微波辐射Bi2O3/沸石-H2O2体系降解废水中的硝基苯

研究了微波辐射下,以负载于沸石上的三氧化二铋为催化剂,以双氧水为氧化剂的催化氧化体系处理硝基苯工艺。通过单因素实验法,从反应催化剂负载量、pH、双氧水用量、微波功率、反应时间、催化剂用量等方面初步考察了硝基苯在该体系中的催化氧化效果。在氧化铋负载量3%（质量比）,pH=2,2 mL 30%双氧水,火力为中火,催化剂投加量为0.7 g,反应2 m in,对降解过程所得的中间产物和终产物进行了分析。结果表明,该体系对硝基苯的去除率能够达到99.2%,COD去除率为73.91%。     

Enhanced photocatalytic reduction reaction over Bi(3+)-TiO(2) nanoparticles in presence of formic acid as a hole scavenger

A series of Bi(3+)-doped TiO(2) (Bi(3+)-TiO(2)) catalysts with a doping concentration up to 2wt% were prepared by a sol-gel method. The prepared photocatalysts were characterized by different means to determine their chemical composition, surface structure and light absorption properties. The photocatalytic activity of different Bi(3+)-TiO(2) catalysts was evaluated in the photocatalytic reduction of nitrate in aqueous solution under UV illumination. In the experiments, formic acid was used as a hole scavenger to enhance the photocatalytic reduction reaction. The experiments demonstrated that nitrate was effectively degraded in aqueous Bi(3+)-TiO(2) suspension by more than 83% within 150min, while the pH of the solution increased from 3.19 to 5.83 due to the consumption of formic acid. The experimental results indicate that the presence of Bi(3+) in TiO(2) catalysts substantially enhances the photocatalytic reaction of nitrate reduction. It was found that the optimal dosage of 1.5wt% Bi(3+) in TiO(2) achieved the fastest reaction of nitrate reduction under the experimental condition. Bismuth ions deposit on the TiO(2) surface behaves as sites where electrons accumulate. Better separation of electrons and holes on the modified TiO(2) surface allows more efficient channeling of the charge carriers into useful reduction and oxidation reactions rather than recombination reactions. Two intermediate products of nitrite and ammonia during the reaction were also monitored to explore the possible mechanisms of photoluminescence quenching and photocatalytic reduction in the context of donor-acceptor interaction with electron trapping centers.     

一种新型铋基光催化剂的合成及其可见光催化性能

采用水热法合成铋基光催化剂Bi4VO8Br,通过X-射线粉末衍射、扫描电镜等手段对其进行表征.选择甲基橙为目标降解物来评价不同条件下合成的Bi4VO8Br在可见光下的光催化活性,发现pH 3、反应时间15 h、反应温度160℃为材料水热合成的最佳条件.考察了Bi4VO8Br在可见光及紫外光下对几种农药和增塑剂的光催化降解性能,显示了Bi4VO8Br对不易光解的含苯环有机物的可见光高活性.五氯酚的光催化过程影响因素优化结果表明,可见光和紫外光分别照射120 min和20 min,其降解率分别达到97%和99%,Bi4VO8Br表面上活性基团的捕获即空穴的氧化作用是主要反应原理.     

Synthesis of γ-Fe2O3/La/Bi2WO6 composites for enhanced visible light-driven photocatalytic degradation of tetracycline hydrochloride

Environmental Science and Pollution Research - γ-Fe2O3/La/Bi2WO6 heterojunction composites have been successfully synthesized by simple and convenient hydrothermal method. The photocatalytic...     

羟基铋离子改性蒙脱土的制备及其对碘离子的吸附

水体的碘污染问题正日益引起人们的广泛关注。以Swy-2型钠基蒙脱土为载体,利用其层间离子交换特性,简单快速制备了羟基铋离子改性蒙脱土,并通过扫描电镜（SEM）、X射线衍射（XRD）和X射线光电子能谱（XPS）对材料吸附碘前后的物化特性进行了表征,研究了材料对水体中碘离子的去除效果,探讨了相关吸附机理。结果表明：合成材料对碘离子的吸附动力学符合假二级动力学方程,吸附等温线符合Langmuir模型,其最大吸附量为107.5 mg·g-1,换算成氧化铋对碘的吸附量高达595.2mg·g-1;因此,以Swy-2型钠基蒙脱土为载体,进行羟基铋离子改性,可以大大地提高铋利用效果。对吸附碘后材料的XPS和XRD进一步分析推测,羟基铋离子改性蒙脱土对碘离子的去除,可能是经由化学吸附,生成Bi4I2O5所造成的。     

