测定电镀废水中痕量Cr(Ⅵ)的高灵敏光度法

利用偶氮胂Ⅲ与Ｃｒ２Ｏ７２ － 的褪色反应, 对含Ｃｒ６ ＋ 电镀废水中痕量铬（ Ⅵ） 进行测定。结果表明, 在硝酸介质中褪色反应具有高的灵敏度, 反应产物的摩尔吸光系数为３ ．９ ×１０６ Ｌ·ｍｏｌ － １ ·ｃｍ － １ 。铬（ Ⅵ） 含量在０ ．０ ～４０ ．０ μｇ／Ｌ 范围内服从比耳定律。 该法用于测定电镀废水中的铬（ Ⅵ） , 得到了满意的结果。     

离子色谱法和原子吸收光谱法测定电镀液中Cr(Ⅵ)和Cr(Ⅲ)

提出一种前处理简单、操作方便、灵敏度高的测定电镀液中Cr(Ⅵ)和Cr(Ⅲ)的分析方法。先用原子吸收光谱法检测电镀液的总铬含量,然后用离子色谱法检测Cr(Ⅵ)的总量,由两者的差值得出Cr(Ⅲ)的含量。原子吸收光谱法检测铬的加标回收率为97.3%～99.5%,检出限(3S/D)为0.01 mg/L。离子色谱法检测Cr(Ⅵ)的加标回收率为92.2%～102.2%,检出限(3S/D)为0.05 mg/L。     

电镀废水中三价铬和六价铬含量的测定

建立了一种可分别同时测定电镀废水中三价铬和六价铬含量的紫外-可见分光光度法。在同一样品溶液中分别于540nm和350nm处同时测定Cr（Ⅲ）和Cr（Ⅵ）的吸光度,在控制酸度的条件下,由于两组分不相互干扰,通过线性方程分别可求出组分中的含量。Cr（Ⅲ）在8．85×10^-7～1．54×10^-5mol／L范围内服从比耳定律,回收率为99．6％,100．2％;Cr（Ⅵ）在9．23×10^-57-1．15×10^-5mol／L范围内服从比耳定律,回收率为97．0％-101．1％。该法与传统国标法相比,操作简便、快速、准确。     

Cr(Ⅲ)-羧基配位状态稳定性的理论研究

本文采用模型实验结合密度泛函理论B3LYP方法,研究了单核单齿配位、单核螯合配位、多核单齿配位以及多核双点配位Cr(Ⅲ)的氧化还原稳定性。结果显示,单核单齿配位体系的氧化还原稳定性低于单核螯合配位体系。模型实验与理论预测活性得出的结论一致。在此基础上,计算分析了多核Cr(Ⅲ)离子与羧基形成单齿配位结合和双点单齿配位结合后理论参数的差异。前线轨道能差表明这些配合物中Cr(Ⅲ)的氧化还原稳定性顺序为:单核螯合配位>单核单齿配位>四核双点单齿配位>三核单齿配位>二核单齿配位。研究结果将有益于控制皮革中Cr(Ⅵ)的产生。     

Cr(Ⅵ)及Cr(Ⅲ)混合物中Cr(Ⅵ)的原子吸收测定——Cr(TTA)_3在石墨炉中挥发条件的研究

在pH5.7的乙酸-乙酸钠缓冲介质中,噻吩甲酰三氟丙酮(TTA)与Cr(Ⅲ)络合,生成的络合物具有挥发性.Cr(Ⅵ)在同样条件下不发生反应.利用此特点可实现Cr(Ⅵ)和Cr(Ⅲ)在石墨炉内分离并测定Cr(Ⅵ).研究了影响Cr(Ⅲ)与TTA络合的反应酸度、试剂加入量、静置时间等条件,并对石墨炉内定量挥发Cr(Ⅲ),保留Cr(Ⅵ)的原子化条件进行了探讨,所拟定的方法用于合成水样分析,获得满意结果.     

