铁氧体—高压水解一步除氰,镍的机理研究

本文研究了在１．０１３ＭＰａ，１８０℃条件下，废水中ＣＮ＾－，ＮＨ３，Ｎｉ＾２＋并存时，以形成铁氧体同时进行高压水解一步除氰，除镍的反应机理。结果发现，镍铁氧体的形成是由于镍离子取代了Ｆｅ３Ｏ４中的两价铁的晶格位置形成的，新生太的Ｆｅ３Ｏ４具有表面吸附作用，但随着反应时间的延长吸附量会有所下降；氰水解是镍形成铁氧体的前提，为含氰、含镍废水在高压水解条件下铁氧体一步法治理奠定了理论基础。     

纳米Fe3O4对小鼠肺细胞的氧化损伤

纳米Fe3O4作为一种功能材料,在生物医药、生物靶向材料、微波吸收材料和高梯度磁分离器等方面应用前景广阔,其潜在的生物毒性也备受关注。为研究纳米Fe3O4对生物体可能造成的氧化损伤,以昆明小鼠为受试体,设置5、10、20和40mg·kg-14个染毒组,腹腔注射染毒7d后,测定小鼠肺组织中活性氧(reactive oxygen species,ROS)、还原型谷胱甘肽(glutathione,GSH)和丙二醛(malondialdehyde,MDA)的含量。结果显示,随着纳米Fe3O4染毒剂量的升高,肺组织ROS和MDA含量逐渐上升,GSH含量逐渐降低,各指标均呈一定的剂量-效应关系。剂量≥10mg·kg-1,肺组织ROS含量与对照组相比有显著差异(p<0.05);剂量≥20mg·kg-1,肺组织MDA含量与对照组相比有显著差异(p<0.05);剂量≥40mg·kg-1,肺组织GSH含量与对照组相比有显著差异(p<0.05)。研究表明,较高剂量(≥20mg·kg-1)的纳米Fe3O4颗粒材料会引起小鼠肺细胞的氧化损伤。     

NiFe2O4直接分解二氧化碳成碳循环反应过程结构演变研究

用XRD Rietveld分析法,对共沉淀法制备的NiFe2O4在H2／CO2循环反应中的结构演变进行研究,发现随着循环反应次数的增加,NiFe2O4物相的含量逐渐降低,Fe2Ni1-x物相的含量及其(200)衍射的平均晶粒逐渐增大,并出现Fe3C物相,其含量增长较快．纯NiEe2O4经15次循环反应后,体系中NiFe2O4物相的含量只剩下5％左右,样品基本失去分解CO2的活性．NiFe2O4掺杂4％铬后,明显提高了NiFe2O4骨架结构的稳定性,虽经50次H2／CO2循环反应,体系中NiFe2O4物相含量仍然有20％,分解CO2的活性仍达到初始活性的40％．     

Immobilization of NZVI in polydopamine surface-modified biochar for adsorption and degradation of tetracycline in aqueous solution

Polydopamine/NZVI@biochar composite (PDA/NZVI@BC) with high removal efficiency of tetracycline (TC) in aqueous solutions was successfully synthesized. The resultant composite demonstrated high reactivity, excellent stability and reusability over the reaction course. Such excellent performance can be attributed to the presence of the huge surface area on biochar (BC), which could enhance NZVI dispersion and prolong its longevity. The carbonyl group contained on the surface of biochar could combine with the amino group on polydopamine(PDA). The hydroxyl groups in PDA is able to enhance the dispersion and loading of NZVI on BC. Being modified by PDA, the hydrophilicity of biochar was improved. Among BC, pristine NZVI and PDA/NZVI@BC, PDA/ NZVI@BC exhibited the highest activity for removal of TC. Compared with NZVI, the removal efficiency of TC could be increased by 55.9% by using PDA/NZVI@BC under the same conditions. The optimal modification time of PDA was 8h, and the ratio of NZVI to BC was 1:2. In addition, the possible degradation mechanism of TC was proposed, which was based on the analysis of degraded products by LC-MS. Different important factors impacting on TC removal (including mass ratio of NZVI to BC/PDA, initial concentration, pH value and the initial temperature of the solution) were investigated as well. Overall, this study provides a promising alternative material and environmental pollution management option for antibiotic wastewater treatment.

