Multi-ion migration of Ca2+, Mg2+, Na+ and K+ in the CREDI process

In this paper, the migration of Ca²⁺, Mg²⁺, Na⁺ and K⁺ in cation-bed electrodeionisation was studied. The results showed that it was longer for divalent cations to be balanced compared with monovalent cations. At relatively low current densities, the membrane fluxes of monovalent cations were higher than that of divalent cations, whereas the results were reversed at relatively high current densities. In the resin phase, it was observed that the ionic transport was in relation to various hydration ionic radii. The reaction orders for Ca²⁺, Mg²⁺, Na⁺ and K⁺ were 2, 2, 1 and 1.5, respectively.     

Binary ion exchange equilibrium for Ca2+, Mg2+, K+, Na+ and H+ ions on amberlite IR-120

Experimental data are reported for ion exchange equilibria of binary systems on Amberlite IR-120 resin, at different temperatures and total ionic concentrations in aqueous solutions. These systems exhibit non-ideal behaviour in both phases, and the equilibrium characterization has been based on the law of mass action, using Wilson and Meisssner, and Kusik equations to correlate the activity coefficients in the resin and aqueous solutions, respectively. Equilibrium constants, standard thermodynamic properties (Gibbs free enthalpy changes, enthalpy and entropy) and Wilson binary parameters were obtained as functions of temperature.     

Influence of Na+, K+, Mg2+, Ca2+, and Fe3+on filterability and settleability of drilling sludge

Solid–liquid separation is a vital step in drilling sludge disposal, and the filterability and settleability of drilling sludge are the main evaluating indicators for the separation process. The influence of Na~+,K~+,Mg~(2+),Ca~(2+),and Fe~(3+) on drilling sludge filterability and settleability was investigated in our research. The water content,filtration rate, supernatant volume and supernatant turbidity were measured to evaluate the filterability and settleability of drilling sludge. Meanwhile, the zeta potential, specific surface area of sludge flocs, particle size distribution and Fourier-transformed infrared spectra were employed to clarify the influencing mechanism.The experimental results showed that the filterability and settleability of drilling sludge were related to concentration and types of cations. Mg~(2+),Ca~(2+),and Fe~(3+) performed better than Na~+, K~+, and the cations with smaller hydrated radius got superior solid–liquid separation behavior at same valence. Finally, the spectra indicated that no chemical adsorption occurred between inorganic cations and drilling sludge flocs. The variation of surface charge and flocs growth after adding different inorganic cations were the reasons for the changes of the filterability and settleability.     

Charge reduction and regeneration in K+, Na+, Mg2+, Ni2+ and Co2+-exchanged Wyoming Bentonite

Controlled calcination of ion-exchanged Wyoming Bentonite in the presence and absence of ammonia leads to layer charge reductions. Detailed chemical analyses of both unexchangeable and exchangeable species lead to the conclusion that in no case is there migration of the original interlamellar cations into the octahedral region of the layers although, in terms of ionic radius alone, Mg²⁺, Ni²⁺ and, possibly Co²⁺, might be expected to do so. The production of unexchangeable Mg, Ni or Co, is identified as resulting from high temperature hydrolysis leading to hydroxide or oxide formation.     

Ion-Exchange Equilibrium of Ca2+, Mg2+, K+, Na+, and H+ Ions on Amberlite IR-120: Experimental Determination and Theoretical Prediction of the Ternary and Quaternary Equilibrium Data

Abstract

A study of the cation-exchange equilibria between Amberlite IR-120 resin and aqueous solutions of calcium, magnesium, potassium, and sodium chlorides and hydrochloric acid has been made. Experiments were carried out at 283, 303, and 323 K with solutions having total cation concentrations of approximately 0.1, 0.3, and 0.5 N. Experimental data for the ion-exchange equilibria of the ternary and quaternary systems are reported. These systems exhibit nonideal characteristics in both phases. The predictions have been based on the reaction equilibrium constants and correlations for the activity coefficients in both phases. A model which allows the prediction of multicomponent ion-exchange equilibria from binary data has been developed. Predictions of ternary and quaternary systems based solely on the binary data are in good agreement with the experimental results.     

