Diffusion Of Cl Research Articles

A Comprehensive Evaluation of Electrochemical Performance of Aluminum Hybrid Nanocomposites Reinforced with Alumina (Al2O3) and Graphene Oxide (GO)

The electrochemical performance of in-house developed, spark plasma-sintered, Aluminum metal–matrix composites (MMCs) was evaluated using different electrochemical techniques. X-ray diffraction (XRD) and Raman spectra were used to characterize the nanocomposites along with FE-SEM and EDS for morphological, structural, and elemental analysis, respectively. The highest charge transfer resistance (Rct), lowest corrosion current density, lowest electrochemical potential noise (EPN), and electrochemical current noise (ECN) were observed for GO-reinforced Al-MMC. The addition of honeycomb-like structure in the Al matrix assisted in blocking the diffusion of Cl− or SO4−2. However, poor wettability in between Al matrix and Al2O3 reinforcement resulted in the formation of porous interface regions, leading to a degradation in the corrosion resistance of the composite. Post-corrosion surface analysis by optical profilometer indicated that, unlike its counterparts, the lowest surface roughness (Ra) was provided by GO-reinforced MMC.

Development of a ReaxFF Reactive Force Field for Pt/Cl Systems with Application to Platinum Metal Etching with Chlorine and Hydrogen Chloride Gases.

In this study, we present the development of a ReaxFF Pt/Cl/H reactive force field designed to elucidate the etching process by Cl for Pt surfaces. The ReaxFF force field parameters were optimized based on a quantum mechanical training set, which included adsorption energies of Cl and dissociation of HCl on Pt(100) and Pt(111) surfaces, energy/volume relations of PtCl2 crystals, and Cl diffusion on Pt(100) and Pt(111) surfaces. The predictive capability of the force field was further established through molecular dynamics simulations, which investigated the interactions of Cl2 and HCl molecules with the (100) and (111) surfaces of c-Pt crystalline solid slabs. A comparative analysis revealed that the Pt (100) surface exhibited higher susceptibility to chlorination and etching, leading to a more dominant removal of surface Pt atoms, whereas the Pt (111) surface showed greater resistance to these processes. This resistance impeded the access of Cl atoms to the Pt surface, resulting in a slower formation of PtxCly molecules. The etching ratios between HCl and Cl2 were compared with experimental results, yielding satisfactory agreement. This indicates that the developed ReaxFF protocol serves as a valuable tool for studying atomistic-scale details of the etching process in platinum metal systems.

Tailoring anionic solar evaporator with an enhanced Donnan effect for a highly effective salt resistance desalination and water purification

Emerging solar-driven interfacial water evaporation demonstrates immense potential in mitigating worldwide water shortages, offering exceptional solar-to-vapor conversion efficiency, off-grid operability, zero liquid discharge capability and low carbon footprint. A critical requirement for sustainable extraction clean water from brine is the development of solar evaporators with both salt resistance and high evaporation rates. In response to this demand, this research proposed an enhanced Donnan effect anionic solar evaporator through filling wood in situ with PVA/PAA hydrogel. The resulting anionic solar evaporator demonstrated broadband spectral absorption, excellent photothermal conversion, and water activation capability. Notably, based on the negative charge property of the –COO– group anionic hydrogel, it could enhance Donnan effect and restrict the diffusion of Cl− to the evaporator, ensure enduring salt resistance and stability in purifying brine effectively. Experiments proved that the anionic anionic solar evaporator attained a remarkable water evaporation rate of 2.439 kg m−2 h−1 during a desalination of 15 wt% NaCl solution under 1 kW m−2 solar radiation, and no obvious salt accumulation had been observed during prolonged evaporation processes. With high efficiency, renewability, deployability, low cost, and durability, the anionic solar evaporator emerges as a promising solution for mitigating water scarcity, especially in economically challenged regions and provides valuable perspectives for future investigations into the water-energy-climate nexus.

