Ions In Solution Research Articles

Dynamic interactions of negatively charged gold nanoparticles (AuNPs) in aqueous environments with different ionic compositions

This study provides a comprehensive analysis of the interactions between negatively charged gold nanoparticles (Au)144(SRCOO1−)60 and both divalent (Mg2+, Ca2+) and monovalent (Na+, K+) ions in aqueous solution, employing molecular dynamics simulations. The investigation focuses on elucidating the energetics, hydrogen bond patterns and radial distribution of ions surrounding gold nanoparticles. Our results reveal distinct differences in the Coulombic and van der Waals energies between gold nanoparticles and ions, as well as between gold nanoparticles and water, which exert influence on hydrogen bond patterns and lifetimes, as even as ion and water mobility. These findings have important implications for potential applications in nanotechnology and materials science. This research contributes to a deeper understanding of ion-nanoparticle interactions and provides valuable insights for the design and development of new nanomaterials with properties and functionalities.

Application of Marine Mollusk Shells (Meretrix lusoria) as Low-Cost Biosorbent for Removing Cd2+ and Pb2+ Ions from Aqueous Solution: Kinetic and Equilibrium Study

The present work aims to evaluate the applicability of mollusk (Meretrix lusoria) shells as a biosorbent for toxic metal ions (Cd2+ and Pb2+) following the batch mode biosorption procedure. Some well-known analytical methods have been used to characterize the biosorbent such as a scanning electron microscope (SEM), an energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction. The mechanism of metal ion biosorption was examined using various analytical techniques. Therefore, an evaluation of operating factors such as contact time, pH, initial concentration of metal ions, biosorbent dose, and temperature was performed. The results obtained in this investigation indicated that the optimum conditions for the biosorption of Cd+2 and Pb+2 ions are as follows: pH = 6; contact times of 90 min; and the 20 mg/L of initial [M2+]. And a biosorbent dosage of 1.0 g/100 mL for each metal ion solution was also determined. The maximum removal efficiency results were 90.6% for Cd+2 and 91.5% for Pb+2 at pH 6.0. The biosorption isotherm was investigated using three forms of linear equilibrium (Freundlich, Langmuir, and Temkin models). Kinetic studies were also conducted to determine the equilibrium time for the biosorption of the studied metals utilizing the pseudo-second-order, pseudo-first-order, and intraparticle diffusion model. The data indicate that the biosorption kinetics of Cd2+ and Pb2+ follow the pseudo-second-order models. According to the present study, it can be identified that the shell of Meretrix lusoria is a suitable biosorbent for Cd2+ and Pb2+ ions and can contribute to their removal from environmentally polluted water.

Dinitrophenyl and NBD platforms based fluorescent sensors for nanomolar detection of zinc ions: Synthesis, zinc ions sensing and DFT studies

The design and synthesis of two new fluorescent probes based on dinitrophenyl (1) and 7-nitrobenz-2-oxa-1,3-diazole (2) platforms is reported. Both probes, containing bis(pyridin-2-ylmethyl)amine as a receptor unit can efficiently detect zin ions (Zn2+) in aqueous solution, with limit of detections of 124 nM and 1.06 µM, respectively. Probe 1 and 2 led to 3-fold and 2.4-fold fluorescent enhancements, respectively, with the addition of Zn2+ which suggested that working mechanism of these probes is based on the inhibition of the photoinduced electron transfer from the electron donating receptor towards the excited fluorophore. Studying binding stoichiometry by job’s plot suggested 1:1 complexation between the probe and Zn2+. Moreover, the formation of probes-Zn2+ complexes was validated by both FT-IR and 1H NMR wherein marked changes in the absorption frequencies as well as distinct downfield shifts in the resonance peaks of pyridine function along with the CH2 group linked directly to the tertiary nitrogen of the DPA unit were observed. Density functional theory (DFT) calculations suggested that the electronic density of the HOMO in 1 was concentrated on the linker between DPA and dinitrophenyl, whereas the density of the LUMO was concentrated on dinitrophenyl moiety. Upon Zn2+ binding, the electronic density in HOMO and LUMO become more delocalized. However, in case of probe 2 the delocalization of electronic density does not appreciably occur. Based on DFT simulations, both sensors form thermodynamic stable complexes with Zn2+ ions. However, sensor 2 exhibited slightly better binding preference toward Zn2+ as compared to 1. The PET based probes exhibited good selectivity to detect Zn2+ in the presence of a variety of competing metal cations. These sensors have higher sensitivity and would be able to detect chronic level of Zn2+ in the freshwater (>1.84 μM) as permitted by the US EPA.

