Characteristics of hydrogen nanobubbles in solutions obtained with water electrolysis

A solution supersaturated with hydrogen obtained by water electrolysis was studied using cyclic voltammetry. The cyclic voltammogram of the solution supersaturated with hydrogen gave a peak current at −0.1 V vs. AgAgCl. No peak current in a solution saturated with hydrogen was observed by bubbling hydrogen gas through the solution. The peak current was influenced by the temperature and ion type of the electrolyte. The peak current was found to be due to the presence of hydrogen nanobubbles. The peak current increased with increasing hydrogen nanobubble concentration and decreased to zero within 3 h after electrolysis.     

Transport of Tb3+in Dispersion Supported Liquid Membrane System with Carrier P507

The Tb³⁺ transport in dispersion supported liquid membrane (DSLM) consisting of polyvinylidene fluoride membrane (PVDF) as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2‐ethyl hexyl phosphonic acid‐mono‐2‐ethyl hexyl ester (P507) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb³⁺ and different ionic strength in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on transport of Tb³⁺ has also been investigated, respectively. As a result, the optimum transport conditon of Tb³⁺ was that concentration of HCl solution was 4.0 mol/L, concentration of P507 was 0.10 mol/L, and volume ratio of membrane solution and stripping solution was 1.0 in the dispersion phase, and pH value was 5.2 in the feed phase. Ionic strength had no obvious effect on transport of Tb³⁺. Under the optimum condition studied, when initial concentration of Tb³⁺ was 1.0×10^?4 mol/L, the transport rate of Tb³⁺ was up to 95.2% during the transport time of 95 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The results were in good agreement with the literature data.     

Concentration determination of oxygen nanobubbles in electrolyzed water

Water electrolysis is well known to produce solutions supersaturated with oxygen. The oxygen in electrolyzed solutions was analyzed with a dissolved oxygen meter and the Winkler method of chemical analysis. The concentration of oxygen measured with the dissolved oxygen meter agreed with that obtained using the Winkler method. However, measurements using a 10-fold dilution method showed a larger concentration of dissolved oxygen compared to the above methods. We developed a modified Winkler method to measure total oxygen concentration more accurately, which agreed with the results obtained from the 10-fold dilution experiment. The difference in measurements is due to the existence of oxygen nanobubbles, as confirmed by the observation of dynamic light scattering using a laser. Further analysis of the oxygen nanobubbles demonstrated that the stability of the nanobubbles was sufficient for chemical reaction and solvation to bulk solution.     

基于单颗粒电感耦合等离子体质谱法测定环境基质水样中纳米银颗粒

采用单颗粒电感耦合等离子体质谱法(SP-ICP-MS)同时测定环境水样中纳米银颗粒(AgNPs)的颗粒浓度、质量浓度和粒径分布,并考察了溶液的pH值、溶解性有机质(DOM)浓度以及离子强度等对AgNPs测定的影响。结果表明:SP-ICP-MS方法对60 nm AgNPs标准溶液的测定结果与标准值一致,准确性较好;pH值(5.0～7.0)、离子强度(≤1 mmol/L)和DOM浓度(≤30 mg/L)对测定结果影响较小;当溶液的pH值≤5.0或离子强度1 mmol/L时,AgNPs的颗粒浓度和粒径随pH值的下降或离子强度的增强而减小。采用SP-ICP-MS方法测定河水、染料废水、养殖废水3种水样中AgNPs的加标回收率分别为98.1%、83.3%和93.3%,表明该方法在合适的基质条件下可用于快速准确测定环境水样中AgNPs的颗粒浓度、质量浓度和粒径分布。     

2,10-Br离子聚合物与聚丙烯酸钠的复合作用

2,10-Br-PAANa不水溶性复合物中, [COO~-]/[N]为6/4, 其组成不受聚合物总浓度的影响。低浓盐水溶液有利于不溶性复合物的形成, 但高浓盐的“屏蔽效应”会把复合物溶解。在水中复合反应瞬间完成, 复合物稳定; 在盐-水中,复合物的稳定性则随时间发生明显变化。2,6-Br、2,10-Br和6,10-Br对抑制大肠杆菌的生长都有明显效果, 其中以6,10-Br最为有效。     

