High Concentration Of Chloride Ions Research Articles

Experimental Study on Chloride Ion Removal in High-Salt Wastewater System

Chlorine is usually present in the environment in an ionic state, is highly mobile and difficult to degrade. High-chlorine wastewater can corrode buildings and affect the growth of animals and plants. Therefore, how to solve the environmental problem of high concentration of chloride ions well and effectively has drawn the intensive attention of the society. In this paper, chloride ion is removed from wastewater with the method of coprous chloride precipitation, and investigation is made on the effects of pH, temperature, amount of precipitant, titration time and reaction time on the removal efficiency of chloride ions. The results show that: when nCuSO4:nNa2SO3:nNaCl: n(ascorbic acid) =1.3:1.1:1: 0.01, and reaction pH is 3, temperature is 80 °C, titration time of sodium sulfite is 20min, reaction time after titration is 30min, the chloride ion has the optimal removal efficiency. SEM method is used for the characterization of the precipitates formed by the reaction. The results show that the experimentally produced complex cuprous chloride is irregular polyhedron with uneven particle size.

ОЦЕНКА ЗАГРЯЗНЕНИЯ ХЛОРИД-ИОНАМИ МАЛЫХ РЕК НИЖНЕВАРТОВСКОГО РАЙОНА

Важное значение в оценке экологической ситуации в Ханты-Мансийском автономном округе представляют концентрации химических веществ в поверхностных водах и донных отложениях, которые характеризуют техногенные потоки загрязняющих веществ в районах нефтепромыслов. Хлоридное загрязнение малых рек приводит к их накоплению в донных отложениях. Высокие концентрации хлорид-ионов в поверхностных водах и донных отложениях негативно воздействуют на речную экосистему.

Lead Chlorides in Paint on a Della Robbia Terracotta Sculpture.

Materials in the paint layers of an early 16th-century painted and glazed terracotta sculpture by Giovanni della Robbia, Pietà, were identified. The presence of the rare lead chloride salts cotunnite (PbCl2) and challacolloite (KPb2Cl5) was confirmed using Raman spectroscopy and electron backscatter diffraction. The well-formed habit of large crystals of challacolloite indicates slow growth from solution. The stability and potential pathways for the in situ formation of lead chloride compounds are discussed. The presence of lead chloride phases in the Pietà indicates the conditions of high chloride ion concentrations (i.e., activities) and/or low pH led to the alteration of the pigment lead white (hydrocerussite, 2PbCO3·Pb(OH)2). This work highlights the role of ion transport in the alteration of materials in cultural heritage objects, emphasizes the importance of considering the role of treatments and environmental factors in changes in materials, and reinforces our awareness of the ongoing chemistry occurring in works of art.

Atmospheric corrosion of carbon steels in tropical and subtropical climates in Southern China

AbstractQ235 and Q345 carbon steels were exposed for up to 24 months at three test sites of tropical and subtropical climate. The atmospheric corrosion kinetics of Q235 and Q345 was studied by weight‐loss measurement. The results show that the ranking of the atmospheric corrosivity from weak to strong of the three test sites is Xishuangbanna, Guangzhou, and Wanning. The kinetics of the atmospheric corrosion process presents two stages with an accelerated second stage in marine environments of high chloride ion content and high relative humidity, whereas no second stage appears in the kinetics curves in rural and industrial urban environments. The corrosion acceleration stage in the marine environment of the Wanning site is attributed mainly to the high chloride ion concentration and loose rust layer structure.

Prediction of chemical oxygen demand (COD) with total organic carbon (TOC) to eliminate the interferences of high concentration of chloride ion in oilfield wastewaters

ABSTRACT Chemical oxygen demand (COD) is one of the most commonly used indexes for monitoring water quality. However, the accuracy of the conventional COD test is significantly affected by the high concentration of chloride ion in water samples. In addition, the conventional COD test results in the production of hazardous wastes including mercury and hexavalent chromium. This study proposed the prediction of COD with total organic carbon (TOC) for monitoring high-chloride wastewater by comparing their relationship using simulated wastewaters and actual oilfield wastewaters from two wastewater treatment stations at Xinjiang oilfield, China. The theoretical analysis and experimental results showed that there are significant linear correlations between the COD and TOC in simulated wastewaters and actual oilfield wastewaters. High correlation coefficients (R) of 0.9777 and 0.9710 between COD and TOC were obtained for oilfield wastewaters from Xinjiang 81# and 91# stations, respectively. By using the established conversion models, the COD values in the two groups of mixed oilfield wastewaters from Xinjiang 81# and 91# stations were successfully predicted, with relative errors <±5%. It was demonstrated that the proposed method could be promisingly used as an alternative for the green determination of COD values in high-chloride oilfield wastewaters while eliminating the hazardous wastes and chloride interferences.