Bi2MoO6/ZnIn2S4 S-scheme heterojunction containing oxygen vacancies for photocatalytic degradation of organic pollutant

Photocatalytic removal of organic pollutants is a promising strategy to alleviate environmental pollution. In this study, S-scheme heterojunctions Bi2MoO6/ZnIn2S4 (BMO/ZIS) containing oxygen vacancies were synthesized by the solvothermal method. Oxygen vacancies improved the utilization of sunlight and accelerated the separation of charge carriers. The S-scheme charge transfer mechanism provided a channel for the directed migration of photogenerated charges. 10Bi2MoO6/ZnIn2S4 (10BMO/ZIS) efficiently degraded various organic pollutants with a small amount of photocatalyst (15 mg) under visible light irradiation. 10BMO/ZIS presented the highest RhB removal efficiency of 96.52 %, which was 7.02 and 3.67 times greater than Bi2MoO6 containing oxygen vacancies (BMO-Vo) and ZnIn2S4 (ZIS), respectively. Meanwhile, in various inorganic salt ion solutions, 10BMO/ZIS still exhibited high degradation performance. In addition, the photocatalytic degradation pathway was inferred, and the threat of degradation intermediates to the ecological environment was evaluated. This work contributes to a deeper understanding of the photocatalytic mechanisms of oxygen vacancy-modified heterojunction photocatalysts and offers insights for designing efficient environmental remediation photocatalysts.

Silver induced self-assembly of a rhodanine derived reversible fluorescent chemosensor: Applications in smart-phone color assist app, logic gate, real sample analysis and bio-imaging

An innovative chemosensor, Rhodanine-appended benzaldehyde (RB), was developed and analyzed using spectroscopic methods to detect silver ions (Ag+) in a THF–H2O buffer solution via fluorimetry. The RB probe exhibited low fluorescence due to C-N free rotation and inhibition of electron transfer. However, interaction with Ag+ ions resulted in a noteworthy redshift of approximately 6 nm and increased fluorescence intensity owing to the chelation-enhanced fluorescence (CHEF) effect, which hindered the Intramolecular Charge Transfer (ICT) process. The binding ratio between RB and Ag+ ions was determined to be 2:1 using the job plot method. The association constant (Ka) was calculated to be 4.84 × 105 M−1 and further confirmed through ESI-TOF spectroscopic and DFT analyses. The limit of detection (LOD) and quantification (LOQ) for RB in binding with Ag+ ions were found to be 1.7 × 10−8 M and 5.4 × 10−8 M, respectively. Additionally, the color changes of RB when binding with Ag+ ions were effectively leveraged in an RGB-assisted smartphone color analysis app for precise sample analysis for Ag+ ion detection. Most importantly, the RB probe’s ability to detect silver ions in the E. coli pathogen was successfully demonstrated, providing reassurance about its practical application, using a confocal scanning electron microscope via the green channel.

