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.     

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.     

Removal of Arsenic from Ground Water by Manganese Dioxide–Coated Sand

In a laboratory study, manganese dioxide–coated sand (MDCS), prepared by reacting potassium permanganate with manganese chloride under an alkaline condition and in the presence of sand, showed promise as a medium for use in small systems or home-treatment units in developing areas of the world, for removing arsenic(III) and arsenic(V) from ground water. In ten cycles of downflow column tests [bed depth 400 mm; empty-bed contact time 74 min; influent arsenic 0.5 mg As∕L of arsenic(III) and 0.5 mg As∕L of arsenic(V)], breakthrough bed volumes at the World Health Organization guideline value of 0.01 mg As∕L for arsenic in drinking water were in the range of 153–185 per cycle. During regeneration (backwashing with 2 L of a 0.2 N sodium hydroxide solution), 85.0% of the removed arsenic was recovered in the first cycle, and 94.6–98.3% was recovered in subsequent cycles. A low-cost, simple home arsenic removal unit, containing 6 kg (4 L) of the MDCS medium and operated at 6 L∕h, produced 740 and 700 L of water in two cycles of runs when the influent arsenic concentration was 0.5 mg As∕L of arsenic(III) and 0.5 mg As∕L of arsenic(V). No arsenic(III) or leaching of manganese from the medium was detected in the effluent. A detailed study addressing the effects of some important factors (water pH, concentration and type of competing anions, and cations) on the process is needed. The home arsenic removal unit should be subjected to field trials to assess the long-term effects on performance.     

Modeling TOC Breakthrough in Granular Activated Carbon Adsorbers

Linear regression techniques were used to develop practical models to predict total organic carbon (TOC) breakthrough in bituminous granular activated carbon (GAC) adsorbers. Models were developed for two field-scale GAC sizes (8×30 and 12×40?mesh) and two empty bed contact times (EBCTs) (10 and 20 min). Model input parameters include two water quality variables, influent TOC concentration (TOC0) and pH, that impact performance. The dependent variables for the models were normalized breakthrough time, throughput in bed volumes, to six fractional (TOC/TOC0 = 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7) and three mass (TOC = 1.0, 1.5, and 2.0 mg/L) effluent concentrations. Model development was performed using small-scale breakthrough data from 35 different source waters; external model validation was performed with small-scale breakthrough data from 14 source waters; a sensitivity analysis was performed to ensure that the models effectively capture expected breakthrough trend; and a scalability test was performed to verify the models’ ability to predict breakthrough for field-scale GAC adsorbers.     

电感耦合等离子体原子发射光谱法测定钢丝黄铜镀层中铝磷锰铁镍砷锡锑铅

提出了一种用电感耦合等离子体原子发射光谱法(ICP-AES)快速测定钢丝黄铜镀层中铝、磷、锰、铁、镍、砷、锡、锑和铅元素含量的分析方法。利用稀氨水和过氧化氢将黄铜层从钢丝上剥离下来,取出钢丝后在镀层液中加入盐酸酸化,选择309.271, 178.284, 257.610, 238.204, 231.604, 189.042, 189.989,206.833和182.205 nm波长的光谱线分别作为铝、磷、锰、铁、镍、砷、锡、锑和铅的分析谱线,在优化的试验条件下用ICP-AES测定试液中铝、磷、锰、铁、镍、砷、锡、锑和铅含量。其信号强度与铝、磷、锰、铁、镍、砷、锡、锑和铅的质量浓度分别在0.05~15.0、 0.05~1.0、 0.05~15.0、 0.05~15.0、 0.05~20.0、 0.05~1.0、 0.05~1.0、 0.05~1.0和0.05~15.0 mg/L范围内呈线性关系,方法的检出限(3S/N)分别为0.009, 0.015, 0.001, 0.010, 0.002, 0.003, 0.009, 0.007和0.010 mg/L。方法可用于钢丝黄铜镀层中铝、磷、锰、铁、镍、砷、锡、锑和铅含量的测定,回收率在96%~107%之间,相对标准偏差(n=6)在0.46%~4.1%之间,不同方法间测定值一致。     