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芬顿试剂法制备磁性碳纳米管及其对亚甲基蓝的吸附性能

采用芬顿试剂法在碳纳米管纯化样品表面负载纳米磁性氧化铁颗粒,制备磁性碳纳米管杂化材料(MWCNTs/Fe2O3),该杂化材料具有较高的纳米氧化铁负载率(>50%)和优异的磁性能,制备过程中无需额外添加阳离子,不会对环境造成不利影响.将磁性碳纳米管杂化材料应用于染料废水处理中,结果发现MWCNTs/Fe2O3对亚甲基蓝染料吸附性能较好,吸附后用磁铁易于达到固液分离的效果.吸附性能研究表明,磁性碳纳米管对水溶液中亚甲基蓝的吸附在40 min内吸附容量迅速上升,其值达到最大平衡吸附容量的88%以上,60 min基本达到平衡,吸附过程符合准二级动力学模型(R2>0.999).磁性碳纳米管吸附亚甲基蓝的平衡吸附量qe与亚甲基蓝溶液的平衡浓度Ce的关系满足Langmuir(R2>0.999)、Freundlich(R2>0.97)以及Dubinin-Radushkevich(D-R)(R2>0.96)等温吸附模型.通过Langmuir模型计算可知磁性碳纳米管对亚甲基蓝的最大吸附容量为69.98 mg.g-1,吸附过程为有利吸附,由D-R模型计算结果可以推断MWCNTs/Fe2O3对水溶液中亚甲基蓝的吸附机制以化学吸附为主.     

太阳辐射减弱麦田根际土壤酶与有效微量元素的相关性分析

由于大气气溶胶浓度增加地表太阳辐射减弱地球变暗。采用遮光网模拟太阳辐射减弱,设置60%、40%、20%、15%、0%的遮光递度,大田种植冬小麦,测定了冬小麦拔节期、孕穗期、抽穗期、灌浆期根际土壤过氧化氢酶、转化酶、脲酶的活性以及根际土壤Cu、Fe、Mn、Zn等有效微量元素的含量。采用相关性分析、通径分析和主成分分析等方法分析了太阳辐射减弱后土壤酶活性和土壤有效微量元素的相关性。结果显示,太阳辐射减弱,降低了小麦根际有效Fe、Zn和Mn的含量以及脲酶活性。有效Cu元素除了孕穗期有所增加外其它时期也均为降低。过氧化氢酶和转化酶的活性的变化没有明显规律性。太阳辐射减弱使得土壤过氧化氢酶活性与有效Fe、Zn极显著的正相关,脲酶与Zn也达显著水平。Zn和Fe对土壤酶的直接通径系数和间接通径系数都较大。太阳辐射减弱改变了土壤酶和微量元素在土壤肥力中的权重,最大肥力权重脲酶被过氧化氢酶所取代。结果表明,太阳辐射减弱影响了土壤根际有效微量元素含量和土壤酶的活性,提高了土壤酶和微量元素之间的相关性,反映土壤肥力微小变化的敏感土壤质量指标有一定的变化,脲酶的肥力权重降低,过氧化氢酶的肥力权重增加。     

High-valent iron-based oxidants to treat perfluorooctanesulfonate and perfluorooctanoic acid in water