How GABA makes the switch

Neurodevelopment A high concentration of chloride ions in neurons interferes with signaling mediated by the neurotransmitter γ-aminobutyric acid (GABA). The transporter KCC2 extrudes chloride ions, and Watanabe et al. and Pisella et al. examined mice expressing KCC2 with mutations that mimicked constitutive phosphorylation at two regulatory sites (see the Focus by Zamponi). Dephosphorylation of these sites in KCC2 enables GABA to switch from being an excitatory to being an inhibitory neurotransmitter during neurodevelopment, thus allowing the maturation of the neurocircuitry underlying cognition and respiration. Sci. Signal. 12 , eaaw9315, eaay0300, eaay8960 (2019).

Protective Mechanism of Silane on Concrete upon Marine Exposure

Due to the high chloride ion concentration in marine environments, chloride ions can penetrate into concrete, along with the transportation of water molecules, and thus, cause rebar corrosion. This is an important reason for the decrease in the concrete durability. In this paper, by means of the sol–gel synthesis method, a silane emulsion, a silane compound emulsion, and silane compound gel were prepared by using isobutyl triethoxysilane and ethyl orthosilicate (TEOS) as the main raw materials. These silane materials were coated on a concrete surface and then placed in the marine exposure sites of Wheat Island, in Qingdao, for one year. The results show that these silane materials can effectively inhibit the chloride ions transporting in concrete. Upon the increase of the exposure time, the protection ability of the silane emulsion declined gradually, while the silane compound emulsion had stable protective effects. In comparison with the permeability coefficient of chloride ions in the blank test block, the permeability coefficient of chloride ions in the test block coated with the silane emulsion, the composition of silane emulsion, and silane compound gel fell off around 20%, 30%, and 50%, respectively. The test results indicate that the three kinds of protective materials have good inhibition abilities against chloride ion transportation, on which the compound gel had the best effect.

Removal and recovery of chloride ions in concentrated leachate by Bi(III) containing oxides quantum dots/two-dimensional flakes

The high concentration of chloride (Cl−) ions in leachate often has negative effects in their harmless treatments, and the common treatments containing the ion exchange method consume excessive antichlors due to their large particle sizes and unfavorable morphologies. Herein, the antichlors of the Bi(III) containing oxides with quantum dots (QDs) or two-dimensional (2D) structures are first explored for the removal and recovery of Cl− ions in concentrated leachate. By using the QDs/2D flakes constructed antichlors of Bi2O3 and the magnetite Bi-Ti composite, the maximum Cl− removal rates of 61.8% and 66.1% are respectively achieved under the optimum conditions. The higher removal efficiency of the magnetite Bi-Ti composite is contributed by its less stable crystal phases of Bi25FeO40/Bi12TiO20, which can proceed more deeply in the removal of Cl− ions compared with that of Bi2O3. The recovered terminal magnetite Bi-Ti precipitate with Bi2O3/BiOCl heterostructure exhibits excellent photocatalytic activity in the degradation of the dechlorinated leachate, where a total organic carbon removal rate of 87.2% is achieved under UV–vis-near-infrared irradiation. Therefore, the selection of Bi(III) containing oxides opens a promising and high-value method for the removal and recovery of Cl− ions in leachate and other waste waters.

