NH_4~+对混合菌种的生长及光合产氢的影响

针对NH4+浓度对混合菌种的生长与光合产氢的影响进行了试验研究.通过对3种生长模型的对比,确定了修正的Compertz方程作为描述混合菌种光合生长的模型.结果表明NH4+对混合菌种的最大菌浊度影响不大.通过pH值的控制与不控制时不同NH4+浓度的对比产氢试验,发现不控制pH值时,NH4+对混合菌种光合产氢的抑制作用显著;而控制pH=7.0时,2.8mmol/L的NH4+浓度比无NH4+时的产氢率高、产氢速率快,而后随着NH4+浓度的继续增大,产氢率不断减少.这表明控制pH时,适当低浓度的NH4+可以提高混合菌种的光合产氢率以及产氢速率.无论是否控制pH值,只有NH4+被菌体的生长所消耗掉,才开始产氢,这表明NH4+对产氢的抑制作用在一定范围内是可恢复的.同时通过混合菌种与纯菌株Rh.Palustris Z02的对比试验发现,无论对于生长还是产氢,NH4+对混合菌种的影响均小于对纯菌株Rh.Palustris Z02的影响.     

零价铁和二价铁离子对发酵产氢效能的影响

研究了零价铁和二价铁离子对纯菌种R3及混合菌种生长与产氢作用的影响.在纯菌种间歇试验中,当添加零价铁浓度为100mg/L时,R3氢气含量的最大值为47%,而添加二价铁离子浓度为100mg/L时,R3氢气含量的最大值为45%,零价铁在浓度范围为0.4～100mg,L时对R3产氢的促进作用较明显,而在添加的零价铁和二价铁离子浓度分别大于100mg/L和200mg/L时,则都呈现了"反馈抑制"的现象,但是高浓度的零价铁对R3的"毒害"作用与二价铁离子相比也较低.在混合菌种连续流试验中,添加了零价铁的反应器Ⅰ运行至第4天时,出水pH值下降至4.3,达到了乙醇型发酵状态,氢气含量最大值为27%;而添加二价铁离子的反应器Ⅱ则是运行至第8天时,出水pH值才达到了乙醇型发酵状态,氢气含量最大值为26%.零价铁对混合菌种连续流试验的产氢促进作用同样优于二价铁离子.     

活性污泥分离混合菌的光合产氢特性分析

对从沼气池活性污泥分离出以多种光合细菌为主的混合菌种与纯菌种沼泽红假单胞菌Rh.Palustris Z02进行了光合产氢的实验研究,并利用修正的Gompertz方程进行产氢动力学分析.结果表明,混合菌种比纯菌种的光合细菌表现出更高的产氢能力和更好的稳定性.尤其在对蔗糖和可溶性淀粉的利用上,混合菌种对这两种碳源的利用比较充分,产氢率分别为3.47mol H2/mol蔗糖和6.68mmol H2/g可溶性淀粉,氢气含量分别为83.30%和76.06%,气相中没有甲烷气产生.而纯菌种Rh.Palustris Z02产氢率分别只有0.49mol H2/mol蔗糖和1.95mmol H2/g可溶性淀粉.混合菌种的产氢条件较肋Rh Palustris Z02更为宽松,以乙酸钠做碳源为例,混合菌种在温度20～40℃,pH=5～8时产氢较好,甚至在pH=5.0和9.0时,仍有微量氢气产生.而纯菌种Rh.Palustris Z02仅在25～35℃产氢较佳,在20℃仅有微量产氢(0.23mol H2/mol乙酸钠),产氢pH范围6～8,光强产氢范围同混合菌种相似,但是产氢率低于混合菌种.     

气相条件对混合菌种光合产氢的影响

针对不同气相条件对混合菌种以及纯菌种生长与产氢的影响进行了试验研究.结果表明N2、O2、Ar、H2的高纯气相条件均能够促进菌体的生长,但对产氢有明显的抑制,表明高纯气创造出的厌氧环境不适于产氢.CO2不仅对产氢有抑制作用,同时明显抑制菌体的生长.气相中大量的O2对固氮酶以及氢酶的毒害导致无法产氢,而微量O2的存在却能对产氢有促进作用,尤其是在Ar与微量O2的混合气相条件下,产氢率达到最高的2.38mol/mol乙酸钠,且产氢延迟期最短.同时发现气相条件对混合菌种产氢较纯菌种Rh.Palustris Z02的影响小.     

