Common Ion Effect Research Articles

Common-Ion Effect Triggered Highly Sustained Seawater Electrolysis with Additional NaCl Production.

Developing efficient seawater-electrolysis system for mass production of hydrogen is highly desirable due to the abundance of seawater. However, continuous electrolysis with seawater feeding boosts the concentration of sodium chloride in the electrolyzer, leading to severe electrode corrosion and chlorine evolution. Herein, the common-ion effect was utilized into the electrolyzer to depress the solubility of NaCl. Specifically, utilization of 6 M NaOH halved the solubility of NaCl in the electrolyte, affording efficient, durable, and sustained seawater electrolysis in NaCl-saturated electrolytes with triple production of H2, O2, and crystalline NaCl. Ternary NiCoFe phosphide was employed as a bifunctional anode and cathode in simulative and Ca/Mg-free seawater-electrolysis systems, which could stably work under 500 mA/cm2 for over 100 h. We attribute the high stability to the increased Na+ concentration, which reduces the concentration of dissolved Cl− in the electrolyte according to the common-ion effect, resulting in crystallization of NaCl, eliminated anode corrosion, and chlorine oxidation during continuous supplementation of Ca/Mg-free seawater to the electrolysis system.

Colloidal biliquid aphron demulsification using polyaluminum chloride and density modification of DNAPLs: optimal conditions and common ion effect.

Dense non-aqueous phase liquids (DNAPLs) entrapped and pooled in aquifers serve as a long term source of groundwater contamination because of their low solubility and high density. Density modification displacement (DMD) with colloidal biliquid aphrons (CBLAs) is a promising approach to prevent DNAPL downward migration during surfactant-based remediation processes. CBLA demulsification and quick release of internal light organic matter is the key to density modification of DNAPLs. In this work, it is reported for the first time that polyaluminum chloride (PAC) could destabilize CBLAs efficiently. The optimum conditions for demulsification of CBLAs by PAC were obtained; the effects of several specific ions in groundwater on demulsification of CBLAs by PAC were investigated. The results indicated that the CBLA was completely demulsified by PAC within 10 minutes and released light organic matter. It recorded the highest demulsification efficiency when the addition ratio (VPAC/VCBLA) was 2 : 1, concentration of PAC was 0.7 g L-1 and the PVR of CBLAs was 8. Most cations (sodium, magnesium and calcium ions) had inhibitory effects on demulsification of CBLAs by PAC with increasing ion concentration, but iron ions had no effect on it. Sulfate anions showed a stronger inhibitory effect on demulsification of CBLAs by PAC compared to chloride ions. With PAC as the demulsifier, CBLAs could be demulsified efficiently, irreversibly modifying the density of trichloroethylene in 5 minutes.

Kinetics Study of Surface Reaction Between Acid and Sandstone Based on the Rotation Disk Instrument

The chemical reaction between acid and rock mineral during the acidizing process is the key point for the acidizing technique. In this study a rotating disk method is used to simulate strata conditions, such as high temperature, high pressure, and acid shear flow reaction. The work investigates the kinetics of the rock acidizing reaction and analyzes the factors effecting the reaction rate, including mineral composition, temperature, pressure, acid concentration, shear velocity, and common-ion effect. The kinetic parameters, such as velocity constant, reaction order, activation energy, and frequency factor, were successfully extracted by curve fitting and the linear regression method. In was shown that hydrochloric acid does not participate directly in the reaction between mud acid (which is a mixture of hydrochloric and hydrofluoric acids) and sandstone mineral but catalyzes the reaction between hydrofluoric acid and sandstone. In this work, the acid rock reaction rate equation has been established, and the impact of the hydrochloric acid catalytic effect has been considered.

