Effects of Cu2+ on stability and composition of water soluble ternary polyacrylic acid-Cu2+-protein complexes against radiation damage

Summary The formation of water soluble ternary complexes of polyacrylic acid (PAA) and bovine serum albumin (BSA) in the presence of divalent copper ions was investigated at the neutral pH. Aqueous solutions of PAA, BSA, and their mixture (PAA-BSA, PAA-Cu²⁺-BSA) have been irradiated with ⁶⁰Co -rays and the changes occurred have been measured by high performance liquid chromatography (HPLC) and spectrophotometry. Addition of Cu²⁺ ions to PAA-BSA mixture have been shown to protect the PAA and BSA components of ternary PAA-Cu²⁺-BSA complexes against radiation damage. A structural model of ternary polycomplexes was proposed and the mechanism of observed protection effect was discussed.     

超临界水氧化处理偏二甲肼废水研究

采用Cu2+为催化剂、H2O2为氧化剂,在24~30MPa和480~500℃的条件下,在一连续流反应器中进行了催化超临界水氧化偏二甲肼实验。研究了温度、压力、停留时间和Cu2+浓度对偏二甲肼氧化降解的影响。结果表明,在超临界水中偏二甲肼能被有效去除。偏二甲肼的去除率随反应温度和压力的升高、停留时间的延长和Cu2+浓度增大而提高。当Cu2+浓度为30 mg.L-1时,偏二甲肼的去除率与无催化剂时相比有了较大的提高。当30MPa、500℃、3.9s和Cu2+浓度为15 mg.L-1时,COD去除率高达99.4%。     

净水厂干化铝污泥对水中Pb2+和Cu2+的吸附研究

采用净水厂干化铝污泥吸附处理水中的Pb^2+和Cu^2+,研究了污泥投加量、pH、Pb^2+和Cu^2+初始浓度、吸附时间以及温度对吸附效果的影响。结果表明,Pb^2+和Cu^2+的去除率均随污泥投加量的增加和溶液pH的升高而增大;Langmuir模型能够准确描述干化铝污泥对Pb^2+和Cu^2+的吸附特性,20℃时其对Pb^2+和Cu^2+的饱和吸附量分别可达212.77、73.53 mg/g;干化铝污泥对Pb^2+和Cu^2+的吸附动力学符合准二级动力学模型;吸附过程为自发、吸热、熵增的反应。     

一种高吸水树脂对电镀废水中铜离子的吸附研究

以废弃聚乙烯(PE)塑料与具有亲水性基团的丙烯酸(AA)及其盐接枝共聚合成一种高吸水性树脂,并将所得高吸水树脂用于溶液中Cu2+的吸附。通过分光光度法研究了树脂去除水溶液中Cu2+的情况,考察了起始pH、树脂用量、金属离子起始浓度和吸附时间对金属离子去除率的影响。结果表明,该树脂对Cu2+具有较强的吸附性能。树脂初期吸附速率大,吸附达到平衡时的接触时间为30 min。当溶液pH为7.0,Cu2+初始浓度为25 mg/L,树脂用量在8 g/L时,树脂对Cu2+的去除率可达95.0%以上。     

碳纳米管溶胶对水中微量Cd~(2+)与Cu~(2+)吸附的研究

采用强酸表面氧化法对碳纳米管进行处理,制备稳定具有高效吸附性能的碳纳米管溶胶,用于去除水中低质量浓度重金属Cd2+,Cu2+。研究表明,在实验的pH值为2.5—9.5,对Cd2+的去除,吸附起主要作用,优化的pH值为6.0;对Cu2+的去除,pH<6.7时,吸附起主要作用,在pH>6.7时,金属离子沉淀是主要的去除原因,在pH=9.5时,达到最大去除率。在相同碳纳米管溶胶投加质量浓度情况下,对Cd2+的吸附去除率远远大于对Cu2+的去除。碳纳米管溶胶对Cd2+,Cu2+的吸附等温线呈线性,对Cd2+的吸附性能优于对Cu2+的吸附性能。     