Na-DDTC沉淀法从氯化轻稀土溶液中去除低含量锰的研究

Na-DDTC能与氯化轻稀土溶液中的Mn     

Arsenite Oxidation by Batch Cultures of Thiomonas Arsenivorans Strain b6

Arsenite [As(III)] oxidation by Thiomonas arsenivorans Strain b6 was investigated in batch reactors at pH 6 and 30°C over As(III) concentrations ranging from 10 to 1,000 mg/L in the absence of added organic carbon. Strain b6 completely oxidized As(III) to arsenate [As(V)] during exponential growth phase for lower levels of As(III) concentrations ( ≤ 100?mg/L). At higher levels of 500 and 1,000 mg/L, As(III) oxidation was observed mostly in the exponential phase but continued into the stationary phase of growth. The Haldane substrate inhibition model was used to estimate biokinetic parameters for As(III) oxidation. The best fit parameters of half saturation constant Ks = 33.2±1.87?mg/L, maximum specific substrate utilization rate k = (0.85±0.18)-mg As(III)/mg dry cell weight/h, substrate inhibition coefficient Ki = 602.4±33.6?mg/L, yield coefficient Y = (0.088±0.0048)-mg cell dry weight/mg As(III), and endogenous decay coefficient kd = 0.006±0.002?h?1 were obtained using the Adams-Bashforth-Moulton algorithm and nonlinear regression technique. Sensitivity analysis revealed that Y and Ki are the most sensitive to model predictions, while kd is the least sensitive to model simulation at both low and high concentrations of As(III).     

Kinetics of Arsenite Oxidation by Chemoautotrophic Thiomonas arsenivorans Strain b6 in a Continuous Stirred Tank Reactor

As(III) oxidation by a chemoautotrophic bacterium, Thiomonas arsenivorans strain b6, was evaluated in a continuous stirred tank reactor (CSTR) under a range of influent As(III) concentrations (2,000–4,000 mg/L) and hydraulic retention times (HRTs) (21.7–74.9 h). Five steady states were obtained after the CSTR was continuously operated for 115 days with over 99% As(III) oxidized under the optimal growth conditions for strain b6 at pH 6 and 30°C. The culture exhibited strong resilience by recovering from an As(III) overloading of 4,847.4±290.9?mg/day/L operated at a HRT of 21.7 h. Arsenic mass balance analysis revealed that As(III) was mainly oxidized to As(V), with unaccounted arsenic well within the analytical error of measurement. The best estimates of biokinetic parameters for As(III) oxidation were obtained using the steady-state data and the Monod expression based model [k = 5?mg As(III)/mg dry cell weight/h; Ks = 20.1?mg/L; kd = 0.008?h?1; and Y = 0.011?mg cell dry weight/mg As(III)]. The Monod model and the reactor mass balance successfully simulated both the steady-state and transient phases of CSTR operation. Sensitivity analyses defined Y and k to be the most sensitive to model predictions, whereas kd and Ks were least sensitive to model simulations of As(III) oxidation under steady-state conditions.     

焦化废水除盐深度处理试验研究

分别采用同步和分步条件试验,考察反应时间和加药量对高碱石灰铝盐法去除氯离子的影响。分步处理效果优于同步处理,反应时间可控制在45 min+45 min。随着加药量的增加,氯离子和硫酸根离子的去除效果明显改善,最佳条件下氯离子的去除率达到66%,出水氯离子浓度低于350mg/L,满足循环冷却水的水质要求。对硫酸根离子去除效果更为明显,去除率可达到90%,出水硫酸根离子浓度低于25 mg/L。经处理后,出水中钙离子浓度、镁离子浓度和硬度等均低于0.05 mg/L。出水指标均达到循环冷却水的水质标准要求。     

电感耦合等离子体原子发射光谱法测定铜熔炼渣中铅锌镍锑铋砷

铜熔炼渣是火法造锍捕金过程中产生的冶炼废渣,建立渣中铅、锌、镍等杂质元素的测定方法对底吹炉熔炼工艺控制极为重要.实验采用硝酸、盐酸、氢氟酸、高氯酸溶解样品,采用电感耦合等离子体原子发射光谱法测定铅、锌、镍、锑、铋、砷,选择Pb 220.353 nm、Zn 213.856 nm、Ni 231.604 nm、Sb 206....     

