高吸水性树脂的吸水机理

高吸水性树脂是三度空间网络聚合物，是高分子电介质。在高分子网络链上嵌有可电离的离子对，遇水形成离子网络。该树脂能吸收自身重量几百倍至几千倍的水，且保水性好，即使在压力下，水也不从中溢出。其吸水机理可用Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ热力学公式来解释。     

Ion Product of Pure Water Characterized by Physics-Based Water Model

Pure water has been characterized for nearly a century, by its dissociation into hydronium (H₃O)¹⁺ and hydroxide (HO)^1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product or the product of the equilibrium concentration of the two ion species, has been extensively measured by chemists over the liquid water temper-ature and pressure range. The experimental data have been nonlinear least-squares fitted to chemical thermodynamic-based equilibrium equations, which have been accepted as the industrial standard for 35 years. In this study, a new and statistical-physics-based water ion product equation is presented, in which, the ions are the positively charged protons and the negatively charged proton-holes or prohols. Nonlinear least squares fits of our equation to the experimental data in the 0-100 ℃ pure liquid water range, give a factor of two better precision than the 35-year industrial standard.     

Improvement of Atmospheric Water Surface Discharge with Water Resistive Barrier

Atmospheric water surface discharge is a promising method for water treatment. The selection of discharge gap distance must take a pair of conflicting aspects into account: the chemical efficiency grows as the discharge gap distance decreases, while the spark breakdown voltage decreases as the gap distance decreases. To raise the spark breakdown voltage and the chemical efficiency of atmospheric pressure water surface discharge, resistive barrier discharge is introduced in this paper. Both the high voltage electrode and the ground electrode are suspended above water surface to form an electrode-water-electrode discharge system. The water layer plays the role of a resistive barrier which inhibits the growth rate of discharge current as voltage increases. Experiments conducted at different discharge gap distances and water conductivities indicate that both the spark breakdown voltage and the chemical efficiency are remarkably raised in comparison with traditional water surface discharge. After parameter optimization, the discharge reactor is scaled up with activated carbon fiber electrodes and advantages of water resistive barrier discharge are kept.     

Spectral Irradiance in Pond Water: Influence of Water Chemistry

Knowing the depth of UV penetration in ponds and the chemical variables that control underwater spectral irradiance is a prerequisite to predicting the influence of UV on amphibians and other pond organisms. The present study found that over 99% of UVB (280–315 nm) radiation was attenuated in the top 10–20 cm of ponds sampled on the edge of the Canadian Shield near Peterborough, Ontario. While the principal attenuating substance was, as in lakes, dissolved organic carbon (DOC), neither DOC nor DOC fluorescence were useful predictors of the attenuation coefficients other than the observation that all values of DOC were high and all attenuation coefficients were also high. The lack of a reliable relationship between DOC and attenuation resulted from differences throughout the season in the fraction of the DOC capable of absorbing radiation (chromophores) and the fraction capable of fluorescing (fluorophores). Attenuation was higher than predicted from DOC during springtime when amphibians lay their eggs. Absorbance coefficients measured using a spectrophotometer proved to be reliable predictors of both UVB and UVA attenuation coefficients measured in the ponds with a spectro-radiometer. While DOC provides an effective sun screen against the direct damage of UV radiation, the high attenuation means that the photochemical activity spread over at least 15 m in the ocean is confined to only a few centimeters in ponds.     

还原荧光法测定水和废水中的对硝基酚

本文用乙酸丁酯萃取水和废水中的对硝基酚,用氢氧化钠溶液反萃取,然后用硼氢化钾还原对硝基酚为对氨基酚,用荧光法进行分析测定。荧光激发波长和发射波长分别为274nm和372nm。检测限为3.0μg/L。样品加标回收率为89％～96％。     

纯水与自来水中氰离子的比色检测

设计合成了水溶性比色传感器磺酸功能化的偶氮水杨醛吖嗪(S),其结构经由~1H NMR,ESI-MS确证。S在纯水与自来水中对氰离子(CN~-)具有专一选择性的比色检测能力,最低检出限分别为0.16和0.63μmol/L。可逆的质子转移检测机制赋予S循环再利用的优势,借助于检测试纸,实现了CN~-可逆的比色检测。该工作为纯水相中CN~-的检测提供了实验依据。     