Modelling the kinetics of chalcocite leaching in acidified cupric chloride media under fully controlled pH and potential

The use of seawater in heap leaching of secondary copper sulfide minerals is a feasible alternative to freshwater in regions with limited freshwater supply. Seawater contains high concentrations of chloride ions that facilitate the formation of cupric/cuprous chloride complexes. The cupric ions formed can serve as an oxidizing agent for chalcocite oxidation. Even though copper leaching in chloride media has been well studied, most of the kinetics data were collected under uncontrolled leaching conditions. In this study, we modelled chalcocite leaching kinetics in chloride media using leaching data collected under fully-controlled pH and solution potential. Specifically, we carried out leaching tests with high-purity chalcocite sample in jacketed reactors to quantify the effects of chloride concentration, cupric concentration, particle size, and temperature on the copper extraction rate. The experimental results show that increases in chloride concentration and temperature remarkably enhanced the leaching rate; chalcocite leaching was insensitive to the initial cupric chloride concentration. Using the leaching data collected, we derived two individual kinetic models to describe the first and second stage of chalcocite leaching. This study provides fundamental kinetic models for predicting the performance of chalcocite leaching in cupric chloride for heap leach operations that intend to use seawater.

Laboratory Investigation on the Fresh, Mechanical, and Durability Properties of Roller Compacted Concrete Pavement Containing Reclaimed Asphalt Pavement Aggregates

The present study evaluates the potential and suitability of different fractions of reclaimed asphalt pavement (RAP) for roller compacted concrete pavement (RCCP) mixes. Natural coarse and fine aggregates were replaced, partially and in combination, by coarse RAP, fine RAP, and combined RAP for preparation of RCCP mixes. The considered properties to determine the optimum RAP fraction and its proportion for RCCP were fresh density and water demand, compressive strength, flexural strength, split tensile strength, porosity, water absorption, abrasion resistance, and performance in aggressive environments of chloride- and sulfate-rich ions. It was observed that inclusions of all the fractions of RAP considered could reduce the strength related properties of RCCP mixes significantly at all curing ages. However, fine RAP mixes were found to exhibit better strength properties than coarse RAP and combined RAP mixes. It was also observed that none of the RAP mixes could achieve the recommended compressive strength criterion of 27.6 MPa, however, they exhibited enough flexural strength to replace a fraction of conventional aggregates, individually or in combination, for construction using RCCP. In fact, 50% coarse and 50% fine RAP mixes had higher flexural strength than the target laboratory mean strength of 4.3 MPa. Similarly, these mixes were found to have sufficient abrasion resistance and could be included in RCCP (surface course) to be constructed in areas having high concentrations of chloride and sulfate ions. Additionally, the results also indicated that higher proportions of fine RAP may be suggested for RCCP mixes to be laid in sulfatic environments.

Influence of temperature and chloride ion concentration on the corrosion behaviour of Mg–4Al–3Ca–0.5RE alloy

AbstractThe influence of temperature and chloride ion concentration on the corrosion behaviour of Mg−4Al−3Ca−0.5RE alloys were studied in this paper. Corrosion rates of the alloys were measured by weight loss test and electrochemical measurement. The results revealed that a shorter incubation period to the onset of corrosion, a more negative corrosion potential, and a higher corrosion rate was correlated with a higher temperature in 3% NaCl solution and a higher chloride ion concentration at 30°C. The corrosion behaviour of the alloys was affected by surface film and the corrosion mainly occurred at the breaks or defects in surface films.

An Ionic Limit to Life in the Deep Subsurface.

The physical and chemical factors that can limit or prevent microbial growth in the deep subsurface are not well defined. Brines from an evaporite sequence were sampled in the Boulby Mine, United Kingdom between 800 and 1300 m depth. Ionic, hydrogen and oxygen isotopic composition were used to identify two brine sources, an aquifer situated in strata overlying the mine, and another ambiguous source distinct from the regional groundwater. The ability of the brines to support microbial replication was tested with culturing experiments using a diversity of inocula. The examined brines were found to be permissive for growth, except one. Testing this brine’s physicochemical properties showed it to have low water activity and to be chaotropic, which we attribute to the high concentration of magnesium and chloride ions. Metagenomic sequencing of the brines that supported growth showed their microbial communities to be similar to each other and comparable to those found in other hypersaline environments. These data show that solutions high in dissolved ions can shape the microbial diversity of the continental deep subsurface biosphere. Furthermore, under certain circumstances, complex brines can establish a hard limit to microbial replication in the deep biosphere, highlighting the potential for subsurface uninhabitable aqueous environments at depths far shallower than a geothermally-defined limit to life.

