断续流动-氢化物发生原子荧光光谱法测定矿石中高含量砷

利用王水分解矿石样品,采用断续流动进样氢化物发生-原子荧光光谱法测定样品中的砷。实验讨论了矿石样品中主量元素对砷测定的干扰及消除方法;分析了测定结果准确性的影响因素,选择了合适的仪器条件、还原剂浓度、测定介质和载流酸度等。在选定的测定条件下,砷的检出限为0.05μg/L,精密度为0.4%,砷的测定结果与国家标准方法测定结果较吻合。采用该方法分别参加了铜、铅、锌精矿的实验室能力验证比对,其结果均为满意。     

Modeling Arsenite Adsorption on Rusting Metallic Iron

Experimental data on As(III) adsorption by rusted zero valent iron (ZVI) could be modeled using a simple Langmuir isotherm model. However, the adsorption equilibrium was observed to shift with time, as continued rusting produced additional sites on the rusted ZVI surface for potential arsenic adsorption. A modified Langmuir isotherm model was formulated taking into consideration the temporal variation in the site concentration for potential arsenic adsorption on the rusted ZVI surface. This model simulated the long-term experimental data on As(III) adsorption quite well. The model was further refined by apportioning the arsenic adsorbed on the rusted ZVI surface into labile and irreversibly adsorbed fractions. Finally, the developed model was used to simulate the performance of an adsorption column. The simulation results indicate that an adsorption column of length 0.4 m and diameter 0.056 m, i.e., containing 0.001?m3 of rusted ZVI weighing 4.76 kg, and operated at an empty bed contact time of 12 min, can treat 2,375–2,525 L of water containing 100?μg?L?1 of As(III) such that the effluent As(III) concentration from the column is less than 10?μg?L?1.     

New Approach: Waste Materials as Sorbents for Arsenic Removal from Water

The sorption of inorganic arsenic species (arsenite and arsenate) from aqueous solutions onto steel-mill waste and waste filter sand, under neutral conditions, was investigated in this study. Additionally, the steel-mill waste material was modified in order to minimize its deteriorating impact on the initial water quality and to meet the drinking water standards. The influence of contact time and initial arsenic concentration was investigated using batch system techniques. To evaluate the application for real groundwater treatment, the capacities of the obtained waste materials were further compared to those exhibited by commercial sorbents, which were examined under the same experimental conditions. Kinetic studies revealed that waste slag materials are the most efficient in arsenic removal, reaching equilibrium arsenic sorption capacities in the range 47.6–55.2?μg/g, while waste filter sand exhibited capacities of 25.4–29.8?μg/g (for an initial arsenic concentration Co = 0.5?mg/L). The higher iron content in the slag materials was considered to be responsible for the better removal efficiencies, and the specific arsenic removal efficiency was estimated to be 220?μgAs/gFe. The specific arsenic removal efficiency of the second active substance found in waste filter sand, manganese, was estimated to be 115?μgAs/gMn. Equilibrium studies revealed the occurrence of both chemisorption and physical sorption processes. All the waste materials exhibited higher performances for As(V). The highest maximum sorption capacity was obtained by waste iron slag: 4040?μg/g for As(V). The waste materials reached the arsenic removal capacities of the examined commercial materials, suggesting the feasibility of their application in real groundwater treatment.     

微分脉冲阳极溶出伏安法测定水处理剂用铝酸钙中砷

采用活性面位于侧面的金电极作为工作电极,建立了微分脉冲阳极溶出伏安法测定水处理剂用铝酸钙中砷含量的检测方法。将水处理剂用铝酸钙粉用氯化铝溶液加热回流溶解,经过滤后,对滤液进行稀释,以18%(质量分数)盐酸为支持电解质,对样品稀释液进行微分脉冲扫描阳极溶出伏安法测定。结果表明,砷在金电极上于峰电位为+0.09V左右产生灵敏的溶出峰,该峰峰高与砷的质量浓度在0.5~10μg/L之间呈现良好的线性关系,相关系数为0.997 7,检出限为0.15μg/L。按照实验方法对水处理剂用铝酸钙样品进行测定,并采用电感耦合等离子体质谱法(ICP-MS)做方法对照,同时加入砷标准溶液进行加标回收试验,结果表明,两种方法的测定结果基本一致,且实验方法的加标回收率为90%~102%。对3个水处理剂用铝酸钙样品测定结果的相对标准偏差(RSD,n=6)为2.1%~3.3%。     

