淀粉基重金属捕集材料的微观结构及捕集效能

天然淀粉具有低毒、易降解、可循环利用等优点,经多元修饰后,具备捕集重金属的能力。使用季铵型醚化剂,磷酸盐及尿素对淀粉分子进行多元修饰,最终获得了多种电荷分布的淀粉分子修饰产品。通过红外光谱、固体核磁共振、扫描电镜及捕集效能评价等手段研究了淀粉基捕集剂的微观结构、特性及捕集机理。结果表明：淀粉分子成功引入阳离子季铵基团、阴离子磷酸基团及非离子的酰胺基团;比表面积增大,分子量增大,有利于对重金属离子进行捕集;0.06g淀粉基捕集剂对30mg/L混合溶液中铜、铅、镉、镍离子的去除率分别为97.80%、99.83%、99.23%、99.53%,均优于国家排放标准;其捕集吸附过程符合伪二级吸附模型,且由电性中和反应和微孔吸附联合共同控制。     

马铃薯改性淀粉重金属捕集剂

为了改变重金属废水的水质,使其达到排放标准,对改性淀粉重金属捕集剂进行了重点研究。通过整理相关文献可以发现,目前利用马铃薯改性淀粉制作的重金属捕集剂主要有黄原酸酯淀粉、磷酸酯淀粉、羟基淀粉、氨基淀粉、丙烯酰胺改性淀粉等。     

固废源CaO基CO2捕集材料的制备与捕集性能研究进展

CO₂捕集技术是当前应对全球气候变化、缓解温室效应的重要途径。利用含钙固体废弃物制备高效CaO基CO₂捕集材料有利于实现固废资源高值化利用、以废治废和清洁生产,具有重要的环境效益、经济效益和社会效益。基于固废源高效廉价CaO基CO₂捕集材料的良好应用前景,本文介绍了工业废渣、生物质和其他含钙固体废弃物的产生与资源化利用现状,综述了CaO基吸附剂的捕集原理、碳酸化动力学过程和CO₂捕集性能,对比了以不同含钙固体废弃物为前驱体制备CaO基吸附剂的吸附-脱附循环性能和不同改性方法对其吸附稳定性的影响,从经济角度分析了固废源CaO基吸附剂在钢铁厂、燃煤电厂和生物制氢中的应用潜力,展望了固废源CaO基CO₂捕集材料的应用前景和发展方向。该文旨在为固废源CaO基吸附剂前驱体的选择、吸附性能的提高和固废吸附材料的工业应用提供帮助。     

重金属捕集剂的合成与应用研究

将两种低分子量多胺物质与二硫化碳通过二步反应制得重金属捕集剂.通过正交实验优化,所合成重金属捕集剂对2 mg·L-1Cu2+和Ni2+废水的去除率分别达到98.35%和95.65%.并讨论了重金属捕集剂投加量、pH值及Cu2+、Ni2+共存条件对捕集剂处理低浓度Cu2+和Ni2+废水的影响.结果表明,重金属捕集剂投加量为0.0621～0.0955 mg·L-1时,处理后的水即可达到国家排放标准;pH值为7～10时,重金属捕集剂处理效果较好;在不同比例的Cu2+、Ni2+共存情况下,重金属捕集剂对两种离子均有较高的去除率,具有进一步研究应用价值.     

改性玉米淀粉对重金属捕集性能的研究

研究了二硫代氨基甲酸改性玉米淀粉(DTCS)对单一重金属溶液中重金属离子的捕集作用,考察了影响其捕集作用的因素,包括重金属种类、pH、温度、混凝时间、无机离子的干扰等,确定了合适的应用条件.结果表明,在单一重金属离子浓度为1.0×10-3 mol/L的溶液中,DTCS对重金属离子捕集的选择性:Cu2 ＞Pb2 ＞Cd2 ＞Zn2 ＞Ni2 ,去除率分别为99.91%、99.88%、87.36%、85.17%、66.36%,且K 、Ca2 等无机离子对其去除效果影响不大.     

重金属捕集剂对废水中铅捕集效果研究

研究了几种重金属捕集剂对含铅废水的处理效果，讨论了反应时间、捕集剂加入量、pH值及多种重金属离子共存条件下各种捕集剂对铅处理效果的影响。实验结果表明，在反应时间为20min，捕集剂加入量为理论用量的1．2倍，pH值为2～6时处理效果较好，捕集效率在99％以上，且多种重金属离子共存条件下对捕集效果没有影响，处理后的废水能达到重金属国家排放标准。因此采用该方法优于传统处理方法，有很好的应用前景。     

淀粉基重金属捕集剂的研究进展

与传统水处理药剂相比,改性淀粉作为絮凝剂和重金属捕集剂,具有成本低廉、可生物降解、毒性小、可再生等优点.按照反应类型,阐述了近年来酯化、醚化、接枝、氧化等几类改性淀粉作为重金属捕集剂的研究进展、应用现状及优缺点,同时对淀粉基重金属捕集剂的前景及发展趋势进行了展望.     