Quaternary nitrate and chloride molten salts for the next concentrating solar power plants: Corrosion considerations for the use of AISI 304L steel

The study addresses the advancement in concentrating solar power (CSP) plants by transitioning from binary nitrate salts to nitrate and chloride quaternary salts, focusing on the corrosivity of four salts as evaluated by immersion testing of AISI 304L stainless steel. Four compositions of salts were evaluated, from solar salt to equimolar NaNO3‐KNO3‐NaCl‐KCl, up to 21 days (500 h) at 500 °C in an open atmosphere, determining the corrosion kinetics using gravimetry. The morphology, chemical composition, and microstructure of the corrosion products were characterized using XRD, FESEM-EDS, and GD-OES. Exposure to the molten salt with 0 mol% Cl‐ (Solar Salt) resulted in negligible corrosion kinetics, consistent with previous studies. The salt with 14 mol% Cl‐ caused a stable corrosion product with a corrosion rate 30 times higher than without chloride. All quaternary salts exhibited a multilayer structure of the top surface with selective chromium (Cr) removal. Specimens exposed to salts with more than 29 mol% Cl‐ displayed a similar structure with Cr and iron (Fe) removal, resulting in more brittle layers and corrosion rates 90 to 250 times higher than the salt without chloride. GD-OES analysis confirmed Cl diffusion into the oxide layer, highlighting the role of pCl2(g) and pO2(g) in driving corrosivity. Based on the results, using in salts with 29 mol% Cl‐ at 500 °C is discouraged, while using 304L with 14 mol% Cl‐ in a cold tank may be considered.

PbS quantum dot thin film dry etching

Many consumer products used daily contain sensors and image sensors (smartphones, cars, automated tools, etc.). There is a growing demand to enhance the capabilities of industrial products to probe their environment more efficiently, i.e., under difficult conditions (smoke, darkness, etc.). One solution is to extend the capabilities of image sensors to detect light toward the near-infrared and short-wave infrared (SWIR) regions. Because silicon has weak absorption properties in the infrared, especially in the SWIR region, manufacturers are investigating the use of new materials to build these sensors. To this end, colloidal quantum dot (QD) thin films made from the assembly of PbS nanoparticles have emerged as promising materials. They offer tunable bandgaps, favorable absorption properties, and scalability in production. However, patterning the active parts of photodiodes by plasma etching of this new material presents challenges. The etching chemistry must be selected to volatilize Pb and S without modifying the unetched active part of the PbS QD photodiode, and the etching profile should be anisotropic. In this study, we have screened several plasma operating conditions (power, pressure, and temperature) in various chemistries (H2, Cl2, HBr, and N2). To understand the etch mechanisms and profiles, ToF-SIMS and TEM/energy dispersive x-ray were employed. Our findings reveal that halogen-based plasmas cause QD material deterioration through Cl or Br diffusion deep in the film. While H2 plasmas are efficient to etch PbS QD films, they result in high roughness due to the removal of the carbonated ligands that separate PbS QDs. This ligand etching is followed by QD coalescence leading to significant roughness. However, the addition of N2 to H2 can prevent this phenomenon by forming a diffusion barrier at the surface, resulting in favorable etching characteristics.

Nanofluid-Guided Janus Membrane for High-Efficiency Electricity Generation from Water Evaporation.

Harvesting electricity from widespread water evaporation provides an alternative route to cleaner power generation technology. However, current evaporation power generation (EPG) mainly depends on the dissociation process of certain functional groups (e.g., SO3 H) in water, which suffers from low power density and short-term output. Herein, the Janus membrane is prepared by combining nanofluid and water-grabbing material for EPG, where the nanoconfined ionic liquids (NCILs) serve as ion sources instead of the functional groups. Benefiting from the selective and fast transport of anions in NCILs, such EPG demonstrates excellent power performance with a voltage of 0.63V, a short-circuit current of 140µA, and a maximum power density of 16.55 µW cm-2 while operating for at least 180 h consistently. Molecular dynamics (MD) simulation and surface potential analysis reveal the molecular mechanism, that is, the diffusion of Cl- anions during evaporation is much faster than that of cations, generating the voltage and current across the membrane. Furthermore, the device performs well in varying environmental conditions, including different water temperatures and sources of evaporating water, showcasing its adaptability and integrability. Overall, the nanofluid-guided Janus membrane can efficiently transform low-grade thermal energy in evaporation into electricity, showing a competitive advantage over other sustainable applied approaches.

