ng/L in SIM mode and from 4 to 66 ng/L in full-scan mode; while in river water from 0.4 to 14 and 2–29 ng/L in SIM and full-scan mode, respectively. We obtained a linearity of the calibration curves over two orders of magnitude. The method has been applied to the screening of a large number of organic contaminants – not only to a subset of targets – in urban wastewaters from different wastewater treatment plants and also in river waters. Most of the target compounds were detected at concentration levels ranging from 11 to 8697 ng/L and from 7 to 1861 ng/L in effluent wastewater and river waters, respectively. Additionally, a group of 12 new compounds were automatically identified using the AMDIS and NIST libraries. Other compounds, such as the 4-amino musk xylene, a synthetic fragrance metabolite, which was not included in the databases, but has been manually searched in the full-scan chromatograms.     

单晶铁金属表面污染物的激光烧蚀机理

激光惯性约束核聚变装置中要求光学元件能够承受极高的激光通量,因此对装置内部洁净度有很高的要求.研究表明装置内部的颗粒污染物主要来源于装置内的机械结构件,杂散光作用下机械结构件表面的损伤将产生颗粒污染物.精密金属构件的激光诱导损伤问题是制约高功率激光装置超洁净制造的重要因素.由于机械结构件表面不可避免地存在污染物,因此本文基于传统的分子动力学能量耦合方式,模拟了激光与表面吸附污染物单晶铁的相互作用过程,探讨了铁材料在激光作用下的烧蚀行为,并分析了激光加载方式和激光能量密度对铁材料烧蚀的作用情况,对比研究了材料表面有无污染物对材料烧蚀的影响情况.研究表明：激光作用下铁材料表面原子在污染物原子的剧烈碰撞下呈现出不同的运动状态;激光能量瞬时加载时更容易烧蚀铁材料;当激光能量密度低于0.0064 J/cm²时,将去除铁材料表面的污染物并不会对铁材料产生烧蚀现象,进一步分析表明铁材料表面吸附污染物时更容易被激光烧蚀.研究结果可为提高高功率激光装置的内部洁净度、实现系统超洁净控制提供理论依据.     

高功率激光装置中的气载分子污染物测量和分析

 研究了高功率激光装置光路中的分子级污染程度。采用专用空气采样动力设备及吸附管,在一定时间内对光路中的空气进行采样并作痕量分析后,得出了卤素、含硫化合物、可溶性胺类和氨、碳氢化合物 (C₆～C₁₆有机物) 4类物质在打靶前后的数密度变化。结果显示：除含硫化合物外,其余3种物质数密度超过了美国NIF标准的上限,其中氨和可溶性胺类、碳氢化合物的数密度超过较多;卤素、含硫化合物、氨和可溶性胺类的数密度在打靶后比打靶前有所降低,而碳氢化合物的数密度在打靶后比打靶前有所升高。结果表明在该装置中存在比较严重的气载分子污染物污染。分析了气载分子污染物数密度变化的原因以及可能的产生源,并对如何去除这些气载分子污染物提出了建议。     

Investigating the Influence of Column Depth on the Treatment of Textile Wastewater Using Natural Zeolite

Textile industry production processes generate one of the most highly polluted wastewaters in the world. Unfortunately, the field is also challenged by the availability of relatively cheap and highly effective technologies for wastewater purification. The application of natural zeolite as a depth filter offers an alternative and potential approach for textile wastewater treatment. The performance of a depth filter treatment system can be deeply affected by the column depth and the characteristics of the wastewater to be treated. Regrettably, the information on the potential of these filter materials for the purification of textile wastewater is still scarce. Therefore, this study investigated the potential applicability of natural zeolite in terms of column depth for the treatment of textile wastewater. From the analysis results, it was observed that the filtration efficiencies were relatively low (6.1 to 13.7%) for some parameters such as total dissolved solids, electrical conductivity, chemical oxygen demand, and sodium chloride when the wastewater samples were subjected to the 0.5 m column depth. Relatively high efficiency of 82 and 93.8% was observed from color and total suspended solids, respectively, when the wastewater samples were subjected to the 0.5 m column depth. Generally, the 0.75 m column depth achieved removal efficiencies ranging from 52.3% to 97.5%, whereas the 1 m column depth achieved removal efficiencies ranging from 86.9% to 99.4%. The highest removal efficiency was achieved with a combination of total suspended solids and 1 m column depth (99.4%). In summary, the treatment approach was observed to be highly effective for the removal of total suspended solids, with a 93.8% removal efficiency when the wastewater was subjected to the 0.5 m column depth, 97.5% for 0.75 m column depth, and 99.4% for 1 m column depth. Moreover, up to 218.233 mg of color per g of the filter material was captured. The results derived in this study provide useful information towards the potential applicability of natural zeolite in the textile wastewater treatment field.     

