原子吸收分光光度法测定水中的重金属铅和镉

水样采用Mg(OH)2作为共沉淀剂,预富集水中的铅和镉,建立火焰原子吸收分光光度法直接测定了水样中的铅和镉的含量。通过测定得出方法 RSD为1.9%~4.1%,加标回收率为93.0%~106.5%,另外与石墨炉原子吸收分光光度法对照测定值,两种方法测定结果基本一致。方法简便、快速、实用,具有较高的准确度和精密度,结果令人满意,适用于大体积水样预处理及重金属元素的测定。     

Implications of desalination for water resources in China — an economic perspective

China is a country with severe water shortages. Water is becoming scarcer due to population growth, industrialization and urbanization. Recent studies show that by the next 50 years water resources per capita will go down to around 1700 m³, which is the threshold of severe water scarcity. Especially in North China, water shortage has become a critical constraint factor for socioeconomic development in the long run. To solve or eliminate water shortage problems, seawater desalination draws more and more attention as an alternative water supply source. The objective of the study is to assess the potential of desalination as a viable alternate water source for China through analysis of the costs of desalination, the water demand and supply situation as well as water pricing practices in China. Based on the investment costs and estimated operation and maintenance costs, an economic appraisal for the costs of desalination for two main processes, MSF and RO, has been conducted. The study shows that there is a decline of unit cost of desalination over time and the average unit cost of the RO process was lower than that of the MSF process. A unit cost of 0.6 $/m³ for desalting brackish water and 1.0 $/m³ for seawater are suggested to be appropriate for the potential application of desalination in China. Future trends and challenges associated with water shortages and water prices are discussed, leading to conclusions and recommendations regarding the role of desalination as a feasible source of water for the future.     

A further method for chloride analysis of cement and cementitious materials — ICP-OES

This paper describes the novel application of inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the analysis of the chloride content in various South African cements and cementitious materials. Samples were introduced into the plasma as slurries, with and without 5% (v/v) nitric acid. They were agitated in an ultrasonic bath for 10 min to fully disperse and stabilize the slurries. Calibration was performed by using aqueous solutions of reference materials. Measurements were made on a simultaneous SpectroCIROS^CCD ICP-OES with side on plasma. The accuracy of the chloride determination was verified by the analysis of certified reference material. The findings of this investigation are compared with results obtained for the chloride content by the standard EN196-2 indirect Volhard titration and potentiometry with an ion-selective electrode (ISE), previously described as the preferred method. The results obtained with potentiometry and ICP-OES of various commercially available cements were comparable.     

微分电位溶出法同时测定琼脂中的铜、铅、镉

提出了利用微分电位溶出法同时测定琼脂中的铜、铅、镉含量的方法,探讨了硝酸镁和盐酸浓度对分析物稳定性及灵敏度的影响并作了试验和优化。试验结果表明,铜、铅、镉的回收率达到95.5％-99.5％之间,测定结果的相对标准偏差1.5％-6.0％之间,检出限分别为0.50mg/Ag、0.05mg／kg、0.05mg/kg。     

玉米、爆米中铅、镉含量的测定

用原子吸收光谱法对玉米、爆米中污染元素铅、镉进行了测定。铅在0.00-1.80μg/L(R=0.9933)；镉在0.00-0.50μg/mL(R=0.9950）范围内均具有良好的线性关系。本方法的RSD≤4.9%，回收率在95.0-103.8%。方法快速简便，结果准确。可用于粮食中铅、镉含量的监测。     

EDTA选择滴定法测定易熔合金中的镉

在弱酸性溶液中邻菲咯啉与镉（Ⅱ）形成无色可溶性配合物,其稳定性高于相对应的乙二胺四乙酸（ＥＤＴＡ）配合物,在镉（Ⅱ）的ＥＤＴＡ配合物溶液中加入掩蔽剂邻菲咯啉,则配合物分解。通过铅（Ⅱ）标准溶液滴定释放出的 ＥＤＴＡ可测定镉（Ⅱ１）的含量     

Simultaneous determination of trace aluminum (III), copper (II) and cadmium (II) in water samples by square-wave adsorptive cathodic stripping voltammetry in the presence of oxine

A validated adsorptive cathodic stripping voltammetry method is described for simultaneous determination of Al(III), Cu(II) and Cd(II) in water samples. In acetate buffer (pH 5) containing 10 μM oxine, these metal ions were determined as oxine complexes following adsorptive accumulation onto the HMDE at −0.05 V versus Ag/AgCl/KCl_s. The best signal to noise ratio was obtained using a square wave of scan increment 10 mV, frequency 120 Hz, and pulse-amplitude 25 mV. Limits of detection as low as 0.020 μg L⁻¹ Al(III), 0.012 μg L⁻¹ Cu(II) and 0.028 μg L⁻¹ Cd(II) were achieved. Interference due to various cations (K(I), Na(I), Mg(II), Ca(II), Mn(II), Fe(III), Bi(III), Sb(III), Se(IV), Pb(II), Zn(II), Ni(II), Co(II)), anions (Cl⁻, NO³⁻, SO₄ ²⁻, PO₄ ³⁻) and ascorbic acid was minimal as the measured signals change by 4% at the maximum. The stripping voltammetry method was successfully applied for simultaneous determination of Al(III), Cu(II) and Cd(II) in tap and natural bottled water samples.     

