Concentrated Chloride Solutions Research Articles

Optimization of Immobilization Condition of Protease Extracted from Silver Catfish (Pangasius Sutchi) Viscera in Calcium Alginate by using Response Surface Methodology (RSM)

The term of immobilized enzymes refers to enzymes that physically entrapped within pores of synthetic or natural polymeric network with no alteration in the enzyme catalytic activities. In this study, protease from silver catfish viscera have been extracted, partially purified by acetone precipitation method and immobilised in the calcium alginate beads. Various range of sodium alginate (1–5% w/v) and calcium chloride (0.1–0.5 M) concentrations were used for the optimization purpose. Proteolytic activity of the protease in the alginate beads was measured as a response to the independent variables by using casein as a substrate. The highest actual and predicted proteolytic activities were at run 12 with 674.77 CDU/mg and 639.26 CDU/mg, respectively, under predetermined factors, in which the sodium alginate and calcium chloride solution concentrations were at 3.00% (w/v) and 0.30 M, respectively. The lowest actual and predicted proteolytic activities were at run 2 with the values of 77.35 CDU/mg and 71.53 CDU/mg, respectively, whereby factors include were a sodium alginate of 4.00% (w/v) and 0.20 M of calcium chloride solution. For the experimental feasibilities, the optimum conditions that was feasible to be carried out was with a sodium alginate of 2.99% (w/v) and 0.30 M calcium chloride solution. Verification for the optimum condition was performed and there was no significant difference (p > 0.05) between the predicted (638.19 CDU/mg) and verified (699.82 CDU/mg) values. Thus, indicating that the model was significant and can be used to produce the immobilize protease under the optimum condition.

Adsorption and Separation of Carbon Dioxide/Methane in Landfill Gas with Barium Ion–Modified Silica Gel

Environmental issues caused by greenhouse gases are becoming more and more severe. The main components of landfill gas, carbon dioxide (CO2) and methane (CH4), are greenhouse gases, and the separation and recovery of them are a popular research topic. In order to improve the adsorption capacity of the silica gel adsorbent for landfill gas, a method such as modify silica gel with alkali metal ions is often used. It is to improve the selective adsorption capacity of CO2 by adjusting the polarizability and charge distribution of the silica gel surface while improving the separation effect of the mixed gas. In this study, the adsorption performance of a silica gel adsorbent modified or not with alkali metal ions was measured in terms of the adsorption and separation of a CO2/CH4 mixture (simulating landfill gas). The N2 adsorption and desorption curve of the silica gel adsorbent at 77 K was plotted by determining the specific surface area and pore-size distribution. The results indicated that the unmodified silica gel adsorbent had a large micropore volume and specific surface area and exhibited a high capacity to adsorb gas. After potassium chloride, calcium chloride, magnesium chloride, or barium chloride solution was used to modify the silica gel adsorbent, the adsorption performance of the modified silica gels was ranked as barium chloride > potassium chloride > calcium chloride > magnesium chloride. The best-performing concentration of barium chloride solution was 0.1 mol/L. The research results will provide certain reference for the fields of chemistry and environmental science.

Chloride binding and desorption properties of the concrete containing corn stover ash

This study investigates the performance of binary blended concrete mixtures containing ordinary Portland cement (OPC) and corn stover ash (CSA) in terms of chloride ingress, chloride binding capacity, and resistance to chloride desorption. Concrete mixtures with water-to-cementitious material ratios of 0.45 and 0.54, and CSA replacement levels of 5 and 20% by mass of cement were prepared and exposed to various chloride solution concentrations ranging from 0.1 to 2 mol/L after 28 and 112 d of curing. Results show that pretreated CSA can improve the long-term chloride resistance of concrete, mainly due to its positive influence on promoting pozzolanic reactions. The results demonstrate that CSA concrete has a lower chloride binding capacity than OPC. However, the chloride desorption testing results in a low-pH environment suggest that CSA concrete is more durable than OPC concrete, and fewer chlorides disassociate from a drop in pH of the exposure solution.

Corrosion Characteristics of Anchor Cables in Electrolytic Corrosion Test and the Applicability of the Test Method in Study of Anchor Cable Corrosion

The selection of corrosion test method in the corrosion study of the prestressed anchors is an important issue. In this paper, the corrosion test of anchors was conducted with electrolytic corrosion test method. The corrosion characteristics of the anchor cables were examined. The effects of sodium chloride solution concentration, current, test time, and prestress level on corrosion were studied. The applicability of electrolytic corrosion method in anchor cable corrosion study is discussed subsequently. The results show that the corrosion of the anchor appears to be uniform corrosion. With the corrosion of the anchor, the central wire of the cable was basically not corroded, and the cross-sectional shape of the outer wire changes from a round to fan shape. The sodium chloride concentration and prestress level have no obvious effects on the corrosion of the anchor. The variation of test time does not affect the difference between the measured and theoretical calculated results, while a proper current in the electrolysis test may help reduce the difference. The measured corrosion rate fluctuates from −4% to 10% and tends to be higher compared with calculated results based on Faraday’s law. The study indicates that the electrolytic corrosion test is applicable in the anchor corrosion study.