维生素B4对秸秆类生物质光发酵产氢的影响

以玉米秸秆类生物质为产氢原料,研究维生素B4对HAU-M1光合细菌生长和产氢过程的影响规律。结果表明,当维生素B4浓度为75 mg/L时,光合细菌生长情况最好,细菌干重最大值为0.934 g/L;维生素B4浓度为100 mg/L时,氢气累积产量达178 mL,比对照组显著提高了43.8%,对光合细菌产氢的促进效果最好;添加维生素B4对HAU-M1光合细菌发酵产氢过程的pH值影响显著,可减弱发酵液酸化,有利于光合细菌发酵产氢。显见,维生素B4对HAU-M1光合细菌生长及秸秆类生物质光合产氢具有明显的促进作用,可为进一步研究开发秸秆类生物质光合细菌发酵产氢工艺技术提供科学参考。     

光照波长对HAU-M1光合菌群产氢影响的研究

以菌体干重、比产氢速率、pH值和葡萄糖浓度等为主要实验指标,研究不同波长光源对HAU-M1光合菌群生长及光发酵产氢的影响,并用产氢动力学对光合菌群产氢进行分析.结果表明:相同光照强度下,相对于连续全光谱,492～622 nm波长光照能促进光合菌群生长及产氢;492～577 nm波长下菌群生长及产氢效果最佳,菌体干重达到...     

光合细菌利用葡萄糖产氢过程中菌体衰亡性研究

研究了葡萄糖作为产氢基质在产氢过程中对光合细菌的生长活性及产氢的影响,分析了产氢过程中菌体生长活性下降发生衰亡的原因,并就抑制菌体发生衰亡的相关措施进行了初步探讨.研究发现:光合细菌利用葡萄糖产氢过程中细胞生长活性下降迅速,葡萄糖会抑制菌体的生长,促使细胞衰亡.产氢过程中批次添加葡萄糖虽然可以在一定程度上抑制菌体的衰亡,但对产氢并没有促进作用,产氢速率低,产氢总量只达到对照组的87%.产氢过程中外源调节菌液pH值对菌体的生长及产氢有显著促进作用,细胞生长达到对照组的1.46倍,产氢总量达到对照组的1.36倍.     

海洋光合菌群利用乙酸产氢的实验研究

通过富集获得产氢海洋光合菌群,该菌群可以有效利用发酵产氢的关键副产物乙酸作为产氢碳源.温度、光照强度、起始pH和乙酸浓度都对该菌群产氢和生长有明显影响.当在30℃、4000lx光照和起始pH=8.0的条件下培养时,此光合菌群产氢量和底物转化效率较高.乙酸浓度对产氢影响巨大,低浓度乙酸的底物转化效率较高,但总产氢量不高;高浓度乙酸的底物转化效率不高,但总产氢量较高.此实验结果为海洋光合细菌与海洋发酵细菌偶联产氢提供科学参考.     

光合细菌小分子酸醇产氢试验研究

以光合产氢混合菌群为研究对象,研究了光合细菌在乙酸、乙醇、乳酸、丁酸几种小分子脂肪酸条件下菌体的生长和产氢特性,详细考察了乙酸和丁酸对光合产氢细菌生长和产氢的影响.研究发现,乙酸、丁酸既是光合细菌良好的生长碳源,也是高效氢供体,光合细菌在乙酸和丁酸条件下产氢率分别达到2.05和2.81molH2/mol.光合细菌以乙酸和丁酸产氢时,乙酸和丁酸的最佳添加浓度均为40mmol/L;光合细菌在乳酸条件下有较高的生长活性,但乳酸并不是光合细菌高效氢供体,光合细菌在乳酸条件下产氢活性较低;乙醇既不是光合细菌良好生长碳源,也不是高效氢供体,乙醇对光合细菌的生长和产氢均有较强的抑制作用.     

铁、铜金属卟啉络合物光助催化分解水产氢的研究

用非贵金属卟啉络合物(Cu、Fe、Zn、Mn、Co、Ni)为光敏剂,三乙醇胺为电子给体,氯铂酸钾为催化剂,2,2′-联吡啶为助剂,Triton x-305为表面活性剂,做成胶束溶液体系,探讨了该体系在紫外光照下还原水产氢的功能。观察了不同pH值、组成,表面活性剂浓度和光照时间等对产氢量的影响,并提出了各组份的协同作用和可能的产氢机理。     