Probing the distribution and contamination levels of 10 trace metal/metalloids in soils near a Pb/Zn smelter in Middle China

The horizontal and vertical distribution patterns and contamination status of ten trace metal/metalloids (Ag, Bi, Co, Cr, Ge, In, Ni, Sb, Sn, Tl) in soils around one of the largest Chinese Pb–Zn smelter in Zhuzhou City, Central China, were revealed. Different soil samples were collected from 11 areas, including ten agricultural areas and one city park area, with a total of 83 surface soil samples and six soil cores obtained. Trace metal/metalloids were determined by inductively coupled plasma–mass spectrometry after digestion by an acid mixture of HF and HNO₃. The results showed that Ag, Bi, In, Sb, Sn, and Tl contents decreased both with the distance to the Pb–Zn smelter as well as the soil depth, hinting that these elements were mainly originated from the Pb–Zn smelting operations and were introduced into soils through atmospheric deposition. Soil Ge was influenced by the smelter at a less extent, while the distributions of Co, Cr, and Ni were roughly even among most sampling sites and soil depths, suggesting that they were primarily derived from natural sources. The contamination status, as revealed by the geo-accumulation index (I _geo), indicated that In and Ag were the most enriched elements, followed by Sb, Bi, and Sn. In general, Cr, Tl, Co, Ni, and Ge were of an uncontaminated status.     

钨酸铋光催化降解萘普生效果及其机理

以萘普生(NPX)为目标污染物,钨酸铋(Bi₂WO₆)为光催化剂,考察NPX浓度、Bi₂WO₆投加量、阴离子种类、溶液pH对Bi₂WO₆光催化降解NPX效果的影响并确定最佳反应条件。通过原位捕获实验、中间产物识别及反应体系化学需氧量(COD)去除效果,解析光催化过程产生的活性自由基种类及其作用、NPX降解路径及反应体系矿化度,揭示NPX降解机理。结果表明：经水热法制备的Bi₂WO₆为纯正交晶系,具有由2D纳米方片构成的3D花朵状结构,平均孔径为10.79 nm,比表面积为32.54 m²·g⁻¹,带隙能为2.54 eV;在500 W长弧氙灯照射下,当NPX浓度为10 mg·L⁻¹、Bi₂WO₆投加量0.4 g·L⁻¹、溶液pH值为4.6时,NPX降解率可达99.83%,光照180 min时矿化度为67.91%,光照反应时间延长至360 min时矿化度为82.14%;Bi₂WO₆价带电势(3.01 eV)高于OH⁻/·OH和H₂O/·OH的电势,因此,空穴(h⁺)能氧化OH⁻和H₂O生成羟基自由基(·OH);而Bi₂WO₆导带电势(0.47 eV)同样高于O₂/$ \cdot {\rm{O}}_2^ - $的电势,单电子(e⁻)还原O₂过程很难发生,只能经多e⁻还原O₂,生成超氧自由基($ \cdot {\rm{O}}_2^ - $)。同时还发现,h⁺和·OH在NPX降解过程中起主要氧化作用,$ \cdot {\rm{O}}_2^ - $起辅助作用。综合上述结果,NPX的降解机理是在活性自由基协同氧化下,NPX分子中的C—C、C—O、C=C键断裂发生脱羧反应和羟基化反应,生成结构简单的中间产物,中间产物继续氧化分解为小分子化合物并部分矿化成CO₂和H₂O。     

Trace element contamination of Norwegian Lake sediments

Concentrations of Sb, Hg, Bi, Cd, Mo, As, Co, Ni, Cr, Cu, V, Pb and Zn in surface and preindustrial sediments from 210 lakes in Norway were used for studying modern atmospheric depositions of these elements. Surface sediments had considerably higher concentrations of Sb, Hg, Bi, Cd, As, Pb than preindustrial sediments. The differences decreased with latitude and altitude. A multivariate analysis including the trace elements and the major constituents (organic matter, Si, Al, Fe and Mn) of surface sediments suggested the following relationships: Sb, Hg, Bi, As, and Pb formed a group with strong associations to organic matter. Ni, Cr and Cu formed a second group, weakly associated to the inorganic sediment fraction (Si and Al). Zn and Cd formed a third group with weak associations to organic matter. Co was associated to Mn, whereas Mo and V showed no important covariations with any other trace elements or major components.     

