Pure NaCl Solution Research Articles

A novel self-cleaning functional composite coating with extraordinary anti-corrosion performance in high pressure CO2 conditions

This study demonstrates an alternative method for fabricating a novel integrated anticorrosion self-cleaning functional coating using the GO nanosheets with the TiO2–ZnO heterostructure to effectively induce charge separation and to accomplish photoinduced hydrophilic conversion. Through ultraviolet light (UV) irradiation, the PFDTMS-modified filler transformed from hydrophobic to hydrophilic, while the fluorine groups on the surface of the filler still existed. Research of EIS shows that the impedance at 0.01 Hz of 20% F/T-Z-G Polyurea coating was about 1 × 103 times higher than polyurea coatings, after 24 h of immersion in 2.8 MPa, 110 °C pure CO2 and NaCl solution. The results demonstrate that F/T-Z improves the dispersion of GO and make the polyurea matrix denser, inhibiting the diffusion of corrosive medium. Additionally, the GO and fluorine groups strengthen the shielding performance of the coating. Moreover, the TiO2–ZnO heterojunction traps H2O molecules to form hydroxyl radicals (OH•). Simultaneously, Fe2+ and Fe3+ combine with OH• to form Fe3O4, and the passivation film was formed on the surface of steel. It is believed that this hydrophilic-hydrophobic integrated functional coating will be an excellent candidate for technological applications, such as anticorrosion, self-cleaning materials and composite coatings.

An Accurate Model for Estimating H2 Solubility in Pure Water and Aqueous NaCl Solutions

By employing a specific particle interaction theory and a high-precision equation of states for the liquid and vapor phases of H2, respectively, a new H2 solubility model in pure water and aqueous NaCl solutions is proposed in this study. The model established by fitting the experimental data of H2 solubility can be used to estimate H2 solubility in pure water at temperatures and pressures of 273.15–423.15 K and 0–1100 bar, respectively, and in salt solutions (NaCl concentration = 0–5 mol/kg) at temperatures and pressures of 273.15–373.15 K and 0–230 bar, respectively. By adopting the theory of liquid electrolyte solutions, the model can also be used to predict H2 solubility in seawater without fitting the experimental data of a seawater system. Within or close to experimental data uncertainty, the mean absolute percentage error between the model-predicted and experimentally obtained H2 solubilities was less than 1.14%.

A dynamic intercalation mechanism in pre-intercalation carbon nanosheets for capacitive deionization cells

Given that carbon-based electrodes suffer from poor long-term stabilities and limited desalination capacity, the optimized charge storage mechanism used for improving desalination performance remains requisite. In this work, the KC-pre-intercalated carbon nanosheets (PCNs) with abundant conjugated carbonyl groups were designed via a one-step smelting method for the first time as a novel intercalation electrode in the symmetric capacitive deionization. Interestingly, below 500 mg/L, the physical electrical double-layer mechanism is mainly influential. Benefitting from the proposed dynamic intercalation mechanism, a remarkable ion removal capacity of 1.65 g g−1 and impressive cyclability of 300 cycles (97.96%) were observed in the high salt concentrations (>1000 mg/L) and simulated seawater system rather than pure NaCl solution. The ultrahigh adsorption capacity and prominent cycling stability make the PCNs-based device rank top three among these of all the symmetric CDI systems reported in the literatures so far. The Na+ ions are intercalated in the enlarged interlayer spacing without a host structure deformation, thus offering a high ion removal rate (2.04 mg g−1 min−1) and a low energy consumption (0.28 Wh g−1). Our work exemplifies the importance of engineering conjugated carbonyl groups and pre-intercalated structure to capacitive deionization for brine.

