Na2SO4 Solution Research Articles

Corrosion protection mechanism of Ce3+/polyethylene glycol systems inhibitors for mild steel in sulfate solution

AbstractIn the present paper, cerium nitrate salt was used as a green inhibitor to improve the corrosion resistance of mild steel in 0.1 M Na2SO4 solution. To increase the barrier effect and film stability of the protective layer, polyethylene glycol (PEG) was added. The corrosion tests were evaluated using d.c polarization techniques and electrochemical impedance spectroscopy. The composition and morphology of the sample surface were characterized using Raman spectroscopy and MEB/EDS analysis. The results show that the presence of PEG improved relatively the corrosion resistance of mild steel due to the removal of cracks, the pores blocking the formed film and the enhancement of adhesion and compactness of the cerium‐based film. Consequently, the protective film became more coherent on the steel surface. Furthermore, the potentiodynamic polarization indicated that the Ce3+/PEG system behaved as a mixed‐type inhibitor with the dominant effect of the cathodic part.

Electrochemical oxidation of carbamazepine in water using enhanced blue TiO2 nanotube arrays anode on porous titanium substrate

In this study, a blue TiO2 nanotube arrays anode on porous titanium substrate (Ti-porous/blue TiO2 NTA) was successfully fabricated by facile anodization and in situ reduction, and was used to investigate the electrochemical oxidation of carbamazepine (CBZ) in aqueous solution. The surface morphology and crystalline phase of the fabricated anode were characterized by SEM, XRD, Raman spectroscopy and XPS, and the electrochemical analysis confirmed that blue TiO2 NTA on Ti-porous substrate had larger electroactive surface area, better electrochemical performance and higher ⋅OH generation ability than that on Ti-plate substrate. The removal efficiency of 20 mg L−1 CBZ in 0.05 M Na2SO4 solution reached 99.75% at 8 mA cm−2 after 60 min electrochemical oxidation, and the rate constant was 0.101 min−1 with low energy consumption. EPR analysis and free radical sacrificing experiments showed that ⋅OH played a key role in the electrochemical oxidation. The possible oxidation pathways of CBZ were proposed through the identification of degradation products, and the main reactions may involve deamidization, oxidization, hydroxylation and ring-opening. Compared with Ti-plate/blue TiO2 NTA anode, Ti-porous/blue TiO2 NTA anode displayed excellent stability and reusability, and is promising to be used in the electrochemical oxidation of CBZ in wastewater.

Incorporation of Functionalized Halloysite Nanotubes (HNTs) into Thin-Film Nanocomposite (TFN) Nanofiltration Membranes for Water Softening

Incorporating nanoparticles (NPs) into the selective layer of thin-film composite (TFC) membranes is a common approach to improve the performance of the resulting thin-film nanocomposite (TFN) membranes. The main challenge in this approach is the leaching out of NPs during membrane operation. Halloysite nanotubes (HNTs) modified with the first generation of poly(amidoamine) (PAMAM) dendrimers (G1) have shown excellent stability in the PA layer of TFN reverse-osmosis (RO) membranes. This study explores, for the first time, using these NPs to improve the properties of TFN nanofiltration (NF) membranes. Membrane performance was evaluated in a cross-flow nanofiltration (NF) system using 3000 ppm aqueous solutions of MgCl2, Na2SO4 and NaCl, respectively, as feed at 10 bar and ambient temperature. All membranes showed high rejection of Na2SO4 (around 97-98%) and low NaCl rejection, with the corresponding water fluxes greater than 100 L m-2 h-1. The rejection of MgCl2 (ranging from 82 to 90%) was less than that for Na2SO4. However, our values are much greater than those reported in the literature for other TFN membranes. The remarkable rejection of MgCl2 is attributed to positively charged HNT-G1 nanoparticles incorporated in the selective polyamide (PA) layer of the TFN membranes.