顺序注射氢化物发生-原子荧光光谱法同时测定环境水样中铋和汞

建立了一种顺序注射氢化物发生-原子荧光光谱法同时测定水样中的Bi和Hg含量的方法。考察了光电倍增管负高压、铋和汞灯电流、原子化器高度、载气流量、屏蔽气流量等因素对测定结果的的影响。研究发现:载流HCl的浓度为0.3~0.6 mol/L,KBH4浓度为4 g/L,稳定剂K2Cr2O7浓度为5 g/L时,同时测定铋和汞的效果最佳。在最佳实验条件下,铋和汞的检出限分别为0.005 8μg/L和0.007 5μg/L。方法用于河水、井水和池水水样中铋和汞的测定,加标回收率为91.0%~109%,相对标准偏差小于3.4%,被测水样中共存的离子对铋和汞的测定没有干扰。     

超声提取—顺序注射氢化物发生-原子荧光光谱法测定煤中无机砷

利用6 mol/L盐酸作为提取试剂,样品经超声提取后,用顺序注射氢化物发生-原子荧光光谱法测定煤中无机砷的含量。对超声提取条件(提取试剂浓度、时间、温度)进行了优化。在优化的实验条件下,砷的浓度在0.20～100 μg/L范围内与荧光强度呈线性关系,相关系数为0.999 7,砷的检出限为0.025 μg/L,对10 μg/L砷标准溶液进行重复11次测量 , 得出相对标准偏差(RSD)为0.9 %。用该法对煤飞灰成分分析标准物质GBW08401和煤样进行分析,测得回收率在95%～102%之间,标准样品的测定值和认定值相符。     

Arsenic Removal by a Colloidal Iron Oxide Coated Sand

A novel treatment process for arsenic removal from contaminated groundwater has been developed for use as a reactive barrier or a small drinking water treatment unit. In this study, modified porous media was made by the deposition of colloidal iron oxide onto sand grains at intermediate pH and ionic strength. Kd values from column experiments were 0.016–0.37?L/kg for As(III) and 0.023–0.85?L/kg for As(V), being lower than those of batch experiments (0.50 and 1.30?L/kg for As(III) and As(V), respectively) due to lower availability of surface adsorption sites in the packed column. Media-independent Kd values reflect the enhancement of arsenic adsorption with an increase of colloidal iron oxide coated sand fraction, apparently due to adsorption equilibration during arsenic transport under the same flow column conditions. The heterogeneous composition of two groundwater samples also reduced arsenic adsorption. Therefore, arsenic elution near the initial breakthrough was regulated by available adsorption surface in a porous coated sand media as well as the effects of competing oxyanions. The exhaustion of adsorption capacity near the critical contamination level is sensitive to geochemical and remedial properties of the contaminants.     

固相萃取-原子荧光光谱法测定不锈钢中痕量砷

通过氢化物发生原子荧光光谱法测定不锈钢样品中痕量砷,采用On-Guard H柱去除消解液中重金属,避免了共存金属元素和大量基体元素铁对砷测定的干扰,且On-Guard H柱对测定无明显干扰。结果表明:砷检出限为0.02μg/L,采用该方法测定不锈钢标准样品,测定结果与理论值相符合。该方法操作简单,且大大提高了不锈钢中痕量砷测定的灵敏度和准确度。     

