New thin-film composite reverse osmosis membranes and spiral wound modules

Two new series of thin-film composite reverse osmosis membranes have been developed and fabricated into spiral wound modules. The NTR-7100 series membrane is able to desalt sea and brackish water. The NTR-7250 membrane is designed for use at pressures below 20 kg/cm². The membrane has a very high water permeability and is resistant to chemical and microbiological attack. In particular, the membrane is stable to chlorine, as shown by long-term reverse osmosis tests with tap water containing about 1 ppm of residual chlorine. The membrane has an unusual pattern of solute rejection. Salts containing divalent anions, such as sodium sulphate or magnesium sulfate, are rejected more than 98%; while salts with monovalent anions and bivalent cations, such as magnesium chloride, are rejected about 90% and salts with monovalent anions and cations, such as sodium chloride, are rejected 30–50%. Neutral solutes have relatively high rejection; for example, glucose, 90% and sucrose, <99%.     

Reverse osmosis separation of inorganic solutes in aqueous solutions using porous cellulose acetate membranes

Using a modified form of the Born expression for the free energy of ion-solvent interaction, to both the bulk solution phase and the membrane–solution interface, a parameter is obtained to express the repulsion of the ion at the interface. This parameter, called the free energy parameter for ions, is then related to solute transport parameter obtained from reverse osmosis experiments. Numerical values of this free energy parameter have been obtained for six monovalent and four divalent cations and for 12 monovalent anions. Using the experimental data for the reverse osmosis separation of sodium chloride as reference, the utility of the above parameter for predicting solute separation in reverse osmosis is illustrated for 32 other inorganic salts.     

Highly Efficient,Tripodal Ion-Pair Receptors for Switching Selectivity between Acetates and Sulfates Using Solid–Liquid and Liquid–Liquid Extractions

A tripodal, squaramide-based ion-pair receptor 1 was synthesized in a modular fashion, and ¹H NMR and UV-vis studies revealed its ability to interact more efficiently with anions with the assistance of cations. The reference tripodal anion receptor 2, lacking a crown ether unit, was found to lose the enhancement in anion binding induced by presence of cations. Besides the ability to bind anions in enhanced manner by the “single armed” ion-pair receptor 3, the lack of multiple and prearranged binding sites resulted in its much lower affinity towards anions than in the case of tripodal receptors. Unlike with receptors 2 or 3, the high affinity of 1 towards salts opens up the possibility of extracting extremely hydrophilic sulfate anions from aqueous to organic phase. The disparity in receptor 1 binding modes towards monovalent anions and divalent sulfates assures its selectivity towards sulfates over other lipophilic salts upon liquid–liquid extraction (LLE) and enables the Hofmeister bias to be overcome. By changing the extraction conditions from LLE to SLE (solid–liquid extraction), a switch of selectivity from sulfates to acetates was achieved. X-ray measurements support the ability of anion binding by cooperation of the arms of receptor 1 together with simultaneous binding of cations.     

Ion-specific effects influencing the dissolution of tricalcium silicate

It has been recently demonstrated that the dissolution kinetics of tricalcium silicate (C₃S) is driven by the deviation from its solubility equilibrium. In this article, special attention is paid to ions relevant in cement chemistry likely to interact with C₃S. In order to determine whether specific effects occur at the interface C₃S–water, particular efforts have been made to model ion activities using Pitzer's model. It has been found that monovalent cations and monovalent anions interact very little with the surface of C₃S. On the other side, divalent anions like sulfate slow down the dissolution more strongly by modifying the surface charging of C₃S. Third, aluminate ions covalently bind to surface silicate monomers and inhibit the dissolution in mildly alkaline conditions. The formation and the breaking of these bonds depend on pH and on [Ca^2 +]. Thermodynamic calculations performed using DFT combined with the COSMO-RS solvation method support the experimental findings.     