水蒸气蒸馏-离子色谱法测定湿法炼锌溶液中氟和氯

将水蒸气蒸馏和离子色谱法相结合建立了湿法炼锌溶液中氟和氯的测定方法。在硫酸(2+1)介质中,于165~175 ℃的温度下将样品蒸馏25 min,蒸馏过程中生成的氟化氢和氯化氢随着水蒸气通过冷凝管冷却,然后流入接收瓶,被氢氧化钠碱液吸收。吸收液通过直径为0.22 μm水系滤膜,进入离子色谱仪,氟和氯离子被测定。样品中的基体及与氟、氯离子共存的其他离子对测定没有干扰。氟离子和氯离子的质量浓度分别在0.2~2 mg/L和0.5~5 mg/L范围内与其对应的峰面积呈良好的线性关系,线性回归方程分别为y=0.661 x-0.398和y=0.827 x,检出限分别为0.006 mg/L和0.01 mg/L。方法用于湿法炼锌溶液的合成液和预上清液中氟和氯的测定,合成液的测定值与参考值相符合,相对标准偏差(n=11)分别为3.2%(F)和4.0%(Cl);预上清液中氟和氯的测定值分别为40.0 mg/L和371 mg/L,回收率分别为91%和88%。     

Arsenite Oxidation by Alcaligenes faecalis Strain O1201

Batch experiments were conducted to examine the oxidation of arsenite (As (III)) to arsenate (As (V)) by Alcaligenes faecalis strain O1201 isolated from soils. Pure cultures of O1201 completely oxidized As (III) to As (V) in the exponential growth phase at As (III) concentrations ranging from 10 to 1,000?mg/L in less than 12 h. The growth of O1201 requires an organic substrate as the carbon and energy source, and the oxidation of As (III) was mainly observed in the exponential growth phase. As (III) concentration at 500?mg/L inhibited the growth of O1201, whereas its oxidation product As (V) did not show any inhibition effects even at concentration as high as 1,000?mg/L. Kinetics studies of As (III) oxidation were performed under the optimal conditions for O1201 at pH 7 and 30°C in a chemical defined medium with citrate as the sole carbon source. The Monod expression coupled with a logistic growth model was used to analyze the kinetics of As (III) oxidation. The best fit parameters of half-velocity coefficient Kc of 15?mg/L, maximum reaction rate coefficient kmc of 0.47 mg As (III)/mg dry weight/h, and logistic growth rate coefficient r of 0.22–0.34?h?1 were obtained using a nonlinear regression analysis.     

Lidocaine prolongs the safe duration of circulatory arrest during deep hypothermia in dogs

PURPOSE: To test the hypothesis that lidocaine prolongs the safe period of circulatory arrest during deep hypothermia. METHODS: Sixteen dogs were subjected to cooling, first surface cooling to 30 degrees C and then core cooling to 20 degrees C rectal temperature). The circulation was then stopped for 90 min. In the lidocaine group, 4 mg.kg-1 lidocaine was injected into the oxygenator two minutes before circulatory arrest and 2 mg.kg-1 at the beginning of reperfusion and rewarming. The control group received equivalent volumes of normal saline. Post-operatively, using a neurological deficit scoring system (maximum deficit score-100; minimum-zero indicating that no scored deficit could be detected). Neurological function was evaluated hourly for six hours and then daily for one week, the pharmacokinetic parameters were calculated using one compartment model. RESULTS: On the seventh day, the neurological deficit score and overall performance were better in the lidocaine (0.83 +/- 2.04) than in the control group (8.33 +/- 4.08 P < 0.05). During the experiment, the base excess values were also better in the lidocaine than in the control group (at 30 min reperfusion: -4.24 +/- 1.30 vs -8.20 +/- 2.82 P < 0.01, at 60 min reperfusion was -3.34 +/- 1.87 vs -7.52 +/- 2.40 (P < 0.01). On the eighth day the extent of pathological changes were milder in the lidocaine group than that in the control group. The elimination half life of lidocaine was 40.44 +/- 7.99 during hypothermia and 2.01 +/- 4.56 during rewarming. CONCLUSIONS: In dogs lidocaine prolongs the safe duration of circulatory arrest during hypothermia.     