工业含铬废水的络合萃取处理工艺研究

采用络合萃取法处理工业含铬废水,考察了起始pH、流速和接触时间等对络合萃取处理效果的影响,探讨了铬盐生产废水和电镀废水的处理工艺。结果表明;在废水起始pH为1.0-2.0时,络合萃取法能方便、快速、有效地去除废水中的六价铬。络合萃取．碱沉淀法适用于六价铬含量远大于三价铬含量的电镀废水的处理,氧化．络合萃取法可用于三价铬含量较高的电镀废水的处理。采用两级处理能使高浓度铬盐生产废水的出水达到国家排放标准。     

萃取-火焰原子吸收法测定河水中的Cr(Ⅵ)和Cr(Ⅲ)

铬被广泛应用于电镀、印染、制革及纺织等行业,是造成河水和土壤铬污染的主要原因。铬在河水中主要以Cr(Ⅵ)和Cr(Ⅲ)形式存在,其价态不同,毒性也不同。适量Cr(Ⅲ)为人体所必需,以维持正常的新陈代谢;而Cr(Ⅵ)则被证明由于其强氧化性和对皮肤的高渗透性可以通过皮肤接触引起皮肤的溃烂、发炎,甚至导致生物的癌变,所以必须对样品中的Cr(Ⅵ)和Cr(Ⅲ)进行分别测定。     

污泥/钛铁矿复合吸附剂的制备及其吸附Cr(Ⅵ)研究

以城市污水处理厂剩余污泥为原料,添加微量钛铁矿,采用氯化锌活化法制备复合吸附剂,并考察了其对含Cr(Ⅵ)废水的处理效果。研究表明:钛铁矿添加量1.5%、氯化锌浓度3 mol/L、固液比1∶2、活化温度550℃和活化时间40 min时,复合吸附剂碘吸附值可达523.24mg/g,比表面积为285.003 m2/g,相对于不添加钛铁矿的纯污泥吸附剂分别提高了27.95%和43.08%;吸附Cr(Ⅵ)废水研究表明,当pH为1.5、吸附剂用量为4 g/L、吸附时间为120 min时,吸附率可达99.17%,吸附量为12.4 mg/g。     

用三辛胺萃取法处理高浓度含Cr（Ⅵ）废水

用三辛胺萃取法处理高浓度含Ｃｒ（Ⅵ）废水褚莹，刘沛妍，阎淑荣，吴子生，严忠（东北师范大学化学系长春１３００２４）关键词三辛胺，Ｃｒ（Ⅵ），萃取处理含Ｃｒ（Ⅵ）废水的萃取剂有三烷基胺（Ｎ２３５）、三辛胺（ＴＯＡ）、季胺盐及磷酸三丁脂（ＴＢＰ），稀释剂为...     

萃取光度法测定电镀废水中微量镉

采用双硫腙-TBP萃取光度法快速测定电镀废水中微量镉。在磷酸盐的中性缓冲溶液中,双硫腙-TBP显绿色,与镉离子生成橙红色配合物。镀镉废水中的干扰离子用钛铁试剂-酒石酸钾钠-碘化钾联合掩蔽。镉-双硫腙配合物萃取至有机相直接进行光度法测定。试验结果表明,在500 nm波长处,表观摩尔吸光系数为6.0×104L.mol-1.cm-1,Sandell灵敏度为0.001 9μg.cm-2;5 mL有机萃取相中镉含量在0~8.0μg/5 mL符合比耳定律。应用电镀废水样品中微量镉的直接萃取测定,分析结果的相对偏差小于2.8%,回收率为99.5%。     

乳状液膜处理合铬废水的研究

本文对乳状液膜从含铬（VI）废液中提取铬进行了研究，考察了影响铬迁移的几种因素：内外水相pH、表面活性剂、流动载体、添加剂等．结果表明，在合适的操作条件下，当废水中铬的含量在4．8×10－3mol·L－1时，经过一级液膜处理，废水中铬的提取率可达99％以上，提余液可以直接排放．     

Chromium speciation studies in human plasma and stability studies of Cr(III) and Cr(VI) species in a candidate water reference material

The aim of the research on Cr-speciation in plasma is to study the distribution of Cr over the plasma proteins. Cr is known to be mainly bound to transferrin and albumin. Therefore, a suitable separation procedure was developed for the two proteins. It consisted of a combination of FPLC cation and anion exchange, ensuring a complete resolution of both proteins and a total recovery of the Cr.In order to investigate the environmental impact of Cr(III) and Cr(VI) discharges, an aqueous reference material is needed to assess the quality of measurement between different laboratories. A pilot study was initiated to investigate the stability of a Cr(III) and Cr(VI) mixture in a bicarbonate/ carbonate buffer. Different parameters liable to influence the stability of the solutions have been investigated.     