Synthesis and characterization of chitosan Schiff base grafted with formaldehyde and aminoethanol: As an effective adsorbent for removal of Pb(II), Hg(II), and Cu(II) ions from aqueous media

Grafted chitosan materials show the characteristics of high stability, easy separation and recovery, and good heavy metal adsorption capacity, and have received much attention in the adsorption process. Therefore, in this work, novel grafted chitosan-based adsorbent CS-EHBSB@F-AE was prepared by a one-pot reaction of chitosan (CS), 3-ethoxy-4-hydroxybenzaldehyde (EHB), formaldehyde (F) and aminoethanol (F). The microstructure and morphology of the as-prepared composite CS-EHBSB@F-AE were characterized by FT-IR, TGA, DSC, FE-SEM, and BET analyses. The adsorption performance of the as-prepared CS-EHBSB@F-AE composite on Pb(II), Hg(II), and Cu(II) ions from aqueous was investigated using batch experiment and the effects of the initial pH of the solution, contact time, and initial metal ions concentration and temperature on the adsorption efficiency were investigated and discussed. At the best conditions, CS-EHBSB@F-AE exhibited remarkable adsorption capacity of 246.7 mg/g, 203.9 mg/g, and 234.4 mg/g in absorbing Pb(II), Hg(II), and Cu(II), respectively. The adsorption equilibrium and the kinetic studies confirmed that the ions adsorption process fits well with the Langmuir isotherm and pseudo-second-order (PSO) models. Additionally, the adsorption efficiency of Pb(II), Hg(II), and Cu(II) metal ions by the composite CS-EHBSB@F-AE was reduced by increasing the temperature from 298 K to 318 K. In addition, after the sixth ads/des cycles, the as-prepared adsorbent still exhibited high removal efficiency with a decrease in adsorption efficiency of Pb(II) (5.53 %), Hg(II) (15.43 %) and Cu(II) (8.27 %). Finally, we proposed that the ions adsorption by CS-EHBSB@F-AE has happened using the coordination of active groups containing nitrogen and oxygen atoms on the surface of the adsorbent with the Pb(II), Hg(II), and Cu(II) metal ions.

Adsorption of Fluoride Ions Using Si–Al–Mg Layered Double Hydroxides

ABSTRACT Removal of fluoride ions from water environments has become a research topic because high concentrations of fluoride ions in drinking water are harmful to the human body. The adsorption of fluoride ions by a Si – Al – Mg layered double hydroxide (LDH) was investigated in this study. The prepared adsorbent had a hydrotalcite-like LDH structure, which was decomposed by calcination and reconstructed upon contacting water. The adsorption process followed pseudo-second-order kinetics. Granulation of the adsorbent for application to chromatographic operation decreased the adsorption rate constant. Adsorption of fluoride ions was high at 7 < pHeq <10 and decreased at higher pHs. The adsorption mechanism involved ion exchange between the fluoride ions in aqueous solution and chloride ions in the adsorbent as well as physisorption via van der Waals forces. The adsorbent was selective towards fluoride ions over nitrate and sulfate ions, although the adsorption of fluoride ions was suppressed in the presence of chloride, carbonate, and phosphate ions. Chromatographic operation using the granulated adsorbent with an alumina-based binder was characterized by slow kinetics, necessitating a low flow rate for the feed solution. The prepared adsorbent was also used to selectively adsorb fluoride ions from simulated wastewater produced by the semiconductor manufacturing process.

Fluorescence Carbon Dots from Blood-Berries for Sensing Cr6+ Ions in Water and Application in White Light Emitting Diode.

Conventional techniques for identifying heavy metal ions in water are laborious and time-consuming. Therefore, it is necessary to create innovative sensing technologies that can detect with greater sensitivity and speed. Although there have been reports of optical-based assays utilising fluorescent nanomaterials, these assays usually rely on variations in signal strength. However, this approach has significant drawbacks when it comes to environmental monitoring. Fluorescence carbon dots (CDs) have been prepared by facile synthesis from Blood berries. A homemade heavy metal optical detector is constructed to accurately identify heavy metal ions, exclusively Cr6+ ions in a water medium. Their optical emission signature varies based on the specific chromium ions in solution, and the emission intensity also changes depending on its concentration. The quenching behaviour is attributed to the interaction between the metallic cations and the fluorescent surface states of the carbon dots. Another application is the encapsulation of CDs in PVDF polymer to form a flexible film and use it as a phosphor for LED conversion.