次氯酸钙—硫酸亚铁处理钨冶炼含砷含氨氮废水

采用次氯酸钙—硫酸亚铁分解两步法静态处理钨冶炼工艺中高浓度含氨氮和含砷废水,通过单因素试验确定了最佳工艺条件。结果表明,在最佳条件下,氨氮和含砷去除率均达到了99%以上。处理后的废水中As<0.05mg/L、氨氮<0.15mg/L,出水水质达到排放要求。     

Morphologic features and function of the airways in early asbestosis in the sheep model

Previous studies of asbestos exposure in humans and small animals have suggested that air flow limitation associated with small airway disease may be an early manifestation of asbestosis, but the subject is still controversial. In this report, we present the airway morphologic aspects and function of our sheep model of the disease. Three groups of 6 sheep were exposed to repeated intratracheal injections of either saline (control group), 2 mg of UICC Canadian chrysotile asbestos in saline (low exposure group), or 128 mg of the same fibers (high exposure group). At the end of the twelfth month of exposure, an alveolitis had developed in the high exposure group only. Detailed pulmonary function tests were followed within 48 by lung biopsies according to methods described, to which were added air-helium flow-volume curves. Lung biopsies in control and low exposure groups did not demonstrate significant morphologic changes, whereas all biopsies in the high exposure group showed alveolitis characterized by an alveolar and interstitial accumulation of macrophages and mononuclear cells without interstitial fibrosis. On all biopsies, over half of the airways were altered by a similar peribronchiolar process, which at times compressed the peripheral airways. Functionally there was no significant difference between low exposure and control groups. However, compared with the control group, the high exposure group had significantly lower vital capacity (2.0 +/- 0.1 versus 2.9 + 0.1 L, p less than 0.01), lower static lung compliance (91 + 13 versus 132 + 9 ml/cmH2O, p less than 0.05), higher isoflow volume (2.15 + 0.08 versus 1.4 + 0.1 L, p less than 0.01), and higher upstream resistance below the isoflow volume (3.3 + 0.2 versus 1.3 + 0.3 cmH2O L/s, p less than 0.02). These data demonstrate that in the early asbestos-induced peribronchiolar alveolitis of the sheep, which restricts lung volumes, there is a concomitant small airway disease that significantly limits air flow.     

Dissolved Oxygen Demand at the Sediment-Water Interface of a Stream: Near-Bed Turbulence and Pore Water Flow Effects

A microbial dissolved oxygen (DO) uptake model was developed for a stream bed, including the effect of turbulence in the flow over the bed and pore water flow in the porous bed. The fine-grained sediment bed has hydraulic conductivities 0.01 ≤ k ≤ 1??cm/s, i.e., sediment particle diameter 0.006 ≤ ds ≤ 0.06??cm. The pore water flow is driven by pressure fluctuations at the sediment-water interface, mostly attributable to near-bed coherent motions in the turbulent boundary layer above the sediment bed. An effective mass transfer coefficient (De) coupled to a pore water flow model was used in the DO transport and DO uptake model. DO flux across the sediment-water interface and into the sediment, i.e., sedimentary oxygen demand (SOD), was related to hydraulic conductivity and microbial oxygen uptake rate in the sediment and shear velocity at the sediment-water interface. Simulated SOD values were validated against experimental data. For hydraulic conductivities of the sediment bed up to k ≈ 0.01??cm/s, the pore water flow effect on SOD was found negligible. Above this threshold, the effective mass (DO) transfer coefficient in the sediment bed (De) becomes larger as the hydraulic conductivity (k) becomes larger as the interstitial flow velocities increase; consequently, DO penetration depth increases with larger hydraulic conductivity of the sediment bed (k), and SOD increases as well. The enhancement of vertical DO transport into the sediment bed is strongest near the sediment-water interface, and rapidly diminishes with depth into the sediment layer. An increase in shear velocity at the sediment-water interface also enhances DO transfer. Shear velocity increases at the sediment-water interface will raise SOD regardless of the maximum oxidation rate if the hydraulic conductivity is above the threshold of k ≈ 1??cm/s. The relationship is nearly linear when U*<0.8??cm/s. At shear velocity U* = 1.6??cm/s, SOD for oxidation rates μ = 1000 and 2000??mg?l-1?d-1 are almost five times larger than those with no pore water flow. When pore water transport of DO is not limiting, SOD is a linear function of oxygen demand rate μ in the sediment when 0 ≤ μ ≤ 200??mg?l-1?d-1.     

