原子吸收光谱法测定镀锌板表面钝化的铬层重量

电镀、热镀、彩涂真空镀等是许多产品表面处理和表面装饰重要的通用技术,具有装饰性、功能性、防护性等特点.已渐渐为人门熟知并利用.测定铬层重量是检验镀锌板表面钝化质量的重要指标.本文就金属表面的钝化工艺中铬层重量分析.提出了一项实用测试技术.可用于镀层的表面分析.     

上海开展离子交换法处理电镀废水的现状和对策研究

为了总结离子交换工艺在处理电镀废水方面的成绩和不足,上海市经委下达了“离子交换法处理电镀废水的现状和对策”研究课题,经上海市电镀协会等有关单位一年多的努力,已于最近在上海通过专家评审。     

工业含铬废水的络合萃取处理工艺研究

采用络合萃取法处理工业含铬废水,考察了起始pH、流速和接触时间等对络合萃取处理效果的影响,探讨了铬盐生产废水和电镀废水的处理工艺。结果表明;在废水起始pH为1.0-2.0时,络合萃取法能方便、快速、有效地去除废水中的六价铬。络合萃取．碱沉淀法适用于六价铬含量远大于三价铬含量的电镀废水的处理,氧化．络合萃取法可用于三价铬含量较高的电镀废水的处理。采用两级处理能使高浓度铬盐生产废水的出水达到国家排放标准。     

拉曼光谱法测定废水中六价铬的含量北大核心CSCD

在铬盐的生产、铬渣的处理、铬铁的质检及电镀、制革等过程中通常含有高浓度水平的六价铬,如果未经处理就排放到环境中,会对环境造成不可估量的危害,伴随着物质循环与转移,最终会危害人类身体健康和生命安全,因此测定六价铬的含量对含铬废水的处理起到重要作用[1-3]。     

无氰电镀

无氰电镀,在无产阶级文化大革命以前虽有一些单位搞过,但这一工艺的普遍推广应用,并形成群众性科学实验运动,是在无产阶级文化大革命推动下发展起来的,所以它也是无产阶级文化大革命中涌现出来的新生事物。以前,电镀行业中,一直沿用氰化电镀的传统工艺,采用氰化物为络合剂。由于氰化物是剧毒品,氰化电镀挥发出来的气体会危害工人健康,生产中排出的有毒废水,会污染江河、农田。氰化物以前还要部分依靠进口,帝修反曾企图借禁用来卡我们。广大电镀工人坚决遵照毛主席关于“独立自主、自力更生”的教导,组成了以工人为主体的三结合试验队伍,提出了“攻克无氰关,打击帝修反”的战斗口号,在激烈的两条路线斗争中,通过群众性科学试验实践活动,终于掌握了无氰电镀工艺,并应用到电镀多种单金属和合金上。一些无氰电镀新工艺还适应了自动化生产的要求。为什么过去电镀要用氰化物做络合剂?络合剂在电镀中起什么作用?怎样用其他络合剂代替氰化物?回答这些问题之前,先讲讲电镀及其原理。电镀及其原理     

微波消解-电感耦合等离子体质谱(ICP-MS)法测定电镀污泥中的重金属

将电镀污泥样品自然风干,以研磨的方式对电镀污泥进行处理.比较了不同消解体系和消解时间对样品消解的影响,确定采用硝酸+盐酸+氢氟酸消解体系,利用微波消解系统对电镀污泥进行消解,消解时间为25 min.使用ICP-MS法对污泥中的重金属元素进行测定,测定结果表明所检测项目工作曲线线性关系好,相关系数r均大于0.999.铬、...     

流动注射在线分离预浓集分光光度法测定环境水样中的痕量铬(Ⅵ)

利用自制微型离子交换柱 ,采用流动分析技术 ,对含铬 (Ⅵ )环境水样在线自动化分离和预浓集处理 ,联用分光光度检测手段 ,实现了在线自动化样品分离富集及测定。方法的线性范围是 1～ 40ng mL铬 (Ⅵ )。用于测定井水、自来水、电镀液、电镀废液、电镀排放液中的痕量铬 (Ⅵ ) ,回收率在 95 .7%～ 1 0 5 %之间     

电解法处理含氰废水

电镀车间含氰废水,来源于镀件在氰化镀槽电镀后表面附着带出的氰镀液,再经流动水漂洗后就产生大量含氰废水。氰为剧毒物质,若不经处理,直接排入水体,将严重污染环境,破坏水体资源,危害人民健康。     