Ethylene glycol-assisted microwave synthesis of bismuth-rich oxychlorides photocatalysts with oxygen vacancies for efficient degradation of bisphenol A and oxidation of arsenite

The bismuth-rich strategy, which involves increasing the bismuth content within the BiOCl structure, offers an effective approach for tailoring the physicochemical and optoelectrical properties of BiOCl photocatalysts for enhanced photocatalytic performance. In this study, BiOCl, Bi12O15Cl6, and Bi12O17Cl2 were selectively synthesized using the ethylene glycol (EG)-assisted microwave irradiation method by regulating the pH of the reaction solution. Photocatalytic performance was evaluated by studying bisphenol A (BPA) degradation and arsenite (As(III)) oxidation under visible-light irradiation. The energy structures and bandgaps of the materials were tuned according to their chemical compositions, affecting their photocatalytic activity. Bi12O17Cl2 (EG-pH 9) exhibited superior photo-efficiency: 85.4 % of BPA and 97.6 % of As(III) were removed by Bi12O17Cl2 (EG-pH 9) at rates 17.7 and 18.4 times higher than those of BiOCl (EG-initial pH 3), respectively. This superior performance attributed to the synergistic effect between the bismuth-rich nature and oxygen vacancies (OVs) induced by EG, along with the presence of OH− ions in the reaction solution. The increased number of OVs in Bi12O17Cl2 led to enhanced photocurrent density and charge transfer efficiency. Trapping experiments, DMPO-ESR spin-trapping, nitroblue tetrazolium transformation, terephthalic acid photoluminescence probing, and o-tolidine oxidation experiments identified holes (h+), superoxide radicals (•O2−), superoxide radicals (•OH) and electrons (e−) as the reactive species. Density functional theory calculations further highlight the OV of Bi12O17Cl2 as the active site for O2 adsorption. This study not only developed an effective method for fabricating bismuth-rich oxychlorides with OVs but also demonstrated the potential of these photocatalysts for wastewater treatment.

COMPETITIVE ADSORPTION OF Fe2+, Pb2+, AND Zn2+ IONS FROM MULTI-METAL ION SOLUTION ON AMMONIUM OXALATE MODIFIED KAOLINITE CLAY

The competitive adsorption of Fe2+, Pb2+, and Zn2+ ions from mixed multi-metal aqueous solution on ammonium oxalate-modified kaolinite clay (AOK) was studied to determine the competitive influence of the metal ions on the adsorption of other metal ions. The kaolinite clay was modified by treating it with 0.2 M of ammonium oxalate solution at 50 oC. The adsorption of the metal ions was carried out using initial concentrations of 20, 35, and 50 mg L-1 in both the single and multi-metal ion solutions. The results revealed that at a low concentration of 20 mg L-1, the adsorption capacity for the uptake of the metal ions on AOK is non-competitive. At higher adsorbate concentrations of 35 and 50 mg L-1, the single to multi-metal ions equilibrium adsorption capacity ratio value obtained was less than 1. This indicated an antagonistic effect on competing for the adsorption site in the following order: Pb2+ (9.9 mg g-1) &gt; Fe2+ (3.85 mg g-1) &gt; Zn2+ (2.85 mg g-1). The outcome revealed that ammonium oxalate-modified kaolinite is a potential adsorbent for remediation of multi-heavy metal-laden wastewater with preferentially higher affinity for Pb2+ ions than other metal ions.

Amphetamine-like Deferiprone and Clioquinol Derivatives as Iron Chelating Agents.

The accumulation of iron in dopaminergic neurons can cause oxidative stress and dopaminergic neuron degeneration. Iron chelation therapy may reduce dopaminergic neurodegeneration, but chelators should be targeted towards dopaminergic cells. In this work, two series of compounds based on 8-hydroxyquinoline and deferiprone, iron chelators that have amphetamine-like structures, have been designed, synthesized and characterized. Each of these compounds chelated iron ions in aqueous solution. The hydroxyquinoline-based compounds exhibited stronger iron-binding constants than those of the deferiprone derivatives. The hydroxyquinoline-based compounds also exhibited greater free radical scavenging activities compared to the deferiprone derivatives. Molecular dynamics simulations showed that the hydroxyquinoline-based compounds generally bound well within human dopamine transporter cavities. Thus, these compounds are excellent candidates for future exploration as drugs against diseases that are affected by iron-induced dopaminergic neuron damage, such as Parkinson's disease.