Superabsorbent polymeric materials III. Effect of initial total monomer concentration on the swelling behavior of crosslinked poly(sodium acrylate) in aqueous salt solution

A series of xerogels based on sodium acrylate (SA) and N,N′-methylene-bisacrylamide (NMBA) were prepared by inverse suspension polymerization. The water absorbency or swelling behaviors for these hydrogels in water or various saline solutions was investigated. Experimental results indicate that the absorbency of poly(SA) in deionized water increases with decrease in the initial total monomer concentration. Results obtained from this study show that the water absorbency, respectively, exhibited a value of 992 g H₂O/g sample and 106 g H₂O/g sample in deionized water and a 0.9 wt % NaCl solution at an initial total monomer concentration of 3.03M. The absorbency in the chloride salt solutions decreases with increase in the ionic strength of the salt. For the same ionic strength of various salt solutions, the swelling amount has the following tendency: Co²⁺ > Ni²⁺ > Cu²⁺ for the higher ionic strength of 6.25 × 10⁻⁴ to 2.0 × 10⁻³M, and Co²⁺, Ni²⁺, and Cu²⁺ approximately have the same swelling amount for the lower ionic strength of < 6.25 × 10⁻⁴M. The influence of monovalent, divalent, and trivalent anions with a common cationic ion (Na⁺) on the water absorbency shows the tendency of monovalent < divalent < trivalent anions for the same ionic strength. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2371–2380, 1997     

Nanoparticles modified Polyacrylonitrile/Polyacrylonitrile – Polyvinylidenefluoride blends as substrate of high flux anti-fouling nanofiltration membranes

Thin-film composite nanofiltration membranes were prepared by interfacial polymerization reaction of piperazine and trimesoylchloride on virgin and nanoparticles (SiO₂/TiO₂) modified Polyacrylonitrile/70:30 and 30:70 Polyacrylonitrile – Polyvinylidenefluoride blend ultrafiltration substrates. The membranes were characterized for surface hydrophilicity and potential, surface and cross-sectional morphology and equilibrium water content. Pure water permeability and differential rejection of multi (MgSO₄) and monovalent salts (NaCl) of the membranes were studied. Nanofiltration (NF) membranes prepared on nanoparticle modified UF substrates exhibit higher flux than the membranes prepared on virgin UF substrates. NF membranes prepared on TiO₂ modified substrates are exhibiting higher flux than the other membranes. Membrane prepared on TiO₂ modified 70:30 blend substrate exhibits the highest rejection ratio (4.63) of divalent to monovalent salts. Nanofiltration membranes prepared on nanoparticle modified substrates are displaying comparatively higher flux recovery ratio (FRR) and lower total fouling ratio (TFR) values than the NF membranes prepared on virgin ultrafiltration substrates.     

Synergistic effect of salt ions and water-soluble amphiphilic compounds of acidic crude oil on surface and interfacial tension

This study investigated the effect of solubility of amphiphilic compounds of acidic crude oil in water on the surface and interfacial tension (IFT) with NaCl, MgCl₂, CaCl₂, and Na₂SO₄ salts. Accordingly, distilled water, along with the salts mentioned in zero ionic strength up to 2 mol were put in contact with crude oil to become saturated with amphiphilic compounds. The effects of these compounds were investigated on the properties of contact water by pH, total organic carbon (TOC), FTIR (Fourier transform infrared spectroscopy), water-air surface tension (ST), and water-n-decane IFT tests. The results showed that some of the organic components of crude oil, especially acidic and basic compounds, are present or soluble in water, which have a significant effect on reducing the surface and IFT. The IFT reduction of water-n-decane was greater than the water-air ST system. Also, the observations showed that for both NaCl and Na₂SO₄ salt water, with increasing ionic strength of water, there was an optimum salinity within the range of 0.1-0.25 mol/L for both salts with the amount of surface and IFT minimized at this point. In the other two salts, this point was delayed upon elevation of ionic strength and was observed at high salinity. In this case, divalent cations reduce tension rate compared to monovalent cations. Due to solubility of acidic and basic groups in water, pH of salt water illustrates an acidic trend. Results of the FTIR test confirmed solubility of these compounds as well.     

Preparation,characterization, and some properties of ionomers from a sulfonated styrene–butadiene–styrene triblock copolymer without gelation