Encapsulation of Extract from Unused Chokeberries by Spray Drying, Co-crystallization, and Ionic Gelation

The objective of this work is to optimize a new method of unused chokeberries application in food industries, based on the encapsulation by spray drying, co-crystallization, and ionic gelation of their phenolic extract. For each method, the effects of various parameters on efficiency and yield were studied and the optimum operating conditions were predicted. In the spray drying method, the optimum values of encapsulation efficiency (99.6%) and yield (31.9%) were achieved with a ratio of wall to core of 9.0, an air temperature of 190 °C, an air rate of 19.25 m3/h, and maltodextrin:skim milk powder (50:50) as encapsulating agent. The optimum efficiency of co-crystallization (96.3%) was achieved with a solids concentration of extract of 35 oBrix and a ratio of dry extract to sucrose of 0.7. In the ionic gelation, the optimum conditions (efficiency of 94.2%) were: concentration of sodium alginate solution of 2.0% w/w, concentration of calcium chloride solution of 2.5% w/v, and concentration of extract of 20.0% w/w. Powders encapsulated at the optimum conditions were analyzed for moisture content, bulk density, wetting time, hygroscopicity, color, sorption isotherm, release kinetics, and morphology. Furthermore, the antioxidant capacity and stability of the extracts were evaluated during storage.

Insulin accelerates recovery from QRS complex widening in a frog heart model of hyperkalemia.

Hyperkalemia is one of the most common electrolyte disorders. By injecting various concentrations of potassium chloride (KCl) solutions intravenously into bullfrogs, we demonstrated characteristic electrocardiogram (ECG) abnormalities of hyperkalemia in frog hearts. The widened QRS complexes induced by 100 mM KCl injection were accompanied by an increase in the resting membrane potential in cardiomyocytes and a decreased slope of phase 0 in the action potential. Recording both ECG waveforms and the cardiac action potential enabled us to reveal the mechanisms of hyperkalemia-induced ECG abnormalities. Additionally, pre-treatment with insulin, a powerful stimulator of Na+/K+-ATPase activity, significantly accelerated the recovery from the widened QRS complexes in the ECG, demonstrating a pronounced shift of extracellular potassium ions into the intracellular space.

ELECTROLYSIS TREATMENT OF AMMONIUM CHLORIDE WASTEWATER BY DOUBLE CHAMBER MEMBRANE PROCESS

Aiming at the problem that ammonium chloride wastewater generated from the rare earth and fertilizer industries is difficult to treat, combining with the actual case of a factory in Guangdong province that produced a large amount of ammonium chloride waste solution in the treatment of alkaline copper chloride etching liquid, this paper put forward the method of electrolysis to treat ammonium chloride wastewater and probed into the optimal experimental conditions. It was found that the anion exchange membrane was used to separate the electrolytic cell into a bipolar chamber, which could prevent the contact between chlorine gas and ammonium ion from producing explosive nitrogen trichloride, ensure the safety of operation, and effectively separate chlorine gas from the anode and hydrogen from the cathode, so as to facilitate products collection. On this basis, through exploring the impact of anode chamber and electrolyte concentration, cathode chamber ammonium chloride solution concentration, electrolytic time on treatment effect, optimized experimental condition was as follows:20 mL 5 g/L sodium chloride solution in the anode chamber, 20 mL 100 g/L of ammonium chloride solution in the cathode chamber, constant current of 0.3 A, and electrolysis time of 3 hours, then 93% of chloride ions were transformed into chlorine and sodium hypochlorite. Under this condition, the factory could make an income of at least RMB 1950 by treating 15 t of ammonium chloride waste liquid per day. The membrane electrolysis method could effectively remove chloride ions from ammonium chloride wastewater and produce chlorine gas, sodium hypochlorite and ammonia water. Compared with the traditional electrochemical treatment technology, it had the advantages of simple device and high removal rate, with controllable reaction rate.

