Concentration Of Dilute Solutions Research Articles

Weathering Incongruence in Mountainous Mediterranean Climates Recorded by Stream Lithium Isotope Ratios

AbstractLithium isotope ratios (δ7Li) of rivers are increasingly serving as a diagnostic of the balance between chemical and physical weathering contributions to overall landscape denudation rates. Here, we show that intermediate weathering intensities and highly enriched stream δ7Li values typically associated with lowland floodplains can also describe small upland watersheds subject to cool, wet climates. This behavior is revealed by stream δ7Li between +22.4 and +23.5‰ within a Critical Zone observatory located in the Cévennes region of southern France, where dilute stream solute concentrations and significant atmospheric deposition otherwise mask evidence of incongruence. The water‐rock reaction pathways underlying this behavior are quantified through a multicomponent, isotope‐enabled reactive transport model. Using geochemical characterization of soil profiles, bedrock, and long‐term stream samples as constraints, we evolve the simulation from an initially unweathered granite to a steady state weathering profile which reflects the balance between (a) fluid infiltration and drainage and (b) bedrock uplift and soil erosion. Enriched stream δ7Li occurs because Li is strongly incorporated into actively precipitating secondary clay phases beyond what prior laboratory experiments have suggested. Chemical weathering incongruence is maintained despite relatively slow reaction rates and moderate clay accumulation due to a combination of two factors. First, reactive primary mineral phases persist across the weathering profile and effectively “shield” the secondary clays from resolubilization due to their greater solubility. Second, the clays accumulating in the near‐surface profile are relatively mature weathering byproducts. These factors promote characteristically low total dissolved solute export from the catchment despite significant input of exogenous dust.

Energetic Valorisation of Saltworks Bitterns via Reverse Electrodialysis: A Laboratory Experimental Campaign.

Concentrated bitterns discharged from saltworks have extremely high salinity, often up to 300 g/L, thus their direct disposal not only has a harmful effect on the environment, but also generates a depletion of a potential resource of renewable energy. Here, reverse electrodialysis (RED), an emerging electrochemical membrane process, is proposed to capture and convert the salinity gradient power (SGP) intrinsically conveyed by these bitterns also aiming at the reduction of concentrated salty water disposal. A laboratory-scale RED unit has been adopted to study the SGP potential of such brines, testing ion exchange membranes from different suppliers and under different operating conditions. Membranes supplied by Fujifilm, Fumatech, and Suez were tested, and the results were compared. The unit was fed with synthetic hypersaline solution mimicking the concentration of natural bitterns (5 mol/L of NaCl) on one side, and with variable concentration of NaCl dilute solutions (0.01-0.1 mol/L) on the other. The influence of several operating parameters has also been assessed, including solutions flowrate and temperature. Increasing feed solutions' temperature and velocity has been found to lower the stack resistance, which enhances the output performance of the RED stack. The maximum obtained power density (corrected to account for the effect of electrodic compartments, which can be very relevant in five cell pairs laboratory stacks) reached around 10.5 W/m2cellpair, with FUJIFILM Type 10 membranes, temperature of 40 °C, and a fluid velocity of 3 cm s-1 (as empty channel, considering 270 μm thickness). Notably, the present study results confirm the large potential for SGP generation from hypersaline brines, thus providing useful guidance for the harvesting of SGP in seawater saltworks all around the world.

Thermal Performance Analysis of Solar Seawater Desalination System Based on Heat Pump Cycle

Mathematical model of the solar seawater desalination system based on heat pump cycle was established, which was solved by programming with MATLAB language. The system performance was analyzed by changing four variables, including the initial temperature of water tank, drive hot water temperature drop, the mass concentration of LiBr dilute solution and the system startup temperature. The results show that increasing the initial temperature of water tank is conducive to reducing the heat consumption of the auxiliary heat source and increasing the solar energy supply ratio; Increasing drive hot water temperature drop is beneficial to increase the fresh water production, but the heat of the auxiliary heat source required increases, and the solar energy supply ratio decreases; Increasing the mass concentration of LiBr dilute solution will not change the total heat consumption of the system, the heat consumption of auxiliary heat sources and the solar energy supply ratio, but the fresh water production will decrease; Increasing the system startup temperature will increase the heat consumption of the auxiliary heat source, reduce the solar energy supply ratio, and slightly reduce the fresh water production.