空气/水界面水分子的取向和运动

Here we report a quantitative study of the orientational structure and motion of water molecule at the air/water interface. Analysis of Sum Frequency Generation (SFG) vibrational peak of the free O-H stretching band at 3700 cm-1 in four experimental configurations showed that orientational motion of water molecule at air/water interface is libratory within a limited angular range. The free OH bond of the interfacial water molecule is tilted around 33° from the interface normal and the orientational distribution or motion width is less than 15°. This picture is significantly different from the previous conclusion that the interfacial water molecule orientation varies over a broad range within the ultrafast vibrational relaxation time, the only direct experimental study concluded for ultrafast and broad orientational motion of a liquid interface by Wei et al.(Phys. Rev. Lett. 86, 4799, (2001)) using single SFG experimental configuration.     

Anomalies of Liquid Water

Water at low temperatures (T < 300 K) reveals a multitude of unusual physico-chemical properties, which originate from the strong directivity of the hydrogen bonds. This directivity forces the molecules into a tetrahedral arrangement of first neighbors and thus leads to a poor packing efficiency. All anomalies of the liquid become more pronounced in the metastable range below the melting pressure curve. In the following article, methods for the investigation of the supercooled range are presented. A few anomalous static and dynamic properties are described and compared with the properties of normal liquids. The experimental results are discussed in the context of computer simulations and the more recent theories on cold water. It can be concluded that the anomalies of water, for instance the density maximum of the liquid phase and the initial decrease in viscosity with pressure, are confined to the pT-range: T < 300 K, p ? 200 MPa. At these pressures, lowering the temperature leads to an unexpected behavior of almost all physical properties. They seem to approach a phase transition at T ? (T_M ? 50 K), the nature of which has not yet been fully characterized. This phenomenon has hitherto been observed only in supercooled water.—In the future it will be possible to use supercooled aqueous solutions for kinetic studies, thus expanding the available dynamic range for the investigation of aqueous solutions considerably.     

Nmr Spectroscopic Determination of Water In Deuterium Oxide/Water Mixtures

Abstract

Deuterium oxide was determined in synthetic mixtures of 70–100 % D₂O and 90–100 % D₂O by NMR spectroscopy with a Varian A-60 NMR spectrometer using peak heights and areas. The standard deviation for the best results was 0.4 % D₂O.     

Determination of Anionic Surfactant in Fresh Water and in Sea Water

Ion pairs formed from suitable cationic dye and anionic surfactant in water were separated by solvent extraction. The extracts were used subsequently for spectrophotometric determinations. The extraction of ion pairs with various combinations is described. Of the dyes and solvents examined, ethyl violet and p-xylene are the most useful combination as the cationic dye and extraction solvent. The extracts are determined spectrophotometrically at 611.5 nm; the molar absorptivity is 1, 01 × 10⁵ M^?1 cm^?1. The detection limit is 1.4 ppb in water. The method is simple, rapid and sensitive. It can also be applied to the determination of anionic surfactants in sea water.     

Entropy of Zeolitic Water

Zeolite-water heat-pump system is suitable for effective use of low temperature heat sources such as solar energy and waste heats from factories, that is,for energy saving. The heat exchange function of zeolite owes obviously to the nature of the zeolitic water, the state of which can be described in terms of the entropy value as an independent component of H₂O. Most entropy values of zeolitic water have been given so far to be intermediate between those of liquid water (69.9 J mol^-1 K^-1 at 298 K) and ice (41.5 J mol^-1 K^-1 at 273 K).The present calorimetric measurements proved, however, that the entropy value for Mg-exchanged A-type zeolite is so small, even at the ambient temperature, as to be compared with the residual entropy of ice at 0 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

Water cavitation of hydrogels

Using the cavitation rheology (CR) technique developed in our labs, we show that fluids with negligible interfacial tensions with a surrounding material can be used to induce an elastic, cavitation instability in that material. We do this by changing the cavitation media from air, which was demonstrated to induce cavitation at the tip of a syringe needle in previous studies, to water, which has a negligible surface tension with the surrounding poly(vinyl alcohol) hydrogel material. In this case, the critical pressure in which this instability occurs can be directly related to the elastic modulus of the surrounding network and is shown to be nearly independent of length scale. This independence of size scale has important implications in the use of CR for the characterization of mechanical properties from molecular to macroscopic length scales. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1423–1427, 2010     