Evaluating of efficiency of concentrated sodium chloride solutions conversion processes for obtaining aluminum coagulant

In this work, the processes of sodium chloride solutions electrochemical processing in order to obtain aluminum chloride and alkali in a three-chamber electrolyzer with anion exchange membrane MA-41 and a cation exchange membrane MС-40 and in a two-chamber electrolyzer with a cation exchange membrane МС-40 were investigated. The presented method of processing salt concentrates using a soluble aluminum anode is economically feasible, as the electrolysis simultaneously demineralizes liquid waste to the level of regulatory requirements and production from source concentrates of marketable products. The disadvantage of this method of obtaining a coagulant is the interaction of aluminum with water. However, it is proved that with increasing anodic current density during electrolysis, the yield of aluminum chloride is almost entirely due to the electrochemical dissolution of the anode, and the chemical dissolution of aluminum is almost absent. The stability of the obtained solutions of coagulants for a long time is maintained by low values of the reaction medium (pH ≤ 3). Thus, at a current of 1A (current density 8.34 A/dm2) and an initial concentration of sodium chloride of 1900 mg-eq/dm3, the total concentration of aluminum ions in the resulting solution reaches 3884 mg-eq/dm3. Chemically dissolved aluminum is not more than 12 %. According to the initial parameters, the yield of aluminum ions, taking into account the chemical dissolution of the anode is 100–108 %. At the same time in the cathode chamber is the concentration of alkali to a level of approximately 1500 mg-eq/dm3. Its current output reaches 92 %. The degree of diffusion of chloride ions through the anion exchange membrane from the working chamber into the anode region is 99 %. It is shown that the process of sodium chloride solution electrolysis in a two-chamber electrolyzer with a cation exchange membrane is not as efficient as when using a three-chamber electrolyzer. At the initial stage of the process, the current yield is 61 % for aluminum chloride and 64 % for alkali. Subsequently, due to the poisoning of the cation exchange membrane by aluminum cations, which block all the anionic functional groups of this membrane, the process stops.

Preparation of the Orange Flavoured “Boba” Ball in Milk Tea and Its Shelf-Life

Boba milk tea is very popular around the world. The “boba” balls in milk tea are usually made of tapioca. Reports on calcium alginate ball encapsulation in fruit-flavoured drinks have rarely been seen. The preparation method for this kind ball was studied. The “boba” balls were obtained by membrane formation on the interface through the addition of calcium chloride fluids into a sodium alginate solution. The operation conditions were studied, including drop height, flow velocity, sodium alginate and calcium chloride solution concentration. The diameter, mechanical strength, loading ratio and encapsulation rate of the “boba” balls are discussed. The optimized preparation conditions were as follows: the diameter of adding tube was 8 mm, the drop height was 25 cm, the drop flow rate was 60 mL/min, 1.0% sodium alginate, 1.0% calcium chloride. The prepared “boba” balls were stored at different temperatures. No microorganisms were detected in 90 days, and the sensory quality decreased with storage time. Shelf life was predicted using the Arrhenius equation; when the storage temperature was less than 10 °C, it could be stored for more than 1 year. This preparation technology of “boba” balls has potential for application by milk tea ingredient companies or relevant beverage manufacturing factories.

Reactivity of Zinc Cations under Spontaneous Accumulation of Hydrophobic Coexisting Cations in Hydrophobic Nanoporous Silicon.

The ion enrichment behavior due to surface-induced phase separation and the concomitant phase transition of electrolyte solutions between a liquid and a solid confined within nanopores of porous silicon is examined using concentrated aqueous solutions. We performed open-circuit potential measurements and differential scanning calorimetry (DSC) while varying the concentration of aqueous tetraethylammonium chloride (TEACl) solution. Open-circuit potential measurements revealed that the local OH– concentration within the nanopores increases as the bulk TEACl concentration increases. DSC measurements indicated that TEA+ cations are enriched within the nanopores and an extremely high concentration of TEA+ remarkably increases the local OH– concentration. This increase in the local pH should realize the selective precipitation of metal hydroxides within the nanopores. However, such precipitation was not observed in our investigations using aqueous solutions containing zinc cations. The experimental results suggest that ionic species within the nanopores of porous silicon are more stable than those in a bulk solution due to the formation of ion pairs with enhanced stability as well as kinetic factors that increase the activation energy for precipitation.