Chemical composition of salt lakes in East Transbaikalia (Russia)

We have developed a new concept on the formation of diverse geochemical types of salt lakes, in particular for those in the Transbaikal region. This concept explains the nature of their different chemical composition under the close landscape-climatic and geological-geochemical conditions. The extensive hydrogeochemical field data and thermodynamic calculations demonstrate that in addition to evaporation, interactions with rocks play a substantial role in the formation of the composition of these salt lakes. Such processes are most widespread in soda lakes, which is confirmed by the highest pH values (9.0–10.7). These lakes provide evidence of the interaction of the lake waters with aluminosilicates; their hydrolysis provides a pH increase and consequently a high concentration of carbonate ions. These high pH and HCO3− and CO32− contents in turn lead to the maximum precipitation of Ca, Mg and Fe carbonates. Soda lakes also contain high chloride ion concentrations, since a small portion of those ions evaporate under the lake conditions. If evaporation continues and the amount of carbonate ions in the lake does not increase, or increases slowly due to binding with carbonate minerals, the chlorine content becomes higher, the pH lowers to less than 9.0, and the lakes become chloride. Another fundamental process in these lake environments is sulphate reduction, which results in the production of hydrogen sulphide, fundamentally changing the geochemical environment from oxidizing to reducing. The presence of an oxidizing environment and sulphides in rocks gives additional sources for sulphates, which ensures the formation of sulphate-type lakes.

Passivity breakdown of 13Cr stainless steel under high chloride and CO2 environment

Herein, the effect of high chloride ion (Cl−) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO2 environment was demonstrated. The Cl− concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl− concentration on the corrosion potential (Ecorr), passive breakdown potential (Epit), and repassivation potential (Erep). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl− concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl− concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model (PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl− concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film.

Corrosion Behaviour of 316L Stainless Steel in Hot Dilute Sulphuric Acid Solution with Sulphate and NaCl

The corrosion behaviour of 316L stainless steel (316L SS) in 10% H2SO4 solution (94°C) with various concentrations of NaCl (0–0.085 mol/L) was studied by immersion corrosion test and polarization methods, combined with SEM/EDS, XPS and XRD tests. The influence of NaCl on the corrosion of 316L SS was investigated. The results showed that at lower NaCl contents (0–0.0085 mol/L), the steel presented a general corrosion characteristic with a higher corrosion speed and the corrosion rate increased with the NaCl content. At higher NaCl contents (≥0.017 mol/L), the corrosion rate decreased remarkably due to the protective corrosion products precipitation which contained metallic sulphates and NaHSO4. However, the higher concentration of chloride ions caused micron pitting-like local dissolution on the surface. The addition of Na2SO4 effectively inhibited general corrosion of the steel because of a dense and continuous products layer enriched with more NaHSO4 and metallic sulphates formed.

Effects of the Sn ion on the formation of iron oxy-hydroxide in an acidic FeCl3 solution

Abstract In this work, we investigated the effects of Sn ions and the co-existing anions on the formation of β-FeOOH from an Fe3+ solution under atmospheric corrosion conditions and a high chloride ion concentration. By adding a small amount of Sn ions into an FeCl3 acidic solution, α-FeOOH instead of β-FeOOH was formed in the precipitate, regardless of the coordination and valence of the Sn ion. The added Sn2+ affected the coordination of Fe3+ and presumably formed a dinuclear complex with Fe. As a result, Sn2+ inhibited the polymerisation of β-FeOOH, and played a role in catalysing the ligand exchange of Fe3+ and the formation of α-FeOOH.