Enhanced performance CdZnTe single crystal with few surface damages via solution based annealing

In this study, heat treatments were employed using a CdCl2 solution as the annealing medium to investigate the evolution of internal defects and photoelectric properties of CdZnTe crystals. It was observed that CdCl2 crystals formed on the surface of the annealed crystals, and their size increased exponentially with prolonged annealing time. It could be a medium for Cl transport. The liquid-phase annealing process was found to be gentle, resulting in minimal damage and the absence of large defects migrating or accumulating dislocations and less nano-defects on the crystal surface than sample annealed in vapor condition. After a 30 hour annealing, the infrared (IR) transmittance reached 55%, and the resistivity increased to 1.36×1010 Ω·cm. The presence of Cd2+ facilitated the filling of Cd vacancies (VCd) defects through diffusion reduction, while the diffusion of Cl- introduced complex defect with extra VCd, causing the Fermi level to approach the center of the band gap. Consequently, a high-resistance CdZnTe material was achieved.

Dramatic Reduction of Silicon Surface Recombination by ALD TiOx Capping Layer from TiCl4 and H2O: The Role of Chlorine.

Amorphous thin-film TiOx prepared via atomic layer deposition (ALD) has been identified as one of the most promising materials for use in transparent passivating contacts in high-efficiency and low-cost crystalline silicon (c-Si) solar cells. As highlighted in this work, the passivation performance of ALD TiOx layers strongly depends on the metal precursor used, with films prepared using TiCl4 recently showing the best results. However, a full understanding of how such films achieve their high level of surface passivation has not yet been demonstrated. This study provides a clear demonstration that a key part of this passivation mechanism is due to chlorine (Cl) accumulation at the Si surface. This mechanism is demonstrated to be quite general in nature by showing how 2 nm of ALD TiOx (TiCl4 + H2O) can be applied as a capping layer for either ZnO or Al2O3 interlayers to dramatically reduce silicon surface recombination. Cl depth profiles obtained using secondary ion mass spectrometry confirm the presence of Cl extending through the depth of the interlayers with a peak at the silicon interface. Remarkably, this diffusion of Cl is observed following low-temperature (75 °C) deposition of the TiOx capping layer, without any subsequent thermal treatment. Contrary to earlier studies that treated residual Cl in ALD films as a general contamination issue, these findings reveal unequivocally that chlorine plays a crucial role in Si surface passivation and can be classed as an effective passivation element, similar to hydrogen in its ability to passivate Si dangling bonds. The outcomes of this research emphasize the importance of residual chlorine in enhancing the passivation of buried interfaces and provide additional motivation for employing metal chloride precursors for silicon surface passivation applications.

Relevance of diffuse-layer, Stern-layer and interlayers for diffusion in clays: A new model and its application to Na, Sr, and Cs data in bentonite

