Ion-exchange Method Research Articles

Ion-exchange reaction construction of carbon nanotube-modified CoNi@MoO2/C composite for ultra-intense and broad electromagnetic wave absorption

Structural design and composition adjustment are promising approaches for the preparation of lightweight absorbers with high absorption performance and low matching thickness. In this work, a carbon nanotube-modified CoNi@MoO2/C composite was synthesized by ion-exchange, in-situ growth, and pyrolysis methods. For the synthesized CoNi@CNTs@ MoO2/C composite, the minimum reflection loss value (RLmin) was −63.2 dB at a thickness of 2.3 mm, and the effective absorption bandwidth reached 8.8 GHz (9.2–18 GHz) at a thickness of 2.5 mm. The potential microwave absorption mechanism is attributed to the synergistic effects of polarization relaxation, electron transmission, ferromagnetic resonance, as well as multiple reflections and scattering in the hierarchical nanocomposite. In addition, the radar cross-section (RCS) attenuation was calculated via HFSS to analyze the EMW absorption capacity in the actual far field. The RCS reduction was 36 dB m2 for a scattering angle of 0°. Overall, this work provides theoretical support for the controlled growth of metal-catalyzed CNTs and presents an effective guide for optimizing the electromagnetic and absorption performances of MA materials.

Comparison of antibacterial activity and cytotoxicity of silver nanoparticles and silver-loaded montmorillonite and saponite

Although silver nanoparticles are known for their antibacterial activity, little research has been carried out on what synthesis method provides the most effective particles. In this study, silver nanoparticles were synthesised via chemical reduction by using silver nitrate as the silver precursor, ascorbic acid as the reducing agent and sodium citrate as the stabilising agent. The solutions were adjusted to several pH values employing sodium hydroxide, citric acid or nitric acid. Dynamic light scattering and absorption spectra in the ultraviolet/visible region characterisation revealed that employing nitric acid to adjust the pH produced more varied and larger silver particle sizes. Then, silver nanoparticles were supported on montmorillonite and saponite through wet impregnation or ion exchange methods. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy characterisation confirmed that silver nanoparticles were successfully loaded onto the clay minerals. Next, the antibacterial activity of the samples was evaluated against Escherichia coli and Staphylococcus aureus by determining their minimum inhibitory concentrations and minimum bactericidal concentrations. The free silver nanoparticles did not show any antibacterial activity at 125 mg/L. In contrast, the silver-loaded samples obtained by wet impregnation and with a higher silver content displayed the strongest antibacterial effect. Finally, the cytotoxicity of the samples was determined in GM07492-A cell line by using an XTT colorimetric assay. The calculated IC50 values revealed that the supported silver nanoparticles were barely toxic. Thus, the silver-loaded clay minerals obtained here are promising antibacterial materials with a high-grade safety profile.

Efficient fixation of Co2+ and organic sulfur from cation exchange resins into CaO enhanced molten Li2CO3-Na2CO3-K2CO3 system

The radioactive spent resins produced by the nuclear power plant contain a certain amount of 60Co. These spent resins are easy to generate volatile substances during the heat treatment process, resulting in the leakage of radionuclide. The molten salt oxidation (MSO) can effectively prevent the volatilization of Co, and can facilitate the removal of sulfur exists in the resins. In this work, ternary carbonate (Li2CO3-Na2CO3-K2CO3) was used as molten salt system, and CaO was used as a sulfur pollutant capture agent. The non-radioactive CoCl2 served as simulate radioisotopes, and the Co2+ doped cation exchange resins (Co-CERs) were obtained by the ion exchange method. The introduction of Co2+ promoted the further oxidation of the thermally stable structure SC, and the harmful gases SO2 and H2S generated during the MSO process were effectively absorbed by carbonate with the participation of CaO. The retention rate of S could reach 87.79 % with the addition of CaO at 800 °C, which was 1.81 % higher than that without CaO. The test results of X-ray diffraction (XRD), scanning electron microscope (SEM) and inductively coupled plasma mass spectrometry (ICP-MS) confirmed that the addition of CaO promoted the formation of sulfide and thermally stable CoSO4. The retention rate of Co2+ in waste salt reached 97.36 % at 800 °C. The CaO enhanced molten carbonate system can realize the efficient treatment of Co-CERs and possess potential applications on organic contaminant treatment.