The conditions for the sulfonation of a highly unsaturated styrene–butadiene–styrene triblock copolymer (SBS) in cyclohexane containing a small amount of acetone with acetyl sulfate made by sulfuric acid and acetic anhydride without gelation were studied. After neutralization with metallic ions, the ionomers were characterized with IR spectrophotometry, dynamic mechanical analysis, and transmission electron microscopy. The melt flow, solution properties, and mechanical properties of the ionomers were studied. The results showed that gelation occurred during the sulfonation of SBS in cyclohexane at a 5–10% concentration without acetone, whereas in the presence of 5–10 vol % acetone, sulfonation proceeded smoothly without gelation. Transmission electron microphotographs of the lead ionomer indicated the presence of ionic domains. A dynamic mechanical spectrum showed the presence of three transition temperatures: ?82.9, 68, and 96.5°C. The melt viscosity of the ionomer increased with the sulfonate content. The melt viscosity of the different ionomers neutralized with different cations seemed to decrease with decreasing ionic potential for both monovalent cations and divalent cations The solution viscosity of the sodium‐sulfonated ionomer increased with increasing sulfonate content. The ionomer still behaved as a thermoplastic elastomer and showed better mechanical properties than the original SBS. The tensile strength of the different ionomers decreased as follows. For the monovalent cations, it decreased with decreasing ionic potentials: Li⁺ > Na⁺ > K⁺. For the divalent cations, it decreased with increasing ionic potentials: Pb²⁺ > Zn²⁺ > Mg²⁺. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1398–1404, 2005     

Gas‐transport properties through cation‐exchanged sulfonated polysulfone membranes

Sulfonated polysulfone (SPS) membranes were prepared, and the gas‐transport properties of the resulting ionic polymers were examined. Gas‐transport measurements were made on dense films of these polymers with a continuous flow technique. The sulfonation of polysulfone and the metal‐cation exchange of SPS were confirmed with Fourier transform infrared spectroscopy and electron spectroscopy for chemical analysis. The SPS membranes exchanged with the monovalent metal ions showed higher permeability coefficients than the SPS membranes exchanged with the multivalent metal ions, whereas the selectivities of all the metal‐cation‐exchanged sulfonated polysulfone (MeSPS) membranes for O₂/N₂ and CO₂/N₂ gas pairs were higher than those of SPS membranes. When the MeSPS membranes with metal cations of similar ionic radii were compared, the ideal selectivities of O₂/N₂ and CO₂/N₂ through MeSPS with divalent cations were higher than those through MeSPS with monovalent cations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2611–2617, 2002     

Synthesis,Structure and Photoluminescence Properties of Mixed-Valent Trinuclear Copper Complex Assembled from Bis(<Emphasis Type="Italic">N</Emphasis>-imidazolyl)methane

In this work, [Cu₃I₂(PPh₃)₆(L₁)₂]∙2DMSO∙Cl₂ (1) (L₁ = bis(N-imidazolyl)methane) complex was synthesized by solvothermal method. The crystal and complexes were characterized by X-ray diffraction (XRD) analysis, Fourier Transform infrared (FTIR) spectroscopy, elemental analysis and photoluminescence (PL) measurements. XRD and FTIR analysis indicated that the complex 1 is a trinuclear compound, in the compound there are two kinds of copper atoms, i.e. monovalent, and divalent copper cations. For the copper(I) center, it is surrounded by two P, one N, and one iodide atoms to complete its tetrahedron geometry. While the copper(II) center is surrounded by two P and two nitrogen atoms, the chloride anions existed as free counter anions. The copper(II) atom and the copper(I) atoms were bridged by exobidentate L₁ ligand. The PL spectrum showed that the complex displays intense blue emission related to shallow holes.     

Rapid and phase pure synthesis of microporous copper silicate (CuSH–1Na) with 12-ring channel system

Phase pure sample of the microporous copper silicate CuSH–1Na has been obtained by simplified hydrothermal method without using additives (H₂O₂ and Na₂HPO₄). Ion exchange of Na⁺ by Cs⁺, Ca²⁺ and Sr²⁺ ions showed that the structure can suffer partial replacement of the charge compensating cations. Ion exchange with Cs⁺ resulted in distinct dehydration while the ion exchange with Sr²⁺ increased the total amount of water. Water content in the Ca-exchanged sample is comparable to the as-synthesized sodium phase. Raman spectroscopy revealed that the divalent cations as Ca²⁺ and Sr²⁺ induce stronger local structural deformations than the monovalent Cs⁺. These structural changes have been also followed by the refined lattice distortions. Magnetic analyses showed that CuSH–1Na presents a very weak ferromagnetic interaction along the Cu²⁺ chains with a nearly vanishing Curie–Weiss temperature. This magnetic coupling is associated with super-super-exchange interactions through Cu–Na–O–Na–Cu paths. Antiferromagnetic coupling, attributed to inter-chains super-super-exchange interactions, competes with the ferromagnetic one and prevails at the lowest temperature.     