Preconcentration of the cobalt using modified forms of the transcarpathian clinoptylolite

The sorption properties of Na- and H-forms of Transcarpathian clinoptilolite towards trace amounts of Co(II) under dynamic conditions were studied. Acid modified samples of clinoptilolite were obtained by treating this zeolite with solutions of different concentrations of nitric, chloride and sulfuric acids. The most effective acid modifier was 0.5 M HNO 3 . The effect of solution pH and pre-treatment temperature of sorbent samples on the sorption capacity of Na- and H-forms of clinoptilolite was investigated. It is established that the highest sorption capacity both modified forms of clinoptilolite occurs from neutral solutions on the the uncalcined samples. The urotropin buffer solution was used to ensure constant value of pH and ionic strength of the solution. The optimal sorption conditions both modified forms of clinoptilolite are as follows: pH 7.0; the flow rate of a solution of Co(II) with a concentration of 0.25 µg·mL –1 through the sorbent – 5 mL·min –1 ; the diameter of the sorbent grains is 0.200–0.315 mm. The maximum sorption capacity of Na- and H-clinoptilolite towards Co(II) are 3.25 µg·g –1 and 2.85 µg·g –1 , respectively, which exceeds the value of the sorption capacity of the natural form of this zeolite 1.5 and 1.3 times. It has been found that the most effective desorbent of Co(II) from the Na-clinoptilolite are HNO 3 solutions, in particular, a 4.5 M HNO 3 solution, which provides 97 % withdrawal of Co(II) from zeolite. The effective desorbents of Co(II) from the H-clinoptilolite are acidic solutions of alkali metals salts. 1 M NaCl solution acidified with hydrochloric acid to pH 4.0 provides 100% withdrawal of Co (II) from acid-modified clinoptilolite. The effect of common water ions on the maximum sorption capacity of Na- and H-clinoptilolite was investigated. The permissible multiple contents (C ion /C Co(II) ) of the common water ions for Na- and H-clinoptilolite are higher 1.5–4 times then for the natural clinoptilolite. The ability of modified forms of Transcarpathian clinoptilolite to sorb trace amounts of Co(II), high sorption capacity and the presence of effective desorbents give a reason to offer these sorbents for purification of water from Co(II) ions, including radioactive isotopes 60 Co, and also for preconcentration of Co(II) ions at the stage of waters samples preparation for analysis. Methods of Co(II) trace amounts preconcentration in the solid phase mode with its further determination using the atomic absorption method are proposed. Keywords: sorption, solid phase extraction, cobalt, Na-clinoptilolite, H-clinoptilolite.

Solubility of ammonium fluoride in aqueous sodium fluoride solutions of various concentrations from dilute to saturated at 298.15 K for fluorine recovery from wet-process phosphoric acid

Recovery of fluorine from wet-process phosphoric acid (WPA) to produce ammonium fluoride (NH4F) and sodium fluoride (NaF) provides an environmentally-friendly route to purify WPA and produce high value-added fluoride salt. The solubility data and the related electrolyte thermodynamics are essential for a rational separation design of pure NH4F from aqueous NaF solution by crystallization. In this contribution, the solubilities of NH4F in aqueous NaF solutions of different concentrations from dilute to saturated were systematically measured at 298.15 K using a dynamic synthesis method. Experimental results show that the presence of NaF in the solution could significantly decrease the solubility of NH4F due to the common-ion effect which was decreased by 72.4% when the molality of NaF was only around 0.015 mol/kg. The data can be used to determine the yield of NH4F and liquid composition in the vacuum evaporative crystallization of NH4F. The mean activity coefficients of NH4F at saturation were determined from the experimental solubility data and then correlated with the extended Debye-Hükel equation and the Pitzer model. With four adjustable parameters, both models are able to accurately calculate the experimental data over a wide range of salt concentrations. The average relative deviations between the experimental and calculated logarithm of mean activity coefficients of NH4F from the two models are 1.43% and 2.29%, respectively. The binary and ternary ionic parameters for the Pitzer model are found to be concentration dependent and the correlations of them as functions of ionic strength are proposed.

Effects of natural gas acidic components on local porosity generation in a carbonate reservoir: Insights from reactive transport modeling