Iron in Glacial Systems: Speciation, Reactivity, Freezing Behavior, and Alteration During Transport

A more insightful view of iron in glacial systems requires consideration of iron speciation and mineralogy, the potential for iron minerals to undergo weathering in ice-water environments, the impact of freezing on concentration and speciation, and potential for glacial delivery to undergo alteration during transport into the ocean. A size fractionation approach improves recognition of iron speciation by separating dissolved Fe (0.1 wt. %) which represent samples in which the on-going transformation of ferrihydrite to goethite/hematite is incomplete. Numerical models of freezing in subglacial systems show that the nanomolar levels of soluble Fe in icebergs cannot be achieved solely by freezing, and must indicate the presence of nanoparticulate Fe and/or iron desorbed from ice or sediments during melting. Models of freezing effects in sea ice show that nanomolar levels of Fe are achievable because high concentrations of hydroxide and chloride ions maintain dissolved iron as soluble complexes. Delivery of iron through fjords is temporally and spatially variable due to circulation patterns, mixing of different sources and aggregation through salinity gradients.

EFFECT OF SALT COMPOSITION ON THE SEPARATION PROFILE OF CONTAMINATED GROUNDWATER IONS BY ELECTRODIALYSIS

Chloride, nitrate, sulfate, and fluoride ions are sometimes available in groundwater at an elevated level, which is harmful to humans and the environment. The membrane separation technique has been widely explored for controlling the level of those ions in drinking water, particularly the electrodialysis method. In the present study, divalent (AMX) and monovalent ion selective (ACS) anion exchange membranes were used to remove the high concentrations of chloride and other co-existent ions from groundwater samples. The study focuseson the effect of the composition of the salt in the groundwater on the reducing profile of ions, the number of deionized ions, and the rate of ion removal in the diluting compartment. To achieve these experimental objectives, two series of ion samples composed of sodium and calcium were designed. The compositions of the ions wereNaCl, Na2NO3, Na2SO4 for the Na-compound, and CaCl2, Ca(NO3)2.4H2O, CaSO4∙2H2O, and CaF2 for the Cacompound. The electrodialysis experiment was run at a constant applied voltage (8 volts), using sodium nitrate as the electrode solution. In summary, the ED performance for all the investigated parameters was better in the case of ions composed of sodium. Furthermore, a change in the applied current against the electrodialysis operation time was also observed. The results indicated that the current requirement by ED to separate ions composed of calcium needed to be slightly higher than that for ions composed of sodium.

The effect of organic additives for the prevention of copper electrochemical migration

This study describes a method to prevent electrochemical migration (ECM) using additives, polyethylene glycol (PEG) and imidazole, at different chloride ion concentrations by the water drop test and electrochemical test. The addition of PEG increased the ECM time at high chloride ion concentration, while imidazole increased the ECM time at both low and high concentrations of chloride ions. Also, the rates of dendrite formation and growth varied depending on both the additive and chloride ion concentration, which could be ascribed to the different inhibition mechanisms; the PEG inhibited the initial formation of dendrites by the ether-group, whereas imidazole inhibited both initial formation and the growth of dendrites by heterocyclic organic compound. The surface analysis indicated that the dendrite structures in all solutions consisted of a mixture of trunk and lace types, and the PEG and imidazole did not affect the composition of dendrite.

Leaching of chalcopyrite ore agglomerated with high chloride concentration and high curing periods

It is well known that the leaching of chalcopyrite has very slow kinetics. The generally higher reactivity of chalcopyrite in chloride as opposed to sulfate solutions has resulted in many studies of chloride systems for the hydrometallurgical treatment of chalcopyrite. Despite much progress on the chloride leaching process, agglomeration and curing has received less attention over the past years. This paper reports a study on the effect of addition of chloride ion in the agglomeration and the effect of curing time on the overall leaching process of chalcopyrite ore. The work involved leaching tests carried out in columns containing 3.0 kg of agglomerated ore irrigated with raffinate solution under ambient conditions. Experiments with agglomerates produced at different concentration of chloride (20, 50 and 70 kg/t) leach at approximately the same rate. It has been demonstrated that chloride ions presence is necessary to improve the leaching kinetics, but high concentrations of chloride are not essential under ambient conditions. The rate of dissolution of chalcopyrite ore agglomerated with high concentrations of acid and chloride ions increases as the curing period increases from 15 to 80 days observing extraction of copper up to 60% in 20 days of leaching. In all experiments, the shape of the leach curves indicate that the copper that has been solubilized during the curing period is rapidly leached followed by continuous slow leaching thereafter. This study supports the addition of chloride at the agglomeration stage as a viable route for the treatment of low-grade copper sulfide ore.