The diffusive flux of cations is enhanced and that of anions is decreased compared to that of water tracers in bentonite or other clays, as a result of electrostatic interactions between ions and the charged clay surfaces. Clays are often used or foreseen as barriers in waste disposal in order to protect the environment from hazardous materials. A consistent description of diffusion of various ions and uncharged species is important in this context, especially if long-term interactions between clays and other materials shall be predicted by reactive transport simulations. Here, diffusion of a suite of tracers (HTO, Cl, Na, Sr and Cs) in bentonite was investigated. Experimental through-diffusion data at different bentonite dry densities were described with models of increasing complexity. First, ‘standard’ empirical single ion transport models (uncoupled, simple Fickian diffusion) were applied for each density. These models served as reference cases for comparisons. For sorbing tracers (Na, Sr, Cs), surface diffusion models were used in a next step, where average surface mobilities for the cations were determined based on comparisons with transport parameters from HTO diffusion. Finally, a more complex model was developed in order to describe anion and cation diffusion in a coupled way. This model accounts for locally parallel diffusion in different environments, namely in ‘free’ water unaffected by surface charges, in diffuse (Donnan) layer water, within the Stern layer, and within interlayer water (D-S-I model). This coupled model requires additional parameters related to the bentonite microstructure as well as to cation mobilities in the Stern layer and in the interlayer. The latter were taken from literature. Microstructural parameters were constrained in a manner that overall anion exclusion matches anion accessible porosities found by the simple Fickian diffusion model. This was possible with a reasonable choice of microstructure parameters that are consistent with literature values. A good agreement between the experimental data and the simulated cation diffusion coefficients of the D-S-I model was found, using constraints by the HTO and Cl diffusion data. The interlayer pathway was found to be most important for diffusion of Na, Sr and Cs through bentonite. Stern layer diffusion was significant and more important than diffusion through the diffuse layer for Cs and Sr, while for Na the two pathways were of equal importance.

Corrosion characteristics of Inconel 625 cladding layer and NiCrMoAl cladding layer in molten NaCl-KCl and NaCl-KCl-Na2SO4

The high-temperature corrosion characteristics of Inconel 625 and NiCrMoAl cladding layers were investigated in molten NaCl-KCl and NaCl-KCl-K2SO4. In NaCl-KCl, the corrosion was dominated by “electrochemical” mechanism, subsequently triggering “chlorine-active corrosion” mechanism. NiCrMoAl cladding layer provided significantly higher corrosion resistance than Inconel 625 cladding layer, due to the generated greatly Al2O3 enhanced the difficulty of inward diffusion of Cl-. In NaCl-KCl-K2SO4, protective Al2O3 and Cr2O3 faced “basic fluxing” mechanism, considerably aggravating the corrosion. Additionally, Al easily reacted with SO42-, which further consumed Al and generated free S, causing NiCrMoAl cladding layer to suffer serious corrosion than Inconel 625 cladding layer.

Impact of temperature, pH value and multiple ions on the physisorption of chloride ion on C-S-H gel surface

Calcium silicate hydrate (C-S-H) gel, as the main hydration phase of cement, intensely influences the penetration and diffusion of chloride ions (Cl-) by interacting with multiple ions in diverse environments, affecting the durability of reinforced concrete. However, the adsorption mechanism and critical influence factor are indistinct. To reveal the micro/nano mechanism of the adsorption characteristics for Cl-, a comprehensive investigation was conducted, which included ion adsorption experiments, thermodynamic calculations, and molecular dynamic simulations. In contrast to the prevailing opinion that Ca2+ is a potential determining ion in cement paste systems. The results indicate that pH value and concentration of Ca2+ are the partner to determine the Cl- adsorption capacity and potential reversal of C-S-H gels. They are unable to function in isolation from each other. It should be mentioned that OH− is more important than Ca2+ for ions adsorption of C-S-H gels. Compared with Ca2+, the compensation of Na+ on the surface charge and the promotion of Cl- adsorption is limited. SO42- competes for adsorption sites with Cl-, and forms Na-SO4 clusters to inhibit the diffusion and adsorption of Cl-. Furthermore, elevated temperature not only promotes the thermal movement of ions but also decreases the Ca2+ concentration and pH value. Consequently, the activity of SiOH sites is lessened, and ions are subjected to weaker constraints by the gel, resulting in the decline of Cl- adsorption capacity. Moreover, theoretical models for calculating the amount of chloride adsorbed by the C-S-H gels are proposed from the perspectives of thermodynamics and dynamics, and the simulation results are in agreement with the experiment results.