Biogenic Synthesis of High-Performance α-MoO3 Nanoparticles from Tryptophan Derivatives for Antimicrobial Agents and Electrode Materials of Supercapacitors

Molybdenum trioxide nanoparticles (MoO3 NPs) are recognized for their applications in novel multifunctional devices. Here, a biogenic, environmentally friendly method using Lepidagathis cristata leaf extract was employed to synthesize MoO3 NPs. The as-obtained MoO3 NPs exhibited a predominant (0 k0) orientation, representing an α-MoO3 structure. The absorption band at 984 cm-1 observed in the Fourier-transform infrared spectrum corresponded to the terminal Mo = O bond, thereby confirming that the prepared MoO3 NPs were in the orthorhombic phase. Scanning and transmission electron microscopy data revealed that the MoO3 NPs were well crystallized and uniformly distributed with grain sizes in the 70-100 nm range. The biogenic MoO3 NPs demonstrated an excellent zone of inhibition against the selected Gram -ve and Gram +ve bacterial strains, thus providing an alternative to standard antibacterial agents. During electrochemical experiments conducted in a 1 M aqueous Na2SO4 solution, cyclic voltammetry (CV) curves of the MoO3 NPs showed a pseudocapacitive nature, with a high discharge specific capacitance of 294 F/g and good cyclability. These results suggest the feasibility of the proposed biogenic, environmentally friendly method for preparing MoO3 NPs for application in multifunctional devices.

Basal Plane-Activated Boron-Doped MoS2 Nanosheets for Efficient Electrochemical Ammonia Synthesis.

Under the dual pressure of energy crisis and environmental pollution, ammonia (NH3 ) is an indispensable chemical product in the global economy. The electrocatalytic synthesis of NH3 directly from nitrogen and water using renewable electricity has become one of the most attractive and important topics. Basal plane-activated boron-doped MoS2 nanosheets (B-MoS2 ) as a non-noble metal catalyst with excellent performance for N2 electroreduction are synthesized by a facile one-step hydrothermal method. In 0.1 m Na2 SO4 solution, MoS2 nanosheets doped with 300 mg boric acid (B-MoS2 -300) give rise to a good ammonia yield rate of 75.77 μg h-1 mg-1 cat. at -0.75 V vs. RHE, and an excellent Faradaic efficiency of 40.11 % at -0.60 V vs. RHE. In addition, the B-MoS2 -300 nanosheets show good selectivity and chemical stability, and no hydrazine (N2 H4 ) by-product is generated during the reaction. 15 N isotopic labeling confirms that nitrogen in produced ammonia originates from N2 in the electrolyte. On the one hand, the high conductivity of MoS2 guarantees guarantees a high electron transfer rate from nitrogen to ammonia; on the other hand, the successful incorporation of heteroatom B enlarges the interlayer spacing of MoS2 , and the B atom can act as an active site for basal plane activation, providing more active sites for the nitrogen reduction reaction (NRR). Density functional theory calculations show that the doping of B activates the base plane of 1T-MoS2 , which makes the adsorption of N2 on the base plane easier and promotes the NRR.

One-step electrodeposition to fabricate superhydrophobic surfaces on flexible conductive films: Optimization of metallic compounds

Superhydrophobic surfaces were fabricated by a simple one-step electrodeposition technique to deposit three distinct micro/nano hierarchical structures of Ce, Mg, or Cu-based compounds on Ag films on a flexible polymer substrate. Scanning electron microscopy was used to examine the surface morphologies of obtained structures with different deposition. Compared with the bare Ag films, one-step electrodeposition process resulted in superhydrophobicity, including a water contact angle of 159.7° for Ce-modified surfaces, 157.0° for Mg-modified surfaces, and 153.8° for Cu-modified surfaces. Besides, these surfaces showed high thermal stability below 120 ℃, and good flexibility but low electrical conductivity. EDS and XPS results suggest the production of low surface energy materials that formed the superhydrophobic features on the Ag films. Besides, because of the formation of CeO2, Ce-SHS had better superhydrophobicity than Mg-SHS and Cu-SHS. In addition, the potentiodynamic polarization experiments showed that the electrodeposited superhydrophobic surfaces had lower Icorr, higher Ecorr and impedance values in NaCl solution, Na2SO4 solution and Simulated body fluid, and artificial sweat solution compared with the bare silver film, indicating that the electrodeposited protective film has good anti-corrosion properties. These results suggest that the one-step electrodeposition method is a promising strategy to fabricate conducting films with superhydrophobic surfaces for surface protection under various corrosive environments.