气态—紫外分光光度法测定水和废水中硫化物

本文介绍了在对样品无需进行预先吹气分离,显色的条件下,通过对硫化氢气体在气相状态下紫外分光光度法的测定来完成对水和废水中硫化物测定的方法。本方法不但操作简单、快速,而且准确性和精密度都优于标准化学方法,颜色、混浊及其它共存离子对本方法均无干扰。对于低含量样品的测定,本方法具有明显的优点。     

水分子团簇分子力场方法的比较研究

采用传统水分子力场模型(SPC, TIPnP(n=3-5))和极化模型(POL3, AMOEBA, SPC-FQ, TIP4P-FQ)对水分子二聚体团簇性质进行了比较和研究. 以从头计算和实验数据为依据, 分析水分子在外场作用下体系的静电极化, 电荷转移和分子结构变化. 通过水分子二聚体结合能和各分解能量项评价极化静电势能在双分子结合能中的地位和作用, 以及各水分子力场的适用性. 通过水分子团簇多体相互作用能的计算,展示不同极化水分子力场定量计算极化能量的实际能力. 通过对力场模型结果的对比和分析, 为进一步发展极化力场模型, 并应用到其他体系提供借鉴和依据.     

银盐分光光度法测定水和废水中的元素磷

本文拟定一种新的分光光度法分析水或废水中的元素磷(黄磷)。水中元素磷经有机溶剂萃取后,与硝酸银溶液反应,生成亮黄色溶液,直接进行分光光度测定。检测下限0.01μg黄磷;相对标准偏差0％～8％;回收率88％～100％。方法简单、快速、选择性好、精密度和准确度高,无毒,安全。     

Effect of the Solvent on the Water Properties of Water/Oil Microemulsions

Porous poly(styrene-divinylbenzene) (PS-DVB) particles were modified by adsorption of hydrophobically-modified dextrans, to provide chromatographic matrices for biomolecule chromatography. The dextran distribution and the pore characteristics of various coated PS-DVB beads were examined using nitrogen adsorption–desorption, mercury intrusion, and size exclusion chromatography. It was found that the adsorption of dextran does not result in homogeneous layers but rather in inhomogeneous ones. At high dextran loading and high content of hydrophobic groups in the adsorbed polymer, most of the pores of the macroporous rigid material are filled with a soft and porous dextran network being stabilized by hydrophobic interactions. According to chromatographic experiments, most of the surface was nevertheless expected to be covered at least by a thin and dense protecting layer since proteins—even those that are small enough to penetrate the dextran network—cannot interact nonspecifically with the internal pore surface. At low content of hydrophobic groups, dextran deposits preferentially as a thicker and more diffuse layer. However, the thickness of the coating is expected to be irregular and probably contributes to an increase in the roughness of the polystyrene surface.     

影响水中悬浮物质测定的若干因素

许多江河在雨季由于地面大量泥砂和各种污染物的冲入，使水中悬浮物大量增加，地表水中存在悬浮物使水体浑浊，降低透明度，影响水生生物的呼吸和代谢，甚至造成鱼类窒息死亡。悬浮物多时，还可能造成河道阻塞。造纸、皮革、冲渣、选矿、湿法粉碎和喷淋除尘等工业操作中产生大量含无机、有机的悬浮物废水，因此，在水和废水处理中，测定悬浮物具有特定意义。     

水/AOT/正庚烷微乳体系中水结构的FT-IR研究

运用傅立叶变换红外光谱（ＦＴ－ＩＲ）对水／ＡＯＴ／正庚烷微乳体系中水的微结构进行了研究。结果表明，随着体系中加水量的增大，水分子Ｏ－Ｈ伸缩振动的红外光谱由３４９３ｃｍ＾－１向低频移动至３４１７ｃｍ＾－１，微乳体系中，水分子与ＡＯＴ分子的磺酸基作用的同时，与Ｎａ＾＋也有一定的作用，这两种离子对水分子Ｏ－Ｈ键的强度均有一定的影响，磺酸基的作用使水分子中Ｏ－Ｈ伸缩振动向高波数方向移动，而Ｎａ＾＋的作用与