Detection of bacteria causing mastitis in cows with immunoelectric tool.

This study has investigated designing, producing, and evaluating a newly developed immunoelectric device for the identification of the Staphylococcus aureus and Escherichia coli in experimentally or clinically polluted milk samples. The design of the immunoelectric tool parts was carried out and produced by using a 3D printer. The animals were immunized against S. aureus and E. coli; purification of the specific IgG from hyperimmune serum was carried out by ion exchange and affinity chromatography methods. Coupling of the specific rabbit antibodies to the polystyrene filters was performed by DTPA linker. The purified rat antibodies were coupled to Fe nanoparticles and used as detector elements. The experimentally polluted milk and PBS samples were prepared. After optimization, the minimum traceable number of the bacteria was determined using immunoelectric tool. Also, the cow's milk samples with clinical mastitis were tested for bacterial detection by bacterial culture and immunoelectric methods. Coupling of the antibody to the filters and capturing of the target bacteria to the filters were successfully confirmed using enzyme immune assay and electron microscopy. The detection limit of the developed immunoelectric tool was equal to 15 cells/mL in PBS or milk samples for 30 min. Also, in agreement with bacterial cell culture, the clinically infected milk samples by S. aureus and E. coli were successfully detected using the immunoelectric device. The developed immunoelectric device could be utilized for rapid and cost-benefit detection of the bacterial organism.

MATHEMATICAL DESCRIPTION AND ALGORITHM FOR SOLVING THE MODEL OF THE IONITE REGENERATION PROCESS IN THE ION EXCHANGE METHOD OF WATER SOFTENING

Based on the modern representation of the water softening process by the ion exchange method, modeling was carried out, an algorithm was developed and the ionite regeneration process was calculated in a water softening plant with a fixed ionite layer. To solve the system of equations of the model, special, but simple enough for use in engineering calculations, techniques and methods have been developed and applied. The constructed model and its solution algorithm can be used to predict the process of ionite regeneration in an ion exchange apparatus. It can also be used to calculate the time of the ionite regeneration process.

Preparation of C3F7-azo+/LaNb2O7− intercalated nanocomposite by ion-exchange method and its application as electrochemical sensors

Using the excellent ion-exchange property and unique lamellar structure of lanthanum niobate KLaNb2O7, trans-[2-(2,2,3,3,4,4,4-heptafluorobutylamino) ethyl]-{2-[4-(4-hexyphenylazo) -phenoxy] ethyl}-dimethylammonium (abbreviated as C3F7-azo+Br−) was inserted into LaNb2O7− lamellar plate by ion-exchange method, and C3F7-azo+/LaNb2O7− nanocomposite was synthesized for the first time.X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy disperse spectroscopy (EDS) were used to characterize the prepared materials. Differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS) were used to detect and verify the electrochemical performance of C3F7-azo+/LaNb2O7− nanocomposite modified glassy carbon electrode (C3F7-azo+/LaNb2O7−/GCE) for simultaneous detection of dopamine (DA) and ascorbic acid (AA). The results showed that the detection limit of C3F7-azo+/LaNb2O7−/GCE in N2 saturated PBS (pH = 5.0, 0.1 M) was 0.57 μM for AA and 0.61 μM for DA in the range of 5.0 to 77.0 μM. It is concluded that C3F7-azo+/LaNb2O7− nanocomposite has excellent electrochemical performance and can be utilized in detecting AA and DA simultaneously.