改性西瓜皮生物炭对废水中Pb2+的吸附研究

以西瓜皮为原料制备生物炭（WM）吸附水中的Zn²⁺,再将吸附后的生物炭进行二次热解,制得WM-Zn并用于吸附水中的Pb²⁺。研究表明,WM-Zn对Pb²⁺ 的吸附容量（163.84 mg/g）高于WM的吸附容量（87.64 mg/g）。利用X射线光电子能谱（XPS）、傅里叶变换红外光谱（FTIR）、元素分析（EA）、X射线衍射（XRD）、吸附比表面测试法（BET）和Zeta电位对生物炭进行了表征,发现WM-Zn表面孔结构的扩大和官能团的增多均有助于Pb²⁺ 的去除,WM-Zn对Pb²⁺ 的吸附可归结为官能团络合、静电吸附、物理吸附和沉淀作用。此外,WM吸附Zn²⁺ 和WM-Zn吸附Pb²⁺ 均符合Langmuir等温吸附模型和拟二级动力学模型,表明吸附过程是以单分子层吸附为主的化学吸附。在吸附-解吸循环实验中,WM-Zn在第6次循环中吸附量可达到87.36 mg/g,表明WM-Zn吸附具有良好的可重复性。     

Red-emitting CaSc2O4:Eu3+ phosphor for NUV-based warm white LEDs: structural elucidation and Hirshfeld surface analysis

We have prepared Eu³⁺ activated phosphor from the host CaSc₂O₄ (CSO) via high-temperature facial solid-state route and characterized by various spectral techniques. Surface morphology and composition was determined via scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDAX). The crystal structure refinements show the Pnam 62 space group with two active centres for Eu³⁺ in the prepared CSO:Eu³⁺ phosphor. Additionally, first time the detailed investigation of intermolecular interactions through Hirshfeld surface (HSs) analysis for the inorganic phosphor has been reported, the analysis indicates that the Sc/Eu O and Ca O contacts in the CSO:Eu³⁺crystal account for more than 60% and 26% of the total HSs area. The synthesized phosphor shows an intense red emission at 618 nm (Ex 394 nm) with a CIE coordinates of (0.633, 0.358) and measured internal quantum efficiency (IQE) was found to be 84%. Further, correlated colour temperature was estimated to be about 6049 K including colour purity of 93.04% for Eu = 0.10 and the thermal stability were established by their temperature dependent study (400 K = 92%). Therefore, the phosphor of CSO:Eu³⁺ exhibits a potential application for UV-based warm white LEDs and in the determination of intermolecular interactions through HSs surface analysis studies.     

电混凝法处理电镀废水中的Cu^2＋和Zn^2＋

利用电混凝法处理含Cu^2＋和Zn^2＋的电镀废水,系统地考察了电解电压、进水pH值、极板间距、电解时间等因素对废水处理效果的影响,确定了最佳的电解条件。实验结果表明,电混凝法处理的电镀废水出水水质较好。当电压为80 V,pH值为5,电解时间30 min,极板间距为10 mm时,处理后的废水中Zn2＋浓度为0.36mg/L,去除率达到97.9%,Cu^2＋浓度为0.0049 mg/L,去除率达到99.9%,均可达到国家规定的排放标准,且该法运行方便,处理时间短,是较理想的电镀废水处理工艺。     

Mn2+‐doped Zn2GeO4 for photocatalysis hydrogen generation

Zn₂GeO₄ and Zn₂GeO₄:Mn²⁺ were synthesized by a hydrothermal method. The phase, microstructure, and optical and photoelectrochemical properties were investigated. The photocatalytic activities were evaluated by the photocatalytic hydrogen generation. The X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer‐Emmett‐Teller (BET) results indicate the Mn²⁺ doping has no obvious influence on the phase and microstructure of Zn₂GeO₄. But the Mn²⁺ doping influences the optical and photoelectrochemical properties obviously. The Mn²⁺ doping leads to the red shift of band gap edge and the light absorption in visible region. The Zn₂GeO₄:Mn²⁺ has the greater light absorption efficiency, more efficient e^?‐h⁺ pair separation and promoting charge transfer across the electrode/electrolyte interface. These characteristics of Zn₂GeO₄:Mn²⁺ suggest that it has higher activity than that of Zn₂GeO₄ and this is confirmed by the highly efficient hydrogen generation.     