Perfluoroalkyl and polyfluoroalkyl substances are occurring in consumer and industrial products. They have been found globally in the aquatic environment including drinking water sources and treated wastewater effluents, which has raised concern of potential human health effects because these substances may be bioaccumulative and extremely persistent. The saturated carbon–fluorine bonds of the substances make them resistant to degradation by physical, chemical, and biological processes. There is therefore a need for advanced remediation methods. Iron-based methods involving high-valent compounds are appealing to degrade these substances due to their high oxidation potentials and capability to generate environmentally friendly by-products. This article presents for the first time the oxidation ability of tetraoxy anions of iron(V) (Fe^VO₄ ^3?, Fe(V)), and iron(IV) (Fe^IVO₄ ^4?, Fe(IV)), commonly called ferrates, in neutral and alkaline solutions. Solid compounds of Fe(V) (K₃FeO₄) and Fe(IV) (Na₄FeO₄) were added directly into buffered solution containing perfluorooctansulfonate and perfluorooctanoic acid at pH 7.0 and 9.0, and mixed solutions were subjected to analysis for remaining fluoro compounds after 5 days. The analysis was performed by liquid chromatography–mass spectrometry/mass spectrometry technique. Fe(IV) showed the highest ability to oxidize the studied contaminants; the maximum removals were 34 % for perfluorooctansulfonate and 23 % for perfluorooctanoic acid. Both Fe(V) and Fe(IV) had slightly higher tendency to oxidize contaminants at alkaline pH than at neutral pH. Results were described by invoking reactions involved in oxidation of perfluorooctansulfonate and perfluorooctanoic acid by ferrates in aqueous solution. The results demonstrated potentials of Fe(V) and Fe(IV) to degrade perfluoroalkyl substances in contaminated water.     

Heterogeneous photocatalysis for removal of microbes from water

Increasing water pollution by microbes has become a source of serious health concern across the globe. Production of potentially carcinogenic disinfection by-products has marred credibility of traditional water purification techniques like chlorination. Photocatalysis has emerged as a promising alternative technique for the disinfection of water with minimal risk of harmful by-products. The process involves a wide band gap semiconductor material which, upon irradiation of light, produces electrons and holes with high redox potential to degrade organic contaminants and microbes. In this review, we analyze the research trends in photocatalytic inactivation of water borne microorganisms. This report analyzes the major factors that affect the disinfection efficiency using this process. The discussion also includes plausible mechanisms of microbial degradation as well as a kinetic model of the inactivation process. Different approaches, like doping of semiconductors or energy band engineering or plasmon coupling, have been reported for the enhancement and utilization of ambient solar light. Photocatalysis could be a cost-effective and environmentally friendly water purification technique though further research is required to enhance its efficiency with the use of solar light.     

磁性介孔硅胶萃取剂的制备及萃取性能研究

合成了C18基团修饰的磁性介孔硅胶材料,并利用该材料建立了磁性固相萃取-色谱分析方法,测定了几种环境水样中酞酸酯类(PAEs)污染物的含量.结果表明,该材料具有较大的比表面积(273 m.2g-1)和饱和磁通量(29 emu.g-1),对水样中痕量的PAEs有较强的萃取能力,而且萃取剂的磁分离特性使得萃取操作更为方便、快捷.在优化条件下,30 mg萃取剂在40 min内即可从500 mL水样中萃取痕量PAEs,回收率可达80%以上.此外,该萃取剂在处理复杂环境样品时仍能保持较强的萃取能力,环境水样中4种PAEs的检测限可达15.6—32.5 ng.L-1,加标回收率为62%—109%,相对标准偏差为2%—8%.     