Photocatalytic degradation of formaldehyde by ruthenium vanadate quantum dots-V2O5 nanowires array

In this work, ruthenium vanadate quantum dots-V2O5 nanowire arrays are prepared by hydrothermal, ion-exchange and calcination methods, and used for photocatalytic degradation of formaldehyde. The photocatalytic properties of the samples obtained at different calcination temperatures are tested and compared in detail. It is found that the sample calcined at 400 ℃ has a significantly enhanced light absorption due to a large number of uniformly distributed ruthenium vanadate quantum dots and oxygen vacancies on the nanowires. The formaldehyde degradation rate is 98% under 45 min illumination. Compared with the first cycle, the photocatalytic performance of the sample tested 4 cycle maintains 96%. This work provides a fabrication method of ruthenium vanadate quantum dots for effectively improving the light absorption and promoting the application of photocatalyst in the degradation of formaldehyde.

3R-IrO2 Two-Dimensional Nanosheets with Varying Layer Spacing and [IrO6] Distortion for OER

Here, two iridium-based crystal structures, K0.3IrO2·xH2O and Rb0.3IrO2·xH2O, have been synthesized for application in the oxygen evolution reaction (OER). The 3R-type layered IrO2 structures with different lattice parameters were successfully obtained from the two Ir structures by the hydrogen ion exchange method. According to synchrotron radiation spectra and the theoretical calculation of density functional theory (DFT), the increase of oxygen vacancy concentration caused by lattice distortion in the 3R-IrO2 crystal is negatively correlated with the activity of OER. A high concentration of oxygen vacancies will reduce Ir–O hybridization, which is not conducive to the balance between the adsorption and desorption of intermediate products. The higher OH adsorption energy barrier and band gap of the 3R-IrO2 crystal limited the improvement of electrochemical performance. In addition, through the analysis of the bonding orbitals and antibonding orbitals of the two structures, we concluded that 3R-IrO2 belongs to the nonthermodynamically stable structure and is not suitable for hydrogen production by electrolysis of water.

Site occupancy strategy for emission tunable K3HF2W1-xOF6:xMn4+ nanophosphor via ions exchange

A novel uniformly ellipsoidal K3HF2W1-xOF6:xMn4+ nanophosphor were demonstrated by ion exchange method without K2MnF6. The samples had wide excitation range from ultraviolet to visible light and tunable emission spectra from green to red were obtained which can be regulated by the emitting spectra of K3HF2WOF6 host and Mn4+. Energy transfer efficiency from [WOF6]2− to Mn4+ were improved with the increase of Mn4+. The peak position of thermal stability spectra of K3HF2WOF6 were blueshifted while Mn4+ doped samples undergoes a redshift. The crystal field strength and the Racah parameters were estimated and luminescence mechanism was explained by the Tanabe–Sugano energy level diagram of the Mn4+. Microsecond fluorescence lifetime indicates it advantages in fast react displays to avoid ghost images. The results indicate that K3HF2W1-xOF6:xMn4+ nanophosphor has potential application in display, converting phosphors for UV and blue LED and indoor plant supplyment light.

Application of Layered Double Hydroxides as a Slow-Release Phosphate Source: A Comparison of Hydroponic and Soil Systems.

The utilization of slow-release fertilizer materials capable of responding to their environment and releasing nutrient ions efficiently over a prolonged period is an emerging research area in agricultural materials sciences. In this study, two-dimensional layered materials were prepared to release phosphor ions (P) slowly into the soil as well as in the hydroponic system. Various P-intercalated layered double hydroxides (LDHs) (Mg/Al, Zn/Al, and Mg-Zn/Al-LDHs) with a molar ratio of 2:1 were synthesized using an ion-exchange method from corresponding LDHs containing NO3 - ions within the layers. Sodium alginate (SA) was used to encapsulate P-intercalated Mg/Al-LDH to produce bionanocomposite beads (LB) to check the effect of the biopolymer matrix on the release characteristics. The prepared materials were characterized by XRD and FTIR to confirm the incorporation of P in LDHs. TGA, SEM, and elemental analysis were also performed to study the thermal decomposition pattern, surface morphology, and chemical composition of synthesized materials. The P-release experiments were conducted in a soil solution. The performance of the prepared materials was investigated in soil as well as in a hydroponic system for tomato plants under a controlled atmosphere of humidity, temperature, and light. The fertilization ability of the prepared materials was compared with that of a soluble P source (KH2PO4), commercial hydroponic fertilizer (Nutrifeed), and a commercial soil slow-release fertilizer (Wonder plant starter). The prepared materials demonstrated a slow release of P in the soil solution. P-intercalated LDHs were not very effective under hydroponic conditions; however, the LDHs were more effective in the soil system in terms of dry matter production and P content in dry matter. Furthermore, LDHs were able to increase the soil pH value over time.