Effect of structure and operation parameters on heat and mass transfer coefficients of single‐bubble absorption for lithium bromide solution

Bubble absorption has an efficient performance in absorption units, and lithium bromide (LiBr)-H2O is the most popular working medium in absorption system due to its safety and environmental protection. Limited to the vacuum operation, the researches of bubble absorption for LiBr solution are less reported and the bubble absorption characteristic for LiBr solution is still not clear. In this study, a single-bubble heat and mass transfer model is established to investigate the heat and mass transfer coefficients of bubble absorption for LiBr solution under vacuum condition. A visible experimental platform is established to validate the feasibility of vacuum operation and the model accuracy. The experimental results showed the relative deviation is less than 11.9%. Base on the current model, the effects of structure and operation parameters are comprehensively analyzed to explore the appropriate configuration. The results indicate that the heat and mass transfer coefficients increase significantly with the increase of the orifice diameter and the bubble velocity, while they reduce with the increase of solution concentration. It can be explained that large orifice diameter expands the contact area, and high velocity strengthens the convection, which promote the absorption. Dilute solution concentration reduces the viscous force and surface tension, thereby enhancing the heat transfer. It is expected to provide guidance for the heat and mass transfer mechanisms and contribute to advance the structure and configuration of absorption system.

Selective electrodialysis process for the separation of potassium: Transmembrane transport of ions in multicomponent solution systems

With the development of global agriculture, the demand for potash is growing rapidly. The concentration of K+ in bittern can reach 10 g/L, but the economic benefit of existing extraction methods is still a key concern, and a new extraction method is urgently needed. The monovalent selective electrodialysis was proposed in this study to purify K+. The effects of coexisting ion concentration, voltage, temperature, and ionic strength of dilute solution on the separation of K+ from brine were investigated in ternary system, quaternary system, and quinary system, respectively. Monovalent selective electrodialysis was preliminarily applied to separate K+ from actual bittern. The results showed that monovalent selective electrodialysis can effectively extract K+ and reduce the ratio of Mg2+/K+ from 7.11 to 0.92 with a K+ recovery rate of 74.83%.

Multivariate inverse artificial neural network to analyze and improve the mass transfer of ammonia in a Plate Heat Exchanger-Type Absorber with NH3/H2O for solar cooling applications

This work presents a numerical approach to compute optimal operating conditions that maximize the absorption flux into a heat exchanger designed for absorption refrigeration systems. Experimental data were obtained from a test circuit that operates in bubble absorption mode with an inner vapor distributor into a Plate Heat Exchanger-type (PHE-type) and interacts with ammonia vapor, NH3-H2O refrigerant, and cooling water. An artificial neural network (ANN) was trained to correlate the thermal properties of the solution and absorption flux in function of easily measurable parameters (concentrations, mass flows, and pressures of saturated and diluted solutions, flow and temperature of the ammonium vapor, environment temperature, and solution temperature). According to results, ANN is adequate to correlate the operational parameters and the transport phenomena inside the heat exchanger with a precision > 99%. ANN also quantitatively identified the ammonium vapor flow (43.1%), dilute solution flow (18.1%), and dilute solution concentration (13.1%) as the variables most importantly in influencing absorption flux optimization. Subsequently, a multivariable inverse artificial neural network was applied to improve the mass transfer into the PHE-type.It was identified that simultaneous optimization of the ammonia and dilute concentration flow rates improves the absorption flow performance by up to 96.3% under a worst-case scenario (ammonia flow rate<1.4 kg/min) and even 7.04% when even when operating near the amino vapor flow limit (ammonia flow rate>2.0 kg/min). Finally, it was confirmed that incorporating the diluted solution concentration into the optimization contributes to improving the performance of the absorption process 1%. Results obtained are relevant in the search to produce more competitive absorption cooling systems, demonstrating the feasibility of improving the performance of heat exchangers without structural modifications. The proposed methodology represents an interesting option to be implemented to improve performance in solar cooling systems.