Polymerization of methyl methacrylate in water in presence of the metal oxides TiO2 and Cu2O

Rates of sodium bisulfite-initiated polymerization of methyl methacrylate in water were determined in absence and in presence of the metal oxides TiO₂ and Cu₂O at 30°, 40°, 50°, and 60°C. Cuprous oxide and titanium dioxide enhanced the rate of polymerization and reduced the molecular weight as compared with the figures obtained in absence of oxide, the effect of the former being more pronounced than the latter. With TiO₂, the rate was increased from 2.3 to 3.2 × 10^?5, while with Cu₂O, it was increased to 8.6 × 10^?5 mole/l./sec, both at concentrations of 9 g/l. water. The apparent energy of activation for the polymerization of methyl methacrylate between 40°C and 50°C was found to be 15.6 kcal/mole in absence of the metal oxides, and 7.6 kcal/mole and 2.8 kcal/mole in presence of titanium dioxide and cuprous oxide, respectively. The number-average molecular weight was found to decrease slightly with the addition of TiO₂ but to decrease greatly when Cu₂O was added.     

Investigation of binary polymer/surfactant or ternary polymer/surfactant/Cu2+ complexes in aqueous solution through Nile red probing

The optical properties (absorption and emission) of Nile red have been widely used for staining or probing purposes in diverse aqueous systems. However, the applications of Nile red for the determination of the critical aggregation concentration of polymer/surfactant complexes or for the investigation of ternary polymer/surfactant/Cu²⁺ systems are very limited. The interactions between anionic polyelectrolytes and the oppositely charged surfactant N,N,N,N‐dodecyltrimethylammonium chloride were investigated in dilute aqueous solution, exploiting the optical properties of Nile red. It is shown that the emission properties of Nile red present better sensitivity than its absorption properties, concerning the detection of the hydrophobic polymer/surfactant complexes formed in aqueous solution. Moreover, it is found that the formation of ternary polymer/surfactant/Cu²⁺ complexes leads to a pronounced quenching of the luminescence of Nile red. The corresponding Stern–Volmer plots indicate that quenching is more favourable when coordination of Cu²⁺ ions with poly(sodium acrylate) takes place, as compared to simple electrostatic binding of these ions with poly(sodium styrene sulfonate). Nile red is a sensitive and accurate tool, as an alternative to pyrene, for the characterization of binary polymer/surfactant complexes or for obtaining information on the local arrangement of ternary polymer/surfactant/Cu²⁺ systems in aqueous solution. Copyright © 2010 Society of Chemical Industry     

Dynamic adsorption behaviors between Cu2+ ion and water‐insoluble amphoteric starch in aqueous solutions

Dynamic adsorption behavior between Cu²⁺ ion and water‐insoluble amphoteric starch was investigated. The sorption process occurs in two stages: external mass transport occurs in the early stage and intraparticle diffusion occurs in the long‐term stage. The diffusion rate of Cu²⁺ ion in both stages is concentration dependent. In the external mass‐transport process, the diffusion coefficient (D₁) increases with increasing initial concentration in the low‐ (1 × 10^?3‐4 × 10^?3M) and high‐concentration regions (6 × 10^?3‐10 × 10^?3M). The values of adsorption activation energy (k_d1) in the low‐ and high‐concentration regions are 15.46–24.67 and ?1.80 to ?11.57 kJ/mol, respectively. In the intraparticle diffusion process, the diffusion coefficient (D₂) increases with increasing initial concentration in the low‐concentration region (1 × 10^?3‐2 × 10^?3M) and decreases with increasing initial concentration in the high‐concentration region (4 × 10^?3‐10 × 10^?3M). The k_d2 values in the low‐ and high‐concentration regions are 9.96–15.30 and ?15.53 to ?10.71 kJ/mol, respectively. These results indicate that the diffusion process is endothermic in the low‐concentration region and is exothermic in the high‐concentration region for both stages. The external mass‐transport process is more concentration dependent than the intraparticle diffusion process in the high‐concentration region, and the dependence of concentration for both processes is about equal in the low‐concentration region. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2849–2855, 2001     