Interfacially Engineered Nanoporous Cu/MnOx Hybrids for Highly Efficient Electrochemical Ammonia Synthesis via Nitrate Reduction.

Electrochemical reduction of nitrate to ammonia (NH3 ) not only offers a promising strategy for green NH3 synthesis, but also addresses the environmental issues and balances the perturbed nitrogen cycle. However, current electrocatalytic nitrate reduction processes are still inefficient due to the lack of effective electrocatalysts. Here 3D nanoporous Cu/MnOx hybrids are reported as efficient and durable electrocatalysts for nitrate reduction reaction, achieving the NH3 yield rates of 5.53 and 29.3mg h-1 mgcat. -1 with 98.2% and 86.2% Faradic efficiency in 0.1 m Na2 SO4 solution with 10 and 100mm KNO3 , respectively, which are higher than those obtained for most of the reported catalysts under similar conditions. Both the experimental results and density functional theory calculations reveal that the interface effect between Cu/MnOx interface could reduce the free energy of rate determining step and suppress the hydrogen evolution reaction, leading to the enhanced catalytic activity and selectivity. This work provides an approach to design advanced materials for NH3 production via electrochemical nitrate reduction.

Performance deterioration of asphalt mixture exposed to salt-water-temperature-ultraviolet coupling effect

ABSTRACT The intense ultraviolet radiation and large amount of saline-alkali soil in the Golmud region of Province, China, have deteriorated the performance of asphalt pavement. Given the effect of adverse conditions in this area, this paper investigated the collective and interaction effects of salt chemicals, air temperature, and ultraviolet radiation on asphalt and asphalt mixture through laboratory experiments under controlled conditions. In particular, using different concentrations of Na2SO4 and NaCl solutions, simulated salt chemicals for asphalt and asphalt mixture performance impact. The mechanism of performance deterioration of the asphalt mixture suffered from salt attack was explored. The results show that the original asphalt's storage and loss modulus are higher than the modified asphalt at different temperatures with the multi-factors effect. In addition, the modified asphalt's phase angle is 5%∼10% higher than the original asphalt below −2°C. At the same time, strength loss rates of asphalt mixture increase with the cycles and solution concentration, varying from 20%−40%. Wet-dry cycles and the concentration of salt solution are positively correlated with the deterioration of asphalt mixture strength. This research provides the durability prediction and the more reasonable composition design of the asphalt mixture applied in salt enrichment regions.

Corrosion Behavior of Magnesium Potassium Phosphate Cement under Wet-Dry Cycle and Sulfate Attack.

This paper investigated the influence of dry-wet cycles and sulfate attack on the performance of magnesium potassium phosphate cement (MKPC) as well as the effect of waterglass on MKPC. X-ray diffraction (XRD), TG-DTG, and scanning electron microscopy (SEM-EDS) were used to examine the phase composition and microstructure of MKPC. The results showed that the flexural and compressive strength of an MKPC paste increased initially and subsequently decreased in different erosion environments. The final strength of the M0 paste exposed to the SK-II environment was the highest, while that of the M0 paste exposed to the DW-II environment was the lowest. The final volume expansion value of MKPC specimens under four corrosion conditions decreased in the following order: DW-II, M0 > SK-II, M0 > DW-II, M1 > SK-I, M0 > DW-I, M0. Compared to the full-soaking environment, the dry-wet cycles accelerated sulfate erosion and the appearance of damages in the macro and micro structure of the MKPC paste. With the increase in the number of the dry and wet cycles, more intrinsic micro-cracks were observed, and the dissolution of hydration products was accelerated. Under the same number of dry-wet cycles, the strength test and volume stability test showed that the durability in a Na2SO4 solution of the MKPC paste prepared with 2% waterglass (M1) was superior to that of the original M0 cement. The micro analysis indicated that waterglass can improve the compactness of the microstructure of MPC and prevent the dissolution of struvite-K.