Effect of Electrolytes and Correlations for Salinities at the Optimum Formulation of Sodium Dodecyl Benzene Sulfonate Microemulsions

The influences of different kinds of electrolytes on sodium dodecyl benzene sulfonate microemulsions were investigated in this work. Electrolyte cations had a strong influence on the microemulsion phase behavior. The higher the valence of the cation was, the stronger the influence of the electrolyte on the microemulsion phase inversion and the higher the optimum solubilization parameters, ordered as AlCl₃ > MgCl₂ > NH₄Cl > KCl > NaCl. The anion in electrolytes showed a relatively weak influence. The influences of anions with equal valence are almost the same for sodium salts, and a lower valence had a stronger impact on microemulsion phase inversion, ordered as Cl^? > CO₃^2? = SO₄^2? > PO₄^3?. The change of anions in sodium salts had little influence on the optimum solubilization parameters , all in the range of 5.301 ± 0.105 g_oil/g_surfactant. The efficiency ratio of electrolytes was defined based on the cationic charge concentration in mol/l. The efficiency ratios for electrolytes with monovalent cations were inversely proportional to (1 + Z_i), where Z_i is the anion valence, but this was not true for electrolytes with higher valence cations. For a microemulsion using electrolyte mixtures, the efficiency ratio shows a linear relationship with that of the component salts and the composition of the mixture.     

Preparation of polyelectrolyte complex membranes based on sodium cellulose sulfate and poly(dimethyldiallylammonium chloride) and its permeability properties

In this study, polyelectrolyte complex (PELC) membranes prepared by the simultaneous interfacial reaction between aqueous solutions of sodium cellulose sulfate (NaCS) as polyanion and poly(dimethyldiallylammonium chloride) (PDMDAAC) as polycation were proposed. The preparation conditions were optimized. The influence of two important factors, molecular weight (MW) of PDMDAAC and reaction time on the membrane formation procedure and permeability was investigated. Membranes with the preparation conditions as NaCS 3.5% (w/v), PDMDAAC (MW = 200–350 kDa) 7.0% (w/v), the reaction time 30 min, hold a favorable performance, and steady state in water flux experiment. To testify the feasibility of the membrane used in salt separation, membrane performances and selectivity of the inorganic salts as well as their relations to the preparation conditions, the operation parameters, the species of inorganic salts, etc., were investigated in the pressure‐driven experiments. The results showed that this single‐layer PELC membrane afforded higher rejections of divalent ions (SO) to that of monovalent ions (Cl⁻), which indicated the potential application of this membrane system in the salt rejection process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polarography of some anions in presence of aqueous organic solvent mixtures: Reduction of IO−3 ions in presence of various base electrolytes

The present studies treat with the reduction of IO^?₃ ions different types of base electrolytes at the dropping mercury electrode. All the measurements were done in 0.1 M base electrolytes at 30°C. The effect of various sodium and potassium halides, different cations (alkali and alkaline earth metal chloride), various alkali metal nitrates and some ammonium salts, on the polarographic characteristics of iodate ions, have been studied in details, iR measurements have also been carried out in presence of various oxy-anions and sodium salts of organic acids. In all cases the reduction was found to be diffusion controlled but irreversible. The kinetic parameters have been evaluated by Koutecky's method.     

FUNDAMENTAL STUDY OF CLAY: II,MECHANISM OF DEFLOCCULATION IN THE CLAY-WATER SYSTEM*

The effect of bases, basic salts, neutral salts, acid salts, and acids on the viscosity of clay slips cleaned as described in Part I of this study is shown. From these data, a fundamental theory of deflocculation is built up, based on the fact that deflocculation requires the presence of OH anions and monovalent cations. The influence on the viscosity of small traces of soluble salts or adsorbed ions, which are present in commercial clays, is discussed. It is also shown why sodium silicate or carbonate works more satisfactorily than sodium hydroxide in the deflocculation of commercial casting slips.     

Synthesis,structure and dielectric constant property of two novel complexes based on protonated 1-aminoadamantane

The reaction of 1-aminoadamantane hydrochloride and divalent metal chloride in concentrated hydrochloric acid medium yields two unusual complexes containing protonated 1-aminoadamantane, (C₁₀H₁₈N)¹⁺₂[ZnCl₄]^2? (1), (C₁₀H₁₈N)¹⁺₂[MnCl₄(H₂O)₂]^2? (2a) and (C₁₀H₁₈N)¹⁺₂[MnCl₄(D₂O)₂]^2? (2b). Their crystal structures have been determined by X-ray crystallography. Both complexes contain molecular network of (C₁₀H₁₈N)⁺ cations and divalent metal chloride polyhedral anions (Mn and Zn site symmetry 2/m). Dielectric constants of both two organic–inorganic hybrid salts were measured at different temperatures and frequencies. Different structures lead to large discrepancy in the dielectric property measurements. In addition, thermal analysis of complex 2 was studied.     