Experimental study on carbon dioxide hydrate formation in the presence of static magnetic field

The formation kinetic parameters, phase equilibrium and dissociation enthalpy of carbon dioxide hydrate in the presence of static magnetic field were investigated in this work. The experiments were carried out in pure water and (0.029, 0.056 and 0.110, mass fraction) sodium chloride (NaCl) aqueous solution with a magnetic field of 0.39 T. The experimental results showed that the induction time of carbon dioxide hydrate nucleation was shortened, the consumption amount and rate of carbon dioxide were significantly increased with the magnetic field. This phenomenon is mainly attributed to the fact that the magnetic effect decreases the contact angle between water and solid surface to reduce the critical size and critical free energy of hydrate nucleation. Moreover, the phase equilibrium of carbon dioxide hydrate in both pure water and NaCl aqueous solution shifted to lower pressure or higher temperature with the magnetic field, and the equilibrium temperature in pure water decreased by 3.0 K, which is due to the change of the hydrogen bond in small clusters and ions mobility by magnetic effect. In addition, the dissociation enthalpies of carbon dioxide hydrate in pure water and (0.029, 0.056 and 0.110) NaCl solution calculated by Clausius-Clapeyron equation were 91.5, 91.4, 62.8 and 52.0 kJ·mol−1, respectively, in the magnetic field, which is related to the movements of ions caused by magnetic effect and heat absorption.

TiO2/CDs modified thin-film nanocomposite polyamide membrane for simultaneous enhancement of antifouling and chlorine-resistance performance

In this study, a titanium dioxide/carbon dots (TiO2/CDs) hydrophilic nanocomposite photocatalyst with different contents was embedded in the polyamide layer of reverse osmosis (RO) membrane via interfacial polymerization to increase desalination performance and antifouling properties. The modified membranes showed smoother surfaces with reduced contact angles, causing to improve membrane fouling resistance. TiO2/CDs nanocomposite, due to its photocatalytic activity, showed more flux recovery ratio (FRR) after irradiation of UV light during the washing process. The FRR was enhanced from 94.4 to 97.1% for 0.01 wt% TiO2/CDs RO membrane by UV irradiation. The hydrophilic functional groups with negative charge increased the desalination efficiency of the modified membranes (99.2% NaCl rejection for 0.01 wt% TiO2/CDs membrane). The membrane containing 0.01 wt% TiO2/CDs presented the highest pure water and NaCl solution flux of (59.6 and 54.6 L·m−2·h−1) at 15 bar, respectively. In addition, the used nanoparticles improved the chlorine resistance of the membranes. As a result, TiO2/CDs nanocomposite with little amounts could be applied as a suitable nanofiller to increase the permeability, antifouling properties, and chlorine resistance for RO membrane modification.

Membrane Distillation of Saline Water Contaminated with Oil and Surfactants.

Application of the membrane distillation (MD) process for the treatment of high-salinity solutions contaminated with oil and surfactants represents an interesting area of research. Therefore, the aim of this study is to investigate the effect of low-concentration surfactants in oil-contaminated high-salinity solutions on the MD process efficiency. For this purpose, hydrophobic capillary polypropylene (PP) membranes were tested during the long-term MD studies. Baltic Sea water and concentrated NaCl solutions were used as a feed. The feed water was contaminated with oil collected from bilge water and sodium dodecyl sulphate (SDS). It has been demonstrated that PP membranes were non-wetted during the separation of pure NaCl solutions over 960 h of the module exploitation. The presence of oil (100–150 mg/L) in concentrated NaCl solutions caused the adsorption of oil on the membranes surface and a decrease in the permeate flux of 30%. In turn, the presence of SDS (1.5–2.5 mg/L) in the oil-contaminated high-salinity solutions slightly accelerated the phenomenon of membrane wetting. The partial pores’ wetting accelerated the internal scaling and affected degradation of the membrane’s structure. Undoubtedly, the results obtained in the present study may have important implications for understanding the effect of low-concentration SDS on MD process efficiency.