胞外聚合物对水中Cu2+的吸附研究

以胞外聚合物作为生物吸附剂,对水中微量Cu^2＋的生物吸附特性进行研究,分析了原始pH值、胞外聚合物投加量、吸附时间对Cu^2＋吸附去除率的影响.研究结果表明：当初始Cu^2＋的质量浓度为10mg/L时,吸附最佳原始pH值范围为2～5,胞外聚合物的投加量为16mg/g,吸附时间为40min.Cu^2＋的吸附过程可分为3个阶段：①8 min的快速吸附阶段;②8～40 min达表观一级动力学吸附阶段;③吸附-解吸平衡阶段.Cu^2＋吸附等温线与Freundilich方程拟合良好.     

Competitive interaction of polyanions and anionic dye with bovine serum albumin

The binding of anionic dye, p-(2-amino-6-sulfonyl-8-naphthylazo)benzene sulfonic acid disodium salt (ASANA) to bovine serum albumin (BSA) at pH 7.5 has been studied by spectrophotometric techniques. The values of the dissociation constants were obtained with the use of the Benesi-Hildebrand equation for ASANA. Competitive binding of polyanions, sodium poly(styrene sulfonate) (PSSNa), potassium poly(vinyl sulfonate) (PVSK), poly(acrylic acid) (PAA), and poly(methacrylic acid) (PMAA) and anionic dye to BSA was evaluated through the variations in the different spectra of BSA-dye-polymer systems.     

新试剂DOPT对Cu2+和Ni2+的快速鉴定

用新试剂 N 十二烷基 N′ (对氨基苯磺酸纳 )硫脲 (简称 DOPT)鉴定 Cu2 的检出限量 0 0 1 3μg,最低质量浓度0 4 3μg ml;鉴定 Ni2 的检出限量 0 0 4 3μg,最低质量浓度 1 4 4μg ml,且选择性好 ,操作简便 ,在实际样品分析中也获得满意结果。     

Superabsorbent hydrogel based on modified polysaccharide for removal of Pb2+ and Cu2+ from water with excellent performance

This contribution describes the absorption percentage of Pb²⁺ and Cu²⁺ from water by a superabsorbent hydrogel matrix (SH) made from an anionic polysaccharide copolymerized with acrylic acid (AAc) and acrylamide (AAm). Metal‐absorption tests, upon sequential pH variation, indicated that the SH has pH‐sensitivity for the absorption of both metals from solution, attributed to the functional ionic groups (? COOH) present in the AAc and arabic gum (AG) segments. At the pH 5.0, the SH exhibited good absorption capacity: 73.10% for Pb²⁺, 81.99% for Cu²⁺ in water and 63.64% for Pb²⁺, and 76.67% for Cu²⁺ in saline water with 0.1 mol kg^?1 ionic strength. A replicated 2² full factorial design with a central point was built to evaluate the maximum absorption capacity of the metals into the SH. It was found that both the interaction and main effects of the pH and the initial concentration of metal solution on absorption percentage of the metals were statistically significant. Surface response plots indicated that the absorption capacity of both metals into the SH may be appreciably improved by using the solutions with lower initial concentration of metal and with higher pH values. Metal‐absorption results demonstrated that the SH is a convenient material for absorption of Pb²⁺ and Cu²⁺ from pure aqueous and saline aqueous environments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

The inhibitory effect of water on the Co2+ and Cu2+ catalyzed decomposition of methyl linoleate hydroperoxides