Study on diffusion and migration characteristics of impurities in secondary side of simplified u-tube steam generator

During the operation of nuclear power systems, the occurrence of leakage accidents of primary and secondary condensers are a major concern due to the potential threat to safe operation. The entry of seawater into the secondary loop from the condenser, along with impurities such as Cl-, can accumulate near the heat transfer tube, causing wear and corrosion, which can further aggravate the situation. Therefore, it is essential to accurately understand the migration and diffusion process of impurities in the secondary side of the steam generator. This study aims to investigate the three-dimensional multi-tube physical model of fluid–structure coupling heat transfer in the primary and secondary loops of the steam generator, including the heat exchange tube, to gain insights into the migration and diffusion of Cl- and other impurities. The distribution of important thermal parameters, such as volume vapor fraction, temperature, and velocity, in a U-shaped tube bundle were analyzed by numerical simulation of heat transfer and fluid flow. The diffusion and migration of Cl- in a two-phase flow were also studied. Results of this study reveal that impurities concentration is influenced by the effective diffusion coefficient, which is further influenced by the boiling intensity and flow velocity of the coolant. The combined effect of the boiling intensity and flow velocity of the coolant has a synergistic effect on the migration and diffusion of Cl-. In conclusion, this study provides valuable insights into the flow heat transfer impurity migration under a multi-tube coupled heat transfer condition of the steam generator, which can be used as a scientific basis for the design optimization and operation of steam generators.

Physicochemical Analysis of Chloride Diffusion and Adsorption in Water-saturated Concrete: Theory and Measurement

The theory of ionic diffusion in water-saturated concrete accompanying ion exchange with mobile or immobile adsorbed ions was constructed by using the general theory of diffusion and the condition of electrical neutrality. Analysis of the diffusion profile of chloride (Cl−) ions in concrete with the theory revealed that adsorbed Cl− ions in AFm and C-S-H are as mobile as free Cl− ions in the pore solution, so that the adsorption does not retard the ingress of Cl− ions. The existing test methods for determining the effective or apparent diffusion coefficient of Cl− ions were evaluated on the bases of the present theory and new experimental findings. It was revealed that steady-state electrochemical methods such as NTBUILD-355 and ASTM C1202 are not suitable for determining the diffusion coefficient, because the steady state methods expel preexisting diffusible ions which strongly affect the diffusion of Cl− ions. Moreover, the steady state methods overestimate the diffusion rate because the methods assume that adsorbed Cl− ions are immobile. The electrochemically-accelerated method NT BUILD 443 is also unsuitable for the diffusion test, because the acceleration is induced by the electro-osmotic flow of the external solution into concrete. The present diffusion theory necessitates the effective self-diffusion coefficient of not only Cl− ions but also all the other diffusible ions in concrete. A simple method of determining the effective self-diffusion coefficients of arbitrary ions in concrete from the diffusion profile of Cl− ions was presented.

Effect of oxygen doping on the corrosion behavior of nanocrystalline coating under the synergy of solid NaCl deposit and water vapor

Nanocrystalline coating with the same chemical composition as the nickel-based superalloys was proved to possess high resistance to oxidation and scale spallation, meanwhile avoid notable elements interdiffusion. It opens up a new direction for the development of protective coatings. However, in a worse environment containing chlorine and water vapor, the ultrafine grains act like a double-edged sword, which can promote the formation of a protective scale of Al2O3 or Cr2O3, but also favor the inward diffusion of Cl and H2O to accelerate corrosion. In order to solve this problem, moderate amount of oxygen was doped into nanocrystalline coating during magnetron sputtering. Then, corrosion behavior of the two nanocrystalline coatings with or without oxygen doping was studied in the O2 + 38% H2O environment with solid NaCl deposit. Results indicated that the doped oxygen can attract active elements of Ti and Al to form TiO2 and θ-Al2O3, which pinned at grain boundaries to keep the ultrafine grains stable at high temperature while prevent inward diffusion of the corrosive media. Accordingly, a dense and pure chromia scale was formed quickly at surface, ensuring that the oxygen-doped nanocrystalline coating provided the highest corrosion resistance under the synergy of solid NaCl deposit and water vapor. In contrast, the coating without oxygen doping suffered from severe internal corrosion.