Tribocorrosion investigation of 316L stainless steel: the synergistic effect between chloride ion and sulfate ion

Tribocorrosion is a failure phenomenon which involves synergistic effect of electrochemical corrosion and mechanical wear. It usually results into early failure of mechanical components than simple wear and corrosion. Chloride (Cl−) and sulfate ions are often found together in corrosive media. In this study, the synergistic effect of Cl− and on tribocorrosion of 316L stainless steel was studied by changing the ratio of /Cl− in corrosive solution from 0.31 M : 0 to 0 : 0.62 M. The stainless steel was worn against with a ZrO2 sphere. The coefficient of friction (COF), material loss volume, surface micro-topographies and surface chemical composition in different solutions were compared to explore the synergism between and Cl−. The results indicated that the mix of Cl− and reduced material loss volume by a quarter when compared with that in pure Na2SO4 or NaCl solution. More than half of material loss was caused by the synergism between wear and corrosion in mixing solutions. The synergistic effect between and Cl− could promote the transmission of metal into oxides. This had two effects on tribocorrosion. First, the existence of oxides would cause abrasion which accelerated wear-affected corrosion and enhanced mechanical wear (corrosion-affected wear). On the other side, the transmission of metal into oxides benefited for the formation of tribo-film. The flexible stainless steel needed to coordinate deformation with the tribo-film which had relatively low deformability. This aggravated deformation of stainless steel and promoted surface work-hardening effect. It was helpful for stainless steel to resist wear, thus, the corrosion-affected wear was decreased.

Numerical study of bubble behaviors and heat transfer in pool boiling of water/NaCl solutions using the lattice Boltzmann method

Through modification of the equation of state applicable to the non-volatile salt solution and characterization of the effect of solute concentration on the physical properties of the solution, a lattice Boltzmann pseudopotential model was developed and used to study the pool boiling processes of pure water and NaCl solutions. The model quantitatively verified the equilibrium vapor pressure reduction and boiling point rise of the NaCl solution with solute concentration. The complete pool boiling curves of pure water and the NaCl solution were simulated, and the differences in bubble behaviors and heat flux evolutions in pure water and the NaCl solution at different superheats were analyzed. The results revealed that the difference of heat flux between water and NaCl solution in the nucleate boiling regime is dominated by the nucleation site density and bubble departure frequency at lower superheats, while dominated by the bubble interactions at larger superheats. As a result, the NaCl solution presents a lower nucleate boiling heat flux than that of water when the imposed superheat is smaller than a critical superheat, while it exhibits a larger heat flux even a higher critical heat flux than water when the superheat is higher than the critical superheat. Furthermore, the lower bubble departure frequency in NaCl solution film boiling was captured by simulation. The simulated film boiling heat flux of the NaCl solution was smaller than that of water, and both the simulated results fitted the Berenson correlation well.

Molecular dynamics study on water and ions transport mechanism in nanometer channel of 13X zeolite

Understanding the atomistic transport within nanoporous zeolite is essential in a broad field. Herein, molecular dynamics was systematically utilized to elucidate the migration mechanism of pure water and NaCl solution in the 13X zeolite. At nano-scale level, molecular simulation clearly distinguishes the wetting and saturating stages of water transport in porous zeolite. The interior skeleton of 13X zeolite provides plenty of oxygen sites with strong polarity, which attracts frontier water molecules to infiltrate the hydrophilic zeolite surface rapidly in nearly 2 ns. The ladder-like ingress curve for water molecules highlight the discontinuous remain-jump wetting process that is induced by the competition adsorption with oxygen sites between the subsequent water molecules and the front water molecules. Initial wetting on interior surface reduces significantly the permeability of subsequent water transport. Furthermore, the penetrated water molecules, competing oxygen sites with extra-framework cations, can cause cations to exhibit different hydration behavior. Additionally, the permeability of water flux throughout zeolite channel is reduced by 10% as the Na+ and Cl- are incorporated in solution. Na+ with large hydration shells are sieved by bottlenecks formed by the windows of 12-ring structure with a diameter of 7.38 Å. The accumulated Na+ at the entrance region associate with neighboring water molecules and hydroxyl oxygen atoms to form hydrated clusters and ionic pairs, which plays as a physical barrier in blocking water transport. Decoding of the transport mechanism of water and salt solutions in zeolites at the molecular level facilitates breaking the existing upper limit of energy storage density and water treatment efficiency.