In-situ formed hybrid phosphates coating layer enabling co-free Li-rich layered oxides with stable cycle performance

Li-rich layered oxides (LLOs) with high specific capacities over 250 mAh/g, are thought to be promising cathode materials for high energy density lithium-ion batteries. However, sluggish kinetics, irreversible oxygen release, and irreversible evolution of the surface/interface have led to poor cyclic properties, which are the principal barriers to commercial applications. In this work, an in-situ hybrid phosphates coating layer that combines the advantages of superior ionic conductivity (Li3PO4) and structural stability (LiTMPO4, TM = Ni, Mn) is proposed by an ion exchange and heat treatment method. Remarkably, the hybrid phosphates (Li3PO4-LiTMPO4) coating is not only deposited on the secondary particles of polycrystalline Co-free LLO surface, but also incorporated into the pores and edges of secondary particles. Based on the above advantages, the treated LLO exhibits an initial coulombic efficiency of 92.8%, excellent capacity retention, outstanding rate capability, and thermal stability. Advanced in/ex-situ measurements ascertain that the improvement mechanism of hybrid phosphates coating can be attributed to the synergistic effect of Li3PO4 and LiTMPO4, which transports lithium ions while reducing surface side reactions, and the strong P–O bond inhibiting irreversible oxygen release, thereby stabilizing the surface structure.

Selective Hydrogenation of Naphthalene to Produce Tetralin over a Ni/S950 Catalyst under Mild Conditions

Tetralin is an essential chemical that can be generated by the partial hydrogenation of naphthalene. However, it is a challenge to design a catalyst with high efficiency, low-temperature activity, high tetralin selectivity, and a low cost to produce tetralin. A Ni/S950 catalyst with well-dispersed metal particles and high catalytic activity was prepared with an ion-exchange method. A complete conversion of naphthalene and a high tetralin yield of 95.6% were achieved over the Ni/S950 catalyst under 200 °C, 2 h, and 2 MPa H2. Compared with Co/S950 and Cu/S950, both the hydrogenation activity and the selectivity of tetralin over Ni/S950 are much higher due to its well-dispersed Ni particles with a smaller particle size of 6.8 nm and numerous active Ni0 sites.

An Investigative Study on the Structural, Thermal and Mechanical Properties of Clay-Based PVC Polymer Composite Films.

The present study aims to explore the impact of pristine and surfactant-modified clays (montmorillonite, bentonite and vermiculite) on the thermomechanical properties of a poly (vinyl chloride) (PVC) polymer film. Initially, clay was modified by employing the ion exchange method. The modification of clay minerals was confirmed by the XRD pattern and thermogravimetric analysis. Pristine PVC polymer film and clay (montmorillonite, bentonite and vermiculite)-based PVC polymer composite films were fabricated using solution casting. The ideal dispersion of surfactant-modified organo-clays was observed in the PVC polymer matrix due to the hydrophobic nature of modified clays. The resultant pure polymer film and clay polymer composite film were characterized using XRD and TGA, and their mechanical properties were determined using a tensile strength tester and Durometer. From the XRD pattern, the intercalation of the PVC polymer film was found in the interlayer of organo-clay while exfoliation or partial intercalation and exfoliation were observed for pristine clay mineral-based PVC polymer composite films. Thermal analysis indicated a lowering of the decomposition temperature of the composite film as clay promotes the thermal degradation temperature of PVC. Improvement in the tensile strength and hardness was found to be more frequent in the case of organo-clay-based PVC polymer films, which is only due to the hydrophobic nature of organ clays, resulting in greater compatibility with the polymer matrix.