The Seveso episode: The validity of epidemiological inquires in relation with the definition of population at risk

Negative findings do not necessarily mean absence of causal association. Bi sed exposure definition criteria seem to be the reason for the large number of negative epidemiological studies.     

Synthesis of efficient Y-Bi2WO6/G visible light photocatalysts with high stability for pollutant degradation

Environmental Science and Pollution Research - For effective photocatalytic pollutant degradation on bismuth tungstate (Bi2WO6), it is vital to enhance the photogenerated charge separation and the...     

One stone two birds: novel carbon nanotube/Bi4VO8Cl photocatalyst for simultaneous organic pollutants degradation and Cr(VI) reduction

Environmental Science and Pollution Research - In this work, visible light-responsive carbon nanotubes (CNTs)/Bi4VO8Cl composite photocatalysts have been prepared by a facile in situ hydrothermal...     

Temperature dependent properties of environmentally important synthetic musks

Environmental fate determining physical properties including their temperature dependence for five nitro musks and for seven polycyclic musks were estimated. The properties evaluated were vapor pressure in a solid and liquid state (PS and PL), solubility in water (S), Henry's law coefficient (H = PL/S) and log octanol-water partition coefficient (log KOW). Gas chromatography for starting values of vapor pressure estimation and HPLC experiments at 5-20 degrees C for comparison of the theoretical versus experimental solubilities in water were performed. The values of temperature (T) dependence coefficients (Ai and Bi) in equations: log (Property)i = Ai - Bi/T were determined. Values of properties were compared with literature-based data, and an example of their use in environmental hazard estimation by fate modeling was given.     

Dynamic mathematical model for biotransformation and mass transfer of livestock generated VOC-odor in a bioactive dust practice system

A multi-step mass transfer-biodegradation model is developed to describe the bioactive adsorber dynamics for the biotreatment of livestock generated odor causing VOCs (VOC-odor) based on a biologically active dust particle (BADP) process. The BADP process employs dust particles with adsorbat-acclimated microbial culture to form the bioactivated dust particles (BDP) for the simultaneously adsorption, mass transfer, and biodegradation of VOC-odor. The model incorporating age and size distributions of BDP considers the equilibrium partitioning of VOC-odor at BDP and bulk gas interface that followed by two kinetic processes occurring in the bulk and solid phases: bulk gas mass transfer-biodegradation and BDP biofilm diffusion-biodegradation. Analytical equations indicate that the overall biotransformation rate of VOC-odor in a BADP process is controlled by BDP-bulk gas equilibrium processes represented by the slowest of two kinetic processes determined by a dimensionless group: the Thiele modulus (phi 2), the Damkohler number (Da) and the Biot number (Bi). Computer simulations demonstrate that the most favorable performance of a BADP system in reducing VOC-odor concentrations is operated under Bi < 1, Da < 1, or Bi > 1 phi 2 < 1; indicating diffusion-biodegradation controlled. The dimensionless group can be used to identify the dominant rate-limiting processes and to evaluate the overall biomineralization rate in a BADP process. Simulation results allow the determination of preliminary design for prototype development.     

纳米钒酸铋/偕胺肟纤维的制备及光催化性能

以Bi(NO3)3和NH4VO3作为原料,偕胺肟纤维作为配体,采用液相法合成钒酸铋/偕胺肟纤维(BiVO4/AOCF),通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、能谱(EDS)等手段对样品进行了表征分析,结果显示,颗粒状的BiVO4均匀分布在纤维表面,并以配位键的形式与纤维结合。以罗丹明B为模拟污染物来考察BiVO4/AOCF的光催化活性,实验结果表明,BiVO4/AOCF有着很好的光催化活性,并且在酸性条件下的催化活性更好。催化剂对活性黄、亚甲基蓝和甲基橙也表现出很好的光催化活性,且可以重复使用多次,光催化反应过程符合一级反应动力学。     

Effect of physiological conditions and biochemical factors of mussels Mytilus galloprovincialis in radioactivity monitoring programs along the Algerian coast

Environmental Science and Pollution Research - A study was carried out to determine the activities of radionuclides (137Cs, 40K, 226Ra, 214Bi, 214Pb, and 210Pb) and the levels of biochemical...     