Electrolysis of ammonia for hydrogen production catalyzed by Pt and Pt-Ir deposited on nickel foam

Electrolysis of ammonia in alkaline electrolyte solution was applied for the production of hydrogen. Both Pt-loaded Ni foam and Pt-Ir loaded Ni foam electrodes were prepared by electrodeposition and served as anode and cathode in ammonia electrolytic cell, respectively. The electrochemical behaviors of ammonia in KOH solution were individually investigated via cyclic voltammetry on three electrodes, i.e. bare Ni foam electrode, Pt-loaded Ni foam electrode and Pt-Ir loaded Ni foam electrode. The morphology and composition of the prepared Ni foam electrode were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Effects of the concentration of electrolyte solution and temperature of electrolytic cell on the electrolysis reaction were examined in order to enhance the efficiency of ammonia electrolysis. The competition of ammonia electrolysis and water electrolysis in the same alkaline solution was firstly proposed to explain the changes of cell voltage with the electrolysis proceeding. At varying current densities, different cell voltages could be obtained from galvanostatic curves. The low cell voltage of 0.58 V, which is less than the practical electrolysis voltage of water (1.6 V), can be obtained at a current density of 2.5 mA/cm². Based on some experimental parameters, such as the applied current, the resulting cell voltage and output of hydrogen gas, the power consumption per gram of H₂ produced can be estimated.     

Separation of Trivalent Samarium through Facilitated Stripping Dispersion Hollow Fiber Liquid Membrane Using p204 as Mobile Carrier

The separation of Sm(III) through stripping dispersion hollow fiber liquid membrane system (SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HCl solution as the stripping solution and membrane solution of di(2‐ethylhexyl) phosphoric acid (p204) dissolved in kerosene, has been studied. A set of factors were studied, including pH value, initial concentration of Sm(III) and different ionic strength of feed phase, volume ratio of membrane solution and stripping solution (O/W), HCl concentration, carrier concentration, different stripping agents of dispersion phase on Sm(III) separation. Experimental results indicate that the optimum separation conditions of Sm(III) were obtained as that HCl concentration was 4.00 mol/L, p204 concentration was 0.150 mol/L, and volume ratio of membrane solution and stripping solution (O/W) was 1.00 in the dispersion phase, and pH value was 4.60 in the feed phase. Ionic strength had no obvious effect on separation of Sm(III). When initial Sm(III) concentration was 1.00×10^?4 mol/L, the separation rate of Sm(III) was up to 93.5% in 85 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The modeled results were in good agreement with the experiment data.     

Electromigration of a heteroconjugated imidazole-acetate complex in ACN

ACN is an extremely poor hydrogen bond donor and therefore the anions dissolved in it are solvated mainly by other hydrogen bond donors (e.g. uncharged acids) possibly present in the solution. Under properly selected experimental conditions stabilization via hydrogen bonding can be used for separation in CE as has been demonstrated for uncharged acids by several authors. Electromigration based on heteroconjugation can be of importance, e.g. when aqueous separation medium cannot be used due to stability reasons. It also allows CE to be used as a tool for solution chemistry measurements, if the required physicochemical properties of the studied system are known or they can be predicted with sufficient accuracy by existing theories. In the present work we showed that also an uncharged base can stabilize an anion via hydrogen bonding in ACN. In the setup imidazole was chosen as a model base and acetate ion as complexing anion in equimolar acetic acid-acetate buffer. The resulted hydrogen-bonded imidazole-acetate complex (i.e. heteroconjugate) possesses a charge and can thus migrate in CE. It was shown that the studied complexation in ACN is sensitive to competition by other hydrogen bond donors such as water and methanol. On the other hand, acetone, which is a poor hydrogen bond donor, did not have much effect on the complexation. To take the effect of ionic strength on mobility into account, mobilities of the imidazole-acetate complex measured at various ionic strengths were corrected to zero ionic strength by the aid of conductivity equation. A fit of the 1:1 binding isotherm to the ionic strength corrected mobility versus acetate concentration data led to rather good correlation. However, x-reciprocal linear transformation of the binding isotherm showed nonlinearity, which could be partly explained by homoconjugation of acetic acid and acetate ion. Since the homoconjugation constant for acetic acid under present experimental conditions was not available, theoretical simulations were used to demonstrate the effects of homoconjugation. The possibility of multiple complexation of imidazole was discussed as well.     