Understanding systematic growth mechanism of porous Zn1-xCdxSe/TiO2 nanorod heterojunction from ZnSe(en)0.5/TiO2 photoanodes for bias-free solar hydrogen evolution

Herein, a porous Zn1-xCdxSe structure was developed on TiO2 nanorod (NR) array for photoelectrochemical (PEC) application. Firstly, TiO2 NR and ZnO/TiO2 NR photoanode were synthesized via a series of hydrothermal methods on FTO. Next, the solvothermal synthesis method was adopted to develop inorganic–organic hybrid ZnSe(en)0.5 on ZnO /TiO2 NR-based electrode using different concentrations of the selenium (Se). We found that the ZnO NR acts as a mother material for the formation of inorganic–organic hybrid ZnSe(en)0.5, whereas TiO2 NR acts as a building block. In order to further improve the PEC charge transfer performance, inorganic–organic hybrid ZnSe(en)0.5/TiO2 NR electrode was transferred into a porous Zn1-xCdxSe/TiO2 NR photoanode using the Cd2+ ion-exchange method. The optimized porous Zn1-xCdxSe/TiO2 NR -(2) photoanode converted from ZnSe(en)0.5 -(2) electrode (optimized Se concentration) showed a higher photocurrent density of 6.6 mA·cm−2 at applied potential 0 V vs. Ag/AgCl. The enhanced photocurrent density was owing to the effective light absorption, enhanced charge separation, delay the charge recombination, and porous structure of Zn1-xCdxSe. This work highlights the promising strategy for the synthesis of porous Zn1-xCdxSe/TiO2 NR from inorganic-organic ZnSe(en)0.5/TiO2 NR for effective charge separation and prolonging the lifetime during the photoelectrochemical reaction.

Lipid Profile, Renal Function Tests and Inflammatory Markers in Algerian Type 2 Diabetic Patients.

Several studies show the relationship between chronic hyperglycemia and the appearance of macroangiopathy, microangiopathy and neuropathy. The major objective of this study was to investigate the serum lipids, renal function tests and inflammatory markersin type 2 diabetes patients. The study lasted eight years between Feb-2013 and Mar-2021 (Mascara, Algeria). Overall,197 patients and 197 controls were selected during general medicine examinations; enzymatic and immunoturbidimetric colorimetric methods were used to determine the serum levels offasting glycaemia, total cholesterol, highdensity lipoprotein cholesterol, triglycerides, low-density lipoprotein cholesterol, fibrinogen, urea, acid uric, albumin and creatinine, C protein reactive; the glomerular filtration rate is calculated according to the MDRD equation; the glycatedhaemoglobin levels were determined by an ion-exchange resin separation method. Patients had 2.44 times higher fasting glycaemia, 1.71 times higher HbA1c, 1.23 times higher body mass index, 1.30 times higher waist circumference and 1.25times higher systolic blood pressure than control subjects; the findings of the present study also indicate that a significant differences between patients and controls were observed regarding triglycerides (P=0.008), LDL-cholesterol (P=0.011), HDL-cholesterol (P=0.009), urea (P=0.013), uric acid (P=0.015), creatinine (P=0.007), glomerular filtration rate (P=0.006), albumin (P=0.018), fibrinogen (P=0.023) and C protein reactive (P=0.019). All this metabolic disordercould facilitate the appearance of serious complications in future.

