Preconcentration of copper, cadmium, and lead with a thiacalix[4]arenetetrasulfonate-loaded Sephadex A-25 anion-exchanger for graphite-furnace atomic-absorption spectrometry

A rapid column-adsorption method has been developed for concentrating traces of copper, cadmium, and lead in water prior to their determinations by graphite-furnace atomic-absorption spectrometry. The adsorbent used was prepared by loading a strongly basic anion-exchanger QAE-Sephadex A-25 (50 mg) with thiacalix[4]arenetetrasulfonate (20 mol). Two-hundredfold preconcentration of the analyte elements was achieved by passing 100 mL of sample solution (pH 8.0) through a column packed with the adsorbent (6 mm i.d.×7 mm high) at a flow rate of 10 mL min^–1 and by the subsequent elution with 500 L of aqueous nitric acid solution (1 mol L^–1). The practical applicability of the proposed method was evaluated by analyzing certified reference seawater samples.     

Synthesis, spectroscopy, and X-ray structure of the polymer catena-[bis(azido-N)-copper(II)-μ-bis(2-benzimidazolyl)butane]

The title compound, catena-[bis(azido-N)-copper(II)-(bis(2-benzimidazolyl)butane), [Cu(C₁₈H₁₈N₄)(N₃)₂]_n, was obtained from the reaction of the ligand bis(2-benzimidazolyl)butane and Cu(N₃)₂. The x-ray crystal structure is reported. The compound crystallizes in the monoclinic space group P2₁/c with a = 8.2524(10), b = 12.765(5), c = 9.1125(15) Å, = 106.423(12)°, Z = 2. The Cu(II) ions are square-planar coordinated with trans-oriented end-on binding azido ligands. The structure is a polynuclear chain with the benzimidazole bridging at each end. In addition a N_(ligand)-H···N_(azido) H-bridge [N_(ligand)···N_(azido) = 2.994(7) Å] is present, resulting in a pseudo 2-dimensional lattice. The characteristic azido infrared vibrations are found at 2060 and 2077 cm^–1 (_as(N₃)) and 1284 and 1297 cm^–1 ((N₃)).     

氨基酸在固/液界面的吸附作用

本文介绍了氨基酸在固/液界面吸附等温线的特点,氨基酸液相吸附热力学和活性炭、硅胶、二氧化钛、氧化铝、蒙脱土等自水中吸附氨基酸的机制。     

Surface activity and thermodynamic properties of water‐soluble polyester surfactants based on 1,3‐dicarboxymethoxybenzene used for enhanced oil recovery

The surface activity and thermodynamic properties for eight low molecular weight nonionic co‐polyester (PE) surfactants have been investigated. Surface and interfacial tensions (IFT) of surfactants in aqueous solutions were measured using the spinning drop technique. From these measurements, the critical micelle concentration (CMC), the surface pressure at CMC (Y_CMC), the maximum surface concentration (Γ_max), the minimum area/molecule at the aqueous solution/air interface (A_min), the effectiveness of surface tension reduction (Π_CMC), the alkane carbon number (n_min) and the IFT at n_min (Y_min) were determined. The thermodynamic parameters of micellization (ΔG_mic, ΔH_mic and ΔS_mic) and of adsorption (ΔG_ad, ΔH_ad and ΔS_ad) for these polymeric surfactants were also calculated. Structural effects on micellization and adsorption are discussed in terms of these parameters. The results show that the ΔG_ad values were more negative than ΔG_mic values for these compounds, so that they favored adsorption before the micellization process. They exhibited IFT in the order of 10⁻³ to 10⁻⁴ mN/m against the thin alkane carbon number range 6–9. This range seemed to be prefered for enhanced oil recovery. Copyright © 2000 John Wiley & Sons, Ltd.     

Light‐Responsive Block Copolymers

Stimuli‐responsive polymers are the subject of intense research because they are able to show responses to various environmental changes. Among those stimuli, light has attracted much attention since it can be localized in time and space and it can also be triggered from outside of the system. In this paper, we review light‐responsive block copolymers (LRBCs) that combine characteristic features of block copolymers, e.g., self‐assembly behavior, and light‐responsive systems. The different photo‐responsive moieties that have been incorporated so far in block copolymers as well as the proposed applications are discussed.

     

Adsorption of carbon dioxide on microporous carbon adsorbent PAU-10

Carbon dioxide adsorption on the microporous carbon adsorbent PAU-10 within the 177.8—423 K temperature and 0.1—5.13·10⁶ Pa pressure intervals was studied. The isosteres of absolute adsorption are well approximated by straight lines, which do not change their slope on going to temperatures higher than the critical temperature of CO₂. An increase in the differential molar isosteric heat of adsorption (q _st) at 0 < a < 1 mmol g^–1 is explained by the influence of the endothermic effect of adsorption expansion of the adsorbent. In the region of high pressures and nonideal gas phase, q _st is temperature-dependent.     

单分散亲水两性离子交换树脂的制备及其在生物大分子分离中的应用

采用分散聚合与溶胀聚合相结合的方法及高分子溶液致孔技术, 成功地制备了粒径为5.0 μm大孔和超大孔结构的单分散亲水性交联聚甲基丙烯酸环氧丙酯树脂, 并进行了结构表征. 将该树脂经胺化后再与1,3-丙磺酸内酯反应, 得到一种新型的两性离子交换(强阳-强阴型)高效液相色谱填料. 研究了该填料对标准蛋白分离性能及流动相中有机溶剂、 流速和pH值对蛋白保留的影响. 实验结果表明, 在流速为3 mL/min时, 采用线性梯度洗脱, 在4.0 min内可同时快速基线分离3种酸性和2种碱性蛋白.     

酚醛型吸附树脂对咖啡因吸附性能的研究

利用 3种自制吸附树脂JDW 1、JDW 2、JDW 3和DuoliteS 761对咖啡因进行了静态和动态吸附研究 .结果发现 3种自制树脂对咖啡因的吸附性能明显优于DuoliteS 761 ;在吸附咖啡因的初始阶段 ,即达到 3 2 %～5 1 %平衡吸附百分率时 ,吸附速率数据和半经验速率方程很吻合 ,证实吸附咖啡因是粒扩散控制过程 ;酚醛型吸附树脂等温吸附咖啡因的平衡吸附数据符合Langmuir方程 ,相关系数在 0 99以上 ,因此 ,酚醛型吸附树脂吸附咖啡因属单分子层吸附 ;用 1mol LHCl和 40 %的甲醇溶液复合使用 ,效果很好     

间氨基酚在超高交联树脂上的吸附特征

研究了两种超高交联吸附树脂DA-01和DZH-04对间氨基酚的静态吸附热力学及动力学特征。结果表明,在295K~315K及研究的浓度范围内,Freundlich和Langmuir方程能够对静态吸附等温线进行很好的拟合,DA-01和DZH-04树脂对间氨基酚的吸附符合准一级动力学方程。两种树脂吸附间氨基酚的能力都比较强,用乙醇和2mol/LNaOH混合溶液(体积比1:1)洗脱,温度338K,DZH-04树脂的脱附率为99.50%,DA-01树脂的脱附率为75.36%。