Studies of intrinsic volumes of ethylene glycol and polyethylene glycol–300 molecules in aqueous solutions at 298.15 K: Application of Tammann–Tait–Gibson (TTG) equation of state

Systemic density (ρ) measurements have been carried–out for aqueous solutions of polyethylene glycols (PEG's) with the molar mass 200, 300, 400 and 600 D at (288.15, 293.15, 298.15, 303.15 and 308.15) K and at ambient pressure of 0.1 MPa in dilute solute concentration region (0.0119–0.4941 mol⋅kg−1). The ρ data are used to obtain the apparent molar volume (Vϕ) and partial molar volume (V¯2) of studied PEG's in aqueous solutions at finite concentration as well as at infinitely dilute solutions (Vϕ0) at studied temperatures. The coefficient of thermal expansion (α) for solutions, apparent molar expansivity (Eϕ) and limiting apparent molar expansivity (Eϕ0) for solutes are calculated at 293.15, 298.15 and 303.15 K. The densities of studied PEG's in carbon tetrachloride (CCl4) medium are also measured at 298.15 K. The transfer volume (ΔtrVϕ0) for PEG from pure liquid state to CCl4 and to water as solvent are estimated. The literature data of sound velocity (u), coefficient of thermal expansion (α) and specific heat capacity (CP) for solutions have been utilized to obtain thermodynamic properties like adiabatic compressibility (βad) and isothermal compressibility (βT) in case of aqueous solutions of ethylene glycol (EG) and PEG–300 at 298.15 K. The data are further utilized to obtain apparent molar adiabatic compressibility (KϕS) and apparent molar isothermal compressibility (KϕT) for EG and PEG–300 solute molecules at finite and at infinitely dilute solute concentration (KϕS0 and KϕT0, respectively). Further, the data of KϕT, α and CP data have been utilized to estimate internal pressure Pi (=∂U∂VT) of solutions containing EG and PEG–300 molecules as a function of concentration. The intrinsic volumes (Vint.) of these molecules have been calculated by applying Tammann–Tait–Gibson (TTG) equation of state. It is being observed that intrinsic volume differs appreciably from the value based upon EG and PEG–300 in a liquid state as a standard state. The excess volume change (V¯20E=V¯20-V¯int.0) values are found to be −16.1 and −63.8⋅10–6 m3⋅mol−1 for EG and PEG–300, respectively. Similar calculations made for PEG–300 in CCl4 medium also yield excess volume change of −60⋅10–6 m3⋅mol−1 magnitude. These results are explained on the basis of three dimensional hydrogen bonded structure of EG and the linkage ▪ interaction with solvent water having a presence of helical segments. The inferences drawn will be of help to understand the weak denaturing interactions of glycols in protein denaturation studies.

Predicting the temperature dependence of self-diffusion behavior in Ni-Cr alloys via molecular dynamics

Defect-mediated mass transport is a critical phenomenon for many material performance and degradation issues. In the area of stress corrosion cracking, a predictive model of mass transport under realistic, elevated temperatures would be instrumental in predicting crack initiation and propagation tendencies. Molecular simulations can address some of these gaps about underlying processes. In that context, this study presents a robust model that describes self-diffusion at high temperatures in Ni-xCr alloys with varying Cr concentrations. We show that by using a vacancy concentration rescaling factor, it is possible to properly estimate diffusion coefficients in Ni-5Cr, Ni-10Cr and Ni-20Cr. The model reaches its upper limit at 1600 K for Ni-20Cr, because it has been fitted on dilute solute concentrations. Extrapolations at low temperature match experimental trend. Simulations with a theoretical number of vacancies give results comparable to the diffusion coefficients with the rescaling factor. In further simulations of more complex systems, efforts should be made in interstitial formation and migration barrier energy description.

Applications of Lambert-Beer law in the preparation and performance evaluation of graphene modified asphalt