To investigate the mechanism of local porosity modification in a carbonate reservoir caused by the acidic components associated with natural gas generation, a numerical model for the charging of natural gas rich in acidic components (CO2) was developed. The acidic components are originated from maturation of organic matter in the source rock. The model includes coupled gas–water–rock interactions, multiphase flow, and spatial heterogeneities of the geochemical reactions. The simulation results indicate the following. (1) When regional groundwater travels through the gas–water contact (GWC), it is acidified by the CO2(g) in the gas zone and will dissolve carbonate minerals to form local secondary porosity. The generated local secondary porosity is approximately 0.04 (volume fraction), with a maximum value of approximately 0.27, and is located mainly in the vicinity of the GWC. (2) Under reservoir conditions, the solubility of calcite is much higher than dolomite. The higher solubility and common ion effect of Ca results in calcite being the primary reactive mineral in pure carbonate reservoirs (having both calcite and dolomite). The presence of anhydrite in the system does not change this situation. (3) The groundwater flow field causes GWC evolution to be S-shaped. The inflection and gentle-sloping parts at both ends of the GWC have different angles with the groundwater stream lines, resulting in different amounts of mineral dissolution and precipitation and porosity increase. (4) The limited amount of CO2 from the source rock and groundwater flow in the subsurface seems to be sufficient to support local secondary porosity generation.

A Study of the Photoelectrochemical Etching of n-GaN in H3PO4 and KOH Electrolytes

We investigated the photoelectrochemical etching of n-GaN in H3PO4 and KOH as a function of electrolyte concentration, potential and light intensity. Etch rates measured by stylus profilometry were compared with coulometric and amperometric values. In both electrolytes, etch rates increased with concentration, reaching a maximum at 3.0 mol dm−3 and decreasing at higher concentrations. The increase in etch rate with concentration of either H3PO4 or KOH reflects the amphoteric nature of gallium and the decrease above 3.0 mol dm−3 is attributed to common-ion effects. Profilometric etch rates were lower than coulometric and amperometric etch rates reflecting formation of a surface film. SEM and profilometry demonstrated that thick surface films are formed at lower concentrations. Etch rates increased linearly with light intensity indicating a carrier-limited etching regime: a quantum efficiency of 57.6% was obtained. At light intensities greater than ∼35 mW cm−2 the etch rates showed evidence of saturation. AFM and SEM images of the etched GaN surfaces showed a distinctive ridge-trench structure with a hexagonal appearance. Photoluminescence spectra of the etched GaN show a significant increase in the defect-related yellow luminescence peak suggesting correlation to the formation of the ridge structures, which may represent dislocations terminating at the surface.

Hydrogeochemistry and geothermometry of the carbonate-evaporite aquifers controlled by deep-seated faults using major ions and environmental isotopes

Carbonate aquifers probably constitute the most important thermal water resources in non-volcanic areas, and are characteristic of great energy potential and easier production as the most ideal targets for development in the future. The thermal waters in the aquifers within Southeast Chongqing (SEC) of China occur in an extensive region with an area of 198,000 km2, which are mainly hosted in the Cambrian and Ordovician carbonate-evaporite rocks. The thermal waters are mainly in pristine conditions and their genesis has not yet been fully understood. The occurrence of thermal waters in SEC is closely related to the presence of deep-seated faults which constitute pathways for the hydrothermal circulation. In this study, an investigation of water major ions and environmental isotopes from 14 hot springs and three drilled wells was carried out to examine their hydrogeochemical evolution and to estimate reservoir temperature. The thermal waters have outflow temperatures from 19 to 54.2 °C. They are divided into two hydrochemical groups with the Yushan Fault as a boundary: Group A, located to the west of the fault, are characterized by facies of chloride sodium waters with higher TDS; Group B, to the east of the fault, are more complicated sulfate-bicarbonate-chloride alkaline-earth waters with lower TDS. The hydrochemical processes such as dissolution of carbonate, gypsum and/or anhydrite, and halite, the common ion effect, and dedolomitization are evident based on the major ions and δ34SSO4 and δ18OSO4. The δ18O and δD compositions of the thermal waters suggest a meteoric recharge in a relatively wetter and colder climatic condition. The silica geothermometers show that the average reservoir temperatures are 63 ± 18 °C for Group A, and 82 ± 15 °C for Group B. The corresponding average reservoir depths are estimated to be 2.5 ± 0.7 km for Group A, and 3.2 ± 0.7 km for Group B. The corrected 14C ages of the thermal waters average at 14.8 ka BP, corresponding to the late Pleistocene. A conceptual circulation model is proposed for the thermal waters. Driven by gravity of topographic gradients, the percolating groundwater circulates at a specific depth, reaching a higher temperature and interacting with the host carbonate with imbedded evaporitic minerals (gypsum and/or anhydrite, and additional halite for Group A) to be saline deep-seated thermal fluids. The fluids rise along faults and emerge at the surface as thermal springs. The slow renewability rate of the thermal aquifers highlights the importance of assessing the resource before groundwater exploitation and extraction.

