Effect Of Carbonate Ions Research Articles

Effect of nano-Ti-Li-Al hydrotalcite-like on the hydration and hardening properties of sulfoaluminate cement-based materials

The use of sulfoaluminate cement-based materials (SCBMs) in grout reinforcement projects is common, and they also perform well in road repair and other facilities. To obtain high workability and permeability, a large water-to-cement ratio is generally used, which reduces the early mechanical properties of SCBMs. The early mechanical properties of cement-based materials can be improved by adding nanomaterials. The cement hydration product monosulfate (AFm) belongs to the hydrotalcite-like family, which is also called layered double hydroxide (LDHs). At present, there is no literature on the influence of nano-Ti-Li-Al layered double hydroxide materials (TiLiAl-LDHs) on SCBMs. In this study, two types of nano -TiLiAl-LDHs with different Ti/Li/Al molar ratios (Ti1Li3Al4-LDHs and Ti2Li3Al4-LDHs) were synthesized. Nano-Ti1Li3Al4-LDHs promoted the hydration of the slurry and improved the early mechanical properties of SCBMs to a greater extent than nano-Ti2Li3Al4-LDHs. However, the cause of this phenomenon remains unclear. Nano-TiLiAl-LDHs act as nucleation sites for ettringite (AFt) and AFm, both of which are cement hydration products. Among them, Ti1Li3Al4-LDHs preferentially provided nucleation sites for AFt, whereas Ti2Li3Al4-LDHs preferentially provided nucleation sites for AFm. Ti1Li3Al4-LDHs and Ti2Li3Al4-LDHs can release titanium, lithium, and carbonate ions in the SCBMs paste, and Ti1Li3Al4-LDHs release more lithium ions (up to 50 mg/L) while Ti2Li3Al4-LDHs release more titanium ions (up to 100 mg/L). Li+ can consume AlO2− and OH− in the slurry and form amorphous lithium aluminum compounds. Although Li+ inhibits the formation of AFt products, it promotes the hydration of anhydrous calcium sulfoaluminate (ye’elimite). Ti4+ reacts with OH− to form a complex that inhibits the formation of AFt, thus reducing the hydration of SCBMs. CO32− promotes the formation of calcium carbonate and indirectly promotes the dissolution of ye’elimite and gypsum. The nucleation effect and release of titanium, lithium, and carbonate ions acted synergistically to influence the hydration and hardening processes of SCBMs. Compared with Ti2Li3Al4-LDHs, Ti1Li3Al4-LDHs has a greater ability to enhance the hydration and mechanical properties of the slurry owing to its strong nucleation and release of higher concentrations of lithium ions and lower concentrations of titanium ions.

Enhancement in clinker hydration degrees and later stage-ettringite stability of calcium sulfoaluminate cements by the incorporation of dolomite

The hydration degrees of clinkers and ettringite stability in calcium sulfoaluminate (C A) cements in the presence of externally supplied dolomite were investigated in this study. The mineralogical and microstructural characteristics of C A cements containing different dosages of dolomite were characterized using X-ray diffractometry, Rietveld refinement-based quantification analysis, thermogravimetry analysis, mercury intrusion porosimetry, scanning electron microscopy observation, and energy dispersive spectroscopy point analysis. Furthermore, the binder systems were simulated using thermodynamic modeling to observe the phase changes of hydration products and the underlying hydration kinetics. The incorporation of dolomite accelerated clinker consumption and enhanced the stability of ettringite throughout the testing period, due possibly to the nucleation seeding effect and provision of carbonate ions by dolomite. The modeling outcomes showed the stability of ettringite at later stage by the incorporation of dolomite in the simulated timeframe, yet the active dissolution of dolomite assumed in the modeling procedure overestimated the Mg-bearing hydrates in the samples.