The inhibitory effect of water on the decomposition of methyl linoleate hydroperoxides (MLHP) catalyzed by Co²⁺ and Cu²⁺ was studied in a model system using proton nuclear magnetic resonance (NMR) spectroscopy. MLHP were prepared by photoxidation and purified by chromatographic methods. Proton NMR spectroscopy was used to measure reaction rates by monitoring changes in the intensity of the OOH signal. The rate constant of the reaction was obtained by plotting the natural logarithm of MLHP concentrationvs time. In the first part of the study, no transition metals were added to the model system, so that the effect of water could be attributed to the interaction between water and MLHP only. The rate constant of the reaction (K) was found inversely proportional to the concentration of water. There was a downfield chemical shift of both hydroperoxide and water peaks in the NMR spectra when water was added. As temperature increased to 40°C, the difference in K between the systems with 0% and 2% water disappeared. It is proposed that the hydroperoxides were solvated with water which retarded their decomposition. When Co²⁺ was added to the model system, K decreased as the concentration of water increased from 0% to 1.5%. As temperature increased from 18°C to 40°C, differences between the K for 0% and 2% water disappeared. A similar phenomenon was observed in reactions catalyzed with Cu²⁺. These findings would support a mechanism in which the protective effect of water involves both the solvation of OOH and hydration of the metal catalyst. Based on a paper presented at the Symposium on Metals and Lipid Oxidation, held at the AOCS Annual Meeting in Baltimore, MD, Apirl 1990.     

Physicochemical study of the complexation of poly(acrylic acid) with Cu2+ ions in water

The complexation of poly(acrylic acid) (PAA) with Cu²⁺ ions in a dilute aqueous solution has been investigated as a function of the mixing molar ratio of the two species and the neutralization degree (i) of PAA by means of turbidimetry, viscometry, potentiometry, and ultraviolet–visible (UV–vis) spectrophotometry. Turbidimetry reveals that, for i > 0.1, phase separation takes place when the mixing ratio approaches the critical value of two carboxylate ions per Cu²⁺ ion, which is indicative of the formation of a 2 : 1 polymer/metal complex. This complex is very compact, as evidenced by the very low reduced viscosity values obtained just before phase separation. The variation of the fraction of complexed carboxylate anions and complexed Cu²⁺ ions can be followed as a function of the mixing ratio and i from the analysis of the potentiometric results for i < 0.5. Finally, the combination of the potentiometric and UV–vis spectrophotometric results supports the idea that both mononuclear and binuclear PAA/Cu²⁺ complexes are formed in an aqueous solution, depending on the mixing ratio and i. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Conductometric titration of chitosan sulfate polyanions in the presence of extraneous electrolytes

The possibility of determining the concentration of basic substance and H ₂SO₄ and Na₂SO₄ impurities in technical-grade chitosan sulfate (CS) was demonstrated. Water-ethanol solution containing 80±10% ethanol of the volume of the titratable mixture is the optimum medium for titration of technical-grade CS. Translated from Khimicheskie Volokna, No. 2, pp. 21–23, March–April, 1997.     

Corrosion behavior of high-temperature superconductor YBa2Cu3-yAgyO7-x in the presence of water

Because of the presence of water vapor, YBa₂Cu₃O_7-x degrades easily in the atmosphere and thus very difficult to put it to practical use. When Cu is partially substituted with Ag, however, there is not much a decrease in the critical temperature (T_c) : T_c is 89 K compared with 91 K without substitution. Moreover, partial substitution of Ag increases density, hardness, and superconducting particle size and above all improves considerably its stability in water. In this study YBa₂Cu₃O_7-x and YBa₂Cu_3-yAg_yO_7-x as a result of a partial substitution of Ag for Cu were synthesized by pyrophoric method. We investigated their stabilities in water by XRD, SEM, and EPMA after immersing samples in distilled water for 3 hours. We can see that YBa₂Cu_2.94Ag_0.06O_7-x was the largest particle size and anticorrosion behavior.     