The Kinetics of Gypso Anhydrites Dissolution in Water: Experimental Studies

Experiments on the kinetics of gypso anhydrites dissolution in water (25°С, 0.1 MPa) resulted in the development of a model of the process in the form of balance equations of dissolution kinetics for gypsum and anhydrite (first and second order, respectively), as well as of the kinetics of gypsum precipitation (the second order). The data from the experiments were processed based on the Riccati equation. The calculated values were closer to the experimental data when the common-ion effect on the solubility of gypsum and anhydrite was included.

Numerical Simulation of Scale Formation for Injection–Production Units in Oil Reservoirs

Water injection is one of the most economical and effective methods of ensuring the continuous and stable production of an oil field and improving oil recovery. However, scale formation is unavoidable in long-term water injection, and this seriously affects and restricts oil field development. Our research on scale formation in injection–production units was based on the dissolution–precipitation equilibrium, thermodynamics, ionic association theory, the solubility product rule, and the common ion effect. Considering formation temperature, pressure, scale ion concentration, and rate of flow as influencing factors, we established a formation pressure field model, a temperature field model, a porosity model, a scale formation model, and a scale inhibition model, which together constitute a numerical model of scale formation in an injection–production unit. We then used MATLAB software to analyze the influence of various factors on the total amount of scale, the scale range, and the scale distribution, as well as the influence of scale formation on the apparent injectivity index and permeability. To verify the reliability of our model, we introduced a scale inhibition rate, and we compared the scale inhibition rate that we calculated with the scale inhibition rate measured by experiment. The simulation shows that scale formation is mainly affected by formation temperature and scale ion concentration distribution, but that formation pressure has relatively little influence on it. Formation pressure decreases gradually along the direction of water flooding in an injection–production unit, and formation temperature changes mainly near the wellbore of the injection well. Along the direction of water flooding, scale formation first increases rapidly and then decreases rapidly. The reason for this trend is that with low formation temperature near the injection well, a small dissolution equilibrium constant and a high flow rate make scale formation difficult. Radially outward, the formation temperature increases and the flow rate decreases greatly, making it easier for scale to form. Even further out, the scale ion concentration is lower than the minimum scale concentration and scale can no longer form.

Kinetics of hypso anhydrites dissolution in water. Experimental studies

Experimental study of kinetics of dissolution of hypso anhydrites at 25 ᵒC made it possible to formulate model of the process in the form of a balance equation for the kinetics of dissolution of gypsum, anhydrite (first and second orders, respectively) and kinetics of precipitation of gypsum (second order). The processing of the experimental data were carried out on the basis of the solution of the Riccati equation. When taking into account the common-ion effect on the solubility of gypsum and anhydrite, the calculated values turned out to be more comparable with the experimental ones.

The interaction between human serum albumin and antidiabetic agent – exenatide: determination of the mechanism binding and effect on the protein conformation by fluorescence and circular dichroism techniques - Part I

The interactions between transport proteins and drugs are very important from the pharmacological point of view. In this study, using fluorescence and circular dichroism (CD) techniques, we investigated the interaction between human serum albumin (HSA) and incretin antidiabetic drug – exenatide. Moreover, the effect of common metal ions (Ca2+, Zn2+, Cr3+) on the exenatide–HSA binding – was also described. Based on the experimental data under pseudophysiological conditions, the calculated binding constant values are on the order of 104 M−1, and the constants are lower in the presence of metal ions. We observed the increase of the hydrophobicity near the tryptophan-214 residue in subdomain IIA, but almost no change in the hydrophobicity surrounding tyrosine residues. A similar effect on the tryptophan microenvironment is influenced by metal ions. The calculated thermodynamic parameters indicated that the characteristic electrostatic and hydrophobic interactions play an important role in the albumin–exenatide complexes. The CD studies showed that exenatide does not change the secondary structure of the protein but used metal ions have some impact on albumin α-helical content.Communicated by Ramaswamy H. Sarma