离子色谱法电导检测电镀液中的有机酸、S_2O_3~(2-)和SCN~-

电镀工业中,为了改善镀层性能,通常需要在电镀液中加入适量电镀添加剂,起到稳定镀液、细化结晶、提高分散能力与深镀能力、增加镀层光亮性等作用~([1]).添加剂的含量直接影响着电镀产品的质量,因而能否在生产过程中及时准确地监测其浓度变化是控制电镀过程的至关晕要的环节.常见组分采用化学滴定、高效液相~([2,3])等方法分类测定,相比而言,离子色谱法能同时完成的分析,优势更为明显~([4,5]).本研究建立了一种简单易行的离子色谱方法,同时测定了电镀液中弱保留组分和易极化离子S_2O_3~(2-)和SCN~-,使得电镀槽液的组分变化的监测更为精确且更加实时化.     

一氧化碳中温变换催化剂的研究

铁氧体是用铁氧体法处理含铬电镀废水的沉渣,它含有与一氧化碳中温变换铁铬催化剂相类似的组成.一氧化碳中温变换铁铬催化剂是国内需要量极大的一种合成氨生产用催化剂.利用铁氧体为原料制备中温变换催化剂,不但消除污染,而且变废为利,确有实际意义.本文在前一工作的基础上报导由铁氧体为原料制备的一氧化碳中温变换催化剂.     

表面能与晶体生长/溶解动力学研究的新动向

界面现象使物质在结晶过程中出现了临界现象.但最近的研究指出在物质溶解过程中,在表面能量的控制下也存在着临界现象以及尺寸效应.实验发现,当晶体自身小到一 定的程度时(通常在纳米尺度上并和临界蚀坑的大小相近),在溶解过程中其速度会自发降 低,反应被抑制乃至停止.尽管在热力学上表面能的因素可以赋予小颗粒晶体较大的溶解度 ,但表面能却也能通过对临界条件的控制而使这些微粒在动力学上不被溶解.这个发现不仅 解决了纳米颗粒在水溶液中稳定性的问题,而且还从动力学的角度解释了生物矿物选择纳米 尺度作为其基本构成单元的原因.由于表面能和晶体生长/溶解的动力学有着密切的关系, 我们可以通过对表面能的调节来修改它们的动力学速度和晶体的形貌.反过来,也可以用动力学的方法来测定表面能及表面吸附/脱附常数等.相对于常规的界面研究手段,通过生 长和溶解动力学途径所得的数据有着很好的可靠性及重复性.我们认为,晶体生长和溶解的 动力学和表面能的研究相结合,不仅为界面研究提供了新的思路和方法,而且也会推动晶体生长和材料科学的发展.     

Indirect Electroorganic Syntheses—A Modern Chapter of Organic Electrochemistry [New Synthetic Methods (59)]

The electrochemical formation and regeneration of redox agents for organic syntheses (indirect electrolysis) widens the potential of electrochemistry, as higher or totally different selectivities can often be obtained while at the same time the energy input can be lowered significantly. Higher current densities can also be obtained by preventing otherwise often encountered electrode inhibition. New types of redox catalysts can be formed in-situ and can be regenerated after reaction with the substrates. This principle is of increasing importance also for the application of already known redox agents with regard to environmental protection, since large amounts of a product can be generated in a closed circuit using only relatively small amounts of the redox reagent. Consequently the operation of such a process can be greatly simplified, and the release of ecologically objectionable spent reagents into the environment can be prevented. The broad spectrum of redox catalysts currently in use includes, inter alia, metal salts in very low or high oxidation states, halogens in various oxidation states, and, in particular, a wide variety of transition-metal complexes. A great deal of progress has recently been made in the application of organic electron transfer agents, since compounds have been found that are sufficiently stable in both the reduced as well as the oxidized state.     

电化学噪声测量分析系统设计与实现

根据电化学噪声原理,利用微机技术设计实现了电化学噪声测量分析系统。该系统具有高灵敏度,自动选择量程,多回路自动测量,可调整采样参数等功能,并在时／频域内对所测量的电化学噪声进行分析。     

A simple method for thermoanalysis of evolved gases

Thermoanalytical processes involving the splitting-off of ammonia, water, halogens, inorganic acids or acid anhydrides can be simply observed by using a specimen-holder in which specific reactions with the decomposition products can be induced. A special glass or quartz double crucible can be used for this purpose; the products arising in the lower part of the crucible can be oxidized selectively with reagents placed in the upper part, or can be bound or transformed into other compounds. This double crucible is also suitable for studying reactions taking place between solid and gaseous substances.     