Thermodynamic and experimental study on chloride binding of limestone containing concrete in sulfate-chloride solution

Concrete's durability where sulfate and chloride ions coexist is a challenging issue. In addition, utilization of limestone powder (LS) in blended cements tended to result in physically and chemically different hydration processes compared with other cements. The present study aims to evaluate Cl− ingress into concrete samples containing LS in the presence of sulfates in exposure environment. In this regard, 3 different exposure conditions of 165 g/l NaCl, 27.5 g/l Na2SO4 + 165 g/l NaCl, and 55 g/l Na2SO4 + 165 g/l NaCl solutions have been designated. Compressive strength, capillary water absorption, surface electrical resistivity, and rapid chloride ions migration tests have been carried out and the total and water-soluble Cl− penetration profiles were determined. Besides these experimental studies, thermodynamic modelling was conducted to simulate the phase assemblage of samples before and after exposure to NaCl and Na2SO4 solutions. According to the results, using LS in concretes is followed by an increase in permeability and a decrease in compressive strength, which agree well with the outcomes of thermodynamic modelling. In the case of single Cl− attack, adding LS results in up to 60.7% and 36.0% increase in apparent and non-steady state Cl− diffusion coefficients, respectively. In addition, both thermodynamic modelling and experimental studies show that the presence of sulfate ions decreases the chemical Cl− binding ability of binders, and the Cl− diffusion coefficient of samples exposed to the combined condition increases. However, by increasing the sulfate ions concentration, the Cl− ingress may be retarded.

Experimental study on barrier performance and durability under dry-wet cycles of fly ash based geopolymer cutoff wall backfill

Vertical cutoff wall is one of the most effective technologies to restrict the migration of contaminants. In this study, a geopolymer cutoff wall backfill (GCWB) consisting of reactive sodium silicate, fly ash, sand, and water was developed, which does not need Ordinary Portland Cement (OPC) and bentonite. The basic macroscopic properties of GCWB were tested, in terms of workability, unconfined compressive strength, hydraulic conductivity, and chemical compatibility, then the optimal material ratio was determined. In order to evaluate the barrier performance of GCWB under dry-wet cycles, the hydration products and microstructural characteristics were measured by X-ray Diffraction (XRD), Mercury Intrusion Porosimetry (MIP), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). According to the orthogonal analysis, the optimal material ratio with the highest unconfined compressive strength was 30FA1.2M12S and that with the lowest hydraulic conductivity was 40FA1.2M12S. The unconfined compressive strength and hydraulic conductivity of GCWB can achieve 6.62 MPa and 4.83 × 10−11 m/s after cured for 28 days, respectively. The chemical compatibility of GCWB was overall favorable in Na2SO4 and CaCl2 solutions. Under the effect of dry-wet cycles, the variation of hydraulic conductivity, mass and volume in contaminant solutions were basically the same as that in water. The hydraulic conductivity increased sharply by two orders of magnitude after the 1st dry-wet cycle and tended to be stable (slightly larger than 1 × 10−8 m/s) in the subsequent dry-wet cycles. Therefore, the barrier performance and durability of GCWB was desirable in water and contaminant solutions, indicating that it is a promising antifouling cutoff wall material.