Corrosion behavior of DLC-coated NiTi alloy in the presence of serum proteins

Uniform and adherent diamond-like carbon (DLC) coatings are deposited on NiTi alloy by arc enhanced magnetron sputtering (AEMS). The effects of serum proteins, bovine serum albumin (BSA) and fibrinogen (Fib) on the corrosion behavior of DLC-coated NiTi alloy in phosphate buffer saline (PBS) solution are investigated at 37 °C using open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results show that DLC coatings, which enhance the corrosion resistance of the NiTi alloy especially in the presence of BSA, move the OCP to the positive direction, increase the polarization resistance, lower the corrosion current density, and enhance the breakdown potential. The presence of fibrinogen shows the similar effect but less notable than BSA. The associated mechanism is also discussed.     

Cu~(2+)、Zn~(2+)和Pb~(2+)对绿原酸与牛血清白蛋白结合作用的影响

以杜仲绿原酸(CA)为原料,在模拟人体生理条件下,采用荧光光谱和紫外吸收光谱等方法,考察Cu2+、Zn2+和Pb2+对CA与牛血清白蛋白(BSA)相互作用产生的影响。结果表明,金属离子的存在不会改变CA对BSA的猝灭类型,但对其猝灭速率常数(kq)、结合常数(K)以及结合位点(n)会有不同程度的影响;CA与BSA之间的反应属于自发型,主要以范德华力和氢键为主,Zn2+和Pb2+的存在不会改变其作用力类型,Cu2+则会使作用力变为以静电吸引力为主;Zn2+和Pb2+会将供体与受体之间的结合距离分别减小1.975%和14.07%,Cu2+的干扰使CA与BSA之间的结合距离增大11.58%;同步荧光光谱显示CA与BSA中的酪氨酸残基和色氨酸残基都有相互作用,三维荧光测定结果进一步表明猝灭剂对BSA构象及微环境会引起变化。     

Cu2+对磁化蒸馏水改善辉钼矿浮选效果的影响

通过单矿物浮选实验、Zeta电位测试及X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和能谱(EDS)分析,研究了Cu2+对磁化蒸馏水改善辉钼矿浮选效果的影响。结果表明,用磁化蒸馏水浮选时,在煤油用量160 mg/L及2＃油用量80 mg/L的条件下,Cu2+浓度为320 mg/L时辉钼矿回收率可达83.06%,比Cu2+浓度为0时的回收率增加了3.14个百分点,Cu2+对磁化蒸馏水改善辉钼矿浮选效果的影响较小。Cu2+和Cu(OH)+吸附在辉钼矿表面使其Zeta电位正向增大,有利于煤油在辉钼矿表面的吸附。辉钼矿表面上吸附的Cu2+和Cu(OH)+与溶液中的MoO42?反应生成CuMoO4沉淀并覆盖在辉钼矿断裂面上,抑制了辉钼矿断裂面中钼元素和硫元素的氧化反应及氧化钼溶解,最终对磁化蒸馏水改善辉钼矿浮选效果有积极影响。     

A new high-dimensional architecture constructed from paradodecatungstate and [Cu(2-Hpzc)]2+ complexes

A new compound, H₄{[Cu₃(2-Hpzc)₂(H₂O)₄](H₂W₁₂O₄₂)}·13H₂O (1) (2-Hpzc = 2-pyrazinecarboxylic acid), was synthesized in conventional condition and characterized by elemental analyses, IR spectroscopy, thermal gravimetric analysis, X-ray powder diffraction (XRPD) and single X-ray diffraction. In the structure of compound 1, each paradodecatungstate anion acts as a quadridentate ligand coordinating to four Cu²⁺ cations through its terminal oxygen atoms to form a two-dimensional (2D) layer. The infinite [Cu(2-Hpzc)]²⁺ chains connect adjacent layers forming a three-dimensional (3D) architecture. There exist two kinds of channels with sizes of ca. 5.737 × 4.628 Å² and 9.104 × 8.640 Å² along the b and c directions, respectively. The magnetic behavior of 1 exhibits antiferromagnetic interaction.