钴基耐蚀合金的分解

钴基耐蚀合金的溶解方法常见的有稀硝酸 (1+1)、ＨＣｌ+ＨＮＯ3=(5～ 10 ) +1或者于大量浓盐酸中分次滴加少量浓硝酸、Ｈ2 ＳＯ4 (1+9) +ＨＣｌ =5 +1、Ｈ3ＰＯ4 +ＨＣｌＯ4 =1+1并滴加数滴ＨＦ。但对约含碳3%、铬 30 %、Ｗ 18%、Ｓｉ 2 %、Ｍｎ≤ 1%和Ｆｅ≤ 2 %的钴基合金的分解上述方法均不适应。本文用不加水的硫磷混合酸并快速升温 ,浓硝酸破坏碳化物 ,方法可操作性强。操作步骤为 :称取试样 0 .1ｇ置于 15 0～ 2 5 0ｍｌ锥形瓶中 ,加硫酸 10ｍｌ ,磷酸收稿日期 :2 0 0 0 0 4 122 0ｍｌ ,于高温电炉上快速 (3～ 7ｍｉｎ)升温至冒浓Ｓ…     

硅钙合金中钙含量的快速测定方法

硅钙合金中钙含量的测定一般采用ＨＮＯ3 ＨＦ ＨＣｌＯ4 溶样 ,ＨＣｌＯ4 冒烟除硅 ,氨水分离以除去铁铝等干扰后用ＥＤＴＡ直接滴定的方法[1] 。该方法须经ＨＣｌＯ4 两次冒烟、两次氨水分离 ,手续较繁琐、费时 ,成本高、操作不便 ,且易造成测定误差。本文研究了硅对钙测定的干扰及ＥＤＴＡ、磺基水杨酸、三乙醇胺(ＴＥＡ)与钙、铁、铝等离子间的络合平衡关系 ,制定出硅钙合金中钙含量快速测定方法。1　试验部分1.1　主要试剂磺基水杨酸 (ＳＳＡ)溶液 :10 0ｇ·Ｌ- 11.2　试验方法移取含一定量硅、钙、铁、铝离子的试液于铂皿中 ,加入一定…     

吸光光度法测定硝酸银中微量铜

硝酸银制成后测定杂质含量是鉴定纯度的一个重要环节。杂质铜的含量多少直接影响到硝酸银的纯度。本文研究了 0 .1～ 0 .3ｍｏｌ·Ｌ- 1ＫＯＨ介质中 ,用ＫＩＯ4 作为显色剂 ,采用巯基棉分离 ,吸光光度法测定了硝酸银中微量铜 ,结果满意。1　试验部分1.1　主要仪器与试剂756ＭＣ紫外可见分光光度计 (上海第三分析仪器厂 )Ｃｕ2 +标准溶液 :称取ＣｕＳＯ4 ·Ｈ2 Ｏ 1.96 4 4 ｇ于烧杯中 ,加水溶解后 ,再加几滴硫酸 ,移入 50 0ｍｌ容量瓶 ,稀至刻度 ,配成 1ｍｇ·ｍｌ- 1储备液。逐级稀释成10 μｇ·ｍｌ- 1工作液。ＫＩＯ4 溶液 :称取ＫＩＯ4…     

吸附条件对活性碳纤维SACF氧化还原吸附Ag^＋的影响

本文研究了吸附条件对活性碳纤维ＳＡＣＦ氧化还原吸附Ａｇ＾＋的影响。结果表明：Ａｇ＾＋初始浓度的提高，反应温度的升高均可提高ＳＡＣＦ对Ａｇ＾＋的吸附量；Ａｇ＾＋的吸附量还强烈地依赖于溶液的ＰＨ值，用ＮａＡＣ、ＨＡＣ＋ＮａＡＣ或ＮＨ３．Ｈ２Ｏ调高Ａｇ＾＋溶液的ＰＨ，可有效地增加ＳＡＣＦ对Ａｇ＾＋的吸附量；用ＮＨ３．Ｈ２Ｏ调节会再现一个最佳的ＰＨ值；通过增加ＳＡＣＦ用量，Ａｇ＾＋的吸附率可达９９％以上。     