微波消解-阳极溶出伏安法测定皮革中镉含量

用微波消解皮革试样,在CH3COOH-CH3COONa底液中,用阳极溶出伏安法测定消解液中镉元素含量,方法的加标回收率为91.0%~101.0%,相对标准偏差为5.2%。     

Determination of Cadmium(II) in Water and Soil Samples after Preconcentration with a New Solid Phase Extractor

Abstract

A new simple and reliable method has been developed to separate and preconcentrate trace cadmium ion from water and soil samples for subsequent measurement by flame atomic absorption spectrometry (FAAS). Cadmium ions adsorbed quantitatively on Amberlyst 36 cation exchange resin were eluted with a 5 mL of 3 mol/L hydrochloric acid solution. Different factors and matrix effects for the preconcentration step were examined. The analytical figures of merit for the determination of cadmium are as follows: analytical detection limit, 0.51 µg/L; precision (RSD), 2.9%; enrichment factor, 200; capacity of resin 192 mg/g. The method was applied for cadmium determination in tap water, natural drinking water, soil, and roadside dust samples. The accuracy of the method is confirmed by analyzing standard reference material (Montana Soil, SRM 2711).     

Sorption and perturbation of water at polyelectrolyte interfaces. Paper 5—effects of water isotopic dilution

We have carefully examined the possible role of local oscillator coupling in D₂O(or H₂O), and locally concentrated evanescent electric fields in creating a large intensity perturbation of the ν(OD) band of water in the polyelectrolytes SPEES/PES (S₅, S₈ and S₂₀). Isotopic dilution experiments lead to the same (or higher) extinction coefficient while an ATR/transmission experimental comparison also gives a similar intensity. We conclude that neither effect is responsible for enhanced P values, and that these must be caused by strong polymer-water interactions at the anionic SO₃⁻ groups on these polymers.     

日用陶瓷中铅镉溶出量的测定

采用火焰原子吸收分光光度法（AAS）来测定日用陶瓷中铅镉的含量,并对测量结果进行分析。结果表明：方法检出限分为0.21μg·mL-1（Pb）和0.007μg·mL-1（Cd）,回收率为102.45%和94.67,精密度为2.10%和3.14%。该方法灵敏度、准确、快速、检出限低,适用于实验室中微量的铅、镉含量的测定。     

Effect of asymmetry in a bipolar membrane on water dissociation — a mathematical analysis

Based on a simple model established in the previous paper for water dissociation process on a bipolar membrane, this work is concentrated on analyzing the membrane asymmetry on the water dissociation process. Special attention is paid to thickness ratio, fixed group concentration ratio and the water diffusivity ratio of anion layer to cation layer on water concentration, proton or hydroxyl ions concentration in the depletion layer as well as the current density curves. The results suggest that for practical applications, an asymmetric bipolar membrane with the appropriate thickness, proper ion-exchange capacity and high permeability to water will receive more effective results than a symmetric one.     

溶出伏安法测定聚氯化铝中的微量铅、镉

提出了用阳极溶出伏安法测定饮用水处理剂聚氯化铝的微量铅、镉,实验确定最佳支持电解质为0.1 mol/L盐酸溶液,在此体系中测定能得到满意的精密度和回收率。     

Potentiometric stripping analysis of bismuth based on carbon paste electrode modified with cryptand [2.2.1] and multiwalled carbon nanotubes

An electrochemical method based on potentiometric stripping analysis (PSA) employing a cryptand [2.2.1] (CRY) and carbon nanotube (CNT) modified paste electrode (CRY-CNT-PE) has been proposed for the subnanomolar determination of bismuth. The characterization of the electrode surface has been carried out by means of scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). It was observed that by employing CRY-CNT-PE, a 9-fold enhancement in the PSA signal (dt/dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/dE (s/V) was proportional to the Bi(III) concentration in the range of 5.55 × 10⁻⁸ to 9.79 × 10⁻¹¹ M (r = 0.9990) with the detection limit (S/N = 3) of 3.17 × 10⁻¹¹ M. The practical analytical utilities of the modified electrode were demonstrated by the determination of bismuth in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. Moreover, the results obtained for bismuth analysis in commercial and real samples using CRY-CNT-PE and those obtained by atomic absorption spectroscopy (AAS) are in agreement at the 95% confidence level.     