Seasonal patterns of heavy metal deposition to the snow on Lambert Glacier basin,East Antarctica

Al, V, Mn, Fe, Cu, As, Cd, Ba, Pb, Bi and U were determined in a continuous series of 46 snow samples from a 2.3-m snow pit, covering the time period from austral spring 1998 to summer 2002, at a site on the east side of the Lambert Glacier basin in East Antarctica. Concentrations are very low for all metals and differ by orders of magnitude from one metal to another, with the mean concentrations ranging from 0.028 pg g⁻¹ for Bi to 165 pg g⁻¹ for Al. It is estimated that anthropogenic contributions are dominant for Cu, Pb and probably As, in the snow in our study area while the natural contributions from rock and soil dust, sea-salt spray and volcanic emissions account for most of the measured concentrations of the other metals. Our snow profiles show pronounced seasonal variations for Mn, As, Ba, Pb and Bi throughout the year, but a very different situation is observed between different metals. These observations suggest that heavy metals determined in our samples are controlled by different transport and deposition mechanisms related to physical and chemical alterations in the properties and sources of aerosol.     

Elemental composition of Marrubium astracanicum Jacq. growing in tungsten-contaminated sites

Environmental Science and Pollution Research - This study evaluates the elemental (W, Mo, Zn, Fe, Cu, Cd, Mn, Pb, Cr, Co, B, and Bi) composition of Marrubium astracanicum Jacq. (Lamiaceae), around...     

Testing the Bergerhoff method to determine the bulk deposition loads of 49 elements

The suitability of the simple and rather cheap Bergerhoff method for the determination of bulk deposition loads of 49 elements was tested. The method is suitable for the following elements: Ag, Al, As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Ge, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Th, Ti, Tl, V, W, Y and Zn provided that for some of these elements one does not get total recovery with HNO₃-digestion. This, nevertheless, supplies sufficient information for most concerns. Analytical problems were encountered for the following elements: U and Te concentrations in our samples were close to the blanks; P and Ta were highly variable within the sampling areas; B, Hf and Zr leached out of the glass of the digestion vessels; Hg is highly volatile.Field studies at three background sites in Switzerland, two on the northern side of the Alps and one in the southern Alps, showed higher burdens of element emissions in the latter, partly because of higher precipitation, and partly because of higher concentrations in the dust. An anthropogenic influence can be inferred for Ag, Bi, Cd, Cu, Hg, Mo, Pb, Sb, Te, W and Zn and probably also for As, P, S (with associated Se) and Sn.     

Sorption studies of heavy metal ions on a novel chelating resin and its application in the stripping of mercury (II)

A chelating resin containing a stable thiol group was synthesised, using polystyrene as the starting material. The resin is stable towards conc. HCl, 0.1M HNO(3) and 0.1M NaOH. The resin shows affinity towards Ag(+), Hg(2+), Bi(3+), Pb(2+), Cu(2+), Zn(2+) and Cd(2+). Extraction of these metal ions as a function of pH, kinetics of exchange and breakthrough capacities is evaluated. The selectivity of the resin for the metal ions is in the order Ag(+) > Hg2+ > Cu2+ > Pb2+ > Cd2+ > Zn2+. The equilibrium constants for exchange and kinetics of exchange are favourable for the recovery of mercury from lean sources. Application of the resin in the stripping of mercury from chlor-alkali plant affluent, and in the enrichment of mercury from seawater, have been investigated. Mercury sorbed resin can be regenerated using 5% thiourea in 0.1M HCl.     

以PEG为模板剂制备Bi2O2CO3及其可见光光催化性能

以聚乙二醇-6000（PEG-6000）为模板剂水热法制备碳酸氧铋（p-Bi2O2CO3）粉末,采用x射线衍射（XRD）、扫描电镜（SEM）、X射线光电子能谱（XPS）、透射电子显微镜（TEM）和紫外可见漫反射（DRS）对粉末进行了初步表征。在可见光（λ≥420nm）照射下,以罗丹明B（RbB）和水杨酸（SA）光催化降解实验为探针反应,实验结果表明,p-Bi2O2CO3具有较高的光催化活性,对RhB和SA有较好的降解效果。通过紫外-可见光谱（uV-Vis）、红外光谱（IR）和测定总有机碳（TOC）含量,光催化反应35h后RhB的矿化率为77％,同时对SA的降解率达到43％。同时,采用N,N-二乙基对苯二胺（DPD）分光光度法和对苯二甲酸荧光光度法分别测定了降解过程中H2O2和羟基自由基（·OH）的变化,表明p-Bi2O2CO3／Vis光催化降解机理涉及到·OH历程。