动力学光度法测定食品中的碘

催化动力学光度法测定痕量碘 ,大多使用Ｃｅ(ＩＶ) -Ａｓ(ＩＩＩ)体系[1 3] 。我们的实验发现在硫酸介质中 ,Ｉ- 能强烈催化高碘酸钾氧化苋菜红的褪色反应 ,在波长 5 2 5ｎｍ处 ,其反应速度与碘离子的浓度之间符合动力学一级反应关系式 ,并且此法灵敏度、选择性均较高。1　实验部分取两支 2 5ｍｌ比色管 ,各加入 2 0ｍｌ浓度为8 0× 1 0 - 3ｍｏｌ/Ｌ苋菜红溶液 ,3 5ｍｌ( 1 0ｍｏｌ/Ｌ)Ｈ2 ＳＯ4,2 0ｍｌＫＩＯ4( 0 2 0ｍｏｌ/Ｌ)溶液。向其中一支加入适量碘标准溶液 ( 1 μｇ/ｍｌ) (吸光度为Ａ) ,另一支不加碘 (吸光度为Ａ0 ) ,用水…     

活体生物膜控制合成纳米半导体硫化镉

目前 ,用于合成和制备纳米材料的方法除化学和物理方法[1～ 4] 外 ,还有仿生法[5～ 7] ,但尚未见到利用活体生物膜来合成无机纳米材料的报道 .本文利用绿豆芽通过生物膜控制合成了纳米ＣｄＳ .1　实验部分将市售新鲜绿豆芽用去离子水洗净后放入盛有 0 .1ｍｏｌ·Ｌ- 1 Ｎａ2 Ｓ水溶液的试管中 ,浸没茎部 ,露出叶片 .2 4ｈ后取出 ,用去离子水冲洗掉豆芽外部的Ｎａ2 Ｓ溶液 ,转放到盛有ＣｄＣｌ2 水溶液的试管中 ,用同法浸泡 2 4ｈ .取出豆芽 ,小心用玻璃棒将豆芽茎外的黄色ＣｄＳ转入无水乙醇中 .取少量ＣｄＳ乙醇溶液 ,经超声振荡后上铜网 ,…     

固相配位化学反应研究──LXX．二水醋酸镉与邻氨基苯甲酸的分步固相反应

二水醋酸镉与邻氨基苯甲酸（ＨＯＡＢ）在室温下发生固—固相化学反应生成Ｃｄ（ＯＡＢ）２，用等温ＤＳＣ、等温电导法跟踪研究反应过程发现，上述固相反应分两步进行．     

火焰原子吸收光谱法间接测定食品中碘

微量碘的测定一般采用光度法。本文依据 [Ｃｄ(Ｐｈｅｎ) 3]2 + 与Ｉ- 可形成 [Ｃｄ(Ｐｈｅｎ) 3]2 + (Ｉ- ) 2 离子对的原理[1] ,用硝基苯萃取 ,通过测定有机相中镉的含量 ,间接测定碘。用于测定含碘食品 ,结果满意。1　试验部分1.1　主要仪器与试剂ＷＦＸ 1Ｂ型原子吸收分光光度计 (北京第二光学仪器厂 )ｐＨＳ Ⅰ型酸度计 (上海分析仪器厂 )涡流混合器 (上海第一医学院仪器厂 )碘标准储备液 :10ｍｇ·ｍｌ- 1,准确称取碘化钾(ＧＲ) 13.0 80 0ｇ ,用少量无碘水溶解后 ,定容于 1Ｌ容量瓶中。碘标准使用液为 1ｍｇ·Ｌ- 1。三邻菲罗啉镉溶液…     