胆固醇/卵磷脂/壳聚糖体系中碳酸钙模拟生物矿化的研究

本文采用X射线衍射、红外光谱和扫描电子显微镜等方法研究了胆固醇／卵磷脂／壳聚糖体系中碳酸钙模拟生物矿化过程。通过改变有机基质的组成,使有机基质的模板作用 也发生改变,从而使生成方解在一重型里面在酸钙的模板可生成球霰石型的碳酸钙。文中还进一步探讨了体系中壳聚糖、卵磷脂、胆固醇三者的协同作用对生成碳酸钙晶型的影响。     

SCTA and Adsorbents

Sample controlled thermal analysis (SCTA) can be used in several manners with respect to adsorbents. Almost 70% of adsorbent synthesis procedures involve a thermal step that can be adapted to a sample controlled method. In this respect, SCTA has been used for the preparation of activated alumina, calcination of zeolites and activation of carbons. The thermodesorption of adsorbed molecules can also be carried out using a sample controlled method. Here, both the surface area and pore volume of adsorbents can be assessed. Finally, SCTA can be highly beneficial in the thermal pretreatment of adsorbents prior to adsorption. This revised version was published online in July 2006 with corrections to the Cover Date.     

稀土氧化物对中高碳钢堆焊金属中夹杂物变质作用的热力学分析

采用热力学方法,研究了稀土氧化物对中高碳钢堆焊金属中夹杂物的变质作用。夹杂物生成的热力学分析表明,在堆焊熔池中,稀土氧化物可以被碳还原成稀土元素,稀土元素可以与氧、硫生成稀土氧化物、稀土硫化物和稀土硫氧化物,从而达到脱氧、脱硫、净化堆焊熔池的作用;稀土氧化物还可以直接与硫作用,生成稀土硫氧化物,起到脱硫的效果。     

Controlling nanoparticle formation via sizable cages of supramolecular soft materials

We present a new generic strategy to fabricate nanoparticles in the "cages" within the fibrous networks of supramolecular soft materials. As the cages can be acquired by a design-and-production manner, the size of nanoparticles synthesized within the cages can be tuned accordingly. To implement this idea, both selenium and silver were chosen for the detailed investigation. It follows that the sizes of selenium and silver nanoparticles can be controlled by tuning the pore size of the fiber networks in the material. When the concentration of the gelator is high enough, monodisperse nanoparticles can be prepared. More interestingly, the morphology of the nanoparticles can be altered: silver disks can be formed when the concentrations of both the gelator and silver nitrate are sufficiently low. As the fiber network serves as a physical barrier and semisolid support for the nanoparticles, the stability in the aqueous media and the ease of application of these nanoparticles can be substantially enhanced. This robust surfactant-free approach will not only allow the controlled fabrication of nanoparticles, but also can be applied to the fabrication of composite materials for robust applications.     

问题、项目引领式教学法在高校有机化学教学中的应用

问题、项目引领式教学法可分为问题引领式与项目引领式教学两个部分。问题引领式教学法可用于课程的基础部分教学;项目引领教学法主要用于学生已掌握一定的基础知识之后,教师有针对性地提出一些目前亟待解决的小的项目让学生提出思路及解决办法。通过两种方法的互相补充,可显著提高学生对有机化学这门课程的学习兴趣,也能使有机化学的理论知识与实践能力更紧密地联系在一起,从而提高该课程的教学效果,同时也激发学生创新的潜能。     

Surface diffusion as a rate-enhancing mechanism in macromolecular association: The effectiveness of one- and two-dimensional surface sliding

The effective rate for a macromolecular association can be increased if the molecules can be held together loosely by nonspecific surface forces while they search for the specific reactive sites. In this way steric constraints can be relieved. In extreme cases, a specific interaction site can be surrounded by extensive surfaces either essentially linear (e.g. a DNA site) or two-dimensional (e.g. a membrane-bound receptor). If ligands can bind nonspecifically and search these surfaces in a lower-dimensional diffusion process, very substantial rate enhancements can be achieved under suitable conditions. The ranges of concentration and affinity of such nonspecific surfaces that can produce rate enhancements are derived and discussed. It is found that under the expected conditions in the living cell, such rate enhancements will be fairly modest. Nonetheless, nonspecific surface diffusion may play an important role.