New insight into the mechanism of LiPO2F2 on the interface of high-voltage cathode LiNi0.5Mn1.5O4 with truncated octahedral structure

Abstract The development of high energy density material is of great importance and urgency for new generation of energy storage system. However, electrolyte formula for high voltage system remains a challenge. The use of various functional additives gives rise to the complexity of electrolyte system and hinders completely understanding of the action mechanism of additives. Herein, we report the adaptability and mechanism of a single additive LiPO2F2 added in the conventional LiPF6-based electrolyte system. The resulting conclusion displays a notable improvement in the cycling stability for 5 V-class cathode LiNi0.5Mn1.5O4, the capacity retention increase from 85.76% to 95.92%. It is comforting that the rate performance is not reduced due to the increase in cycle stability, and it also shows good advantages in terms of high rate and reversibility. Meanwhile, detailed analysis about interface mechanism for LiPO2F2 by the surface testing (SEM, TEM and XPS) give the direct characterizations. Common ion effect of the decomposition product Li3PO4 from additive is probed from the above characterization and combined with DFT calculations and some clever experiments to prove the positive effect of additives. The findings obtained from this work may provide a useful guidance for the research on electrolyte formulation for high voltage system.

Effects of Anion Impurities on the Solubility and Nucleation of Borax Decahydrate Crystals in Carbonate-Type Brine

Measurements of the solubility and metastable zone width (MSZW) of borax decahydrate (disodium tetraborate decahydrate) within chloride, sulfate and carbonate solutions were carried out. The MSZW was measured by the conventional polythermal method with turbidity technology. The results showed that the addition of impurities decreased solubility. The main factor reducing solubility is the common ion effect, but the salt effect is also significant in the complex system. The addition of impurities broadened the MSZW. The MSZW was wider at first, then decreased with the addition of NaCl, yet the MSZW widened with the addition of Na2SO4 within the concentration range studied. This can be explained by adsorption and diffusion. The data of solubility and MSZW were analyzed by applying the Van’t Hoff equation and the classical 3D nucleation theory approach, respectively. By calculating the corresponding parameters, the experimental phenomena are further explained from the perspective of thermodynamics and dynamics.

Effects of common ions on adsorption and flotation of malachite with salicylaldoxime

Effects of common ions, namely hydroxyl ions and carbonate, on the adsorption and flotation of malachite with salicylaldoxime as a collector was investigated, making use of solubility, micro-flotation, zeta potential, contact angle, FTIR, and XPS measurements. The results suggested that hydroxyl and carbonate ions affect malachite recovery through altering solubility of this mineral. Under conditions of lower solubility, more stable copper atoms acted as adsorption sites for retaining salicylaldoxime on the malachite surface, and the collector consumed by copper species in slurry was reduced. This allowed more collectors to get adsorbed onto malachite surface, resulting in improved malachite recovery. Zeta potential, FTIR, and XPS measurements indicated that salicylaldoxime chemically adsorbs onto malachite by forming copper salicylaldoxime chelates, in which two salicylaldoxime molecules react with one copper atom by N atom and the O atom combined with benzene ring.

Influence of calcium and sodium nitrate on the strength and reaction products of the CaO-activated GGBFS system

Abstract The influence of the added nitrate salts (Ca(NO3)2 and NaNO3) on the CaO-activated ground granulated blast-furnace slag (GGBFS) system was investigated. Both salts significantly increased the early strength of the binder, and the Ca(NO3)2 maintained this tendency until 28 days of curing, whereas NaNO3 did not. At early days, the NaNO3 likely increased pH of samples, resulting in more dissolving GGBFS and formation of C-S-H, while the Ca(NO3)2 slightly decreased pH due to the common ion effect, but because the Ca(NO3)2 supplied additional Ca ions, it also increased the strength. At 28 days, the NaNO3 clearly induced the reduction in C-S-H, which was not the case for the Ca(NO3)2 samples. In addition, the pore size distribution was also significantly dependent on the cation type of nitrate salts.