氢化物发生-原子荧光光谱法测定精碲中微量砷

提出了一种氢化物发生-原子荧光光谱法测定精碲中微量砷的方法。用硝酸溶解样品,氢氧化钾和盐酸调节溶液酸度至pH 5.5~6.5,碲水解沉淀析出。除去了大量基体后,溶液中碲量少于50μg/mL。在盐酸介质中用硫脲-抗坏血酸将砷(预还原为砷(Ⅲ),以标准加入法绘制校准曲线,氢化物发生-原子荧光光谱法测定砷量。方法的检出限为0.02μg/L,砷量在0.02~40μg/L范围内有良好的线性关系。方法操作简便、快速,应用于精碲中痕量砷的测定,测定结果与正戊醇萃取砷钼蓝分光光度法的结果相符,相对标准偏差为4.2%~8.5%,样品的加标回收率在93%~104%之间。     

砷-碘酸钾-中性红体系催化动力学荧光光度法测定痕量砷

在H2SO4介质中,痕量As对碘酸钾氧化中性红的反应具有显著的催化作用,使其荧光强度减弱,据此提出了动力学荧光法测定As的新方法。详细研究了中性红、碘酸钾和硫酸的用量以及反应温度和时间对As测定的影响。结果表明,在最佳条件下,砷的质量浓度在2.0～600 μg/L 范围内与溶液荧光强度的改变值呈良好的线性关系,检出限为0.6 μg/L。本法用于环境水样中As的测定,相对标准偏差小于或等于3.5%,加标回收率为98%～101%。     

Field-Scale Observations of Arsenic and Boron in Soil Irrigated with Drainwater

Addition of a strong acid to irrigation water could enhance sorption of boron and arsenic in a Lahontan Valley field. Approximately 90 soil samples, taken from a field irrigated with mildly brackish drainage water (TDS ≈ 1,250 mg L?1), were analyzed for soluble constituents. When the pH of the saturated soil paste was between 7.2 and 8.8, dissolved arsenic and boron concentrations increased, possibly indicating decreased sorption on oxyhydroxide precipitates of manganese and aluminum, and goethite, inferred from equilibrium aqueous speciation modeling. In the pH range of 7.2–8.8, linear regression models indicate a unit decrease in pH may result in a log[B] reduction of 1.18 and a log[total As] reduction of 1.58, when the concentrations are expressed in mg L?1. Geochemical modeling indicates that a reduction in pH in the observed range should not solubilize carbonates that could counteract acidity increase. Addition of HCl or H2SO4 to reduce soil water pH may be an effective way to minimize deep percolation of boron and arsenic.     

电感耦合等离子体质谱法测定水系沉积物中银铜砷锑铋镉

水系沉积物中银、铜、砷、锑、铋和镉等金属元素的准确测定,对地质找矿工作具有重要的指导意义。实验采用王水于水浴条件下溶解样品,通过选择适宜的同位素以及选用干扰元素校正方程克服了质谱干扰,利用仪器软件在线校正了氯离子对砷的干扰,以2%~3%(V/V)王水为测定介质,建立了电感耦合等离子体质谱法(ICP-MS)测定水系沉积物中银、铜、砷、锑、铋和镉6种元素的方法。在优化的实验条件下,各元素校准曲线线性相关系数均在0.9990以上,方法检出限为0.0028~0.045μg/g,测定下限为0.008~0.13μg/g。采用实验方法测定水系沉积物实际样品中银、铜、砷、锑、铋和镉,测定结果分别与采用交流电弧发射光谱法(ES)测定银,原子荧光光谱法(AFS)测定砷、锑、铋,火焰原子吸收光谱法(FAAS)测定铜,石墨炉原子吸收光谱法(GF-AAS)测定镉的结果基本一致;测得结果的相对标准偏差(RSD,n=11)为0.28%~2.0%。将实验方法应用于水系沉积物标准物质分析,银、铜、砷、锑、铋和镉测定结果的相对标准偏差(n=12)为0.45%~6.0%。     