Tb(III) Transport in Dispersion Supported Liquid Membrane System with D2EHPA as Carrier in Kerosene

The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb(III) and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, conc...     

Electrochemistry of water in 1-butyl-3-methylimidazolium tetrafluoroborate at nickel electrode: application to hydrogen peroxide production and water sensing

The electrochemistry of water dissolved in 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄mim][BF₄]) was studied by cyclic voltammetry and electrochemical impedance spectroscopy using a nickel electrode. Hydrogen peroxide is being produced by direct electrolysis of water in a cooperative process between the nickel electrode and [C₄mim][BF₄]. There is linear response between the concentration of water and the oxidation peak current at 1.60 V. Impedance decreases significantly with increasing concentration of water. The findings resulted in two promising applications: The first is the production of hydrogen peroxide, and the second is in water sensing. Both methods are environmentally friendly and convenient.     

Sampling 4-chlorophenol in water by DGT technique with molecularly imprinted polymer as binding agent and nylon membrane as diffusive layer

For the first time, a diffusive gradients in thin films (DGT) device using molecularly imprinted polymer (MIP) as the binding agent and nylon membrane (NM) as the diffusive layer (NM-MIP-DGT) has been developed for sampling 4-chlorophenol (4-CP) in water. The MIP was prepared by precipitation polymerization with methacrylic acid as monomer and ethyleneglycoldimethacrylate as cross-linker. The diffusion coefficient of 4-CP through NM was obtained to be 0.788 ± 0.040 μ cm² s⁻¹ by diffusion cell method. The ratio was 1.01 ± 0.05 (mean ± standard deviation) for the concentration of 4-CP sampled by NM-MIP-DGT and analyzed by HPLC method to the total concentration of 4-CP in the synthetic solution where free 4-CP species dominated. The results showed that NM-MIP-DGT could sample 4-CP in synthetic solution accurately. The performance of NM-MIP-DGT for sampling 4-CP was independent of pH in the range of 3–7 and ionic strength in the range of 0.0001–0.1 mol L⁻¹ NaCl solution. The concentration of free form of 4-CP sampled by NM-MIP-DGT decreased with the increasing concentration of dissolved organic carbon in different water samples due to the electrostatic interaction of natural organic compounds with 4-CP. 1.8 mg L⁻¹ of the free form of 4-CP was determined by HPLC which was sampled by NM-MIP-DGT in an intermediate untreated industrial effluent. The NM-MIP-DGT can be a potential passive tool for sampling the free form of 4-CP in water.     

Transfer of actinide ion at the interface between aqueous and nitrobenzene solutions studied by controlled-potential electrolysis at the interface

A novel electrochemical method based on controlled-potential electrolysis has been developed for the elucidation of the ion transfer at the interface between two immiscible electrolyte solutions (ITIES). A relationship between the applied interfacial potential (E_app) and the amount of the ion transferred (A_tr) was investigated after an electrolytic equilibrium was attained by controlled-potential electrolysis. The A_tr was determined chemically or radiometrically instead of by current measurement. It was found that (i) controlled-potential electrolysis was applicable to the study of the transfer of such hydrophilic ions as transition metal ions which gave no appreciable current within the potential window in voltammetry or polarography at ITIES, (ii) controlled-potential electrolysis in combination with a sensitive analytical method enabled a study of the transfer reaction of an ion of very dilute concentration, and (iii) even when the transfer reaction of an ion was irreversible or quasi-reversible, a standard ion transfer potential could be determined by controlled-potential electrolysis without using a kinetic parameter. The controlled-potential electrolysis method developed was applied to the transfer reactions of actinide ions such as UO₂ ²⁺ and Am³⁺ from aqueous solution to nitrobenzene solution in the absence or presence of an ionophore facilitating the transfer. The Gibbs energy for the transfer of actinide ion and a stability constant of the complex between an actinide ion and the ionophore in nitrobenzene solution were determined from log D versus E_app plots (D the ratio of the concentration of the ion in nitrobenzene solution to that in aqueous solution). The feasibility of controlled-potential electrolysis as a method for electrolytic separation of actinide ions is discussed.     