Absorption characterization of Ca2+, Na+, and K+ on irradiation crosslinked carboxymethyl sago pulp hydrogel

Hydrogel of carboxymethyl sago pulp (CMSP) of various degree of substitution (DS) was prepared by electron beam irradiation of various radiation doses. The CMSP hydrogels were subjected to swelling in different ionic strength solutions of KCl, NaCl, and CaCl₂. The CMSP hydrogels, due to its polyelectrolyte nature, were found to be highly sensitive to ionic strength of the medium. All the CMSP hydrogels showed the absorption of K⁺ and Ca²⁺ increases with the increase in the concentrations of the respective cation solutions. The cation absorption also decreases with DS and % gel fraction (%GF) of the CMSP hydrogels. Subjecting the CMSP hydrogels in NaCl results in deswelling and releases Na⁺ to swelling medium where the Na⁺ release increases with the increase of DS and %GF. The sorption capacity depends on the extent of crosslinking and decreases with the increase in the extent of crosslinking. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Comprehensive study of the structural and electronic properties of complexes formed by Mz+ (Li+, Na+, K+, Be2+, Mg2+, Ca2+) cation and thiophene and its derivatives

The interactions of metal cations (Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, Ca²⁺) with thiophene and its derivatives have been investigated using MP2/6-311++G** and B3LYP/6-311++G** methods in the gas phase and the water solution. The following substituents are taken into considerations: F, Cl, Br, CH₃, OH and C₂H₃, which cover electron-withdrawing and electron-donating effects. The substituent, the metal cations and the solvent effects on the cation–π interactions are investigated. The physical properties such as dipole moment, chemical potential and chemical hardness of studied complexes have been systematically explored. Natural population analysis data, the electron density and Laplacian properties have been used to evaluate the cation–π interaction. The electron density (ρ) and Laplacian (?²ρ) properties, estimated by atoms-in-molecules calculations, indicate that the cation–π interactions possess low ρ and positive ?²ρ, which are in agreement with electrostatic character of the cation–π interactions. Charge transfer values are calculated using Mulliken charges and reveal that the electron charge transfer takes place from thiophene and its derivatives to the metal cation in the complexes under the study. To evaluate the aromaticity of the rings upon complexation, several well-established indices of aromaticity such as the nucleus-independent chemical shift and the harmonic oscillator model of aromaticity and the aromatic fluctuation index have been used. The molecular electrostatic potential is given the visual representation of the chemically active sites and comparative reactivity of atoms. Furthermore, the effects of interactions on NMR data have been used for more investigation of the analyzed complexes.     

Competition between Li+ and Mg2+ for red blood cell membrane phospholipids: A 31P, 7Li, and 6Li nuclear magnetic resonance study

The mode of action of the lithium ion (Li⁺) in the treatment of manic depression or bipolar illness is still under investigation, although this inorganic drug has been in clinical use for 50 yr. Several research reports have provided evidence for Li⁺/Mg²⁺ competition in biomolecules. We carried out this study to characterize the interactions of Li⁺ and Mg²⁺ with red blood cell (RBC) membrane components to see whether Li⁺/Mg²⁺ competition occurs. ³¹P nuclear magnetic resonance chemical shift measurements of the phospholipids extracted from the RBC membranes indicated that the anionic phospholipids, phosphatidylserine and phosphatidylinositol, bind Li⁺ and Mg²⁺ most strongly. From ⁶Li relaxation measurements, the Li⁺ binding constant to the phospholipid extract was found to be 45±5M⁻¹. Thus, these studies showed that the phospholipids play a major role in metal ion binding. ⁷Li spin-lattice relaxation measurements conducted on unsealed and cytoskeleton-depleted RBC membrane in the presence of magnesium indicated that the removal of the cytoskeleton increases lithium binding to the more exposed anionic phospholipids (357±24 M⁻¹) when compared to lithium binding in the unsealed RBC membrane (221±21 M⁻¹). Therefore, it can be seen that the cytoskeleton does not play a major role in Li⁺ binding or in Li⁺/Mg²⁺ competition.     