二氧化碳捕集技术及应用分析

分析了CO2捕集技术及现状。CO2捕集是CCS的关键技术单元之一,针对不同的CO2气源,国内外研究开发了多种技术。许多CO2捕集技术已经工业化,其中燃烧后烟气中CO2的捕集技术主要是以一乙醇胺(MEA)为基础的胺法;燃烧前的CO2捕集技术主要应用于IGCC电厂,一般需要对煤气中CO进行部分变换,变换后脱碳可采用成熟技术,如Selexol(NHD)等。富氧燃烧则是在中试成功的基础上,进行更大规模的工业示范。国内外大型煤制油化工项目主要采用低温甲醇洗脱除CO2,如果设置CO2产品塔,则可以获得体积分数98%以上的CO2。天然气脱碳主要采用MDEA技术。另外还有低温法、PSA、膜分离等CO2捕集技术及化学链燃烧等一些正在研发的技术。     

燃烧后CO2捕集材料研究进展

简要阐述全球和我国的化石能源及CO2排放现状,针对燃烧后捕集化石燃料电厂烟道气中的CO2气体,以溶液吸收、吸附、膜分离、生物固定4种捕集方法为线索,讨论了各类CO2燃烧后捕集材料的最新进展。     

燃烧后CO_2捕集技术研究

对燃烧前、燃烧后CO2捕集以及富氧燃烧3种CO2捕集技术的特点,以及适用于燃煤电厂的燃烧后CO2捕集技术进行了介绍,分析了吸收分离法、吸附分离法和膜分离法的原理及优缺点。其中,化学吸收法应用最广,但再生能耗大,运行成本高;吸附法虽再生能耗小,但对CO2选择性低,吸附能力有限;膜分离法目前仍处于实验室研究阶段,但应用前景巨大。对上述技术整合形成复合技术以及对新材料进行开发将有助于克服现有CCS技术面临的困难。     

Energy Trapping in Dications

The energy interaction curves of a number of diatomic and polyatomic dication systems were calculated in order to study their energy-trapping properties. Generally, the ab initio complete active space multiconfiguration self-consistent field method was used in an extended valence + polarization basis set, with compact effective potentials replacing the core electrons. The diatomic dications include all ten possible binary combinations of oxygen, sulphur, selenium, and tellurium. O₂²⁺ shows the largest exothermicity, measured from equilibrium to the monocation combination asymptote, and highest barrier to dissociation. The calculated equilibrium bond length and harmonic vibrational frequency agree very well with experiment. The O₂²⁺, SO²⁺, SeO²⁺, and TeO²⁺ series show progressively decreasing exothermicities but similar barrier heights. The non-oxides, in contrast, show similar exothermicities but decreasing barriers with increasing size of the atom constituents. These trends are interpreted in terms of both valence bond curve-crossing and molecular orbital bonding models. The ozone dication, O₃²⁺, is found to have a number of low-lying singlet and triplet stationary state structures spanning near-linear to D_3h2+ symmetries. Although the calculated exothermicity is even larger than for O₂²⁺, the barrier to O₂⁺ + O⁺ dissociation is predicted to be low in each case. O₂²⁺ surrounded by six argon atoms to model an isolating environment shows increased equilibrium O–O bond length, decreased exothermicity, and increased barrier to dissociation, relative to the bare dication. O₂²⁺ flanked at each end by a perpendicularly oriented H₂ molecule in a staggered conformation is obstructed from direct conversion to the water dimer dication by a high barrier. However, [(H₂O)₂]²⁺ dissociates smoothly from equilibrium to two water monocations with a large exothermicity but a small barrier.     

On the Trapping of Vinylgold Intermediates

An internal aryl‐substituted ortho‐alkynylphenol and a similar aniline with stoichiometric amounts of N,N′‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene‐gold tosylate [(IPr)AuOTs] and triethylamine gave the aurated heterocycles as stable intermediates of the corresponding gold(I)‐catalysed hydrooxylation and hydroamination reactions. X‐ray crystal structure analyses of both products could be obtained. A similar internal alkyl‐substituted ortho‐alkynylphenol gave only the cycloisomerised product, no aurated intermediate could be detected.     