Application of double-spike isotope dilution for the accurate determination of Cr(III), Cr(VI) and total Cr in yeast

A method is presented for the simultaneous determination of Cr(III) and Cr(VI) in yeast using species-specific double-spike isotope dilution (SSDSID) with anion-exchange liquid chromatography (LC) separation and sector field inductively coupled plasma mass spectrometric (SF-ICP-MS) detection. Total Cr is quantitated using ID SF-ICP-MS. Samples were digested on a hot plate at 95±2 °C for 6 h in an alkaline solution of 0.5 M NaOH and 0.28 M Na₂CO₃ for the determination of Cr(III) and Cr(VI), whereas microwave-assisted decomposition with HNO₃ and H₂O₂ was used for the determination of total Cr. Concentrations of 2,014±16, 1,952±103 and 76±48 mg kg⁻¹ (one standard deviation, n=4, 3, 3), respectively were obtained for total Cr, Cr(III) and Cr(VI) in the yeast sample. Significant oxidation of Cr(III) to Cr(VI) (24.2±7.6% Cr(III) oxidized, n=3) and reduction of Cr(VI) to Cr(III) (37.6±6.5% Cr(VI) reduced, n=3 ) occurred during alkaline extraction and subsequent chromatographic separation at pH 7. Despite this significant bidirectional redox transformation, quantitative recoveries for both Cr(III) and Cr(VI) were achieved using the SSDSID method. In addition, mass balance between total Cr and the sum of Cr(III) and Cr(VI) concentrations was achieved. Method detection limits of 0.3, 2 and 30 mg kg⁻¹ were obtained for total Cr, Cr(VI) and Cr(III), respectively, based on a 0.2-g sub-sample.     

Determination of Cr(III) and Cr(VI) in industrial and environmental liquid samples by EDXRF method

A rapid, sensitive and selective procedure for determination of Cr(III) and Cr(VI) in environmental and industrial liquid samples via preconcentration with ammonium pyrrolidine dithiocarbamate (APDC) and determination by means of the EDXRF was described. The effect of pH in the range of 3-11 on the recovery of Cr(III) and Cr(VI) has been investigated separately and in combination of these two species. The influence of organic matter, carbonate species and elements V, Mn and Fe on the recovery of each chromium specie (separately/in combination) over whole pH range was also tested in order to simulate condition occurring in natural waters that usually contain certain amount of dissolved organic matter and carbonate ions. Cr(VI) and Cr(III) have shown different behaviors in reaction with APDC at different pH ranges and therefore it is possible to separate those two species. It was found that Cr(VI) creates complex with APDC only in the pH range from 3 to 5 with quantitative recovery (app. 98%) at pH 3, but there was no recovery of Cr(III) at that pH. On the contrary, in pH range from 6 to 11, reaction with Cr(III) and APDC reviled that the only reaction product is Cr(OH)₃ instead of the expected Cr(III)-APDC complex. All reaction products were characterized by IR spectroscopy.     

Enhanced photocatalytic Cr(VI) reduction and diclofenac sodium degradation under simulated sunlight irradiation over MIL-100(Fe)/g-C3N4 heterojunctions

Metal-organic framework MIL-100(Fe) and g-C₃N₄ heterojunctions (MG-x, x = 5%, 10%, 20%, and 30%, x is the mass fraction of MIL-100(Fe) in the hybrids) were facilely fabricated through ball-milling and annealing, and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, UV-visible diffuse-reflectance spectrometry, and photoluminescence emission spectrometry. The photocatalytic activities of the series of MG-x heterojunctions toward Cr(VI) reduction and diclofenac sodium degradation were tested upon irradiation with simulated sunlight. The influence of different organic compounds (ethanol, citric acid, oxalic acid, and diclofenac sodium) as hole scavengers and the pH values (2, 3, 4, 6, and 8) on the photocatalytic activities of the series of MG-x heterojunctions was investigated. MG-20% showed superior photocatalytic Cr(VI) reduction and diclofenac sodium degradation performance than did the individual MIL-100(Fe) and g-C₃N₄ because of the improved separation of photoinduced electron-hole charges, which was clarified via photoluminescence emission and electrochemical data. Moreover, the MG-x exhibited good reusability and stability after several runs.     

Metal ion doped polymers as media for optical memories

Polymer materials are making an impact on optical storage technology to develop high information density and fast access type memories with a high read-out efficiency. The principle and advantages of three-dimensional (3-D) data storage in the form of interference patterns (holograms) have been outlined. Three different information storage materials have been developed by doping metal ions such as Cr(VI) and Fe(III) in water-soluble polymers, namely poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA), which need no further thermal or chemical treatment. Volume transmission holograms have been recorded in dichromated poly(vinyl alcohol) (DCPVA), ferric chloride doped poly(vinyl alcohol) (FePVA) and dichromated poly(acrylic acid) (DCPAA), with and without an electron donor (dimethyl formamide), and xanthene dyes (fluorescein, eosin Y and Rose Bengal). Different parameters influencing the holographic performance have been optimized to achieve a high real-time diffraction efficiency (～70%). An electron transfer process from the polymer matrix to Cr(VI)/Fe(III), leading to the photocrosslinking of the polymer in the form of an interference pattern, has been suggested as the mechanism of information storage (hologram recording) in these materials.     