NMR Studies on Li+, Na+ and K+ Complexes of Orthoester Cryptand o-Me2-1.1.1

Cryptands, a class of three-dimensional macrobicyclic hosts ideally suited for accommodating small guest ions, have played an important role in the early development of supramolecular chemistry. In contrast to related two-dimensional crown ethers, cryptands have so far only found limited applications, owing in large part to their relatively inefficient multistep synthesis. We have recently described a convenient one-pot, template synthesis of cryptands based on O,O,O-orthoesters acting as bridgeheads. Here we report variable-temperature, ¹H-1D EXSY and titration NMR studies on lithium, sodium, and potassium complexes of one such cryptand (o-Me₂-1.1.1). Our results indicate that lithium and sodium ions fit into the central cavity of the cryptand, resulting in a comparably high binding affinity and slow exchange with the bulk. The potassium ion binds instead in an exo fashion, resulting in relatively weak binding, associated with fast exchange kinetics. Collectively, these results indicate that orthoester cryptands such as o-Me₂-1.1.1 exhibit thermodynamic and kinetic properties in between those typically found for classical crown ethers and cryptands and that future efforts should be directed towards increasing the binding constants.     

Effect of Mg2+, Li+, Na+ and K+ on the Electrocrystallization of Nickel from Aqueous Sulfate solutions containing Boric Acid

The effects of metal ions such as Mg²⁺, Li⁺, Na⁺ and K⁺ on the cathodic current efficiency, deposit morphology, crystallographic orientation and polarization behaviour during nickel deposition on stainless steel from aqueous sulfate solutions containing boric acid were investigated. There was virtually no change in current efficiency in presence of these metal ions, but changes were observed in the deposit morphologies and crystal orientations even though all the deposits looked bright, smooth and coherent. Changes were also observed in the polarization behaviour during nickel electrocrystallization in presence and absence of boric acid. An attempt has been made to correlate the effect of these metal ions on various parameters studied.     

298．16K下K^＋，Mg^2＋／／NO3^-，SO4^2- -H2O和Na^＋，K^＋，Mg^2＋／／NO3^- -H2O体系的液固相平衡

采用等温溶解平衡法研究了298.16 K下四元体系K , Mg2 //NO3-, SO42--H2O和Na , K , Mg2 //NO3--H2O的液固相平衡,并根据获得的溶解度数据分别绘制出了平衡相图及投影图.结果表明:在298.16 K下,四元交互体系K , Mg2 //NO3-, SO42--H2O相图中有五个单盐结晶区,七条单变量溶解度曲线和三个零变量点.五个单盐结晶区分别对应于KNO3、K2SO4、Mg(NO3)2·6H2O、MgSO4·7H2O和复盐K2SO4·MgSO4·6H2O;具有同离子的四元体系Na , K , Mg2 //NO3--H2O相图中有三个单盐结晶区,三条单变量溶解度曲线和一个零变量点.三个结晶区分别对应于NaNO3、KNO3、Mg(NO3)2·6H2O.K2SO4和KNO3的结晶区比较大,Mg(NO3)2·6H2O的结晶区最小.     

Al3+、Na+和Mg2+对二水硫酸钙结晶的影响

采用CaHPO₄·2H₂O-H₂SO₄-H₃PO₄-H₂O体系模拟湿法磷酸生产过程,以磷矿浆成分为依据,在单因素条件下分别研究Al³⁺、Na⁺和Mg²⁺对结晶和CaSO₄·2H₂O水洗速率的影响。研究发现：添加Al³⁺有利于CaSO₄·2H₂O晶体粒径增加;添加Na⁺使得0.9% Na₂O含量的Na⁺引起CaSO₄·2H₂O晶体团聚,有利于水洗;Mg²⁺增加溶液黏度,严重影响晶体生长和水洗速率。通过X射线衍射、扫描电子显微镜对CaSO₄·2H₂O进行表征,发现其晶体生长符合非完整光滑突变界面模型,杂质离子影响反应速率和晶面生长速度。     

Catalytic and ortho-directing effect of Zn2+, Mg2+, Ba2+, and Ca2+ metal hydroxides on the preparation of phenolic-formaldehyde resin

A one step method was employed to prepare PF (phenol-formaldehyde) resin adhesive from phenol and formaldehyde with Zn²⁺, Mg²⁺, Ba²⁺, and Ca²⁺ hydroxides as catalysts, and the physicochemical properties of the resulting polymeric material were analyzed. The viscosity of the liquid adhesive decreased at intermediate catalyst concentrations, while the polymerization rate decreased at the highest concentrations; no clear pattern could be observed between catalyst concentration and solid content. Differential scanning calorimetry (DSC) performed on the PF resin catalyzed by Ba²⁺ showed that the polymer had a curing exothermic peak at around 110?°C, while the initial curing temperatures of PF resins were affected by the type of metal hydroxide used, and were in the order Ca²⁺?<?Mg²⁺ <control sample. FTIR spectroscopy was used to monitor the degree of ortho/para substitution during the synthesis of PF resin with Ba²⁺, Ca²⁺, and Mg²⁺ hydroxides. The highest ortho/para ratio was achieved with Ba²⁺ at a concentration of 0.45?wt.%, which also resulted in the most significant increase in the polymerization rate for the formation of PF resin.     