滇池沉积物中重金属污染特征及其生态风险评估

采集了滇池北部和中心区域2根柱状沉积物样品,分析其常量元素（Fe、Mn、Al、Ti、Ca、K）、微量元素（Ba、Sr、Cu、Pb、Zn、V、Cd）剖面分布特征,并采用H？kanson潜在生态危害指数法对典型重金属（Cd、Cu、Zn、Pb）进行了污染潜在生态风险评估。结果表明：沉积物中常量元素以Fe2O3、CaO及Al2O3为主,MnO、K2O及TiO2含量较少,变化范围是Fe2O3为8.0～14.9%、MnO为0.1～0.2%、Al2O3为9.0～20.1%、TiO2为1.5%～2.8%、CaO为0.4～21.7%、K2O为1.5～2.0%;微量元素Pb, Cd, Zn, Ba, Cu, Sr 及V含量均较高,变化范围是Pb为73.8～105.3 mg·kg^-1、Cd为1.0～3.4 mg·kg^-1、Zn为123.4～210.6 mg·kg^-1、Ba为264.8～435.7 mg·kg^-1、Cu为77.5～133.5 mg·kg^-1、Sr为34.9～137.5 mg·kg^-1以及V为177.7～284.7 mg·kg^-1。尤其表层0～12 cm内（1950 s以后）,各元素含量值均明显高于12 cm以下各值,20世纪50年代后滇池流域内工农业发展及污染物输入是造成金属元素含量累积的主要因素。沉积物中典型重金属Cu、Zn、Pb、Cd污染潜在生态风险评估结果：Cu、Zn和Pb处于中度污染,且C if 值越接近表层（0～12 cm）其值越高,这表明自1950S后污染程度不断加重,其中 Cd 累积与污染比较严重,分析多种元素的多因子污染参数之和C d表明滇池沉积物中多种元素污染整体处于“较高”污染程度,分析多种元素的潜在生态风险指数RI表明滇池沉积物中重金属潜在生态风险处于“很高”水平。同时,滇池北部沉积物中重金属潜在危害较严重且近年来污染有加重趋势。     

紫外吸收剂在湖泊中的分布及其对底栖动物的毒性效应

紫外吸收剂大量用于工业材料和个人护理品中,近年来在水体中不断被检出,同时由于其高度亲脂性,易在底泥和水生生物体内富集,产生潜在的毒性效应,已成为一类新型污染物。本文综述了紫外吸收剂在湖泊环境中的分布和生物富集效应,重点分析了二苯甲酮类等典型紫外吸收剂对底栖动物的药物代谢系统、抗氧化系统及其生长发育的影响及其毒性作用机制,并对未来该领域的研究进行了展望。     

部分重金属化合物对淡水发光菌的毒性研究

应用微板毒性分析方法,分别测定了CdCl2·2.5H2O、CoSO4·5H2O、Cr(NO3)3·3H2O、Cu(NO3)2·3H2O、Fe(NO3)3·3H2O、MnCl2·9H2O、Na2SeO3、ZnSO4·7H2O、Ni(NO3)2·6H2O9种重金属离子化合物及其混合物对淡水发光菌—青海弧菌Q67(Vibrio-qinghaiensissp.—Q67)的发光抑制毒性.结果表明,9种重金属离子化合物对Q67的剂量-效应关系均可用Weibull或Logit模型有效描述.由拟合剂量-效应曲线得到这9种重金属离子化合物的半数效应浓度EC50的负对数值(-logEC50)分别为4.35、3.08、2.39、3.83、3.34、2.39、3.32、3.93和2.76,说明其毒性顺序为:CdCl2·2.5H2O>ZnSO4·7H2O>Cu(NO3)2·3H2O>Fe(NO3)3·3H2O>Na2SeO3>CoSO4·5H2O>Ni(NO3)2·6H2O>Cr(NO3)3·3H2O≈MnCl2·9H2O.为了研究重金属混合物的毒性规律,设计了4组等效应浓度(EC50、EC15、EC10和EC5)比混合物,测试了其混合物毒性,并应用剂量加和(DA)、独立作用(IA)原理及经典联合毒性评价方法进行了分析.DA与IA分析表明,所研究的4种混合物的毒性具有拮抗特征,而毒性单位法(TU)和混合指数法(MTI)的评价结果均为部分相加作用,相加指数法(AI)的评价结果则为拮抗作用.所选评价方法不同,混合物毒性评价结果可能也不同.     

Magnetic chitosan/sodium alginate gel bead as a novel composite adsorbent for Cu(II) removal from aqueous solution

Environmental Geochemistry and Health - Using sodium alginate hydrogel as skeleton, in combination with chitosan and magnetic Fe3O4, a new type of magnetic chitosan/sodium alginate gel bead (MCSB)...     