Salt rejection in nanofiltration for single and binary salt mixtures in view of sulphate removal

Three commercial membranes (NF70, NF90 and TFC-SR) were firstly characterized in terms of pure water flux and the rejection of uncharged (alcohols and sugars) compounds. Subsequently, the rejection of monovalent (sodium and chloride) and divalent (calcium and sulphate) ions in single (NaCl, CaCl, and Na₂SO₄) and binary (NaCI/Na₂,SO₄ CaCl₂/CaSO₄, NaCI/CaCl₂, and Na₂SO₄/CaSO₄) salt mixtures was studied. According to the pure water permeability the TFC-SR membrane is a loosely packed NF membrane (12.3 L.m ⁻².h⁻¹.bar⁻¹), while both NF70 and NF90 are tightly packed (2.6 and 3.6 Lm⁻².h⁻¹.bar-). According to the uncharged solute rejection, the MWCO_NF70 = 60, MWCO_NF90= 200 and MWCO_TFC-SR > 500. NF70 and NF90 were equally efficient in rejecting 1-2, 1-1 and 2-1 salts (>90%), while TFC-SR showed typical negatively charged surface behaviour, i.e., R (1-2) salt > R (11) salt > R (2-1). Sulphate rejection decreased in the presence of sodium chloride more significantly than in the presence of calcium chloride due to the more efficient retention of the bivalent calcium.     

Effect of Inorganic Salts on the Aggregation Behavior of AOT at the Air/Water Interface

The aggregation behavior of sodium bis-(2-ethylhexyl)-sulfosuccinate (AOT) at the air/water interface in the absence and presence of inorganic salts was investigated by molecular dynamics simulation. Both monovalent and divalent ions were studied, such as LiCl, NaCl, KCl, MgCl₂ and CaCl₂. It has been proved that these inorganic ions have great influence on the structure of the AOT monolayer and water molecules around its headgroup. In the presence of inorganic salts, AOT molecules are relatively ordered at the interface and water around the headgroups of AOT shows a lower diffusion coefficient compared with the situation without inorganic salts. All the counterions are prone to move toward the headgroups and locate at the interface. Divalent ions have a strong interaction with AOT, thus they affect the aggregation behavior of AOT remarkably.     

膜法电容去离子技术用于水溶液中单/多价阴离子的分离

将电容去离子技术（CDI）与单价阴离子选择性交换膜结合构建新型膜法电容去离子膜堆（PSMCDI）,并探索其在单/多价阴离子分离中的应用。采用自制的测试装置,以Cl^-/SO₄^2-水溶液为模拟体系,并选择现有的两种商业化单价阴离子选择性交换膜（ASV和ACS）作为膜元件,系统地研究了各参数（PSMCDI种类、阴离子组成和浓度、pH、操作时间、电压和流速）对单价离子选择性的影响。结果表明,总阴离子去除量随着阴离子浓度的增加而增加,但是对于单价离子（Cl^-）选择性降低。随着操作时间的增加,单价离子（Cl^-）选择性也降低。对于ASV膜,在1.2 V的直流电压、10 min吸附时间和30 ml·min^-1进料流速的条件下得到1.6的单价阴离子去除选择性。同时,在相同条件下,ACS膜的单价阴离子去除选择性为1.4。     

Effect of soluble ash components on the viscosity of lignite-water mixtures

The removal of multivalent cations from lignite-water mixtures (LWM) was shown to lower mixture apparent viscosity by a factor of about 40, for example, at 100 s^?1 by reducing both the yield stress and plastic viscosity. The cations Ca⁺⁺, Mg⁺⁺, Al⁺⁺⁺, K⁺, and Na⁺, among others, were found to be present in the aqueous phase of the LWM in concentrations ranging from 546 ppm to 8 ppm. The primary anions present were CI^? and SO₄⁼. The degree to which the cations affected viscosity were of order trivalent > divalent > monovalent. The nature of the anion was found to be relatively unimportant. A process utilizing ion-exchange resins for removing multivalent cations to produce low viscosity lignite-water or coal-water mixtures is described.