从物质本原到干水:水的概念的发展史

在古代哲学中,水被视为一种物质本原。17世纪化学学科形成后,水被定义成一种化学元素。18世纪的化学革命中,水被发现是氢氧化合物。19世纪原子分子论的创立,使水的概念得到微观表征。至20世纪,重水的发现和干水的发明使水的概念有了新的发展。总之,水的概念的发展史,反映了化学思想的发展和科学技术的进步,对化学研究和化学教育均有重要的启示。     

A model study on the mechanism and kinetics for the dissociation of water anion

Quantum chemical computations using both density functional theory (B3LYP functional) and wavefunction (MP2 and CCSD(T)) methods, with the 6-311++G(3df,2p) and aug-cc-pVnZ (n = D,T,Q) basis sets, in conjunction with a polarizable continuum model (PCM) method for treating structures in solution, were carried out to look again at a series of small negatively charged water species [(H₂O)_n]^•–. For each size n of [(H₂O)_n]^•– in aqueous solution with n = 2, 3, and 4, two distinct structural motifs can be identified: a classical water radical anion formed by hydrogen bonds and a molecular pincer in which the excess electron is directly interacting with H atoms. In aqueous solution, both motifs have comparable energy content and likely coexist and compete for the ground state. Some water anion isomers can dissociate when interaction with a water molecule, [(H₂O)_n]^•– + H₂O → H^•(H₂O)_m + OH^–(H₂O)_n–m, through successive hydrogen transfers with moderate energy barriers. This reaction can also be regarded as a water-splitting process in which the H transfers involved take place mainly within a water trimer, whereas other water molecules tend to stabilize transition structures through microsolvation rather than direct participation. Calculated absolute rate constants for the reversed reaction H^•(H₂O)₂ + OH^–(H₂O)₂ → [(H₂O)₄]^•־ + H₂O with both H and D isotopes agree well with the experimentally evaluated counterpart and lend a kinetic support for the involvement of a tetramer unit.     

电解离子水及其生成器

本文介绍了电解离子水的制备原理和应用。原水经电解后，阳极室生成酸性离子水，阴极室生成碱性离子水。酸性离子水具有杀菌消毒作用，碱性离子水具有保健作用。同时，简要介绍了离子水生成器的研究进展。     

永州潇水河水源地水质现状分析及污染防治

通过对潇水河零陵区饮用水水源地的水质的检测,分析了潇水河水源地水污染现状,及造成潇水河水源地水体污染的原因,并提出了相应的水污染防治措施。     

雎水流域的水化学特征及其地表水与地下水的相互转化

为了解特定流域的水化学特征及其运移和转化的历史,为水资源科学管理提供依据,分析了小流域雎水河的水化学特征。结果表明:(1)雎水河流域主要是大气降水补给的地矿化度的溶滤水。(2)雎水河全线都是地下水补给地表水。(3)部分泉点矿化度相对较高与SO24-较高有关,可能是因为流经了含煤地层。     

Sorption and diffusion of water vapor in polyimide films

Sorption and diffusion of water vapor are investigated gravimetrically for polyimide films. The activity dependence of the solubility and diffusion coefficients, S and D, respectively, is classified under four types: (1) constant S and D type, (2) dual-mode sorption and transport type, (3) dual-mode type followed by a deviation due to a plasticization effect at high vapor activity, and (4) constant S and D type followed by a deviation due to water cluster formation at high activity. For the dual-mode type, the Henry's law component is much larger than the Langmuir component except at low activity, and therefore deviation in behavior from the first type is small. S is larger for polyimides with higher content of polar groups such as carbonyl, carboxyl, and sulfonyl. D is larger for polyimides with a higher fraction of free space, with some exceptions. The polyimide from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and dimethyl-3,7-diaminodibenzothiophene-5, 5-dioxide belongs to the third type and displays both large S and large D. The polyimide from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 4,4′-oxydianiline belongs to the fourth type, and has the largest D but rather small S because of the hydrophobic C(CF₃)₂ groups. © 1992 John Wiley & Sons, Inc.     