Trapping levels in pulse-counting synthetic diamond detectors

Type Ib synthetic diamonds were used as pulse-counting radiation detectors. Special ion-implanted contacts to the diamond were used. These contacts were shown to suppress the development of space charge within the diamond, and to cause no significant voltage drop across the contacts. An initial large γ-ray pre-irradiation dose markedly improved the pulse counting response of the diamond. It is suggested that this improvement is due to relevent and involved traps being filled to saturation by charge carriers whereas the same traps in an under-populated state actively inhibit the charge collection for pulse formation. The traps are depopulated by exposure to ambient light and, using this depopulation effect, the effective energy level of these involved traps was measured to be 2.2 eV. Shallow trapping levels are postulated and are believed to be responsible for the trapping of the carriers which gives rise to space charge effects.     

Trapping Iron Oxide into Hollow Gold Nanoparticles

Synthesis of the core/shell-structured Fe₃O₄/Au nanoparticles by trapping Fe₃O₄ inside hollow Au nanoparticles is described. The produced composite nanoparticles are strongly magnetic with their surface plasmon resonance peaks in the near infrared region (wavelength from 700 to 800 nm), combining desirable magnetic and plasmonic properties into one nanoparticle. They are particularly suitable for in vivo diagnostic and therapeutic applications. The intact Au surface provides convenient anchorage sites for attachment of targeting molecules, and the particles can be activated by both near infrared lights and magnetic fields. As more and more hollow nanoparticles become available, this synthetic method would find general applications in the fabrication of core–shell multifunctional nanostructures.     

Probability of Trapping Solid Particles during Zone Melting

Abstract

The probability P of trapping of glass beads was measured for tilt rotating zone melting of camphor. P increased with increasing zone travel rate, increasing tilt angle, decreasing tube rotation, and increasing mass of beads. P also decreased dramatically with distance down the tube. This is attributed to increasing impurity content as the zone moves down the tube and by the changing shape of the freezing interface due to the diminished content of glass beads. Trapping was predominantly by periodic bands, indicating one or more catastrophic trapping mechanisms.     

External Trapping of Halomethyllithium Enabled by Flow Microreactors

This work demonstrates that the accurate control of the reaction parameters realized within microreactor systems allowed for a taming of the reactivity of thermally unstable intermediates such as haloalkyllithiums. The first example of effective external trapping of a reactive carbenoid such as the chloromethyllithium is described. By using microreactor systems, a continuous flow synthesis of chloro alcohols and chloro amines could be achieved with high yields. By controlling the residence time the highly reactive chloromethyllithium could be generated and reacted with electrophiles at temperatures much higher than in batch‐mode and without internal quenching. The developed continuous‐flow process matches the requirements for sustainability.

     

Trapping of Phyllophaga elenans with a female-produced pheromone

Attraction of Phyllophaga elenas to vaned bucket traps baited with the recently identified female-produced pheromone, L-isoleucine methyl ester (LIME), is efficient. Pheromone-baited vaned buckets with water to retain insects were more effective than buckets without vanes or plastic containers with the sides cut out. Pheromone-baited vaned bucket traps from which water was omitted required the addition of a funnel below the vanes to retain insects. Normally used light traps were about 10 times more effective than pheromone-baited vane bucket traps in capturing P. elenans. Over 95% of P. elenans were captured between 6:00 and 9:00 PM. The male–female ratio was 3–4:1 in both light and pheromone traps, and the ratio was relatively unchanged throughout the capture period. Most P. elenans were captured in the treed areas surrounding sugarcane fields. More P. elenans were captured in treed borders than in grassy borders of sugarcane fields. The effective radius of the pheromone-baited vaned bucket trap is between 5 and 15 m.     

Trapping two-particle arrays in a double-ring electrodynamic balance

A new technique has been developed to explore the characteristics and dynamics of the electrodynamic balance (EDB). It is demonstrated that by trapping a pair of microparticles, the electric field of and EDB can be characterized and particle stability can be investigated. The electric field in the neighborhood of the null-point was examined by comparing the oscillatory motion of the two-particle system with a theoretical analysis. In addition, the relevant balance constants were evaluated by five methods: (i) determination of the stabilization strength constant, C₁, using measurements on two-particle arrays, (ii) determination of the levitation strength constant, C₀, using measurements on single particles of known mass and charge, (iii) computation of C₁ and C₀ by solving the three-dimensional Laplace equation for the non-axisymmetric electrode system, (iv) computation of C₀ using a ring charge simulation technique, and (v) determination of the ratio C₁/C₀ by measurements of the marginal stability limit. The results of the different methods are compared and shown to be consistent.