Novel Potentiometric 2,6-Dichlorophenolindo-phenolate (DCPIP) Membrane-Based Sensors: Assessment of Their Input in the Determination of Total Phenolics and Ascorbic Acid in Beverages

In this work, we demonstrated proof-of-concept for the use of ion-selective electrodes (ISEs) as a promising tool for the assessment of total antioxidant capacity (TAC). Novel membrane sensors for 2,6-dichlorophenolindophenolate (DCPIP) ions were prepared and characterized. The sensors membranes were based on the use of either CuII-neocuproin/2,6-dichlorophenolindo-phenolate ([Cu(Neocup)2][DCPIP]2) (sensor I), or methylene blue/2,6-dichlorophenolindophenolate (MB/DCPIP) (sensor II) ion association complexes in a plasticized PVC matrix. The sensors revealed significantly enhanced response towards DCPIP ions over the concentration range 5.13 × 10−5–1.0 × 10−2 and 5.15 × 10−5–1.0 × 10−2 M at pH 7 with detection limits of 6.3 and 9.2 µg/mL with near-Nernstian slope of −56.2 ± 1.7 and −51.6 ± 2 mV/decade for sensors I and II, respectively. The effects of plasticizers and various foreign common ions were also tested. The sensors showed enhanced selectivity towards DCPIP over many other phenolic and inorganic ions. Long life span, high potential stability, high reproducibility, and fast response were also observed. Method validation was also verified by measuring the detection limit, linearity range, accuracy, precision, repeatability and between-day-variability. The sensors were introduced for direct determination of TAC in fresh and canned juice samples collected from local markets. The obtained results agreed fairly well with the data obtained by the standard method.

Efficient Removal of Sulfuric Acid from Sodium Lactate Aqueous Solution Based on the Common-Ion Effect for the Absorption of SO2 of Flue Gas

Sulfur dioxide (SO2) is the main component of air pollution. Recently, sodium lactate (NaLa) aqueous solution (aq) was demonstrated as a highly efficient, renewable, and stable absorbent for SO2 ab...

Assessment of groundwater quality for the irrigation of melon farms: a comparison between two arable plains in northeastern Iran

Obtaining groundwater of a suitable quality for irrigating crops can be difficult in semi-arid regions in low-income countries like Iran, particularly under conditions where annual rainfall may be declining due to the effects of climate change. Due to substantial difference in the melon production of two important groundwater basins in the Jim-Abad and Torbate-Jam areas in northeastern Iran, groundwater was sampled from 23 wells from these basins and chemically analyzed for physicochemical parameters appropriate for irrigation. These data were used to determine sodium adsorption ratio (SAR), salinity hazard (SH) and irrigation water quality index (IWQI) values and were subjected to statistical assessment to determine the key factors that influence the chemical composition of groundwater in the area. The results of the IWQI survey indicated that 67% of groundwater samples from the Jim-Abad plain and all but one of the samples from the Torbate-Jam plain had a severe limitation for irrigation use. A Piper plot indicated that groundwater quality in the two basins was dominated by sodium and chloride ions. A Gibbs plot suggests that evaporation is the dominant control on groundwater quality in the two basins, although there appears to a significant influence of water–rock reactions in the Torbate-Jam basin. An assessment of the data using cluster analysis and principal component analysis suggests that carbonate dissolution under the influence of the common ion effect also has a significant effect on the quality of groundwater in the region.

Solubility Determination and Thermodynamic Modeling for the System NaCl–NH4Cl–Diethanolamine–H2O

In this work, the solubility behavior of salts NaCl and NH4Cl was investigated in aqueous diethanolamine (DEA) solution by varying both temperature and the solvent composition. DEA has been prevalently used in the postcombustion process to capture CO2, but a limited amount of references can be found pertaining to any solid–liquid system containing DEA. It was experimentally determined that the solubility of NaCl decreases, whereas the solubility of NH4Cl increases with the addition of DEA (x′DEA = 0–0.2). The solubility of both salts increases if temperature is raised from 283 to 353 K. The common-ion effect was examined for the quaternary system when both salts are present in the solution. By the regression of solubility data with the Mixed Solvent Electrolyte model, we proved that readjusting the middle-range interaction parameters between Cl–-DEA and DEAH+-Cl– would lower the relative deviation (within 5%) for each proposed ternary system. A comprehensive chemical model was further constructed based on...