Ca~(2+)、Mg~(2+)对好氧污泥颗粒化的影响研究

研究了投加不同金属离子(Ca2+、Mg2+)在好氧污泥颗粒化过程中的作用,简要分析了颗粒形成过程中污泥的形态和物化性质变化,重点探究Zeta电位、胞外多聚物(EPS)的变化以及两者之间的关系。在接种普通活性污泥的2个序批式反应器中分别投加等量40 mg/L的Ca2+和Mg2+,培养运行34 d,2个反应器都已全部颗粒化,结果显示添加Mg2+更有利于缩短好氧颗粒污泥系统的启动时间,而添加Ca2+形成的颗粒污泥平均粒径较小,添加Mg2+更能促进EPS的分泌。底物匮乏期,添加Mg2+较添加Ca2+的微生物更易利用EPS作为碳源,且在饱食-饥饿期的交替阶段Mg2+对污泥表面Zeta电位造成的影响更大。     

试剂水合肼中钾钠钙镁的测定

采用水浴蒸发方法将水合肼主体除法,火焰光谱法测定钾,钠,原子吸收法测定钙、镁。     

粗硫酸镍脱除钙镁的工艺研究

研究了用化学沉淀法脱除粗硫酸镍中的Ｃａ、Ｍｇ。实验表明,络合沉淀剂是一种效果较好的沉淀剂,在６０℃、ＰＨ值在３．０－６．０之间、用量系数为１．５、反应时间１ｈ以上时,其脱除Ｃａ、Ｍｇ的效果良好,能达到电池用酸镍标准。     

Tunable single-phase white-light-emitting Ba2Mg(BO3)2:Ce3+, Na+, Tb3+, Eu2+ phosphor based on energy transfer

A series of white-light-emitting phosphors of single-phase Ba₂Mg(BO₃)₂:Ce³⁺, Na⁺, Tb³⁺, Eu²⁺ were synthesized by conventional solid-state reaction. The crystal structure of the host was characterized by X-ray diffraction and investigated by Rietveld refinement. Photoluminescence properties were studied in detail. The energy transfer from Ce³⁺ to Tb³⁺ in Ba₂Mg(BO₃)₂ host was investigated and demonstrated to be a resonant type via a quadrupole–quadrupole mechanism. White light with wavelength tunable was realized by coupling the emission bands peaking at 417, 543 and 626 nm attributed to Ce³⁺, Tb³⁺ and Eu²⁺, respectively. By properly tuning the relative composition of Ce³⁺(Na⁺)/Tb³⁺/Eu²⁺, optimized Commission Internationale de l׳Eclairage (CIE) chromaticity coordinates (0.363, 0.295), high color rendering index (CRI) 90 and low correlated color temperature (CCT) 3793 K were obtained from the phosphor of Ba_1.90Ce_0.04Na_0.04Eu_0.02Mg_0.94Tb_0.06(BO₃)₂ upon the excitation of 296 nm UV radiation. These results indicate that Ba₂Mg(BO₃)₂:Ce³⁺, Na⁺, Tb³⁺, Eu²⁺ phosphor has a potential application as an UV radiation down-converting phosphor in white-light-emitting diodes.     

ATMP对钙、镁离子阻垢作用机理的配位化学研究

采用电位滴定方法，运用先进的配位常数计算程序，通过恰当配位化学模型的建立，研究了水溶液中氨基三亚甲基膦酸(ATMP)自身的解离以及与Ca^2 、Mg^2 离子间的配位化学作用，测定了相应的解离常数和配合物稳定常数，并得到了各配合物物种在不同pH条件下的形态分布，从溶液配位化学的角度对ATMP的阻垢作用机理进行了讨论。