Application of the Swimming Pool Backwash Water Recovery System with the Use of Filter Tubes

During the operation of swimming pools, large losses of water from the backwash of swimming pool filters are observed. This water is often discharged into sewers or used to sprinkle sports grounds. The aim of the research was to design and build an installation for purification and recovery of backwash water (BWW). It consists of flocculation, pre-filtration, and ultrafiltration based on filter tubes and ozone disinfection. Backwash water treatment installation contributes to purification and improvement of water quality. The effectiveness of the removal of microbial contamination with the use of the system was over 99%. The high efficiency of removing physicochemical impurities was also achieved. Water turbidity was reduced from 96.9 NTU to 0.13 NTU. After using the system, the oxidability of water decreased from 6.26 mg O₂∙dm⁻³ to 0.4 mg O₂∙dm⁻³. When using the system, a reduction of total organic carbon by 80% was also noticed. After the treatment process, water meets the strict criteria and can be returned to the pool system of water as fresh water with parameters of supply water—directly to the overflow tank. It has been shown that up to 96% of water can be recovered with the technology. The cost comparison showed annual savings of over EUR 9000.     

Trace Analysis of Iron in Environmental Water and Snow Samples from Poland

Abstract

A voltammetric method for the determination of iron at detection limit of 4 μg/l is described, using the catalytic current of the reduction of the Fe(III)-triethanolamine (TEA) complex in the presence of bromate ions. the determination was performed at a mercury hanging drop electrode without preconcentration, using the TEA alkaline solution as a supporting electrolyte and the differential pulse technique. A peak current for the Fe(III)-TEA catalytic reduction was observed at a potential of-1.0 V (Ag/AgCl saturated electrode). the influence of TEA, BrO³ and NaOH concentrations on the peak height was studied. It was found that a 100-fold excess of Mn, a 50-fold excess of Cr(VI) and Zn did not interfere in the determination. This method was applied to the determination of iron in water, snow and waste water samples.     

Supercooled water. Considerations about the system organization of liquid water

Summary Supercooled water shows increasing values in heat capacity, free energy difference (in relation to ice) and compressibility as the temperature is lowered, whereas the density is decreased. After careful consideration of the boundary conditions, as they are required for the preparation of supercooled water, the reorganizations within the liquid were investigated and the changes in differentiations examined. Different groups of water molecules are distinguished, namely those at the interface, around dissolved gas molecules, around hydrophilic solutes and the vast majority of the remaining water molecules. It is emphasized that all of these groups are required for the existence of liquid water. Their continuous interrelations are described by the introduction of hierarchic levels, as they are characteristic for a system organization.The highest hierarchic level is that of the interface, the forces of which regulate and control the exchange of matter and energy both with the environment and within the liquid phase. Subordinated to this level is that of the dissolved gas molecules and their surrounding water molecules. In both of these levels the dynamic aspects are highly developed. Subordinated to this level is that of the hydrophilic solutes and their surrounding water molecules. Their unavoidable presence in liquid water is evidenced by the self-ionization equilibrium. The lowest level is that of all of the other water molecules, which provides some kind of more static boundary conditions for the exercise of the better developed dynamic features of the higher levels.In order to obtain supercooled water, the dynamic features must be improved in the higher hierarchic levels, whereas in the lower levels the more static features should remain as small as possible. The former is achieved by certain cooling modes, by increased surface area, by hydrophobic environment and by increasing gas concentration in the liquid. On the other hand, the concentration of hydrophilic solutes must be minimized (the purity of water enhanced). The metastable state is dynamically better maintained, the better the system organization is developed. The state of supercooled water approaches that of optimal system organization in the temperature range between –20° and –30°C.

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Unterkühltes Wasser. Betrachtungen über die Systemorganisation von flüssigem Wasser