Using flow-through reactor to enhance ferric ions electrochemical regeneration in electro-fenton for wastewater treatment

Electrochemical regeneration of ferric ions catches more and more attention since it could decrease iron sludge to avoid the sludge problem while it could simultaneously obtain similar robust removal efficiency to refractory organic contaminants in wastewater treatment as the normal Fenton agent method. However, the electrochemical regeneration of ferric ions in aqueous solution was very slow. In this paper, the mass transfer limit of ferric ions in electro-Fenton reaction was evaluated. Koutecky-Levich equation reveals an extremely low diffusion coefficient (D0) value of ferric ions since its complex coordination of [Fe(HO)x(H2O)6-x]3-x. The D0 value was only 2.70 × 10−6 cm2·s−1. Flow-through reactor was therefore introduced in which the ferric ions was designed to penetrate through the 73.1 μm porous holes in the graphite fiber electrode. The μm-scaled confinement of ferric ions diffusion inside the holes was proved to successfully enhance the reduction current of ferric ions by more than 200 % since the diffusion distance of the ferric ions was significantly decreased in the flow-through reactor. However, besides the benefit of the flow-through reactor, the ferric ions reduction electro-Fenton (FeRR electro-Fenton) in flow-through still faces both the pH limit and H2O2 decomposition problems. Hydrogen evolution reaction (HER) could also cause the decrease of pH which exceeded the optimal pH window for Fenton and therefore destroyed the electro-Fenton reaction consequently although the electrochemical reaction of FeRR was 770 mV prior to HER reaction. The regeneration of Fe (II) process simultaneous destruction of H2O2 since H2O2 e-reduction was 120 mV prior to FeRR reaction, which resulted in only very low H2O2 concentration suitable for FeRR electro-Fenton. Even using stepwise addition of H2O2 in electro-Fenton, the decomposition of H2O2 still could not be avoided. Although the decomposition of H2O2 quite limited the application of FeRR electro-Fenton in real application, FeRR electro-Fenton still supports the enhancement removal efficiency of the refractory organic contaminants under low organic contaminants application.

Atomistic Simulations Reveal Crucial Role of Metal Ions for Ligand Binding in Guanidine-I Riboswitch.

Riboswitches are structured ribonucleic acid (RNA)segments that act as specific sensors for small molecules in bacterial metabolism. Due to the flexible nature of these highly charged macromolecules, molecular dynamics simulations are instrumental to investigating the mechanistic details of their regulatory function. In the present study, the guanidine-I riboswitch serves as an example of how atomistic simulations can shed light on the effect of ions on the structure and dynamics of RNA and on ligand binding. Relying on two orthologous crystal structures from different bacterial species, it is demonstrated how the ion setup crucially determines whether the simulation yields meaningful insights into the conformational stability of the RNA, functionally relevant residues and RNA-ligand interactions. The ion setup in this context includes diffuse ions in solution and bound ions associated directly with the RNA, in particular a triad of 2 Mg2+ ions and a K+ ion in close proximity to the guanidinium binding site. A detailed investigation of the binding pocket reveals that the K+ from the ion triad plays a decisive role in stabilizing the ligand binding by stabilizing important localized interactions, which in turn contribute to the overall shape of the folded state of the RNA.