石墨炉原子吸收光谱法测定饲料及矿物饲料中的痕量镉

镉是对畜禽生长有害的金属元素。动物长期采食被镉污染的饲料会导致慢性镉中毒。其毒性作用除干扰铜、锌和钴等微量元素的代谢外 ,还直接抑制某些酶系统[1] 。测定食品以及饲料中镉含量是我国食品以及饲料卫生标准的要求。用ＦＡＡＳ测镉使用的基体改进剂有钯[2 ] 、ＮＨ4 Ｈ2 ＰＯ4[2 ] 和Ｐｄ +Ｍｇ(ＮＯ4 )2[3] 等。本文针对饲料样品及矿物元素饲料的镉 ,通过对基体改进剂钯和ＮＨ4 Ｈ2 ＰＯ4 在梯度浓度的条件下 ,其对应镉的吸光度和对离子的抑制情况进行比较测试 ,以便寻找一种更加适合饲料以及矿物元素饲料中痕量镉的测定的基体改进剂…     

氨基膦酸树脂吸附镨的研究

氨基膦酸树脂 (简称ＡＰＡＲ)是一类性能优良的螯合树脂 ,功能基为 ＣＨ2 ＮＨＣＨ2 Ｐ(Ｏ) (ＯＨ) 2 ,由于功能基上同时含有Ｎ和Ｏ等配位原子 ,它能与多种金属离子形成比较稳定的配合物。近年来有关含磷的螯合树脂吸附金属离子的各种研究比较活跃[1～ 4] 。本文就氨基膦酸树脂在ＨＡｃ ＮａＡｃ体系中对镨 (Ⅲ )的吸附行为进行了研究。获得了诸多基本参数 ,为氨基膦酸树脂在湿法冶金中对镨离子的富集、提取等方面的应用提供了理论依据。1　实验部分1 1　试剂及仪器72 1型分光光度计 ,ＳＨＡ Ｃ水浴恒温振荡器(± 0 .1℃ ) ,ｐＨＳ 3ｃ型…     

Coadsorption of Cd(II) and oxalate ions at the TiO2/electrolyte solution interface

The study of the adsorptions of cadmium and oxalate ions at the titania/electrolyte interface and the changes of the electrical double layer (edl) structure in this system are presented. The adsorption of cadmium or oxalate ions was calculated from an uptake of their concentration from the solution. The concentration of Cd(II) or oxalate ions in the solution was determined by radiotracer method. For labeling the solution 14C and 115Cd isotopes were used. Coadsorption of Cd(II) and oxalic ions was determined simultaneously. Besides, the main properties of the edl, i.e., surface charge density and zeta potential were determined by potentiometer titration and electrophoresis measurements, respectively. The adsorption of cadmium ions increases with pH increase and shifts with an increase of the initial concentration of Cd(II) ions towards higher pH values. The adsorption process causes an increase of negatively charged sites on anatase and a decrease of the zeta potential with an increase of initial concentration of these ions. The adsorption of oxalate anions at the titania/electrolyte interface proceeds through the exchange with hydroxyl groups. A decrease of pH produces an increase of adsorption of oxalate ions. The processes of anion adsorption lead to increase the number of the positively charged sites at the titania surface. However, specific adsorption of bidenate ligand as oxalate on one surface hydroxyl group may form inner sphere complexes on the metal oxide surface and may overcharge the compact part of the edl. The presence of oxalate ions in the system affects the adsorption of Cd(II) ions on TiO2, increasing the adsorption at low pH range and decreasing the adsorption at high pH range. Using adsorption as a function of pH data, some characteristic parameters of adsorption envelope were calculated.     

Adsorption behavior of cadmium ion onto synthetic ferrihydrite: effects of pH and natural seawater ligands

Batch experiments were conducted to study the adsorption behavior of cadmium ion onto the synthetic ferrihydrite. The adsorbent was characterized using X-ray diffraction and N₂ adsorption–desorption measurements. The effects of pH value and the major seawater anions (nitrate, carbonate, chloride and sulphate) at their natural concentrations on the adsorption of cadmium ion were investigated. The results showed that the adsorption of cadmium ion was highly pH-dependent and suppressed in the presence of chloride, sulphate and nitrate, while carbonate was found to enhance the adsorption of cadmium ion over the examined range of 4.0–7.5. The maximum percentage of cadmium ion adsorbed can reach 89.96 % at pH 7.5. It is proposed that the competition for binding sites played a key role in the reduction of cadmium ion adsorption by nitrate, chloride and sulphate. X-ray diffraction spectroscopic data for cadmium adsorbed on ferrihydrite showed that CdCO₃(s) was formed on ferrihydrite; the formation of CdCO₃ precipitation or surface precipitation in carbonate system may be the reason for the increase of cadmium adsorption.     