Corrosion resistance of magnesium phosphate cement under long-term immersion in different solutions

Magnesium phosphate cement (MPC) is widely utilised in engineering. However, it may be subject to corrosion in the Western Chinese saline soil environment. This study analysed the factors of magnesium phosphorus ratio, borax content, water binder ratio and fly ash content. Mix proportions of MPC were devised through orthogonal testing. The corrosion performance of MPC specimens in water, 5% Na2SO4 solution, 5% NaCl solution and saline soil solution were analysed in terms of mass loss and the strength anti-corrosion coefficient. The corrosion mechanisms of MPC in different solutions were analysed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric and differential scanning calorimetry (TG-DSC) and Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). There were no obvious changes in MPC appearance or morphology after soaking in different solutions for 180 days. The mass loss was < 5% and the strength loss was < 25%, indicating that MPC has good resistance to saline soil and other saline solutions. The strength anti-corrosion coefficients of MPC soaked in various solutions for 180 days were > 0.75, and the influences on strength can be ranked as follows: 5% Na2SO4 solution > saline soil solution > water > 5% NaCl solution. On the basis of TG-DSC, FTIR and XRD analyses, when MPC was soaked in different solutions for 180 d, the contents of the hydration product MgKPO4·6H2O (MKP) were ranked as water > 5% NaCl solution > saline soil solution > 5% Na2SO4 solution. SEM-EDS analysis shows that MKP was corroded to varying degrees after the MPC was soaked in different solutions, with the 5% Na2SO4 solution causing the greatest corrosion.

The Preparation and Modification of Strontium Titanate Ceramic Films for High‐Performance Flexible Supercapacitor

AbstractBased on previous research, the perovskite‐type SrTiO3 can be considered as a potential energy storage material because of its good electrical conductivity properties and oxygen‐vacancy structure. In this work, Ce‐doped SrTiO3 nanofibers film with excellent flexibility was successfully fabricated by using electrospinning and conventional sintering route at 600 °C. For the series of the SrCexTi1‐xO3 (SCTO‐x) films (0≤x≤0.5), although the corresponding nanofibers structure could remain intact, their lattice structure transferred from cubic into tetragonal phase with the increase of Ce doing amount. Moreover, the electrochemical measurement results shown that the working electrode fabricated by SCTO‐0.3 sample as active materials exhibited the best electrochemical performance possessing with a maximum specific capacitance value of 2895 mF ⋅ cm−2 at 3 mA ⋅ cm−2 (1809.4F ⋅ g−1 at 1.875 A ⋅ g−1).Therefore, a symmetrical flexible device was assembled by two SCTO‐0.3 electrodes with 1 M Na2SO4 solution, showing a good energy density of 89.5 Wh ⋅ kg−1 (at power density of 1250 W ⋅ kg−1). However, while the super‐concentrated electrolyte (1 M Na2SO4+66.7 wt % sucrose) was instead of the 1 M Na2SO4 solution in the fabrication of the device, it could display higher energy density (151 Wh ⋅ kg−1 vs. 1600 W ⋅ kg−1), good cycling stability and better mechanical flexibility. Herein, this work may provide a new potential electrode material for flexible energy storage device design.

Continuous H2O2 production sustained by anodic O2 for the destruction of the antibiotic ampicillin by photoelectro-Fenton process in a rotating cylinder electrode reactor