Enhanced removal of lead ions from wastewaters by electrochemical adsorption using nitrogen-doped Ti3C2Tx MXene

As a two-dimensional material containing transition metal carbides and nitrides, MXene is often used in capacitive deionization for its excellent hydrophilic and pseudocapacitive properties. Nitrogen doping is widely used to improve the adsorption properties of certain materials. However, the effect of nitrogen doping on the electrochemical adsorption properties of MXene remains unclear. In this work, nitrogen-doped Ti3C2Tx MXene was synthesized using a simple hydrothermal method to achieve highly selective and efficient removal of Pb(II) at a constant cell voltage. The concentration of Pb(II) decreased from 4.95 to 0.02 mg L−1 in a 100 mg L−1 NaCl supporting electrolyte after electrosorption. The removal efficiency of Pb(II) reached 99.5%, whereas it was only 15.2% for Na+. The introduction of nitrogen functional groups increased the electrical conductivity and layer spacing of MXene, thereby improving the pseudocapacitive adsorption performance in the presence of Pb(II). The complexation function of the Ti-OH group on nitrogen-doped Ti3C2Tx surface increased and contributed to the selective adsorption of Pb(II). The removal efficiency of Pb(II) increased with increasing solution pH and cell voltage, reaching the maximum value at pH 5.0 and 1.5 V, respectively. The effect of supporting electrolyte type on the removal of Pb(II) was negligible. In addition, the removal efficiency for mixed heavy metal ion solutions, including Cu(II), Ni(II), and Pb(II), exceeded 79.0%. It exhibited the highest removal efficiency for Pb(II) at 97.9%. After five cycles of electrochemical adsorption–desorption, the nitrogen-doped Ti3C2Tx maintained a stable Pb(II) removal efficiency of 97.0%. This work provides a promising material for the electrochemical removal of low-concentration heavy metal ions from wastewaters.

Interactions between supported lipid bilayers and substrates that affect lateral diffusion of lipids

Changes in the diffusion coefficient of supported lipid bilayers affected by their interaction with the substrate were evaluated by fluorescence recovery after photobleaching under different surface charges and ambient conditions (presence of divalent ions in solution). The diffusion coefficients of each leaflet were estimated separately by quenching only the leaflet on the far side from the substrate with Co2+ ions. The potential valleys, which are created by the divalent ions between the supported lipid bilayer and the substrate or the positive charges on the substrate surface, act as diffusion barriers, and the diffusion coefficient of the leaflet on the side closer to the substrate decreases. At the same time, the other leaflet far from the substrate also showed a somewhat decrease in diffusion coefficient due to interleaflet coupling.

Oxygen-Controlled Electrocatalysis for Selective Dechlorination of 2-Chloro-5-Trichloromethyl Pyridine on Activated Ag Electrode

Electrochemical selective dechlorination can be regarded as one of the most promising strategies for generating high-valued chemicals. In the electrochemical dechlorination process of 2-chloro-5-trichloromethylpyridine (TCMP), except the anticipated dechlorination products involving 2-chloro-5-dichloromethylpyridine (DCMP), 2-chloro-5-chloromethylpyridine (CCMP), and 2-chloro-5-methylpyridine (CMP), some unexpected oxygen-incorporated products (6-chloronicotinic acid (CNA) and 6-chloronicotinoyl methyl ester (MCN)) can be obtained. Consequently, understanding the electrochemical dechlorination behavior of TCMP is crucial. Our research revealed that the activated Ag electrodes in halide ion solution exhibit enhanced electrochemical activities for electrochemical dechlorination of TCMP, compared with the pure Ag owing to the increased active specific surface areas and charge transfer. Second, oxygen participation in the reaction is a necessary condition for the formation of oxygen-incorporated products. A 100% selectivity of oxygen-incorporated products can be obtained at the potential of −0.6 V vs Ag/AgCl. Conversely, insufficient oxygen may lead to the potential becoming the determining condition that affects the reaction pathways. A more negative potential (−1.2 V vs Ag/AgCl) is conducive to the formation of dechlorination products with 94.2% conversion and 100% selectivity. This study, for the first time, elucidates the electrocatalyst, atmosphere, and potential-dependent activity and selectivity for the two dechlorination pathways of TCMP.