阴离子交换树脂分离-原子荧光法测定色母粒中的镉

采用微波消解溶样,结合离子交换法对色母粒样品进行待测元素的提取及净化处理,利用原子荧光光度计进行镉含量的测定。研究了717型阴离子交换树脂对色母粒样品中镉的吸附及分离条件,解决了样品中铅、铜等元素的干扰问题。方法加标回收率在92.4%～117.4%之间,相对标准偏差小于3.0%。     

129Xe NMR spectroscopy study of porous cyanometallates

Zinc and cadmium hexacyanocobaltates(III) were prepared, and their porous networks were explored using 129Xe spectroscopy. The crystal structures of these two compounds are representative of porous hexacyanometallates, cubic (Fm-3m) for cadmium and rhombohedral (R-3c) for zinc. In the cubic structure, the porosity is related to systematic vacancies created from the elemental building block (i.e., the hexacyanometallate anion), whereas the rhombohedral (R-3c) structure is free of vacant sites but has tetrahedral coordination for the zinc atom, which leads to relatively large ellipsoidal pores communicated by elliptical windows. According to the Xe adsorption isotherms, these porous frameworks were found to be accessible to the Xe atom. The structure of the higher electric field gradient at the pore surface (Fm-3m) appears and is accompanied by a stronger guest-host interaction for the Xe atoms and a higher capacity for Xe sorption. For cadmium, the 129Xe NMR signal is typical of isotropic movement for the Xe atom, indicating that it remains trapped within a spherical cavity. From spectra recorded for different amounts of adsorbed Xe, the cavity diameter was estimated. For the zinc complex, 129Xe NMR spectra are asymmetric because of the Xe atom movement within an elongated cavity. The line-shape asymmetry changes when the Xe loading within the porous framework increases, which was ascribed to Xe-Xe interactions through the cavity windows. The Xe adsorption revealed additional structural information for the studied materials.     

纳米钛酸钙粉体的制备及其对水中铅和镉的吸附行为

采用柠檬酸络合溶胶-凝胶法制备了纳米钛酸钙粉体. 以X射线衍射(XRD)、透射电子显微镜(TEM)和傅立叶变换红外光谱(FTIR)对其进行了表征. 考察了该纳米粉体对水中重金属铅和镉的吸附性能, 并以镉离子为例, 系统地研究了吸附热力学和动力学. 结果表明, 该法合成的钛酸钙为钙钛矿结构的纳米粉体, 粒径大小受灼烧温度的影响, 灼烧温度越高, 粉体平均粒径越大, 600 ℃灼烧2 h条件下, 粉体的平均粒径最小, 约为20 nm. 当介质的pH值为4～8时, 钛酸钙对水中的铅和镉具有很强的吸附能力. 其对镉离子的吸附行为符合Langmuir 吸附等温模型和HO准二级动力学方程式, 吸附过程焓变(ΔH)为39.312 kJ•mol－1, 各温度下的自由能变(ΔG)均小于零, 熵变(ΔS)均为正值, 吸附过程的活化能(Ea)为20.359 kJ•mol－1. 该吸附过程是自发的吸热物理过程. 被吸附的铅和镉均可用1 mol•L－1的硝酸完全洗脱回收. 对铅和镉的富集因子均超过200. 将其应用于水中痕量铅和镉的吸附富集和测定, 回收率分别为96.3%～107.2%和93.5%～104.0%, 与石墨炉原子吸收光谱法测定结果一致.     