Fe_2O_3-SiO_2对燃煤过程中石灰石固硫特性的影响

本文探讨了不同温度条件下,Ca/S摩尔比、添加剂Fe_2O_3或SiO_2以及不同比例Fe_2O_3和SiO_2的混合物对石灰石固硫能力的影响,实验结果表明,温度能够大幅度地影响Ca/S比与石灰石固硫能力的关系,添加剂Fe_2O_3或SiO_2单独存在于煤样及煤样与石灰石共混样中的作用不同且不明显,同时添加一定比例的Fe_2O_3和SiO_2时,其促进作用较大,固硫能力大大优于纯石灰石。     

Photosynthetic oxygen production and PAM fluorescence in the brown algaPadina pavonica measured in the field under solar radiation

The effects of solar radiation on photosynthetic oxygen production, pulse amplitude-modulated (PAM) fluorescence and pigmentation were measured in the Mediterranean brown macroalgaPadina pavonica (Linnaeus) Lamouroux under field conditions and natural sunlight. Exposure of thalli to solar radiation for 1 h caused a dramatic decrease of their photosynthetic quantum yield, which recovered to initial levels after they had been placed in the shade for 3 h. Photoinhibition also occurred at the natural growth site ofP. pavonica during the hours of maximal solar irradiance. Photosynthetic oxygen production was also affected by high levels of solar radiation both in algae harvested from the surface and from 6 m depth; oxygen production started to decrease after a few minutes of exposure, and negative values were found after 1 h of solar exposure. Chlorophylla content inP. pavonica also decreased during the hours of maximal solar irradiation. These results suggest that photoinhibition ofP. pavonica occurs during part of a typical summer day on Mediterranean coasts.     

Utilization of nano/micro-size iron recovered from the fine fraction of automobile shredder residue for phenol degradation in water

Phenol removal by n/m Fe in the presence of H₂O₂ was highly effective. Increasing the amounts of n/m Fe and H₂O₂?increased the phenol removal rate. Phenol removal was decreased with an increase in the concentration of phenol. The natural pH (6.9) of the solution was highly effective for phenol removal. The pseudo-first-order kinetics was best fitted for the degradation of phenol. The study investigates the magnetic separation of Fe from automobile shredder residue (ASR) (<0.25 mm) and its application for phenol degradation in water. The magnetically separated Fe was subjected to an ultrasonically assisted acid treatment, and the degradation of phenol in an aqueous solution using nano/micro-size Fe (n/m Fe) was investigated in an effort to evaluate the possibility of utilizing n/m Fe to remove phenol from wastewater. The prepared n/m Fe was analyzed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The effects of the dosages of n/mFe, pH, concentration of phenol and amount of H₂O₂ on phenol removal were evaluated. The results confirm that the phenol degradation rate was improved with an increase in the dosages of n/mFe and H₂O₂; however, the rate is reduced when the phenol concentration is higher. The degradation of phenol by n/mFe followed the pseudo-first-order kinetics. The value of the reaction rate constant (k) was increased as the amounts of n/m Fe and H₂O₂ increased. Conversely, the value of k was reduced when the concentration of phenol was increased. The probable mechanism behind the degradation of phenol by n/m Fe is the oxidation of phenol through hydroxyl radicals which are produced during the reaction between H₂O₂ and n/m Fe.     