Effect of oxygen content in CuO x nanofilms on chloride ion detection for ion sensor applications

Sensors for detecting chloride ions have been required for routine monitoring of industry and human health. This study proposes a concept of an ion sensor based on CuO x nanofilms with different oxygen contents. The CuO x -based sensors exhibited an increase in DC current for those with low oxygen content and a decrease for those with high oxygen content following exposure to a chloride ion solution. AC impedance analysis suggested differential reactions of chloride ions in the bulk and surface regions of CuO x , dependent on the oxygen content. For the CuO x -based sensors with a ratio of 0.78 oxygen to copper atoms at chloride ion concentrations of 10−1000 ppm, the sensitivity in the bulk region calculated from AC impedance was 61−2926, which was higher than the sensitivity of 1.3−2.6 calculated from DC impedance. Finally, CuO x -based sensors demonstrated identifiability for chloride ions compared to sodium and calcium ions.

Preparation and application of DES doped carbon quantum dots for fluorescent chromium ions determination

ABSTRACT This paper uses orange peel and deep eutectic solvents as precursors to prepare DES-CQDs via one-step hydrothermal method. The average size of DES-CQDs is 5.5 nm, with abundant luminescent groups such as amino and hydroxyl groups on the surface. Under the excitation of ultraviolet light at 360 nm, blue fluorescence with a wavelength of 452 nm is emitted. In addition, to investigate the practical application effect of DES-CQDs, this study further used DES-CQDs as fluorescent sensor to detect Cr6+ ions in solutions. The results showed that Cr6+ exhibited a significant quenching effect on DES-CQDs, consistent with the quenching mechanism of static quenching and internal filtering effect, and the limit of detection was 3.2 nM. The recovery rates of Cr6+ spiked in four environmental samples are 94.27 ~ 100.51%, indicating that DES-CQDs can be used for the detection of Cr6+ in complex environmental samples.

Preparation of electroless deposition of NiTiZr(P) quaternary alloy and their properties

The exceptional super elasticity and corrosion-resistance of Ni-Ti alloys have attracted a lot of attention and interest lately for a wide range of applications, and complex alloy components could be prepared effectively by different preparation techniques. Ni(P), Ni-Ti(P), Ni-Zr(P), and Ni-Ti -Zr(P) binary, ternary, and quaternary alloys were coated on mild steel by electroless deposition which is a method of plating metallic films on a substrate by the reduction of metallic complex ions in solution with the aid of reducing agent from an alkaline bath. The ternary Ni-Ti-Zr(P) alloy is considered to be one of the most promising high-temperature SMAs. SEM, XRD and EDS were used to examine the morphology, phase composition and elemental composition which demonstrate the microstructure of the deposits. The mechanical characteristics of the samples were examined through scratch test and micro hardness analysis and the value increased from 261 HV200 to 405 HV200 and that the coefficient of friction raised significantly from 0.23 to 3.5 owing to the presences of added elements in Ni(P) matrix. Polarization analysis and EIS were tested to evaluate the corrosion properties of coated samples in a non-deaerated 3.5 %wt. (NaCl) solution. The outcomes indicate that as the amount of Ti-Zr elements in the bath raised, the corrosion potential became more positive and the corrosion current density decreased to 14.903 μA/cm2. Furthermore, Ni-Ti-Zr(P) alloy coating strengthens corrosion resistance in comparison to Ni(P).

Thermodynamics-based sealing method for anodized aluminum used in semiconductor processing apparatuses

A principle was proposed for designing a method to seal anodized aluminum used in semiconductor processing apparatuses. Thermodynamic calculations and Fick's second law were used to reveal trends in the metal ion deposition, deposition product stability, vapor pressures of halides for selected metal ions, the holding temperature, and time. Interactions between ion concentrations and the sealing temperature were also revealed. According to the design principles, anodized aluminum dipped in 1 mM Cr3+ ion solution and steam-sealed for 18 h exhibited the highest corrosion resistance when exposed to 5 wt.% HCl solution and HCl gas, verifying the designed results.