Zusammenfassung In unterkühltem Wasser nehmen die Wärmekapazität, die Differenz der freien Enthalpie in bezug auf Eis und die Kompressibilität mit sinkender Temperatur zu, während die Dichte abnimmt. Unter Berücksichtigung aller Randbedingungen, unter denen Wasser unterkühlbar ist, wurden die Reorganisationen innerhalb der Flüssigkeit untersucht. Die Eigenschaften von Wassermolekülen an der Phasengrenzfläche, in der Umgebung von Gasmolekülen, in der Umgebung hydrophiler Teilchen und der großen Zahl der übrigen Wassermoleküle sind unterschiedlich. Ihre kontinuierlichen Wechselbeziehungen werden durch Einführung hierarchischer Ebenen beschrieben, wie sie für eine Systemorganisation charakteristisch sind.Die höchste hierarchische Ebene ist diejenige der Moleküle an der Phasengrenzfläche, deren Kräfte den Austausch von Materie und Energie sowohl mit der Umgebung als auch innerhalb der flüssigen Phase regulieren und kontrollieren. Dieser Ebene untergeordnet ist diejenige der gelösten Gasmoleküle und der sie umgebenden Wassermoleküle. In diesen beiden Ebenen sind die dynamischen Aspekte hoch entwickelt. Dieser Ebene nachgeordnet ist diejenige der die hydrophilen Bereiche umgebenden Wassermoleküle. Die niedrigste Ebene ist diejenige aller anderen Wassermoleküle, welche eine Art statischer Randbedingungen für die Ausübung der in den höheren Ebenen besser entwickelten dynamischen Aspekte bieten.Um unterkühltes Wasser zu erhalten, müssen in den höheren hierarchischen Ebenen die dynamischen Eigenschaften verbessert werden, während in den unteren hierarchischen Ebenen die Differenziertheit so klein wie möglich bleiben soll. Ersteres wird durch Vergrößerung der Oberfläche, bestimmte Abkühlungsbedingungen, hydrophobe Umgebung und durch zunehmende Konzentration an gelösten Gasen erreicht, letzteres durch Erhöhung der Reinheit (Minimisierung der Konzentration hydrophiler Teilchen). Der metastabile Zustand wird umso besser dynamisch aufrechterhalten, je besser seine Systemorganisation entwickelt ist. Der Zustand des unterkühlten Wassers kommt der optimalen Systemorganisation im Temperaturbereich zwischen –20° und –30°C am nächsten.

     

Water sorption in poly(zwitterions) of the ammonioalkoxydicyanoethenolate type

Water sorption by amorphous (meth)acrylic poly(zwitterions)-bearing quaternary ammonioalkoxydicyanoethenolate side groups , dipole moment μ(D) = 25.9 and 30.8 for p = 2 and 3, respectively was studied at 23°C over a broad range of water activity a (0.14–0.98). Water diffusion is nearly Fickian (D_s = 5.9 10^?7 cm².s^?1 for a = 0.63) and the sorption isotherms may be quantitatively analyzed according to the Guggenheim-Anderson-De Boer equation for a multilayer process characterized by a number of site-bound water molecules per monomeric unit, n_m ? 0.7. The Flory χ interaction parameter is a strongly increasing function of the water content in the glassy hydrated systems and it always remains higher than 0.75. Clustering of water molecules (Zimm-Lundberg theory) is never observed. Differential scanning calorimetry allows to quantify nonfreezable bound water (type I) of strong plasticization efficiency, n(I) = 2.8 mol. of water per monomeric unit, and it points out the quasisimultaneous emergence of low amounts of freezable bound water (type II) crystallizing at ?40°C and melting at ?1°C and of bulkfree water (type III, n(II)/n(III) ? 0.1). All these typical features distinguish these rather hydrophobic poly(zwitterions) from their hydrophilic homologues of the quaternary ammoniopropanesulfonate type . © 1995 John Wiley & Sons, Inc.     

The effect of pressure on the ionization of water at various temperatures from molal-volume data1

The apparent molal volumes of dilute (0.002 to 1.0m) aqueous HCl and NaOH solutions have been determined at 0, 25, and 50°C and NaCl solutions at 50°C. The partial molal volumes ( ) of HCl, NaOH, and NaCl solutions have been determined from these apparent molal volumes and other reliable data from the literature. The partial-molal-volume changes ( ) for the ionization of water, H₂OH⁺+OH^–, have been determined from 0 to 50°C and 0 to 1m ionic strength from the partial molal volumes of HCl, NaOH, NaCl, and H₂O. The partial molal compressibilities ( for HCl, NaOH, NaCl, and H₂O have been estimated from data in the literature and used to determine the partial molal compressibility changes ( ) for the ionization of water from 0 to 50°C and 0 to 1m ionic strength. The effect of pressure on the ionization constant of water has been estimated from partial-molal-volume and compressibility changes using the relation from 0 to 50°C and 0 to 2000 bars. The results agree very well with the directly measured values.Contribution Number 1548 from the University of Miami.     