Tailoring of Ag3PO4-Anchored Hydroxyapatite Nanophotocatalyst with Tunable Particle Size by a Facile Ion-Exchange Method for Organic Textile Dyes Photodegradation

Silver phosphate (Ag3PO4) exhibits excellent photocatalytic performance but has limitation in its stability and reusability. To overcome the issue of reusability, composites of silver phosphate nanostructures are tailored. This paper elucidates the photocatalytic study of silver phosphate-anchored hydroxyapatite (HA) (Ca10(PO4)6(OH)2) on the degradation of commercial textile dye, Sunfix Red (SR) S3B 150% by changing the experimental parameters such as catalyst concentration, dye concentration, and pH of the dye solution under the sunlight. Silver phosphate-anchored HA (HA_Ag3PO4(x)) was prepared via a two-step process. HA was synthesized by a simple wet chemical precipitation and silver phosphate-anchored HA (HA_Ag3PO4(x)) via in situ ion-exchange method. The synthesized photocatalysts were subjected to characterization studies such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). All the synthesized composites exhibited the bandgap of 2.34 eV and degraded SR in 45 min with the rate constant 0.07168 min−1 under sunlight. The trapping tests for radicals were done to study the role of free radicals in the degradation of the dye, SR, and the possible degradation mechanism was proposed. The postphotocatalytic analysis of XRD showed that the structure of Ag3PO4 remained intact declaring its structural stability. It was observed that the concentration of AgNO3 precursor influenced the number of nucleation over the surface of HA and the particle size of Ag3PO4. The applicability of the synthesized material was extended to other organic dyes such as Sunzol Black (SB) DN conc., methylene blue (MB), and rhodamine B (RhB) by the prepared composite and the findings were presented.

Carboxymethyl chitosan nanoparticles loaded with Ctenopharyngodon idella interferon-γ2 (CiIFN-γ2) enhance protective efficacy against bacterial infection in grass carp

Type II interferon may be one of the most important immunomodulatory factors involved in the coordination of immune responses in vertebrates, but the efficacy of protein molecular drugs in treating bacterial infection still needs to be improved. Therefore, stable delivery technologies are required to improve the efficacy of proteins. This work evaluates the feasibility and biological activity of the carboxymethyl chitosan (CMCS) load with the interferon-γ2 of Ctenopharyngodon idella (CiIFN-γ2). Moreover, the resistance to Aeromonas hydrophila infection in grass carp will also be examined. The nanoparticle based on CMCS load with CiIFN-γ2 was constructed and designated as CMCS-CiIFN-γ2 (CMCS-Ciγ2) by ion exchange method. The CMCS-loading protein efficiency was measured at 28.46 ± 2.87%. The hemolytic analysis and cytotoxicity assays were performed to assess the biocompatibility of CMCS-Ciγ2. The cytotoxicity of CMCS-Ciγ2 nanoparticles was 90.8 ± 0.95% at the highest tested concentration (200 μg/mL), which proves that it is safe and non-toxic. Additionally, the findings indicated that the expression levels of pro-inflammatory cytokines (IL-1β, TNF-α, iNOS) in macrophages activated by nanoparticles CMCS-Ciγ2, were significantly enhanced, and nitric oxide (NO) was detected at high levels. In vivo imaging system (IVIS) results showed that the CMCS-Ciγ2 can still be detected at 8 h after oral gavage. This remains inside the host for a longer period of time contributing to the effective uptake of the protein. The challenge test revealed that CMCS-Ciγ2 had a higher relative immune protection rate than other treatment groups. The findings also showed that there was a reduction in tissue bacterial loads and damage. The in-vivo experiment results showed that the CMCS-Ciγ2 elicited higher levels of serum biochemical indexes and increased expressions of several immune-related genes (IL-1β, TNF-α) in grass carp. In turn, these results demonstrated that the CMCS-Ciγ2 can effectively regulate the immune system and facilitate the development of an immune barrier that enables the host to cope with external environment changes. This research will provide critical insights into the development and application of nanomaterials, which can be used to prevent and treat bacterial diseases in aquaculture.