紫外光作用下氯酚的矿化程度比较

有关氯酚污染物光化学降解的研究,已有报道。ＨｕａｎｇＣＰ的工作较有系统性,他研究了四类深度化学氧化过程,检测指标是氯酚浓度。本文研究了在紫外光以及其它因素作用下,氯酚混合溶液的矿化程度,以溶液总有机磷浓度ＴＯＣ作为指标。所得结论,对于含有氯酚废水的治理,具有指导意义;对于难降解     

First continuous shipboard δ18O and δD measurements in sea water by diffusion sampling—cavity ring-down spectrometry

Combined measurements of salinity and the oxygen/hydrogen stable isotope composition of marine waters can characterise processes such as freshwater mixing, evaporation, precipitation and sea-ice formation. However, stable isotope data with high spatial and temporal resolution are necessary for a detailed understanding of mixed water bodies with multiple inputs. So far analysis of ??¹⁸O and ??D values in water has been a relatively expensive, laboratory-based technique requiring collection of discrete samples. This has greatly limited the scope and scale of field research that can be undertaken using stable isotope analysis. Here, we report the first continuous shipboard measurements of ??¹⁸O and ??D values in water by diffusion sampling-cavity ring-down spectrometry. Combined with continuous salinity recordings, a data set of nearly 6,000 measurements was made at 30-s intervals during a 3-day voyage through the Great Barrier Reef Lagoon. Our results show that continuous shipboard measurement of ??¹⁸O/??D values provides additional discriminatory power for assessing water mass formation processes and histories. Precise identification of river plumes within the Great Barrier Reef Lagoon was only possible because unique ??¹⁸O/??D?Csalinity relationships of individual plumes were measured at high spatial and temporal resolution. The main advantage of this new technique is the ability to collect continuous, real-time isotope data at a small fraction of the cost of traditional isotope analysi s of discrete samples. Water ??¹⁸O and ??D values measured by diffusion sampling-cavity ring-down spectrometry and laboratory-based isotope ratio mass spectrometry have similar accuracy and precision.     

Optimal exploitation of energy resources: Solar power and electricity generation in below sea level basins

This paper analyzes the generation of hydroelectric power by the transfer of seawater to locations which are significantly below sea level (e.g., the Dead Sea in Israel and the Qatara depression in Egypt) combined with solar energy that via evaporation will perpetuate the hydroelectric power capacity. Two scenarios are depicted. The first focuses on optimal planning of the canal capacity and optimal use of its water to generate hydroelectric power while filling the basin to its steady-state level. The second includes the impact of solar pools as a new technology whose date of adoption is a random event. It is shown that the optimal flow of water through the canal depends on the relationship between optimal canal capacity and the rate of water evaporation in the basin. The optimal design of the canal can be considered a hybrid between depletion of a natural resouce (the height differences in filling up the basin) and use of a renewable resource (solar energy to evaporate the basin water). The optimal policy is shown to consist of sequential intervals, some of which may vanish under certain conditions: first, the operation of the canal at full capacity; then the gradual decrease of water flow at a rate equal to the elasticity of the marginal product of electricity generation times the sum of interest rate and the marginal evaporation rate; and, finally, the stabilization of the water flow at the rate of steady-state evaporation. The stochastic model with the introduction of solar pools technology treated as a random event is formulated as a two-stage maximization problem. It is shown that, in contrast to the scenario without solar pools, the canal may be operated underutilizing its capacity in the initial period. But even in this case, the quantity of water flowing through the canal is a nonincreasing monotonic function over time with a jump in the quantity of flow at the date the solar pools are introduced.     

Efficient photocatalytic degradation of Rhodamine B dye using ZnO/graphitic C<Subscript>3</Subscript>N<Subscript>4</Subscript> nanocomposites synthesized by microwave

Semiconductor photocatalysis is a solution to issues of environmental pollution and energy shortage because photocatalysis can use solar energy to degrade pollutants. The photocatalytic activity can be improved by using composites of ZnO and other semiconductors. Here, composites of ZnO and polymeric graphite-like C₃N₄ (g-C₃N₄) with high photocatalytic activities were prepared by microwave synthesis. Products were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible and Fourier transform infrared spectroscopy. The photocatalytic degradation of Rhodamine B was tested under irradiation from a Xe lamp. Results show that adding graphite-like C₃N₄ promotes the photocatalytic activity of ZnO. Composites with 1.0 wt% g-C₃N₄ showed the best photodegradation efficiency, and the reaction average energy was approximately 33.71 kJ mol^?1.