ICP-MS法测定微(痕)量金方法的改进

本文研究了硫脲浓度对地质样品中痕量金测定的影响。硫脲沉积会降低ICP-MS使用寿命,影响测试准确度。为解决这一问题,探讨了降低硫脲浓度的可行性,当硫脲浓度降至0.5 g/L时,相关系数r=0.999 6,加标回收率:95～107%,结果符合实验室相关的质控要求。故ICP-MS改进方法能够有效解决微痕量金分析中硫脲沉积问题,提高测试效率,延长仪器使用寿命。     

金在碱性硫脲溶液中溶解的电化学动力学

研究了金在碱性硫脲溶液中阳极溶解的电化学行为及动力学. 结果表明,硫脲浓度由0增加至0.2 mol/L时,开路电势由-130 mV移至-280 mV,达到稳态的时间由400 s延长至800 s. 循环伏安曲线上正向扫描时700 mV的电流峰为金的阳极氧化峰,850 mV之后阳极电流急速上升为氧气的大量析出,反扫时220 mV处为溶液中金离子的还原峰. 溶液中加入硫脲使金的阳极氧化峰电势负移了30 mV,峰电流则提高了15.5倍. 由于硫脲的分解及其产物对金电极表面的钝化,硫脲浓度由0.05 mol/L增加至0.20 mol/L时,阳极峰电势由655 mV负移至480 mV,峰电流则由1.985 mA降至0.09528 mA. pH值升高有利于金在碱性硫脲溶液中的阳极溶解. 温度由25℃升高至35℃时,峰电流由0.761 mA迅速增加至4.387 mA,峰电势由655 mV负移至596 mV,有利于金的溶解;但温度太高会增加硫脲自身的氧化分解. 金的阳极溶解为不可逆电荷转移反应.     

硫脲法浸出废弃电脑线路板中金的研究

废弃电脑线路板是一种典型的电子废弃物,其中含有丰富的贵金属资源,而金的回收是废弃电脑线路板资源化研究的热点。研究了用硫脲浸出废弃电脑线路板中的金,考察了硫脲质量浓度、反应时间、反应温度、三价铁离子质量分数、溶液pH对金浸出率的影响。结果表明,在硫脲质量浓度为12 g/L、反应时间为60 min、反应温度为30 ℃、三价铁离子质量分数为0.45%、溶液pH为1.5条件下,金的浸出率达到90.93%。硫脲法浸金因具有浸出速率快、浸出时无毒、对环境污染小、试剂易再生、干扰离子少等优点而具有广泛的应用前景。     

活性炭从硫脲液吸附黄金

活性炭从硫脲液吸附黄金介绍了巴西里约热内卢大学材料冶金工程系用活性炭从硫脲溶液中回收黄金的研究。发现，在１５～５５℃下用活性炭吸附金离子及硫脲的机理与弗劳特里奇（Ｆｒｅｕｎｄｌｉｃｈ）吸附等温线能很好相符。对金的吸附是一种放热反应，而对硫脲的吸附是一...     

难处理混合型金矿的浸金研究

探讨了用非氰化法从混合型金矿中浸取金的可能性，主要研究了硫脲法浸金时，硫酸铁浓度，硫脲浓度，酸度，温度，浸取时间及固液化等实验条件对金浸出率的影响，并与微波等方法进行了比较。     

高稳定性碱性硫脲体系对不同类型金矿的适应性

为考察碱性硫脲体系对不同类型金矿浸出的适应性,选用理化性质不同的6种含金物料,分析了其化学组成及矿物物相,并对其浸出行为进行了研究. 结果表明,稳定剂Na2SO3和Na2SiO3大大降低了碱性硫脲的分解率,随稳定剂浓度的增大,硫脲分解率逐渐降低;而且Na2SiO3对碱性硫脲的稳定效果明显优于Na2SO3,当Na2SiO3浓度为0.3 mol/L时,硫脲的分解率由72.5%降至33.8%. 铁氰化钾为适合碱性硫脲浸金的温和氧化剂. 碱性硫脲体系中金矿物浸出前后物相基本无变化. 所选择的金矿物中均含有大量耗碱物质,使溶液的pH值由12.5很快降至中性,但稳定剂Na2SiO3能维持体系的pH值在12左右,有利于浸出过程的进行. 碱性硫脲体系中伴生金属浸出率小于0.1%,浸金具有显著的选择性. 碱性硫脲体系适合浸出经预处理的物相主要为SiO2的氧化矿,浸金率高达82.68%,为碱性硫脲成功应用于黄金工业生产提供了一定的理论依据.     

泡沫塑料吸附—电感耦合等离子体质谱法测定区域地球化学样品中微量金方法探讨

泡沫塑料吸附-电感耦合等离子体质谱法是测定区域地球化学样品中微量金的常规方法,拥有极高的分析灵敏性和动态范围,但是经常会出现硫脲解脱率不稳定的问题,从而影响微量金的准确度,而且这个问题往往不容易被发现。针对上述问题,结合常量金的活性炭吸附方法,将泡沫塑料吸附-电感耦合等离子体质谱法中硫脲解脱用泡沫塑料吸附后进行灰化处理来替代,从而避免了硫脲解脱率不稳定的问题,本文将针对这个方法进行探讨。     

聚氨酯泡塑-硫脲介质在泡沫塑料富集原子吸收测定矿石中金含量的应用

建立了采用HCl-HNO3体系消解试样,聚氨酯泡塑分离富集,硫脲解脱,火焰原子吸收法进行测定矿石中金含量的方法。实验对矿石中金的吸附方式进行了优化,利用聚氨酯泡塑分离富集矿石中的金,并对富集了金的聚氨酯泡塑进行不同浓度硫脲解脱液试验,得到了矿石金在实验过程中的最佳硫脲解脱液浓度,通过对该条件下方法的检出限、精密度、加标回收率进行试验,所得到的测试结果均满足规范要求。该方法具有前处理简单、污染小、检出限低、精密度和准确度较好等优点,适用于大批量地球化学样品中金的分析测试。     

硫脲法电镀污泥中提金研究

在电镀行业中金是常用的贵金属之一,提高含金污泥金的回收率一直是研究的热门。论文用酸性硫脲从电镀污泥处理后的树脂中回收金,并探讨了该方法的最佳工艺条件。结果显示,在40℃恒温搅拌条件下用FeCl3.6H2O(加入量2 g/L溶液)、硫脲(浓度1.0 g/L)的混合溶液(pH=1.5)浸取12 h,浸金率最高,可达85%。     

用硫脲从季铵盐萃取液中反萃金,银,铜的探索

本文叙述了硫脲和季镀盐的基本物化性质,分析并论证了硫脲盐酸漓液反萃取季铵盐负载有机相中金、银、铜的可能性及其机理。理论分析和实验结果均表明,在酸性条件下,硫脲具有取代季铵盐萃取金、银、铜的萃合物中CN~-配位体的能力。CN~-配位体被中性硫脲SC(NH_2)_2取代后,使原来带负电的络阴离子M(CN)_2~-变成带正电的络阳离子M(SC(NH_2)_2)_2~+,带相同电荷的两离子(R_3CH_3N)和M(SC(NH_2)_2)_2~+互相排斥,迫使萃合物解离并分别进入有机相和水相,由此达到比较完全的反萃目的。反萃后的金、银、铜硫脲络合物和对应氰离子络合物比较其稳定常数大为降低,故易于被还原成金属元素。同时,通过控制反萃液的酸度,可将金与银、铜大致分离。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。