First‐Principles Molecular Dynamics Study on Ionic Structure and Transport Properties of NaCl‐MgCl2‐CaCl2 Ternary Molten Salt System

AbstractThe carbochlorination in molten salt is an effective method for titanium extraction form low‐grade titanium slag with a high calcium and magnesium content. However, in industrial practice, the fluidity of molten salt will gradually decrease with the increase of CaCl2 content. It is important to elucidate the influencing mechanism of CaCl2 content on the microstructure and diffusion properties of molten salt for the rational selection of a molten salt system and clean utilization of titanium slag. In this study, the densities of molten salt systems with different CaCl2 contents are measured according to the Archimedes principle. Then, using the first‐principles molecular dynamics (FPMD) method, the ionic structure and transport properties of NaCl‐MgCl2‐CaCl2 ternary molten salt systems under different CaCl2 contents are qualitatively and quantitatively described by determining the partial radial distribution functions (PRDF), coordination number (CN), angular distribution functions (ADF), and diffusion coefficient (DC). The results show that with the addition of CaCl2, Ca2+ ion complexed with Cl− ion to form larger ionic clusters, which reduced the proportion of free Cl− ion and restricted the diffusion of Cl− ion.

Research on The Chloride Diffusion Modified Model for Marine Concretes with Nanoparticles under The Action of Multiple Environmental Factors

Marine concrete structures are subject to the action of multiple environments during their service time. This leads to increased deterioration in the durability of marine concretes under the combined action of bending load and dry–wet cycles, salt freeze–thaw cycles, and salt spray erosion. The main reason for the damage of concrete under the action of the above three environments is Cl- attack. The free Cl- content (Cl-f) and the free Cl- diffusion coefficient (Df) of concrete can explain the diffusion of Cl- in concrete. This paper considers the actual environment of marine concrete structures and develops the Cl- diffusion modified model for nano-marine concretes under the action of dry–wet cycles, salt freeze–thaw cycles, and bending load and salt spray erosion. The nano-SiO2, nano-Fe2O3, and nano-Fe3O4 were firstly incorporated into ordinary marine concrete, then the Cl- content of each group of marine concrete was measured at different depths, and the Cl- diffusion coefficients were calculated; finally, the Cl- diffusion modified model was established under different environmental factors. The test results show that the total and free Cl- diffusion coefficients of nano-marine concretes were lower than those of ordinary marine concrete, and the nano-SiO2, nano-Fe2O3, and nano-Fe3O4 of the optimum dosage were 2%, 1%, and 2%, respectively. The fitting results of Cl- content have a good correlation, and the correlation coefficient (R) is basically above 0.98.

Cl-induced passivity breakdown in α-Fe2O3 (0001), α-Cr2O3 (0001), and their interface: A DFT study

The presence of chloride ions is the critical factor of passivity breakdown of the protective film and eventually leads to localized corrosion. However, the mechanism and the role of chlorides in these processes are still controversial. Hematite and chromia are generally believed to be the major components of outer and inner oxide layers on stainless steels. In the present paper, a comparative study of Cl ingress into pristine and defective α-Fe2O3 (0001) surface, α-Cr2O3 (0001) surface, along with their interface, was conducted using density functional theory. Vacancy formation energy calculation confirms good stability of α-Cr2O3 and high reactive activity of the interface region. Cl inserts into an O vacancy is energetically more favorable than Fe vacancy and interstitial site, demonstrating Cl-induced degradation complies with the ion exchange model. Transition state search for Cl diffusion through O vacancies shows α-Cr2O3 is more protective than α-Fe2O3, while the interface region is the weak point of the duplex passive film.