Isolation and Characterization of NP4, Arsenate-Reducing Sulfurospirillum, from Maine Groundwater

Parts of New England have naturally high arsenic concentrations in groundwater. High arsenic correlates broadly with bedrock type, but levels are patchy, so other conditions must affect arsenic mobilization. Microorganisms capable of arsenate (As(V)) respiration, if present, could affect arsenic speciation and mobility in groundwater. An arsenate-reducing bacterium, designated NP4, was isolated from groundwater obtained from a well in Northport, Me., with extremely high (>1,400?μg?L?1) arsenic. Sequencing of the 16S rDNA showed that NP4 groups with the Sulfurospirillum genus. It can grow using arsenate, nitrate, iron(III), selenate, manganese(IV), sulfite, sulfur or thiosulfate as terminal electron acceptors and lactate, formate and pyruvate as electron donors. It can also grow on fumarate or lactate alone. This Sulfurospirillum isolate is distinct from other members of the genus in its carbon and electron acceptor usage. The activity of this type of microorganism could negatively affect groundwater quality by converting As(V) to the more toxic and difficult to remove As(III) form.     

Adsorption of As(V) from Water Using Nanomagnetite

This paper describes a study of the removal of arsenate [As(V)] from aqueous solutions by adsorption on commercial nanomagnetite (NM). The influences of pH, initial arsenate [As(V)] concentration, and adsorbent concentration were investigated in multiple kinetic runs. The adsorption kinetics and isotherms were investigated in batch experiments. The experimental data were determined to be best described by the pseudosecond-order kinetic model. Langmuir and Freundlich isotherms were used to fit the adsorption data from equilibrium experiments. The findings have revealed that NM has high removal efficiency for arsenate, with its capacity to reduce an initial level of 300 to <5-μg/L As(V), i.e., below the limit (10-μg/L As) set for potable water by the World Health Organization.     

Modeling As(V) Removal in Iron Oxide Impregnated Activated Carbon Columns

Iron oxide impregnated onto an activated carbon (FeAC) has a high arsenic (As) removal capacity with the potential to be used in existing activated carbon column systems. Objectives of this research were to investigate As(V) removal from aqueous-phase systems using fixed-beds packed with FeAC and to determine if the triple layer model (TLM) with the homogeneous surface diffusion model (HSDM) could describe As(V) removal in the columns. Rapid small-scale column tests (RSSCT) were conducted at various empty bed contact times (EBCT). Effluent As(V) breakthrough (10?μg/L) was incipient for the 0.20-min EBCT experiment, whereas ～ 2300 bed volumes of water at 1-mg/L inlet concentration of As(V) was treated at an EBCT of 2.1?min before breakthrough occurred. The TLM with three As(V)-FeAC surface reactions coupled with the HSDM provided accurate prediction of As(V) removal in the RSSCT.     

氢化物发生-原子荧光光谱法测定处理废水中砷

研究了氢化物发生-原子荧光光谱法测定砷钙渣固化、高砷烟尘湿法中和、苄基砷酸及仲钨酸铵生产等废水中砷的最佳条件。实验表明,废水样经化学处理,在稀盐酸介质中用硫脲-抗坏血酸将砷预还原为砷,Fe³⁺、Ca²⁺、Na⁺、Cu²⁺、F^-、S^2-、Bi³⁺、Sn⁴⁺、Sb⁵⁺等23 种离子的允许量（mg/50 mL）中高者达250或低至0.5。载液盐酸浓度为5%（V/V）,定量样品与15 g/L硼氢化钾碱性溶液混合生成砷化氢。在选定条件下, 砷量在 2～100 μg/L范围内线性关系良好,检出限（3σ/K）为0.001 4 μg/L。方法用于实际废水样品分析, 相对标准偏差（n=9～11）为1.6%～5.9%,加标回收率在93%～118%之间,固化废水测定值与砷锑钼蓝光度法相符。     