Arsenite Oxidation by Alcaligenes Faecalis Strain O1201 in a Continuous-Flow Bioreactor

As(III) oxidation by a pure bacterial culture, Alcaligenes faecalis strain O1201, was evaluated using a continuous stirred tank reactor. The bioreactor system was operated for 204 days under a wide range of influent As(III) concentrations (500–8,000?mg/L) and hydraulic retention times (25.6–90.7?h) with citrate as the sole carbon and energy source at pH 7 and 30°C. Nine steady-state conditions were obtained with As(III) oxidation efficiency exceeding 95%. The system quickly recovered from an As(III) overloading at 15,000?mg/day/L while it operated at a HRT of 12.8?h. A material balance analysis revealed that nearly all the As(III) removed in the continuous stirred tank reactor (CSTR) was oxidized to As(V) and only 3.2% of the As(III) fed to the CSTR was unaccounted for. Biokinetic parameters, kmc = 0.86?mg/mg cell dry weight/h and Kc = 70?mg/L, for As(III) oxidation were obtained using the Monod expression and data obtained at steady-state conditions.     

Effect of total alkaloids of kudouzi (Sophora alopecuroides L.) on tolerance to anoxia in mice

To several anoxia mice models, total alkaloids of Kudouzi (TASa) can prolong their tolerance time (ip < 1/10, 1/5LD50/kg, P < 0.05-0.01). In the experiment of myocardial ischemia induced by pituitrin, TASa decreased significantly the ST change in ECG (P < 0.05). The acute LD50 of TASa by ip was found to be 130.66 +/- 22.64 mg/kg for mice.     

氧化-铁盐混凝法处理低质量浓度含砷矿井水的试验研究

试验研究了不同氧化工艺与铁盐混凝工艺联合处理矿井水中砷的效果。原水p H值为7.67,砷质量浓度为1 mg/L,采用铁盐混凝法处理时,Fe与As的质量比为6∶1、反应时间为30 min,砷的去除率为62%;当其与空气氧化法联合处理时,Fe与As的质量比为6∶1、反应时间为30 min、曝气量为0.05 m~3/h,砷的去除率为69%;当其与过氧化氢氧化法联合处理时,Fe与As的质量比为6∶1、反应时间为5 min、过氧化氢用量为0.01 m L/L,砷的去除率为99%。试验结果表明:引入氧化体系有助于含砷矿井水的处理,提高了砷的去除率;采用Fenton氧化体系与铁盐混凝法联合处理工艺,降低了铁盐药剂用量,提高了砷的去除率,缩短了反应时间。     

Excess of hMLH1 germline mutations in Swiss families with hereditary non-polyposis colorectal cancer

This article describes a high-performance liquid chromatographic (HPLC) method for the measurement of azithromycin (AZI) and two of its metabolites, 9a-N-desmethylazithromycin (ADES) and N-desmethylazithromycin (NDES), in human tears and plasma. The drug, metabolites, and internal standard (n-propylazithromycin [IS]) were detected electrochemically after injection of the extracted sample into the HPLC system. The peak height ratio (AZI, ADES, or NDES to IS) varied linearly, with concentrations in the ranges of 0.1 mg/L to 2.0 mg/L (tears) and 0.01 mg/L to 2.0 mg/L (plasma) of AZI, ADES, and NDES; the correlation coefficient (r) was more than 0.994 mg/L for all of the compounds (n=6). The analysis of tear samples collected at different intervals within 12 hours to 144 hours after a dose of 20 mg/kg of AZI from a trachoma patient yielded concentrations ranging from 1.52 mg/L to 0.34 mg/L for AZI, 0.79 mg/L to 0.27 mg/L for ADES, and 1.99 mg/L to less than 0.20 mg/L for NDES. The concentration of AZI in plasma ranged from 0.15 mg/L to 0.01 mg/L, whereas ADES and NDES were undetectable.