Simultaneous enhancement of hardness and wear and corrosion resistance of high‐entropy transition‐metal nitride

AbstractBinary transition‐metal nitrides (TMNs) are widely used as protective coating materials, and enhancing key performance characteristics are crucial to improving their robust and durable applications in harsh service environments. Compositional modulation via multiple elemental species offers an effective approach for optimizing physicochemical properties of TMNs, and establishing the composition–property relation is essential to the design of high‐performance TMNs. In this work, we report on a comparative study of our synthesized NbN, NbMoN, and (NbMoTaW)N films and examined their microstructure, mechanical properties, and tribological and corrosion behaviors. The high‐entropy (NbMoTaW)N film exhibits the highest hardness of 23.5 ± 1.35 GPa, which is ascribed to its high structural stability, increased elastic constant, and elastic modulus compared to the NbN and NbMoN films. The (NbMoTaW)N film also possesses the best wear resistance stemming from the highest H/E ratio and formation of self‐lubricating MoO3 and WO3 species; moreover, this film shows the best corrosion resistance attributed to the sluggish diffusion of Cl− due to lattice contraction and the structural stability caused by high‐entropy effect. This work demonstrates simultaneously enhanced hardness and wear and corrosion resistance in a high‐entropy TMN, opening a pathway for developing a new generation of advanced protective coating materials.

Influences of Divalent Ions in Natural Seawater/River Water on Nanofluidic Osmotic Energy Generation.

Besides the dominant NaCl, natural seawater/river water contains trace multivalent ions, which can provide effective screening of surface charges. Here, in both negatively and positively charged nanopores, influences from divalent ions as counterions and co-ions have been investigated with respect to the performance of osmotic energy conversion (OEC) under natural salt gradients. As counterions, trace Ca2+ ions can suppress the electric power and conversion efficiency significantly. The reduced OEC performance is due to the bivalence and low diffusion coefficient of Ca2+ ions instead of the uphill transport of divalent ions discovered in the previous work. Effectively screened charged surfaces by Ca2+ ions induce an enhanced diffusion of Cl- ions which simultaneously decreases the net ion penetration and ionic selectivity of the nanopore. As co-ions, Ca2+ ions have weak effects on the OEC performance. The promotion from charged exterior surfaces in OEC processes for ultrashort nanopores is also studied, with an effective region of ∼200 nm in width beyond pore boundaries independent of the presence of Ca2+ ions. Our results shed light on the physical details of the nanofluidic OEC process under natural seawater/river water conditions, which can provide a useful guide for high-performance osmotic energy harvesting.

A novel electrocoagulation process with centrifugal electrodes for wastewater treatment: Electrochemical behavior of anode and kinetics of heavy metal removal

Anodic passivation is a key problem to impair the efficiency of in the electrocoagulation (EC) process. Process intensification of EC has attracted increasingly greater attention. In this work, a novel centrifugal electrode reactor was designed and applied in EC process to enhance the treatment of simulated heavy metal wastewater using aluminum anode. Results showed that the removal efficiency of heavy metals was significantly improved by the centrifugal electrodes, compared with the stationary electrodes. Electrochemical behavior of centrifugal electrodes was analyzed by an improved rotating disk electrode system. Anodic polarization behavior of aluminium showed a typical characteristic of dissolution in centrifugal electrodes, rather than passivation in static condition. Anode dissolution was controlled by the diffusion of Cl− ion that was enhanced by centrifugal electrodes. Thus, anode passivation was reduced. In addition, the kinetics analysis indicated that the removal of heavy metals in EC by centrifugal electrodes conformed to Variable-Order-Kinetic (VOK) model based on the Langmuir adsorption.