Spectrophotometric Determination of Trace Chromium(VI) in Mass Chromium(III)

There is little conclusive evidence of the toxic effects of Cr(III) so far, but Cr(VI) has carcinogenic activity, so the analysis of the chromine ions is very important in environmental research and the quality control of industry products. Usually Cr(III) and Cr(VI) interfere with each other in the species analysis, the measurement of Cr(VI) of numerous previous papers is related to the Cr(VI) samples, which contain a little Cr(III). When the amount of trivalent chromine exceeds ten …     

Study of the complexation and precipitation equilibria in the system Cr(VI)-Fe(III)-H2O

Potentiometric and spectrophotometric studies of the systems Cr(VI)-Fe(III)-H₂O and Fe(III)-H₂O systems have been performed. The formation of the complex FeCrO ₄ ⁺ is suggested and the corresponding thermodynamic formation constant has been calculated (log₁₁ = 7.77 ± 0.02) . In order to understand the cation-anion interactions, a study of the precipitation equilibrium between Cr(VI) and Fe(III) has been carried out. The results indicate the formation of FeOHCrO₄·2Fe(OH)₃, a mixed precipitate whose thermodynamic solubility product is pK_so=99.8±0.2.     

Coupling of microwave induced plasma optical emission spectrometry with HPLC separation for speciation analysis of Cr(III)/Cr(VI)

Feasibility and limitations of direct coupling of high performance liquid chromatographic (HPLC) separation to microwave induced plasma (MIP)-optical emission spectrometry (OES) for elementspecific detection was tested and compared to inductively coupled plasma (ICP)-optical emission spectrometric detection on the basis of the Cr(III)/Cr(VI) speciation analysis of water samples. Coupling was performed by a hydraulic high pressure nebulizer (HHPN) radiative-heating/watercooling interface which provides about 20 % and 80 % aerosol yield in the case of helium and argon carrier gases, respectively. Desolvation efficiency of aqueous solutions was approximately 80 %. Applying the ion-pair HPLC separation, the organic eluents and reagents in the MIP cause a 50–75 % signal suppression for Cr(VI) and 25–50 % for Cr(III). In a pure aqueous solution the MIP Cr(VI) signal was by 20 % lower than that of Cr(III). These effects were lower using the ICP source, but they cannot be neglected. Easily ionizable matrix elements (Na, Ca) can cause 70 % signal suppression in the MIP, and 20 % in the ICP. Therefore, species dependent calibration is required in both cases. In the case of HPLC detection by MIP-OES, the detection limit was 13 ng for Cr(III), and 18 ng for Cr(VI). Using the ICP-OES detection, the detection limit was 0.2 ng for Cr (III) and 0.4 ng for Cr (VI). The linear dynamic ranges in both cases were two orders of magnitude. Presented at the XVIIIth Slovak Spectroscopic Conference, Spišská Nová Ves, 15–18 October 2006.     

A new efficient adsorbent in the preconcentration studies of the Cr(III) and Fe(III) ions

In this study, the imine‐graphene hybrid material (HM) was used as an adsorbent for removal of Fe(III) and Cr(III) metal ions from the drinking waters. The adsorbent material (HM) was prepared at three steps. At the first step, the graphite was oxidized by Hummer's method for preparation of graphene oxide (GO), in the second step, the silanization derivative (GO‐APTES) was obtained from the reaction of the 3‐(trimethoxysilyl) propylamine and GO. In the final step, the hybrid material (HM) was synthesized from the reaction of the 3,5‐diiodosalicylaldehyde and GO‐APTES. The chemical structures of three materials GO, GO‐APTES and HB were characterized by using the FT‐IR, XRD, EDX, SEM, TEM and UV‐vis methods. Thermal properties of the materials GO, GO‐APTES and HB were investigated by TGA/DTA methods in the 25–1000°C temperature range. Adsorption and desorption studies of the hybrid material toward Fe(III) and Cr(III) metal ions were investigated using the Batch method. The effect of pH, contact time, temperature, concentration on the adsorption properties of the hybrid material were investigated by ICP‐OES. The Fe(III) and Cr(III) ions have the maximum adsorption at the pH 7. The adsorption capacity decreases with the increase in pH values because above pH 9 the adsorption decreases due to the precipitation of metal hydroxide.