The main purpose of this paper is to develop high-performance graphene-modified asphalt (GMA) and characterize graphene occurrence in asphalt and examine its mechanism. The main research methods are: Based on Lambert-Beer law and dispersants dipropylene glycol dimethyl ether (DME) and polyvinyl pyrrolidone (PVP), the absorbance of dilute graphene mother liquor (GML) solutions at different concentrations were obtained via ultraviolet/visible spectrophotometry, and the concentration of dilute GML solutions were obtained via supernatant algorithms. The absorbance and concentration of dilute GML solutions were fitted via regression, which obtained the absorbance coefficient. Then, based on nominal graphene dosage (G) and dispersant and graphene proportion (D/G), respectively, the absorbance coefficients were fitted via regression to establish mathematical GML materials composition models which were solved via First Optimization (1stOpt) analysis software. Following the materials composition, DME-GMA and PVP-GMA was prepared, and the corresponding performance tests were carried out, and GMA was characterized via metallographic microscope and micro/nano-CT scanning to explore the morphology of graphene and mechanism in asphalt. The results are: Based on dispersants DME and PVP, respectively, the materials composition are G = 0.53%, D/G = 160%, and G = 0.26%, D/G = 190%. The penetration, non-recoverable creep compliance at 0.1 kPa and 3.2 kPa of DME-GMA and PVP-GMA (based on matrix asphalt) were decreased by 7.44 and 7.76%, 20.82 and 30.95% (0.1 kPa), and 8.63 and 18.88% (3.2 kPa), respectively. The softening point, maximum force at 5 °C, ductility at 5 °C, fracture energy at 5 °C, antirutting factors at 64 °C, and creep recovery rate at 0.1 kPa and 3.2 kPa were increased by 4.57 and 7.17%, 41.96 and 61.29%, 14.91 and 18.30%, 55.51 and 98.81%, 17.26 and 40.51%, 646.77 and 867.88% (0.1 kPa), and 128.62 and 153.53% (3.2 kPa), respectively. The high- and low-temperature stability of GMA are notably improved via uniformly dispersing graphene in asphalt materials, and graphene occurs as agglomerates in asphalt materials, and dispersants DME and PVP increase the graphene agglomerate dispersion effect in asphalt materials, changing its larger, irregular morphology to a smaller, regular one. The better the graphene dispersion effect is, the better the GMA performance is. PVP-GMA attains a better performance than DME-GMA.

On the interaction of a solute atmosphere with a circular void in two-dimensional elasticity: A statistical mechanics approach

Solid solutions are of critical importance to many technological applications. While continuum frameworks have been developed and invoked in the past for studying behavior of solid solutions, recent studies point to the importance of image stresses in finite systems, and in particular, suggest that the homogenized self-stress field of the solutes, which enter the chemical potential in the prevalent continuum models, should be excluded in a correct treatment. The present work is concerned with the study of a solute atmosphere in the vicinity of a void in two-dimensional elasticity wherein the solute atmosphere is treated as a distribution of solute rods extended indefinitely normal to the plane of analysis. A statistical mechanics framework is adopted based on the Gibbs canonical ensemble, and the well-established path-independent integrals of solid mechanics are used for examining configurational forces on the void induced by the presence of a solute atmosphere. Numerical Monte Carlo simulations fully accounting for the interaction energy between the solute rods are used for calculation of the ensemble averages of the energy release rates associated with void translation and expansion, and semi-analytical solutions are further developed in the limit of dilute solute concentrations and large temperatures. Effect of interaction between the stress fields of a solute atmosphere and an external loading on the configurational forces is also investigated through both numerical and analytical calculations. It is shown that the interaction between the image stress field of a given concentration of solute rods and the stress field of an equi-biaxial loading results in an added contribution to the energy release rate of void expansion which does not fade away even when the solid dimensions grow indefinitely. Numerical simulations are further used to examine the effect of loading-induced solute redistribution on the energetic driving force for void expansion.

Nickel Metal Hydride Battery Waste: Mechano-hydrometallurgical Experimental Study on Recycling Aspects

In this research, the recycling of industrially collected and crushed nickel metal hydride battery waste, rich in valuable metals such as Ni and rare earth elements (REE), was investigated. The crushed waste was characterized based on elemental distribution per particle size class and density. Although issues with sieving, such as agglomeration of shredded separator fibers, were observed, a good separation of Fe and plastics could be achieved by using a 1-mm sieve size. It was observed that, as the waste battery particles were washed with water, some organic compounds were dissolved. Acid consumption of 14 mol H+ ions per 1 kg of battery sample (sieve fraction—1 mm) was determined to be sufficient to achieve the desired final pH of < 1. Selectivity of the leaching at higher equilibrium pH was also investigated by using dilute H2SO4. Pregnant leach solution rich in Ni (46 g/L) and REEs (La: 9 g/L, Ce: 7.5 g/L, Pr: 1.4 g/L, Sm: 0.29 g/L, Y: 0.17 g/L) was obtained and REE precipitation was investigated as a function of dilute Na2SO4 solution concentration (0.01–0.5 M) at a temperature of 50 °C. The best precipitation efficiency was achieved with a Na:REE ratio of 9.1, which resulted in a > 99% precipitation efficiency for the REEs.