钨砷杂多阴离子[KAs4W40O140(M·H2O)2]n-中配位水的取代反应

本文报道了[KAs_4W_(40)O_(140)(M·H_2O_2]~(n-)杂多阴离子中配位水的取代反应.在水溶液中,许多配体,如[Fe(CN)_6]~(4-)、[Fe(CN)_6]~(3-),SO_3~(2-)等都能取代配位水形成具有特征颜色的配离子.在水溶液中不能发生的配体取代配位水的反应,在非极性有机溶剂中却容易发生,这与配位水分子在非极性有机溶剂中易脱去形成配位不饱和态有关.     

一种新型杀菌树脂的合成及其杀菌活性的研究

合成了烷基二甲基苄基氯化铵饮用水消毒树脂,并测定了它的杀菌活性,与已商品化的三碘消毒树脂的杀菌性能进行了比较。使用表面活性剂和超声波进行再生可以获得较好效果。     

Study of water solubilized in AOT/n-decane/water microemulsions

The state of water in AOT-n-decane-water microemulsions has been studied by using Fourier Transform Infrared spectroscopy (FT-IR). The existence of three kinds of water, which correspond to water populations with different degrees of organization, has been observed. Densities of these microemulsions have been measured. From these studies (FT-IR and densities), the apparent molar volumes of the different types of water molecules have been estimated. These apparent molar volumes, as well as their variations with respect to the composition of the microemulsion, depend on the type of water. The volume of the water bound to the ionic heads of the surfactant is lower than that for bulk water and shows a slight dependence on the molar ratio W. In contrast, no dependence on W is found for the volume of water trapped between the tails of the surfactant.     

Adsorption of vapor mixtures of water and organic substance on activated carbons

The isotherms of water adsorption in the presence of an organic substance vapor with a specified concentration are calculated from experimental data on the joint frontal dynamics of adsorption of water vapor and several organic substances (benzene, hexane, cyclohexane, tetrachloromethane, and perfluorotripropylamine) on two samples of activated carbons. The influence of the organic substances on the equilibrium water adsorption decreases with an increase in the molecule size.     

甲基萘磺酸系高效减水剂合成研究

减水剂在建筑混凝土中应用广泛,其中萘系高效减水剂具有减水率高,对混凝土的强度不产生有害影响且成本低的优点,在市场上占80%,其它各种减水剂由于减水率低的缺点在市场上仅占20%。实验以甲基萘油为原料,经过磺化、水解、缩合、中和四步反应,合成减水率高达16.8%的甲基萘磺酸系高效减水剂,并对合成中滴加硫酸温度、磺化温度、水解加水量、甲基萘与甲醛的物质量比等的各种影响因素作了进一步的探讨。     

The Study of Water Structure in Aqueous Solutions of Butoxyethanol by Enthalpy of Mixing Measurements

In order to confirm the existence of regions I and II in aqueous solutions of butoxyethanol(BE), the concentration and temperature dependences of enthalpies of mixing of aqueous BE solutions with some organic solvents were measured. It has been found that the increments of apparent enthalpies of mixing per mole of water with respect to the mole fraction of BE change irregularly at a certain concentration. This concentration nearly corresponds to the reported boundary between regions I and II. Although similar behavior has also been observed in aqueous solutions of iso-butoxyethanol, aqueous solutions oftert-butoxyethanol have shown no anomalous behaviors. This revised version was published online in July 2006 with corrections to the Cover Date.     

Application of FTIR spectroscopy in the study of lattice vibration for mixed crystals

FT-IR spectroscopy was utilized to characterize the structure hydration and dehydration of mucin in vitro. The results indicated that both the protein chain and carbohydrate moiety are hydrated with the water molecules. In addition, the hydration and dehydration mechanism of mucin are quite different in H₂O and D₂O media.     

Photocatalytic Hydrogen and Oxygen Formation from Water over Ga-modified Zeolite

Water could be decomposed into hydrogen and oxygen over Ga-modified ZSM-5 zeolite under UV irradiation. The photocatalytic activity was elevated significantly by supporting the gallium species and was sensitive to the loading amount of gallium species on the ZSM-5 zeolites.     

水质净化过程投加净化剂的最佳选择

对水质净化过程中投加净化剂的效果进行了研究,得出了冬春低温低浊季节,水力循环澄清池－快滤池净化过程投加净化剂脱混的最佳选择。