In this work, the experimental characterization of a rotating cylinder electrode (RCE) reactor employed for the complete degradation of the antibiotic ampicillin (AMP) by photoelectro-Fenton (PEF) process has been addressed for the first time. Once produced from water oxidation at six Ti|IrO2 anodic plates, O2 was quickly transported by forced convection toward the central RCE, which consisted of a 316 stainless-steel cylinder covered with a (C-PTFE)-coated carbon cloth, thus ensuring the continuous production of H2O2 from the two-electron O2 reduction reaction (ORR). The accumulated H2O2 reached a concentration of 83.3 mg L−1 H2O2 after 60 min in a 50 mM Na2SO4 solution at pH 3, operating at an RCE peripheral velocity U = 79.6 cm s−1 and fixed cathodic potential of Ecath = −0.45 V vs. SHE. Furthermore, the optimum PEF conditions led to the complete destruction of 10 mg L−1 AMP in only 10 min upon addition of 0.4 mM Fe2+ as catalyst under UVA light irradiation, with a low electrolytic energy consumption of 0.211 kWh (g TOC)−1. In addition, the evolution of final carboxylic acids and inorganic ions over the electrolysis time was monitored by chromatographic and spectrophotometric techniques. PEF treatment clearly outperformed the anodic oxidation with (AO-H2O2) and the electro-Fenton (EF) processes, which opens the door to a sustainable and powerful electrochemical technology with no need for an air compressor for H2O2 production and viable under limitless sunlight irradiation.

Kinetics behavior of delayed ettringite in limestone calcined clay cement (LC3) by thermodynamic approach and consideration of the time factor

In this study, a thermodynamic and kinetics simulation is used to extract the kinetics diagrams of ettringite (as the main product of sulfate attack) to predict the kinetics behavior of limestone calcined clay cement (LC3) with various cement replacement percentages and the ratio of calcined clay to cement replacement (CC/CC + L) during exposing to a 30 g/l Na2so4 solution. The simulation results are compared with experimental and modeling results to the confirmation of present model's accuracy. The comparison of results shows suitable conformity. Kinetics has to be taken into account in addition to thermodynamics in order to evaluate the performance of LC3 cement in a sulfate-rich environment. Analyzing kinetics diagrams shows that a high CC/CC + L ratio leads to a reduction of ettringite formation during sulfate attack, however, CC/CC + L of 0.6 could be considered as the optimal ratio because of better kinetics performance. Also, three kinetics level for ettringite formation is introduced in this study. Increasing two parameters, cement replacement percentage and CC/CC + L ratio, cause the reduction of ettringite formation and also affects the ettringite production rate during the sulfate attack. In LC3 cement, ettringite formation is controlled kinetically in the first level and so, the exertion of initial sudden stress due to the fast formation of ettringite doesn't happen.

The effectiveness of graphene oxide added in activated carbon for superior supercapacitor performance

Background: Graphene oxide (GO) added to activated carbon electrodes is investigated for the supercapacitor performance. It is well known that GO possesses both low electrical conductivity and surface area but functional groups containing oxygen which assist in attracting cation for improving ion movement.Methods: GO is synthesized via the modified Hummers’ method and added to the activated carbon slurry for preparing the electrode of supercapacitors. The supercapacitor is assembled with symmetric carbon electrodes and hydrogel electrolytes for the electrochemical test.Significant Findings: The Raman spectroscopy analyzes the interface between 1 M Na2SO4 solution and the electrodes with various GO content and indicates the ratio of free ion increases with increasing GO content. The conductivities of electrodes by the 4-point probes method decrease with increasing GO content. A compromise between the free ion ratio and conductivity is obtained with 5 wt% GO in electrode (GO5) in accordance with the minimum equivalent series resistance (ESR) from Nyquist plot. The supercapacitor with GO5 possesses the maximum specific capacitance of 117.7 F g−1 in galvanostatic charge/discharge. SC-GO5 shows a large energy density of 15.6 Wh kg−1 at a high power density of 4.1 kW kg−1.