Manganese Amended Activated Alumina for Adsorption/Oxidation of Arsenic

In a laboratory study, manganese amended activated alumina (MAA), prepared by calcining (400°C) manganese acetate-impregnated activated alumina, showed promise as a more effective medium than activated alumina (AA) for use in small municipal drinking water systems or point-of-use treatment, for removing arsenic [As(III) and As(V)] from groundwater. Batch adsorption/oxidation kinetic tests indicated that in fixed-bed operation, with a bed flowthrough time of 10–20?min, MAA would be a more effective medium than AA in removing arsenic [As(V), As(III), and As(III) and As(V) (present together)] from groundwater. In three cycles of downflow column test [bed depth 200?mm; bed flowthrough time 20?min; influent arsenic 1.0–0.6?mg/L As(III) and 0.4?mg/L As(V)], breakthrough bed volumes at the World Health Organization guideline value of 0.01?mg/L for arsenic in drinking water were 580, 550, and 485, and 825, 770, and 695, respectively, for AA and MAA. During regeneration (backwashing with a sodium hydroxide solution), 84–88% (for AA) and 86–89% (for MAA) of the removed arsenic was recovered. Manganese concentration in the MAA column effluent was low (below 0.02?mg/L). A detailed study addressing the effects of some important factors (water pH, concentration and type of competing ions, and fouling by organics) on the process is needed.     

Arsenic Occurrence and Speciation in Municipal Ground-Water-Based Supply System

The city of Hanford, California, relies on ground water for its municipal water supply. Arsenic concentrations in local wells frequently exceed the current drinking water standard (50 μg∕L), although some dilution is achieved within the distribution system. Water samples were collected from municipal water supply wells and storage tanks in July and December 1996. Total arsenic concentrations ranged from 9 to 75 μg∕L. Arsenic was found to occur predominantly in the +III oxidation state. Lower contributions of As(III) to total arsenic concentrations were found in three wells and one storage tank. In all other samples, the percent As(III) was 89 ± 6%. The very low values of %As(III) in one storage tank (1% in July and 14% in December) indicate that As(III) oxidation occurs within the distribution and storage system.     

ICP-OES法测定铁矿石中的砷

采用盐酸、氢氟酸、高氯酸处理样品，高温冒烟蒸发驱氟，通过优化实验，确定了ICP—OES法测定铁矿石中砷的分析方法。仪器最佳分析条件：高频功率1400W，雾化气流量1．0L／min，辅助气流量0．8L／min，冲洗时间45s；采用匹配基体的方法消除干扰；选择As189．042nm和Asl93．759nm两条分析谱线。结果表明，方法检出限〈0．02μg／mL，RSD〈4％。     

氢化物发生-原子荧光光谱法测定铬矿中砷

铬矿中砷的测定方法对完善铬矿检测方法和质量评价手段有重要意义。在0.5 g样品中加入2 g过氧化钠,于650 ℃熔融20 min,熔融物经盐酸酸化溶解,以10%盐酸为载流,15 g/L硼氢化钾溶液为还原剂,采用氢化物发生-原子荧光光谱法(HG-AFS)进行测定,建立了铬矿中砷测定的新方法。实验表明,砷质量浓度在0.025～100 μg/L范围内与荧光强度呈线性关系,相关系数为1.000 0,方法检出限为0.05 μg/g,定量限为0.17 μg/g。对产地为南非、土耳其、巴基斯坦等19个国家共2 649个铬矿样品的成分进行统计,发现铬矿主要成分为铬、铁、镁、铝和硅;干扰试验表明,这些样品中的共存元素均不干扰测定。按照实验方法对3个不同砷含量的铬矿样品进行精密度和加标回收试验,结果的相对标准偏差(RSD,n=11)为1.4%～6.0%,回收率为96%~109%。将实验方法应用于与铬矿基体近似的铁矿标准物质中砷的测定,测定值与认定值基本一致。