Interaction of nitrate, barium, strontium and cadmium ions with fused quartz/water interfaces studied by second harmonic generation

Inorganic anions and cations are ubiquitous in environmental chemistry. Here, we use second harmonic generation to track the interaction of the environmentally important metal cations barium, strontium, and cadmium and the nitrate anion with fused quartz/water interfaces at pH 7. Using a dynamic flow system, we assess the extent of reversibility in the binding process and report the absolute number density of adsorbed cations, their charge densities, and their free energies of adsorption. We also present resonantly enhanced second harmonic generation experiments that show that nitrate is surface active and report the free energies and binding constants for the adsorption process. The second harmonic generation spectrum of surface-bound nitrate shows a new adsorption band that cuts further into the solar spectrum than nitrate in the aqueous or solid state. The results that we obtain for all four inorganic ions and the implications for tropospheric and aquatic chemistry as well as geochemistry are discussed in the context of fundamental science as well as pollutant transport models.     

邻菲咯啉改性膨润土吸附水中镉离子的研究

通过邻菲咯啉改性膨润土,对水中镉离子进行吸附性能的研究.探讨了投加量、pH值、接触时间、温度等影响因素对改性膨润土吸附镉离子的影响.实验结果表明:在25℃,250 r/min,pH 5.5,NaNO3浓度0.01 mol/L,投加量为5.0 g/L,镉离子质量浓度100 mg/L的条件下,未改性膨润土对水中镉离子的吸附...     

改性活性炭对土壤镉的吸附性影响

目的研究3种改性活性炭对菜地、河流底泥、荷花底泥镉吸附性的影响。方法对活性炭进行酸改性、碱改性和氧化改性,采用双硫腙分光光度法测定镉含量。结果对实验土样,最佳活性炭添加量为0.025 g/g。随着初始镉含量的升高,土壤对镉的吸附量不断增大。结论 3种改性活性炭相比普通活性炭对湿地土壤的镉吸附量均有不同程度的提升,荷花底泥中,酸性、氧化改性活性炭相比普通活性炭,吸附效果提高7.7%,8.3%,吸附效果提升显著。     

不同水煤浆分散剂与煤之间的相互作用规律研究: Ⅹ 分散剂在煤粒表面上的吸附作用特征

研究了6种水煤浆分散剂在14种不同变质程度煤上的吸附作用特征。结果表明，多数分散剂在煤粒表面达到单层饱和吸附后，又形成多层吸附，单层饱和吸附量与煤的变质程度、比表面积以及分散剂的性质有关。在相同粒度分布下，煤的变质程度越低，表面含氧亲水官能团的比例越高，孔隙率越高，比表面积越大，这对增大吸附量有利。煤的变质程度越高，其表面疏水区面积的比例越高，分散剂通过疏水基团紧密吸附在煤表面的比例越大，这对增加高阶煤的吸附量有利。对不同煤，是变质程度还是比表面积为吸附分散剂的主控因素，主要依赖于分散剂的结构与性质。对同种煤，疏水与亲水基团呈线型分立分布的分散剂，吸附量明显高；而疏水与亲水基团呈线型间隔分布的分散剂，吸附量明显小。     

超细煤粉吸附苯胺机理研究

采用筛分和高能球磨得到不同粒度煤粉,进行吸附试验研究。结果表明，粒度较大的四种煤粉对苯胺的吸附符合Lagergren一级吸附速率方程，较小的三种超细煤粉对苯胺的吸附符合二级吸附动力学方程。并求出了一级、二级吸附速率常数和有效扩散系数，表明煤粉吸附苯胺的过程由颗粒内扩散控制；煤粉对苯胺的吸附量随煤粉粒径的减小呈指数关系增加。平均粒径d50为9.30μm、4.28μm、和4.82μm煤粉对苯胺的吸附符合Langmuir吸附等温式，单层饱和吸附容量为109.05×10－3、246.31×10－3和90.91×10－3。超细煤粉对苯胺的吸附性能量明显好于其他煤粉。