Designing high ductility in magnesium alloys

The thermally activated pyramidal-to-basal (PB) transition of 〈c+a〉 dislocations, transforming glissile pyramidal dissociated core structures into sessile basal dissociated ones, lies at the origin of low ductility in pure magnesium (Mg). Solute-accelerated cross-slip and double cross-slip of pyramidal 〈c+a〉 dislocations have recently been proposed as a mechanism that can circumvent the deleterious effects of the PB transition by enabling rapid dislocation multiplication and isolating PB-transformed sessile segments. Here, the theory for solute-accelerated cross-slip is revisited with an explicit atomistic derivation, is extended to include multiple very dilute solute concentrations, and various aspects of the theory are demonstrated computationally. DFT inputs to the theory for a wide range of new alloying elements are presented. The theory is validated by comparing predicted ductility to literature experiments for a range of alloys. The theory is then applied to predict composition ranges for ductility in rare-earth free ternary and quaternary dilute alloys. The wide range of new alloys predicted to be ductile can serve as a guide to experimental development of new ductile Mg alloys.

Evaporation-driven solutocapillary flow of thin liquid films over curved substrates

Evaporation of a volatile solvent induces solutocapillary Marangoni flows by creating gradients in species concentration and surface tension. These flows are experimentally and theoretically investigated in sub-micron films at dilute solute concentrations where Van der Waals effects are important.

Mesoscale modeling of the crystallization parameters identification during the iron-based catalyst preparation process: the dilute concentration case

ABSTRACT In this paper we model the mesoscale crystallization of the crystals in the dilute solution concentration in the sense that the microscale model is a stochastic process and meanwhile the macroscale model is a deterministic heat diffusion process. The crystallization process includes the steps of nucleation, nucleus radial growth and nuclei aggregation. In the case of the dilute solution concentration we may neglect the effect of the nuclei aggregation, i.e. the crystallization neglects the impingement. The coupled model of crystallization and heat diffusion show the mesoscale characteristic between the micro- and macro- aspect. Furthermore we reformulate the simultaneous identification of nucleation rate and crystal growth speed in the stochastic birth-growth process by the inverse approaches. The regularization strategy is adopted to implement the numerical inversion of the inverse problem. Finally, numerical examples are provided to show the effectiveness of the proposed algorithm.

Ab initio magnesium-solute transport database using exact diffusion theory

A recently developed Green function approach informed by ab initio calculations models vacancy-mediated transport of 61 solutes in a hexagonal close packed magnesium. The 8- and 13-frequency diffusion models approximate vacancy jump rates near a solute, leading to the inaccurate calculation of Onsager coefficients. We identify all the symmetry-unique vacancy jumps in the Mg lattice and use the Green function approach to calculate the Onsager coefficients exactly in the limit of dilute solute concentration. Density functional theory-computed solute-vacancy interactions and vacancy jump rates inform the Green function approach and previous diffusion models. Solutes with positive size misfit diffuse faster compared to the self-diffusion of Mg due to the relaxation of solute towards vacancy while solutes with negative size misfit diffuse slower. Transition metal solutes show drag for attractive solute-vacancy binding as well as for repulsive binding, due to faster reorientation rates of the vacancy around the solute compared to dissociation rates. Solutes from the s-block, p-block and lanthanide series with attractive solute-vacancy binding and slower reorientation rates compared to the dissociation rates show drag due to vacancy motion around the solute through alternate dissociation and association jumps. The prediction of activation energy of diffusion from the 8-frequency model deviates by more than 50 meV for solutes with significant correlations effect. Our GF approach prediction of solute diffusion coefficients agree well with the available experimental measurements.

Arsenic removal from water by hybrid electro-regenerated anion exchange resin/electrodialysis process

Abstract One of the major public health concerns worldwide is arsenic presence in the water intended for human consumption in different countries. This paper proposes the use of the hybrid ion exchange/electrodialysis (IXED) process for arsenic removal from water. Its objective is to lower the concentration of dilute solutions of As(V) ions to values below the maximum limit (10 µg L −1 As) recommended by the World Health Organization. To prove this method, a 5-compartment cell was used: a central compartment filled with anion exchange resin and delimited by anion exchange membranes, two adjacent compartments with cationic membranes on the ends and two rinse compartments, one at each electrode. Ion exchange/electrodialysis process was performed as a batch wise operation by recirculating arsenic solutions through the central compartment and the two adjacent compartments. The As(V) ions in the solution are exchanged by OH − in the resin which is regenerated with OH − ions produced by water dissociation at the membrane-electrolyte interface, according to changes in pH, conductivity and As concentration in each compartment. The obtained results show that IXED is capable of removing arsenic from solutions at different concentrations ranging between 2.1 and 15 mg L −1 As, until reaching the final concentration ≤10 μg L −1 with a current efficiency between 8.2 and 47.7% and energy consumption between 7.5 and 63.9 kW h per kg of removed As(V).