Sonochemical conversion of CO2 into hydrocarbons: The Sabatier reaction at ambient conditions

In this study, we investigated an alternative method for the chemical CO2 reduction reaction in which power ultrasound (488 kHz ultrasonic plate transducer) was applied to CO2-saturated (up to 3%) pure water, NaCl and synthetic seawater solutions. Under ultrasonic conditions, the converted CO2 products were found to be mainly CH4, C2H4 and C2H6 including large amount of CO which was subsequently converted into CH4. We have found that introducing molecular H2 plays a crucial role in the CO2 conversion process and that increasing hydrogen concentration increased the yields of hydrocarbons. However, it was observed that at higher hydrogen concentrations, the overall conversion decreased since hydrogen, a diatomic gas, is known to decrease cavitational activity in liquids. It was also found that 1.0 M NaCl solutions saturated with 2% CO2 + 98% H2 led to maximum hydrocarbon yields (close to 5%) and increasing the salt concentrations further decreased the yield of hydrocarbons due to the combined physical and chemical effects of ultrasound. It was shown that CO2 present in a synthetic industrial flue gas (86.74% N2, 13% CO2, 0.2% O2 and 600 ppm of CO) could be converted into hydrocarbons through this method by diluting the flue gas with hydrogen. Moreover, it was observed that in addition to pure water, synthetic seawater can also be used as an ultrasonicating media for the sonochemical process where the presence of NaCl improves the yields of hydrocarbons by ca. 40%. We have also shown that by using low frequency high-power ultrasound in the absence of catalysts, it is possible to carry out the conversion process at ambient conditions i.e., at room temperature and pressure. We are postulating that each cavitation bubble formed during ultrasonication act as a “micro-reactor” where the so-called Sabatier reaction -CO2+4H2→UltrasonicationCH4+2H2O - takes place upon collapse of the bubble. We are naming this novel approach as the “Islam-Pollet-Hihn process”.

Molecular Simulations of Electrotunable Lubrication: Viscosity and Wall Slip in Aqueous Electrolytes

We study the frictional response of water-lubricated gold electrodes subject to an electrostatic potential difference using molecular dynamics simulations. Contrary to previous studies on electrotunable lubrication that were carried out by fixing the charges, our simulations keep electrodes at fixed electrostatic potential using a variable charge method. For pure water and NaCl solutions, viscosity is independent of the polarization of the electrodes, but wall slip depends on the potential difference. Our findings are in agreement with previous analytical theories of how wall slip is affected by interatomic interactions. The simulations shed light on the role of electrode polarization for wall slip and illustrate a mechanism for controlling friction and nanoscale flow in simple aqueous lubricants.

Composition dependent density of ternary aqueous solutions of ionic surfactants and salts

Surfactants exist in atmospheric aerosols mixed with inorganic salts and can significantly influence the formation of cloud droplets due to bulk–surface partitioning and surface tension depression. To model these processes, we need continuous parametrizations of the concentration dependent properties of aqueous surfactant–salt solutions for the full composition range from pure water to pure surfactant or salt. We have developed density functions based on the pseudo-separation method and Young’s mixing rule for apparent partial molal volumes for solutions that mimic atmospheric droplets of marine environments. The developed framework requires only model parameters from binary water–salt and water–surfactant systems and includes the effect of salinity on micellization with composition-dependent functions for the critical micelle concentration (CMC). We evaluate different models and data available in the literature to find the most suitable representations of the apparent partial molal volume of sodium chloride (NaCl) in aqueous solutions and the CMC of selected atmospheric and model surfactants in pure water and aqueous NaCl solutions. We compare model results to experimental density data, available in the literature and obtained from additional measurements, for aqueous solutions containing one of the ionic surfactants sodium octanoate, sodium decanoate, sodium dodecanoate or sodium dodecylsulfate mixed with NaCl in different relative ratios. Our model follows the experimental trends of increasing densities with increasing surfactant concentrations or increasing surfactant–salt mixing ratios both, below and above the CMC, capturing the effect of the inorganic salt on the surfactant micellization.