Novel ternary g-C3N4/Ag3VO4/AgBr nanocomposites with excellent visible-light-driven photocatalytic performance for environmental applications

Novel visible-light-induced photocatalysts were fabricated by integration of Ag₃VO₄ and AgBr semiconductors with graphitic carbon nitride (g-C₃N₄) through a facile refluxing method. The fabricated photocatalysts were extensively characterized by XRD, EDX, SEM, TEM, FT-IR, UV–vis DRS, BET, TGA, and PL instruments. The photocatalytic performance of these samples was studied by degradations of three dye contaminants under visible-light exposure. Among the ternary photocatalysts, the g-C₃N₄/Ag₃VO₄/AgBr (10%) nanocomposite displayed the maximum activity for RhB degradation with rate constant of 1366.6 × 10⁻⁴ min⁻¹, which is 116, 7.23, and 38.5 times as high as those of the g-C₃N₄, g-C₃N₄/AgBr (10%), and g-C₃N₄/Ag₃VO₄ (30%) photocatalysts, respectively. The effects of synthesis time and calcination temperature were also investigated and discussed. Furthermore, according to the trapping experiments, it was found that superoxide anion radicals were the predominant reactive species in this system. Finally, the ternary photocatalyst displayed superlative activity in removal of the contaminants under visible-light exposure, displaying great potential of this ternary photocatalyst for environmental remediation, because of a facile synthesis route and outstanding photocatalytic performance.     

Development of a high‐throughput method based on thin‐film microextraction using a 96‐well plate system with a cork coating for the extraction of emerging contaminants in river water samples

In this study, a new method was developed in which a biosorbent material is used as the extractor phase in conjunction with a recently described sample preparation technique called thin‐film microextraction and a 96‐well plate system. The method was applied for the determination of emerging contaminants, such as 3‐(4‐methylbenzylidene) camphor, ethylparaben, triclocarban, and bisphenol A in water samples. The separation and detection of the analytes were performed by high‐performance liquid chromatography with diode array detection. These contaminants are considered hazardous to human health and other living beings. Thus, the development of an analytical method to determine these compounds is of great interest. The extraction parameters were evaluated using multivariate and univariate optimization techniques. The optimum conditions for the method were 3 h of extraction time, 20 min of desorption with 300 μL of acetonitrile and methanol (50:50, v/v), and the addition of 5% w/v sodium chloride to the sample. The analytical figures of merit showed good results with linear correlation coefficients higher than 0.99, relative recoveries of 72–125%, interday precision (n = 3) of 4–18%, and intraday precision (n = 9) of 1–21%. The limit of detection was 0.3–5.5 μg/L, and the limit of quantification was 0.8–15 μg/L.     

Process scale high-performance liquid chromatography Part II: Dissolution of silica matrices

Summary Possible contamination of purified product by the silica matrix is of considerable importance when considering process scale high-performance liquid chromatography (HPLC) as a separation methodology. The stability of silica supports in normal phase, reversed phase and affinity chromatography modes has been examined with organic solvents and water. Both inorganic and organic components were found, contributed by the support, and the chromatographic and distillation equipment. In all cases, based on assumed values of production, they were found to contribute less than 0.01% of impurities. In critical cases crystallisation or dialysis may be considered as a last stage of purification, with re-chromatography to maximise yields. This work was conducted in the Chemical Technology Unit, University of Manchester Institute of Science and Technology, P. O. Box 88, Manchester M60 1QD, UK.     

高效液相色谱-四极杆/静电场轨道阱高分辨质谱对水产品中未知污染物的非定向快速筛查与测定

建立了高效液相色谱-四极杆/静电场轨道阱高分辨质谱对水产品中污染物的非定向快速筛查与测定的方法。筛查时样品用乙腈提取、氮气浓缩吹干、甲醇-水溶液定容，采用全扫描数据依赖二级扫描模式进样分析。利用Trace Finder软件对水产样品中未知污染物的精确质量数、同位素丰度比、二级碎片离子进行数据库检索匹配。定量时样品采用优化的QuEChERS方法净化，对筛查过程确认的三环唑、咖啡因和乙氧基喹啉3种污染物进行目标离子二级扫描模式定量分析。鱼和虾中3种化合物在5~1000 μg/L范围内线性关系良好，相关系数均大于0.99；方法检出限（LOD）为1 μg/kg，定量限（LOQ）为5 μg/kg，平均回收率为70.5~90.9%，相对标准偏差为5.4%~12.8%。筛查方法具有快速、准确、高通量等优点，结合定量方法能够用于实际水产品中未知污染物的筛查与测定。