Single crystal growth and properties of γ-phase in the CuInSe2+2CdS⇔CuInS2+2CdSe reciprocal system

The intermediate solid solution, γ-phase, exists in the CuInSe₂+2CdS⇔CuInS₂+2CdSe reciprocal system. It crystallizes in the cubic structure and has a wide homogeneity range. Single crystals of the γ-phase are grown by a modified Bridgman method and their composition, crystal structure, optical and electrical properties are studied. The band gap varies from 1.43 to 1.05 eV along the ‘Cu₃Cd₂In₃S₈’-‘CuCd₂InSe₄’ compositional section. The crystals are photosensitive, mostly p-type, with hole concentrations in the 10¹⁵-10¹⁶ cm⁻³ range and mobilities up to 18 cm²/V s. The results indicate that the γ-phase can be considered as a new absorbing material for thin-film solar cells.     

Daytime urban heat islands from Landsat ETM+ and Corine land cover data: An application to major cities in Greece

Satellite images in the thermal infrared can be used for assessing the thermal urban environment as well as for defining heat islands in urban areas. In this study, the thermal environment of major cities in Greece (Athens, Thessaloniki, Patra, Volos and Heraklion) is examined using satellite images provided by the Landsat Enhanced Thematic Mapper (ETM+) sensor on board Landsat 7 satellite corresponding to the daytime and warm period when the surface urban heat island (SUHI) phenomenon is best observed. The spatial structure of the thermal urban environment is analyzed in each case study and the “hottest” surfaces within the urban settings are identified and related to the urban surface characteristics and land use. For the needs of the study, the Corine land cover (CLC) database for Greece is also used, in an effort to define more effectively the link between surface emissivities, land surface temperatures and urban surface characteristics.     

Removal of Cu2+ and Pb2+ in aqueous solutions by fly ash

In this study, the removal of Cu²⁺ and Pb²⁺ ions by precipitation from aqueous solutions by using six fly ashes with different compositions was achieved. The effect of four parameters on the removal of Cu²⁺ and Pb²⁺, which are contact time, fly ash composition, pH of the solution and fly ash concentration, were investigated. The fly ash concentrations required to achieve maximum Cu²⁺ and Pb²⁺ removal were found to vary between 0.2–10 and 0.075–3.5 g/l, respectively. It was also observed that both the Cu²⁺ and Pb²⁺ removal capacities of the fly ashes depend strongly on their CaO content.     

应用Na2O2吸收控制汽车尾气中CO2排放物

简述了汽车排放污染物的种类、危害及各种相应的减排控制措施,针对CO2这一温室气体提出了通过Na2O2吸收的解决方案,并给出了CO2吸收器的基本构造和反应机理,同时也指出了这一方案在实际运行中存在的问题。     

二价铁离子对糖蜜酒精废水厌氧发酵的影响

提高糖蜜酒精废水的厌氧发酵效率,实现其资源化再利用,本文研究了添加一定量Fe²⁺ 对糖蜜酒精废水厌氧发酵处理过程的影响。结果表明：添加Fe²⁺后发酵液中SO₄²⁻ 的去除率由77.12%提高至90.79%;COD去除率由57.34%提高至81.14%;累积沼气产量由386 mL•g⁻¹ VS提高至475 mL•g⁻¹ VS;产气周期由29天缩短为26天;其氧化还原电位（ORP）升高,pH值降低。     

Electrocatalytic performance of TiO2 with different phase state towards V2+/V3+ reaction for vanadium redox flow battery

In this paper, titanium dioxide (TiO₂) nanoparticles were employed as catalysts towards V²⁺/V³⁺ redox couple of vanadium redox flow battery (VRFB). The effect of TiO₂ phase on the electrocatalytic performance for negative couple was systematically investigated. The electrochemical properties of TiO₂ with different phase were assessed via cyclic voltammetry and electrochemical impedance spectroscopy by using AB as conductive agent. Obtained from the results, anatase TiO₂ (α‐TiO₂) exhibits superior electrocatalytic activity to rutile TiO₂ (γ‐TiO₂). The VRFB cell performs well at discharge capacity, voltage efficiency, and energy efficiency by employing α‐TiO₂‐modified negative electrode with current density varying between 50 and 100 mA cm^?2. The discharge capacity of α‐TiO₂‐modified cell with vanadium ion concentration of 1.6 M comes up to 113.5 mA h at 100 mA cm^?2 current density, which is increased by 39.1 mA h after modification for negative electrode. Moreover, the corresponding energy efficiency increases by 7.5% after modification of α‐TiO₂. Experimental results show that TiO₂ is an ideal catalyst for VRFB. Moreover, α‐TiO₂ demonstrates superior electrocatalytic performance to γ‐TiO₂ towards V²⁺/V³⁺ reaction.