Synthesis and characterization of thermoresponsive poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide-co-<Emphasis Type="Italic">N</Emphasis>-hydroxymethylacrylamide-co-2-hydroxyethyl methacrylate) hydrogels

Thermoresponsive hydrogels based on N-isopropylacrylamide, N-hydroxymethylacrylamide, and 2-hydroxyethyl methacrylate, poly(NIPAM–co-NHMAAm–co-HEMA), have been synthesized and their swelling—deswelling behavior studied as a function of NIPAM concentration, NIPAM/NHMAAm and NIPAM/HEMA mole ratio, and total monomer concentration. Copolymers varying in composition have been obtained by redox copolymerization of these three monomers. Temperature has been changed in the ranges from 4 to 70 °C at fixed pH and total ionic strength. Equilibrium swelling ratio, dynamic swelling ratio, and dynamic deswelling ratio were evaluated for all hydrogel systems. The equilibrium swelling ratios of the copolymeric gels decrease with increasing NHMAAm and HEMA content. The formation of the intermolecular hydrogen bonding between hydroxyl and amido groups decreases the hydrophilic group numbers of the gel and the affinity of the gel towards water decreases. The copolymer gels also showed rapid volume transitions with time. The time required for equilibrium shrinking increased with increasing NHMAAm and HEMA content in the gel.     

Effect of the ionic strength and prostaglandin E2 on the free Ca2+ concentration and the Ca2+ influx in human red blood cells

Human red blood cells (RBCs) were loaded with the Ca(2+)-sensitive fluorescent dye fura-2 to investigate the effects of media ionic strength and prostaglandin E2 (PGE2) on the intracellular free Ca2+ concentration ([Ca2+]i). [Ca2+]i of intact RBCs in a Ca(2+)-containing physiological (high) ionic strength (HIS) solution was 75.1 +/- 8.3 nM after 5 min incubation, increasing to 114.9 +/- 9.6 nM after 1 h. In Ca(2+)-containing low ionic strength (LIS) solutions, [Ca2+]i was significantly lower than in the Ca(2+)-containing HIS solution (p = 0.041 or 0.0385 for LIS solutions containing 200 or 250 mM sucrose, respectively), but, as in HIS solution, an increase of [Ca2+]i was seen after 1 h. In Ca(2+)-free (0 Ca2+ plus 15 microM EGTA) media, [Ca2+]i decreased (ranging from 15 to 21 nM), but were not significantly different in HIS or LIS, and did not change following 1 h incubation. The effect of the ionic strength and PGE2 on passive Ca2+ influx was investigated on ATP-depleted RBCs. Ca2+ influx was faster during the initial 10 min in comparison with the subsequent time period (10-45 min), both in HIS and LIS media, decreasing from 20.3 +/- 1.9 to 12.9 +/- 1.3 micromol/(lcells x h) in HIS, and from 36.7 +/- 5.3 to 8.6 +/- 1.2 micromol/(lcells x h) in LIS. Prostaglandin E2 (PGE2; 10(-7)-10(-11) M), dissolved in deionised water or in ethanol, did not affect [Ca2+]i in either normal or in ATP-depleted RBCs suspended in Ca(2+)-containing HIS medium. Finally, the addition of carbachol (100 microM) did not affect [Ca2+]i. The present findings suggest that stimulation of the Ca(2+)-activated K+ channel by PGE2, reported in [J. Biol. Chem. 271 (1996) 18651], cannot be mediated via increased [Ca2+]i.     

离子强度对DNA媒介电荷转移的影响——基于Debye-Hückel 理论的实验结果分析

用电化学的方法研究了溶液离子强度对DNA媒介电荷转移的影响, 观察到[Ru(NH₃)₆]³⁺的还原峰电势随支持电解质的浓度增加向负方向移动. 分析发现微分脉冲伏安法(DPV)的峰电势与溶液离子强度间在一定范围内存在线性关系, 以式电势(E⁰')作为“桥梁”, 用Debye-Hückel理论给予了解释. 在高离子强度下, 峰电势对线性关系的偏移是由于超过了Debye-Hückel理论的适用范围, 而无强电解质存在时, DNA自身堆积的强负电荷对DNA媒介电荷转移起了推动作用.     