Non-Single Charge Ions Effect on Reverse Electrodialysis Technology for Salinity Gradient Power Generation

Salinity Gradient Power (SGP), also known as Blue Energy, is gaining attention in the recent years due to its global availability and renewable nature [1,2]. SGP is based on the physico-chemical potential existing when two water streams of different salinity are mixed. The most important and well-known technology to harvest the SGP energy is the Reverse Electrodialysis (RED), which converts the blue energy into electricity through ion exchange membranes (IEMs). Usually, seawater has been targeted as high concentrated solution and river water as low concentrated solution. Nevertheless, other water bodies are possible, for example, industrial brine solutions, groundwater or treated urban wastewater streams. The presence of the non-single charge ions presents in common water streams can affect power performance due to an increase in the internal resistance of the system [3,4], and thus their effects need to be thoroughly studied.This work aims to model the RED performance providing a robust and comprehensive mathematical tool to predict power output under real conditions. The model takes into account different variables (flowrate and temperature), the RED system characteristics (effective area, thickness of both membranes and spacers and number of cell pair) as well as different scenarios in term of streams composition. In this sense, the concentration of the main compounds presents in the typical water sources was studied achieving different correlations as function of the cationic or anionic type of membrane.For this purpose, electrochemical impedance spectroscopy (EIS) technique was employed to measure the resistance of IEMs in contact with NaCl solution including mixtures of non-single charge ions (Ca2+, Mg2+, SO4 2-) in order to find suitable mathematical correlations to be integrated into the mathematical model [1]. EIS measurements were performed by placing the membranes in a nylon cell system previously submerged in the different solutions for seven days to ensure impregnation.The results obtained were validated with different experimental conditions in terms of water composition. Theoretical and experimental results fit well with errors below 5%, showing that the presence of divalent ions has a negative effect on power performance due to the increase in membrane resistance in comparison to pure NaCl solutions. Nevertheless, the maximum decay in power output, for a wide range of real scenarios studied, was not higher than 16%, which can still be considered acceptable. Acknowledgements: The authors want to acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through the projects: CTQ2015-66078-R, and CTM2017-87850-R. This research is also being supported by the Project “HYLANTIC”-EAPA_204/2016, which is co-financed by the European Regional Development Fund in the framework of the Interreg Atlantic program.

Fabrication of superhydrophobic PDTS-ZnO-PVDF membrane and its anti-wetting analysis in direct contact membrane distillation (DCMD) applications

Membrane distillation (MD) is an emerging water treatment technology suitable for hypersaline wastewater. However, membrane wetting is a primary obstacle to restrict its widespread industrial use. In this study, a superhydrophobic nanofibrous membrane (labeled as FZP) with high water contact angle of 162.3° and sliding angle of 9.8° was fabricated through fluorinating of zinc oxide (ZnO) blended electrospun polyvinylidene fluoride (PVDF) membrane. In comparison with neat and ZnO blended PVDF (ZP) nanofibrous membranes, FZP membrane has much better anti-wetting property due to its superhydrophobicity and higher liquid entry pressure (LEP) value when desalinating both pure NaCl solution and NaCl solutions with low-surface-tension sodium dodecyl sulfate (SDS) and sparingly soluble salt CaSO4. LEP values of membranes for SDS and CaSO4 contained feed solutions were calculated to be smaller than that for pure NaCl solution, accelerating the occurrence of membrane wetting. Temperature gradient across the membrane and Gibbs free energies of CaSO4 heterogeneous nucleation were further calculated to elucidate the wetting mechanism. Our results provide valuable insights for better developing superhydrophobic membrane and understanding its anti-wetting property in MD process.