Evidence of the Uyunbulak Salt Lake Water Recharge in the Kumish Basin, Xinjiang, China, from Boron Isotopes

The reserves of nitrate (NO3-) mineral resources in the Turpan-Hami Basin in Xinjiang rank second after those in the Atacama Desert in Chile, South America. Considerable attention has been devoted to nitrogen (N) sources of NO3- deposits in recent years due to the increase in demand for NO3- fertilizers in agriculture and chemical industries. However, although the potassium nitrate (KNO3) deposits in the Uyunbulak salt lake in the Kumish basin, Xinjiang, China, have received increasing attention from numerous researchers in recent years, they all focused on the study of nitrate sources and agreed that the nitrate source in the Kumish basin is mainly atmospheric sedimentation. Studies on their water sources are scarce; for salt lake nitrate deposits, water supply also plays a crucial role in the genesis of the deposit. As a sensitive indicator, a boron isotope is often used to indicate water bodies from different sources. However, the presence of NO3- ions in water will interfere with the determination of boron isotopes, so the research on boron isotopes in nitrate salt lakes has been hindered. In this study, the three-step ion exchange method published by Ma et al. (2020) was used to eliminate the influence of NO3- ions in water on boron isotope determination, so as to reveal the water supply of Uyunbulak Salt Lake in Kumish basin by using boron isotopes which are more sensitive to water types. In this study, ice and snow meltwater, fissure water, groundwater, and surface water samples were collected from the Kumish basin and analyzed for the determination of boron (B) isotopic and hydrochemical compositions during the migration process of water bodies to reveal the recharge relationship between the water bodies from the northwestern margin of the basin and the study area. The obtained hydrochemical composition results showed a gradual increase in the salinity of the water body from 556 to 7372 mg/L from the northwestern to the southeastern parts of the basin, resulting in a gradual change in the hydrochemical facies type of Uyunbulak salt lake to NaCl. This finding suggested that the water body migrates from the northwestern to southeastern parts of the basin. The results of B isotope composition indicated two types of water bodies from different sources, namely, the ice and snow meltwater of the Southern part of the Tianshan Mountains and groundwater of the basin, exhibiting B isotope composition ranges of 26.66–27.26‰ and 12.75–15.19‰, respectively. These two types of water bodies are mixed at the Uzong spring (Q1). The ice and snow meltwater in the mixed water accounted for 46%, while the groundwater accounted for 54%. The mixed water continues to recharge the Uyunbulak Salt Lake in the southeastern part of the basin.

Promotional effect of Co cations on the catalytic activity of Co/ZSM-5 in 1,2-dichloroethane dehydrochlorination for the production of vinyl chloride monomer

In the catalytic dehydrochlorination of 1, 2-dichloroethane (DCE) for Vinyl chloride monomer (VCM) production, it is important to design catalysts with appropriate acid properties which can activate DCE, while inhibiting the further reaction of VCM. In this study, Co species were introduced into ZSM-5 through an ion-exchange method to change acid site distribution of ZSM-5. The introduction of Co cations significantly improved DCE conversion and VCM selectivity, achieving 6 and 2-fold greater than bare HZSM-5, respectively. Postmortem analyses allowed us to delineate the role of acid sites: Lewis acid sites are the major active sites, whereas Brønsted acid sites give rise to undesired secondary reactions. Thus, our results demonstrate that the introduction of Co cations increases the number of relevant active sites, and simultaneously eliminates undesirable sites. These findings help understand the effect of Brønsted and Lewis acid sites in zeolites on the DCE dehydrochlorination, providing useful information for designing rational catalysts.

In-situ observation and evaluation of silver precipitation behavior in borosilicate glass

Applying voltage to alkali-containing glass, doped with silver ions by the solid-state ion-exchange method, yields silver precipitates inside the glass. We attempted in-situ observation of the precipitation phenomena to elucidate the silver precipitation mechanisms, where the direction of the voltage application was rotated 90 deg. to increase the precipitation area compared to that of our previous method. The results show that the shape of the precipitate changed from clumpy to dendritic as the applied voltage increased. The shape of the precipitate, predicted by the dielectric breakdown model, implied that the higher the precipitation probability (i.e., the higher the frequency of a silver ion to encounter with the precipitate), the more branches the precipitate formed. In addition, the un-doped, silver-doped, and silver-precipitated areas inside the glass were modeled as electrical resistances to predict the growth behavior of the precipitated areas.