Effect of expired paracetamol–Zn+2 system and its synergistic effect towards iron dissolution inhibition and green inhibition performance

Chemical and electrochemical techniques were used to evaluate the effect of expired paracetamil–Zn+2 systems (PC–Zn+2) as potential nontoxic inhibitor for the dissolution process of iron in 2.0 M sodium chloride corrosive solution. The chemical techniques used in this work are gravimetric, thermometric and atomic absorption spectroscopy (AAS), whereas the electrochemical techniques are open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. The dissolution inhibition efficiencies of the used system (PC–Zn+2) were increased with increasing mixed inhibitor concentrations and rising temperature, with significant synergistic effect between expired paracetamol drugs and zinc acetate, the values of polarization resistance (R p) was increased and the capacitance of the interface (C dl) was decreased in the presence of mixed inhibitor system (PC–Zn+2) more than in case of individual inhibitors. Potentiodynamic polarization curves indicate that the used system act as a mixed inhibitor for the dissolution of iron. The inhibition of corrosion is due to adsorption of (PC–Zn+2) on the metal surface and formation of barrier film that separates the metal from the corrosive medium and the inhibitor adsorption was obeying Langmuir adsorption isotherm. The corrosion inhibition is due to adsorption, adhesion of the inhibitor molecules, and formation of a protective layer on the steel surface. The data obtained from different techniques are in good agreement with each other to indicate the possibility of using expired paracetamol drugs—Zn+2 mixed system as eco-friendly corrosion inhibitor for iron in concentrated corrosive sodium chloride solution.

Review of Mg alloy corrosion rates

A review of the literature confirmed that the intrinsic corrosion rate of high-purity Mg as measured by weight-loss is 0.3 mm/y in a concentrated chloride solution. Atmospheric corrosion of Mg alloys has produced corrosion rates of Mg-Al alloys an order of magnitude lower than the intrinsic corrosion rate of Mg in a concentrated chloride solution of 0.3 mm/y. The only successful strategy to produce a Mg alloy with a corrosion rate in a concentrated chloride solution substantially less than the intrinsic corrosion rate as measured by weight loss of Mg of 0.3 mm/y has been to improve the protectiveness of the corrosion product film.

Migration characteristics of chloride in concrete of subsea tunnel under pressure

A self-made pressure control device was developed to study the migration characteristics of chloride in concrete under pressure. The effects of water pressure, pressurized time, strength grade, water-binder ratio, chloride diffusion coefficient, saturation degree and solution concentration on chloride migration are determined. Considering with pressure, the theoretical model of velocity varies with time and position is established. The formula of water permeation depth is obtained. On this basis, the chloride migration model under the coupling of pressure permeation and diffusion is established, and compared with the chloride concentration obtained from the experiment.

Transcriptional and metabolite analysis reveal a shift in fruit quality in response to calcium chloride treatment on "Kyoho" grapevine.

'Kyoho' grapevine (Vitis vinifera) treated by calcium ions solution has been proved as an effective treatment to extend grape quality during storage to reduce disease, but its molecular mechanism was not clear yet. In the current work, grape berries were treated with different concentration of Calcium chloride (CaCl2) solution, and their effects on antioxidant enzyme activity and transcriptome and metabolome in fruit were investigated. CaCl2 treatments reduced weight loss and inhibited the decrement of flesh firmness. 80mM CaCl2 significantly increased the activity of antioxidant enzymes POD, SOD and CAT, which was the optimum experimental concentration. The study showed that the expression level of heat shock transcription factor and UBX which involved in endoplasmic reticulum stress and degradation pathway increased significantly. Moreover, the corresponding metabolites, such as heat shock protein and organic acid, also increased significantly. The misfolded proteins are transported to the cytosol for degradation, so that the preservation ability of grape is improved.

Coprecipitation—An Efficient Method for Removal of Polymer Nanoparticles from Water

Increasing concentrations of micro- and nanoparticles of common polymers are beginning to cause significant damage to our environment. Techniques such as coagulation and flocculation are commonly used for the removal of particles from water. As a proof of concept, here we investigate the removal of synthetic poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) nanoparticles from aqueous solution through the calcium carbonate (CaCO3) coprecipitation method. The physical entrapment and negative surface charges of the polymer particles play a significant role toward the efficient removal during coprecipitation. Critical parameters, such as the amount of solid precipitated, contact time, interfering ions, and initial concentrations of sodium carbonate and calcium chloride solutions were optimized for maximum removal of polymeric nanoparticles. Our study shows that equilibrium was established within 30 min for the complete removal (99%) of both PMMA and PVAc nanoparticles, using relatively low concentrations of Na2CO3 and CaCl2 solutions. The results also imply that such a simple and efficient coprecipitation method using natural and nontoxic materials could be used as an alternative method for the removal of plastic nanoparticles and other pollutants from water.