Enhancing Fe-C micro-electrolysis by coupling MF with electrolyte solution: Mechanism and application

In this study, Fe-C micro-electrolysis rate enhancement was accomplished by a coupled magnetic field (MF) and Electrolyte solution. The rate of micro-electrolysis of Fe-C materials in pure water solution, NaCl solution, NaH2PO4 solution and Al2(SO4)3 solution in the presence of MF was increased by 1.8–6.8 times, and the removal rate of saline organic wastewater was increased by 1.5–4.7 times. The results show that coupling MF with a electrolyte enhances the process of Fe-C micro-electrolysis, and indicates the possible reaction mechanism. SEM and XRD analysis showed that both the electrolyte solution and MF promoted the corrosion of Fe-C materials and accelerated the dissolution of Fe2+. The EDX-mapping results confirmed that MF promotes the accumulation of electrolyte ions on the surface of Fe-C materials. Electrochemical workstation testing showed that the promotion effect of MF in different solutions was different. In addition, MF also enhances the electrolyte activity, reduces the corrosion resistance of Fe-C materials, and improves the local current of Fe-C micro-electrolysis. Moreover, the MF/Fe-C/H2O2 process has good applicability in the treatment of mixed inorganic salt wastewater, and the treatment of saline organic wastewater is more economical and efficient.

Functions of MnOx in NaCl Aqueous Solution for Artificial Photosynthesis.

SummaryPhotoelectrochemical water splitting has been intensively investigated as artificial photosynthesis technology to convert solar energy into chemical energy. The use of seawater and salted water has advantages for minimum environmental burden; however, the oxidation of Cl− ion to hypochlorous acid (HClO), which has toxicity and heavy corrosiveness, should occur at the anode, along with the oxygen evolution. Here, O2 and HClO production in aqueous solution containing Cl− on photoanodes modified with various metal oxides was investigated. The modification of MnOx resulted in the promotion of the O2 evolution reaction (OER) specifically without HClO production over a wide range of conditions. The results will contribute not only to the practical application of artificial photosynthesis using salted water but also to the elucidation of substantial function of manganese as the element for OER center in natural photosynthesis.

Energy Harvesting from Brines by Reverse Electrodialysis Using Nafion Membranes.

Ion exchange membranes (IEMs) have consolidated applications in energy conversion and storage systems, like fuel cells and battery separators. Moreover, in the perspective to address the global need for non-carbon-based and renewable energies, salinity-gradient power (SGP) harvesting by reverse electrodialysis (RED) is attracting significant interest in recent years. In particular, brine solutions produced in desalination plants can be used as concentrated streams in a SGP-RED stack, providing a smart solution to the problem of brine disposal. Although Nafion is probably the most prominent commercial cation exchange membrane for electrochemical applications, no study has investigated yet its potential in RED. In this work, Nafion 117 and Nafion 115 membranes were tested for NaCl and NaCl + MgCl2 solutions, in order to measure the gross power density extracted under high salinity gradient and to evaluate the effect of Mg2+ (the most abundant divalent cation in natural feeds) on the efficiency in energy conversion. Moreover, performance of commercial CMX (Neosepta) and Fuji-CEM 80050 (Fujifilm) cation exchange membranes, already widely applied for RED applications, were used as a benchmark for Nafion membranes. In addition, complementary characterization (i.e., electrochemical impedance and membrane potential test) was carried out on the membranes with the aim to evaluate the predominance of electrochemical properties in different aqueous solutions. In all tests, Nafion 117 exhibited superior performance when 0.5/4.0 M NaCl fed through 500 µm-thick compartments at a linear velocity 1.5 cm·s−1. However, the gross power density of 1.38 W·m−2 detected in the case of pure NaCl solutions decreased to 1.08 W·m−2 in the presence of magnesium chloride. In particular, the presence of magnesium resulted in a drastic effect on the electrochemical properties of Fuji-CEM-80050, while the impact on other membranes investigated was less severe.