A direct analysis of nanomolar metal ions in environmental water samples with Nafion-coated microelectrodes

Square Wave Anodic Stripping Voltammetry (SWASV) was combined with microfabricated microelectrodes to analyze metal ions in aqueous solution and showed excellent performance such as short analysis time about 1 min per experiment, simultaneous detection of several ions and very low detection limit as low as several nanomoles per liter (i.e. sub-ppb in mass) without any of supporting electrolyte and stirring during analysis. Nafion, a famous ion-exchanging polymer, was introduced to protect the electrode surface from obstructing materials. The Nafion-coated microelectrode was free from disturbing impurities and was capable of analyzing natural water samples directly. Results from the direct water analysis showed similar performance to those from pre-treated samples in both sensitivity and analysis time. To secure the reproducibility of Nafion-coated electrode, a simple electrochemical cleaning method with potential sweep was used and the electrode remained reliable to continued experiments. Nafion-coated microelectrodes were further examined via the comparison with ICP-MS data.     

计时电位溶出法测定天麻中的痕量砷

以镀金玻碳电极为工作电极,计时电位溶出法测定天麻中的痕量砷。选择富集电位为-0.45V,溶出低液为3.0 mol/L的硝酸,在+0.14V电位处获得一灵敏的砷(Ⅲ)的二次微分电位溶出峰,且该溶出峰的峰高与砷的质量浓度在2.0～12.0μg/L范围内呈线性关系,方法的检出限(3S/N)为0.96μg/L。方法用于测定天麻中痕量砷的回收率为97.6%～102.4%,RSD为2.7%～3.1%。     

差分脉冲阳极溶出伏安法测定中药材样品中的铜铅镉

用差分脉冲阳极溶出伏安法同时测定了8种中药材样品中铜、铅、镉的含量,它们的溶出电位依次是-0.15 V、-0.45 V、-0.65 V;铜、铅浓度在4.0×10-10~1.0×10-7g/mL范围内与峰电流呈线性关系,线性回归方程分别为y=378.84x(R2=0.9985)、y=661.96x(R2=0.9937)(x为浓度,单位10-6g/mL),镉浓度在4.0×10-10~8.0×10-7g/mL范围内与峰电流呈线性关系,回归方程为y=588.72x(R2=0.9963)(x为浓度,单位10-6g/mL),其检出限依次为1.0×10-11g/mL、1.8×10-11g/mL、1.0×10-11g/mL。此方法用于中草药样品中铜、铅、镉的测定,其回收率依次为88.06%、105.74%,、104.54%,方法简便,灵敏度高,结果准确可靠。     

电感耦合等离子体发射光谱法测定水中微量磷的研究

用ICP－AES法测定水中磷，讨论并确定了试验的最佳测定条件，在选定的最佳条件下测磷的检出限为0．02mg/L，回收率为96．5％－102．1％，RSD为1．65％－2．83％。该法准确、快速、简便，应用于水中磷的测定，结果满意。     

阳极溶出方波伏安法同时测定竹叶提取物中的铜、铅和镉

在CH3COOH-CH3COONa底液中,用阳极溶出方波伏安法同时测定竹叶提取物中铜、铅、镉3种元素含量,该法的最佳条件为:控制CH3COOH-CH3COONa缓冲溶液的pH=4 5,且c(CH3COONa)=0 12mol/L;选择方波频率为30Hz,电位扫描速度为4mV/s,在-0 8V处富集240s后采用方波伏安法正向扫描至0 15V。当铜、铅、镉金属离子的质量浓度为0 05～30μg/L时,线性关系较好,相关系数分别为0 9985,0 9992和0 9985,加标回收率分别为101 6%,99 0%和101 0%。     

A biopolymer‐based 3D printable hydrogel for toxic metal adsorption from water

Herein, we describe a 3D printable hydrogel that is capable of removing toxic metal pollutants from aqueous solution. To achieve this, shear‐thinning hydrogels were prepared by blending chitosan with diacrylated Pluronic F‐127 which allows for UV curing after printing. Several hydrogel compositions were tested for their ability to absorb common metal pollutants such as lead, copper, cadmium and mercury, as well as for their printability. These hydrogels displayed excellent metal adsorption with some examples capable of up to 95% metal removal within 30 min. We show that 3D printed hydrogel structures that would be difficult to fabricate by conventional manufacturing methods can adsorb metal ions significantly faster than solid objects, owing to their higher accessible surface areas. © 2019 Society of Chemical Industry