过饱和度、反应物化学计量比及离子强度对草酸钙晶体生长的影响

肾结石是一种普遍的疾病,全球的发病率约为10%,且其复发率高。2003年欧洲的一项统计表明,尿石患者第一次复发率为40%[1]。草酸钙(CaOxa)是肾结石的主要成分,其体外模拟引起了人们广泛的关注[2,3]。然而,普通溶液体系的模拟环境不能充分反映尿石的形成环境,用类似细胞膜的有序分     

A potentiometric investigation of the hydrolysis of chromate (VI) ion in NaCl media to 175°C

The hydrolysis of chromate ion was studied potentiometrically in a concentration cell fitted with hydrogen electrodes by titrating basic NaCl–Na₂CrO₄ solutions with standardized HCl against a NaOH reference solution. The temperature was varied from 25 to 175°C at 25° intervals at the following ionic strengths (I): 0.1140, 0.2346, 0.5337, 0.9988, 2.940, and 5.239 (NaCl). Depending on the ionic strength, the molality of total chromium was varied from 0.001 to 0.100. The resulting titration curves could be resolved best in terms of three equilibria involving the formation of HCrO ₄ ^– (aq), Cr₂O^3– (aq), and CrO₃Cl^– (aq). The equilibrium quotients for all three reactions were fitted as a function of temperature and ionic strength, and the molal thermodynamic parameters that were computed from these relationships are tabulated at specific ionic strengths over the experimental temperature range.     

Thermodynamic Properties of {NaCl-CsCl-LiCl}(aq) at T=298.15 K: Water Activities, Osmotic and Activity Coefficients

A hygrometric method has been used to measure water activities for the quaternary aqueous system NaCl-CsCl-LiCl-H₂O as a function of the solutes concentrations at T=298.15 K. The measurements were performed by measuring the diameter of solution droplets as a function of the surrounding relative humidity. The total ionic strength range covered in this study was about 0.6 to 6 mol?kg^?1 for different ionic strength fractions y of one of the three solutes ranging from y=1/3 to 1/2, whereas the constant ratio r of molalities of the two other solutes was fixed at unity. The osmotic coefficients of these aqueous mixtures were calculated over this ionic strength range. The obtained data were treated by the ECA I and ECA II rules, and the Pitzer and Kim, and Pitzer-Dinane models. The solute activity coefficients of components in the studied mixtures were also determined for different ionic strength fractions of the different solutes.     

含水离子液体/金属界面结构的SERS研究

利用表面增强拉曼光谱(SERS)研究了不同含水量下离子液体及水分子在银电极上随电位变化吸附方式的改变,通过水的O-H伸缩振动谱峰频率变化特征,详细探究了水在离子液体/电极界面上的存在形式及作用方式以及体系零电荷电位与水含量的关系.水含量较低时O-H伸缩振动的Stark系数值较低,随水含量的增加O-H伸缩振动的谱峰位置逐渐向高波数方向移动,同时O-H伸缩振动的Stark系数也逐渐增大,1molL-1[BMIM]Br水溶液中达到76cm-1V-1,且体系的零电荷电位正移,这些差异与水在离子液体中所形成氢键的程度及水分子的存在形式密切相关,在水的含量较低时水与离子液体阳离子通过氢键作用而存在于界面层中,当水的含量增加时,水分子间氢键的作用增强,水与电极表面直接作用的可能性增大.     

Measurement of the peroxidation of Brji-35 in aqueous solution by hemin and horseradish peroxidase catalyzed fluorogenic reaction

The non-ionic surfactant Brij-35 can easily be oxidized in solution by dissolved oxygen upon light radiation during its storage. Various factors, such as light radiation, temperature, pH, ionic strength as well as dissolved oxygen influencing the stability of Brij-35 were studied. The results showed that light radiation is the most important factor inducing the oxidation by the dissolved oxygen. The oxidized product was confirmed, indirectly, to be the peroxide of Brij-35 based on a number of evidences. The extent of the oxidation can be traced by a peroxidase or hemin catalyzed fluorogenic reaction with p-hydroxyphenylacetic acid as a substrate. The concentration of the peroxide in a Brij-35 solution (0.8%, w/v) stored at room temperature for a month is in the range of 9 × 10^–5 mol/L.