Tailoring electrolyte additives for controlled Mg-Ca anode activity in aqueous Mg-air batteries

Aqueous primary Mg-air batteries exhibit many merits as potential energy storage and conversion devices. In this work, the discharge performance of water based Mg-air batteries with advanced Mg-Ca anode was boosted by adding Mg2+ complexing agents into the electrolyte. The effect of electrolyte additives on the corrosion behavior and discharge properties of micro-alloyed Mg-Ca anode was investigated via hydrogen evolution test and half-cell discharge test. Electrochemical impedance spectroscopy (EIS) was performed to evaluate the effect of different electrolyte additives on the discharge activity of Mg-Ca anode. Basic characteristics of aqueous Mg-air battery in selected additive solution were tested and compared to pure NaCl solution. The results show that the addition of dedicated Mg2+ complexing agents can efficiently increase the discharge voltage and specific energy of respective Mg-air batteries. At 0.5 mA cm−2, the discharge voltage reaches 1.86 V with regard to the cell containing 0.1 M 5-Sulfosalicylate, which is 270 mV higher than the discharge voltage in bulk 3.5 wt % NaCl. The highest specific energy for the tested system is above 3.0 kWh kg−1 in NaCl solution with 0.1 M citrate at 1 mA cm−2 discharge current density.

EFFECT OF ANODE SHAPE AND ELECTROLYTE ON THE EFFICIENCY CHARACTERISTICS OF SACRIFICE ANODE IMMERSE METHOD WITH DNVGL-RPB401

Corrosion is a damage which occurs naturally. One method of corrosion prevention is cathodic protection using the sacrificial anoda. one standard commonly used in cathodic protection design is DnVGL-RPB401. In addition, DnVGLRPB401 method can be used to measure anoda current capacity. In this research, the variation of shape of the anode was the shape of a cylinder anode, beam and cone. The variation of electrolyte is pure NaCl solution, Kitchen Salt solution and Kenjeran sea water. In the electrolyte pure NaCl solution, each anode form has an efficiency of 86%, 83%, and 78% respectively. the cylindrical anode shape has the highest efficiency because the same distance between anode and cathode at the cylindrical anode.so that the current distribution is evenly distributed. Then in the form of cylindrical anodes, each electrolyte medium has an efficiency of 114%, 86% and 83% respectively. The salt solution has the highest efficiency because of the low content of NaCl which is the cause of corrosion and the presence of potassium Iodide which is a corrosion inhibitor.

Effects of salt concentration on the structure and properties of composite fiber of carboxymethyl cellulose/N-2-hydroxylpropyl trimethyl ammonium chloride chitosan prepared by polyelectoyte complexation-freeze drying

The conventional electrospinning process for the preparation of fibers usually require complex equipment and complicated preparation processes, as well as chemical crosslinkers and organic solvents, which limits its application in the preparation of biomedical materials. In the current study, carboxymethyl cellulose/N-2-hydroxylpropyl trimethyl ammonium chloride chitosan (CMC/HACC) composite fibers were fabricated by polyelectrolyte complexation (PEC) and freeze drying coupled method in both pure water and NaCl solution. The structures of the as-prepared fibers and the effects of NaCl concentration on the structures of fibers were studied by FTIR, solid 13C NMR, XRD, XPS and SEM. The formation mechanism of the composite fiber and the effects of NaCl concentration on structure and properties of the composite fiber were simulated in the Materials Studio software and discussed. The swelling properties and the thermal decomposition kinetics of the composite fiber were studied. The results suggest that the addition of NaCl electrolyte to the complexing system significantly affects the structure and properties of the PEC fiber. Our work has provided a new preparation route to the composite fibers of natural polymers with controllable structures and properties by the combination of PEC and freeze drying techniques using NaCl with desired concentration as the electrolyte.