Multiple-Line Particle Focusing under Viscoelastic Flow in a Microfluidic Device.

Particles in a viscoelastic fluid are typically focused at the center and four corners of a rectangular channel because of the combination of fluid elasticity and inertia forces. In this study, we observe the transition between single-line and multiple-line particle focusing in a microfluidic device induced by the synergetic effect of inertia and viscoelasticity. The elastic and inertial forces acting on suspended particles are manipulated by controlling the concentration of dilute polymer solution and the flow rate of a fluid. The finding shows that the confinement effects determined by the channel aspect ratio and the inlet geometry lead to the multiple-line focusing of particles in the microfluidic channel due to the fluid elasticity and hydrodynamic behavior of the fluid. A microfluidic channel with high channel aspect ratio possesses broad minimal region of the elastic force across the channel, which generates a wide particle focusing band rather than a single particle focusing at the center. The multiple-line particle focusing occurs as the inertial force outweighs the elastic force, resulting in the particle migration toward the channel sidewalls.

The Collector Matching Analysis of Solar Cooling System Based on Three Kinds of Woking Medium

Solar collector is an important part of solar cooling system, which provides heat source for the generator. With the help of Aspen Plus software, the three working fluid systems of LiBr/H2O, NH3/H2O, and R134a/DMF are established. And this paper analyzes the corresponding collector type for the three systems.We find that When the condensing-temperature is 38℃and the range of dilute solution concentration is 54%~56%, the LiBr/H2O system can choose low solar thermal collector. When the condensing-temperature is up to 42℃, High/Medium solar thermal collector is appropriate for LiBr/H2O. NH3/H2O system can only choose High/Medium solar thermal collector. And R134a/DMF system can choose low solar thermal collector when deflated range is between 0.17 to 0.3; when deflated range is higher than 0.3, R134a/DMF system can choose high solar thermal collector.

Nuclear magnetic resonance studies of the solvation structures of a high-performance nonaqueous redox flow electrolyte

Understanding the solvation structures of electrolytes is important for developing nonaqueous redox flow batteries that hold considerable potential for future large scale energy storage systems. The utilization of an emerging ionic-derivatived ferrocene compound, ferrocenylmethyl dimethyl ethyl ammonium bis(trifluoromethanesulfonyl)imide (Fc1N112-TFSI), has recently overcome the issue of solubility in the supporting electrolyte. In this work, 13C, 1H and 17O NMR investigations were carried out using electrolyte solutions consisting of Fc1N112-TFSI as the solute and the mixed alkyl carbonate as the solvent. It was observed that the spectra of 13C experience changes of chemical shifts while those of 17O undergo linewidth broadening, indicating interactions between solute and solvent molecules. Quantum chemistry calculations of both molecular structures and chemical shifts (13C, 1H and 17O) are performed for interpreting experimental results and for understanding the detailed solvation structures. The results indicate that Fc1N112-TFSI is dissociated at varying degrees in mixed solvent depending on concentrations. At dilute solute concentrations, most Fc1N112+ and TFSI− are fully disassociated with their own solvation shells formed by solvent molecules. At saturated concentration, Fc1N112+-TFSI- contact ion pairs are formed and the solvent molecules are preferentially interacting with the Fc rings rather than interacting with the ionic pendant arm of Fc1N112-TFSI.

Nanoscale corrosion behavior of polycrystalline copper fine wires in dilute NaCl solution investigated by in-situ atomic force microscopy

In this study, nanoscale corrosion behavior of copper fine wires in dilute NaCl solution is studied by atomic force microscopy and electron backscatter diffraction. The dissolution rate of grains constituting the wires strongly depends on their crystallographic orientation. In pure water, the dissolution rate increases in the order of (111)<(001)<(110). Addition of Cl− dramatically increases the dissolution rate of the (111) surface to alter the order to (110)≈(001)≈(111) at 0.1mM. These results show that the crystallographic orientation dependence is significantly changed by a slight increase of Cl− concentration in dilute solution.