Using highly concentrated chloride solutions to leach valuable metals from cathode-active materials in spent lithium-ion batteries

This study focused on the extraction of valuable metals from the cathode-active materials in spent lithium-ion batteries using a high-concentration chloride solution. The effects of the concentrations of ammonium chloride (NH4Cl), hydrochloric acid (HCl), and reductants such as hydrogen peroxide (H2O2) and urea (CO(NH2)2) on metal extraction and chlorine production were studied experimentally. The leaching mechanism was analyzed, and a leaching model was established. It was found that the addition of solid NH4Cl to an HCl solution significantly improved the metal extraction capability of the latter and reduced the formation of chlorine gas by 96.0% compared to that only using HCl. The activation energies for leaching Li, Ni, Co, and Mn were determined to be 30.4, 38.5, 30.6, and 38.2 kJ·mol−1, respectively. This study demonstrates an environmentally friendly method for recycling metal resources from cathode-active materials and furthers understanding of how NH4Cl inhibits chlorine production when leaching with mixed solutions of HCl and NH4Cl.

Speciation of copper in high chloride concentrations, in the context of corrosion of copper canisters

AbstractCanisters with a cast iron insert for mechanical strength and a 50‐mm thick copper shell as corrosion protection are planned to be used for disposal of spent nuclear fuel in Sweden and Finland. Chloride can be considered “beneficial”, as it promotes active dissolution of copper rather than passivation (which might result in pitting), but a high concentration of chloride in solution would increase the driving force for corrosion through the formation of soluble copper chloro complexes. Thermodynamic calculations are performed in this study with the PHREEQC software and three of its accompanying databases, and a comparison with experimental data is performed to select the database to be used when evaluating repository performance. The activity coefficient models are given special attention. For the assessment of chloride‐assisted corrosion of a KBS‐3 canister, chloride concentrations pessimistically up to 5 mol/kg are used (in Finland and Sweden, the groundwater and bentonite porewater chloride concentrations are not expected to exceed 1 mol/kg). The resulting copper solubilities are then considered in different mass transport cases.

Effect of ferric chloride concentration on the surface micro-nano structure and superhydrophobic property of filter paper

Effect of ferric chloride concentration on micro-nano structure surface and superhydrophobic property of filter paper was investigated by adsorption and simple immersion process. The results showed that the concentration of ferric chloride solution had great impact on the superhydrophobic property of filter paper. When the concentration was 0 mol/L, filter paper presented hydrophilicity. When the concentration was bigger than 0 mol/L, it exhibited hydrophobicity. The modified filter paper’s surface displayed advancing contact angels of 167 ± 2°, which was attributed to its’ formed micro/nano structure. This may contribute to the development in production applications.

Adsorption of Iron(III) Ions on Porous Glass with Different Pore Space Structures

The article studies the adsorption of iron ions from solutions of iron(III) chloride with a concentration of 10–4–10–3 M at pH 3 on micro- and macroporous glass, as well as on microporous glass heat-treated at 750°C, obtained from two-phase sodium borosilicate glass. It is found that the adsorption values at a constant concentration of the iron chloride solution are a function of the structural parameters of the porous glass (PG). It is shown that the Freindlich and Langmuir adsorption isotherms can be used to analyze the experimental data and the constants of these isotherms are found. In the systems studied, adsorption mainly occurs via the monolayer mechanism.

Experimental and Numerical Investigation of the Effect of Bedding Layer Orientation on Fracture Toughness of Shale Rocks

Fracture toughness is a critical parameter responsible for fracture initiation and propagation. Fracture toughness in shale gas reservoir, however, is highly variable because of its anisotropy and spatial variation of clay content. In this paper, a series of laboratory and numerical experiments are carried out to estimate shale fracture toughness at different bedding plane orientations with respect to loading direction (angle of bedding layer with respect to Cracked Chevron notched Brazilian disc (CCNBD) test samples) and in different brine solutions. The CCNBD test was conducted on 12 cylindrical samples for fracture toughness. Shale samples were prepared at four different angles (0°, 30°, 45° and 90°) relative to the bedding plane. The prepared specimens were saturated in potassium chloride (KCL) solutions of different concentrations. The laboratory results of toughness have shown to be highly variable with respect to both bedding plane and brine concentration and that the sample at the angle of 90° in 4% KCL concentration exhibited the highest fracture toughness. Numerical simulations based on extended finite element method (XFEM) were also carried out to simulate fracture evolution and propagation in CCNBD samples with different bedding planes. The results have shown that the bedding layers caused the fracture path to deflect. The deviation from straight crack path is caused by mixed mode fracture initiation and propagation instead of tension mode. The mixed mode fracture propagation behavior was verified by analyzing fracture propagation path using both laboratory experiments and numerical simulation.