Highly permeable and stable hyperbranched polyethyleneimine crosslinked AgNP@Ti3C2Tx MXene membranes for nanofiltration

Two-dimensional (2D) materials have proved their superiorities as building blocks for constructing high-performance nanofiltration (NF) membranes. Herein, we propose a novel MXene-based NF membrane with high water permeability and stability by intercalating Ag nanoparticles (AgNPs) into the laminar structure of Ti3C2Tx MXene with hyperbranched polyethyleneimine (HPEI) crosslinking. The pure Ti3C2Tx MXene membrane, the AgNP-intercalated Ti3C2Tx MXene (AgNP@Ti3C2Tx MXene) membrane and the AgNP@Ti3C2Tx MXene membrane with HPEI crosslinking (HPEI-AgNP@Ti3C2Tx MXene) were comparatively investigated regarding their physicochemical properties and NF performance. The prepared HPEI-AgNP@Ti3C2Tx MXene membrane exhibited competitive water permeabilities (24.64–30.73 L·m−2·h−1·bar−1) and nearly 100% rejections for Congo red, methyl orange, methyl blue and Rhodamine B solutions for long-term operation. Moreover, the HPEI-AgNP@Ti3C2Tx MXene membrane also showed excellent NF performance for MgSO4, MgCl2, Na2SO4 and NaCl solutions with the rejections of 84.15%, 77.01%, 74.67% and 56.58%, respectively. The NF separation mechanisms for the HPEI-AgNP@Ti3C2Tx MXene membrane were elucidated based on its unique physicochemical structure. These findings may offer novel insights into tuning the laminar structures of MXene-based NF membranes for enhanced water purification.

2D porous carbon nanosheets derived from turnip: Preparation, characterization and its electrochemical performance

Biomass-based porous carbon materials have appeal due to their low cost, abundance and sustainability. In this report, a novel kind of heteroatom (N, S) co-doped 2D porous activated carbon using turnip as biomass has been prepared with subsequent non-toxic dual activators. At optimized activation temperature, the activated carbon from turnip-derived using KCl/NaCl (ACTKNa) as activators shows excellent surface area of 1938 m2·g−1 with micro-mesopores distributions. Importantly, ACTKNa as electrode materials for supercapacitors exhibits a superb capacitance value of 570 F·g−1 (0.5 A·g−1) and retains high stability. Interestingly, a symmetric ACTKNa//ACTKNa device can work in the potential window (0–1.5 V) under neutral Na2SO4 solution. Among them, the symmetric device delivers specific energy value 47.5 Wh·kg−1 at specific power of 372 W·kg−1 with outstanding rate capability of 86 % after 20,000 cycles. This work opens the way to enhance the specific energy value by increasing the potential window using neutral electrolyte.

Experimental investigation of simultaneous hydrogen production and desalination via electrodialysis process

The primary purpose of the electrodialysis (ED) process is to desalinate saline water; besides this, hydrogen, a valuable energy carrier gas, is generated at the cathode side of the ED cell in this study. However, hydrogen gas reacts with oxygen gas and reforms water due to the internal recirculation of the electrolyte solution from the anode to the cathode compartment. This study investigates the potential of hydrogen gas generation in an ED system that desalinates sodium sulfate (Na2SO4) solution. The maximum conductivity removal ratio is 98.1% when ion-exchange resins are placed into the diluate compartment at pH 8, and the ED system's hydrogen production rate is 76.8 mg H2/h·kg Na2SO4. The maximum hydrogen production rate is achieved as 118.8 mg H2/h·kg Na2SO4 solution under 14.06 mA/cm2 current density. The maximum energy and exergy efficiencies are calculated as 25.29% and 28.78%, respectively. The results indicate that the conventional ED process makes hydrogen production possible while desalinating saline water.

Selective corrosion of β-Sn and intermetallic compounds in an Ag–Sn alloy at different potentials in NaCl and Na2SO4 solutions

The corrosion behavior of β-Sn and intermetallic compounds in Ag–28Sn alloy was investigated by potentiodynamic polarization and bipolar electrochemistry tests. The potential distribution along the bipolar electrode was measured. The results show that the potential distribution is linear along the center of the bipolar electrode. In the Na2SO4 solution Ag4Sn intermetallic compounds preferentially corrode at high potential and β-Sn at low potential; in the NaCl solution, β-Sn preferentially corrodes at both high and low potential. Based on the potential–pH diagram, the selective corrosion mechanism of the Ag–Sn alloy is elucidated.