Experimental study on the effect of carbonate ions on ITZs of geopolymeric recycled concrete

In this study, carbonated recycled aggregates (CRA) were used in preparing geopolymeric recycled concrete (GRC). The influence of CRA with different carbonation durations on the compressive strength of GRC was studied, and the physical properties of CRA were tested. Bi-material Brazilian disc (BBD) was explored to simulate interfacial transition zones (ITZ). According to the test results, CRA was found to introduce quantities of carbonate ions, causing a similar adverse effect of efflorescence in GRC. Therefore, the compressive strength decreased in the first 24 h of carbonation. After 96 h carbonation, the reduction in compressive strength was insignificant. When using CRA to prepare GRC, it would be advisable to carbonate recycled aggregates for longer than 96 h. The results of the splitting tensile tests and nanoindentation test of BBD revealed that the carbonate ions introduced by carbonation treatment could slightly weaken the bonding properties of ITZ in GRC.

Effect of Sulfate and Carbonate Ions on Lithium Carbonate Precipitation from a Low Concentration Lithium Containing Solution

Effect of Sulfate and Carbonate Ions on Lithium Carbonate Precipitation from a Low Concentration Lithium Containing Solution

Clay peptization and clay swelling inhibition in the presence of carbonic acid, bicarbonate and carbonate ions and calcium ions

Relevance. The need to ensure the integrity of the wellbore, composed of clay rocks, and the stability of drilling fluid when drilling in conditions of carbon dioxide and bicarbonate aggression. Aim. To determine experimentally the effect of carbonic acid, bicarbonate and carbonate ions on clay depending on the presence of calcium ions in the dispersion medium. Objects. Water contaminated with carbonic acid, bicarbonate and carbonate ions with different equivalent concentrations of calcium ions. Methods. Inhibitory and peptizing properties of the objects of study in relation to the clay rock were studied by the method of clay swelling when it was in the water under study (on the Zhigacha-Yarov device); methods of chemical analysis (complexometric and acid-base titration) and potentiometry were used to control water composition and properties. Results. The peptizing and inhibiting properties of drilling fluid depend significantly on the form of carbonic acid present in the dispersion medium and the equivalent content of calcium ions (Ca2+). It was found that carbonic acid (H2CO3) contributes to clay inhibition (coagulation), bicarbonate ions (HCO3–) and carbonate ions (CO32–) – clay peptization. Calcium ions (Ca2+) do not have an inhibitory effect in the presence of carbonic acid (H2CO3) – hydrogen ions (H+) displace exchangeable cations from the interlayer space of clays and, due to their small diameter, independently inhibit clay swelling. In the presence of bicarbonate ions (HCO3–), calcium ions (Ca2+) also do not have an inhibitory effect – bicarbonate ions (HCO3–), being in a dispersion medium, draw calcium ions (Ca2+) from the clay surface, increasing the thickness of the electrical double layer. In the presence of carbonate ions (CO32–) the calcium ions (Ca2+) precipitate and effectively prevent clay peptization only in the presence of hydroxide ions (OH–). The authors proved experimentally that calcium ions (Ca2+) in the presence of hydroxide ions (OH–) have a better inhibitory ability than hydrogen ions (H+) of dissociated carbonic acid (H2CO3). A mechanism was proposed for inhibiting the swelling of clays by calcium ions (Ca2+) in the presence of hydroxide ions (OH-), based on the adsorption of the hydrated calcium ion (Ca2+) on a silica tetrahedral sheet due to the preliminary protonation of its oxygen atoms by water molecules. The conditions required for clay effective peptization are formulated: [CO32–]≥0; [OH–]>0, [Ca2+]=0, pH>11.5; for clay swelling inhibition: [CO32–]=0; [OH–]>0, [Ca2+]>0 and pH>11.5.

Acoustic Emission Waveform Characterization of Crack Origin In Self-Healing of Mortar Due to Internal Carbonation

In this study, self-healing of mortar was achieved by “built-in” carbonation of soluble Na2CO3 and Ca(OH)2. The effect of carbonate and calcium ions, available either internally or externally by conditioning the specimens with Ca(OH)2 and Na2CO3 solution, on the formation of calcite in cracks was investigated. The acoustic events were monitored and compared in the loading process before and after healing. Furthermore, a calibration test was carried out to distinguish the characteristic acoustic emission events of the fracture of the matrix and of healing products. It was found that the distribution of acoustic energy with FMA (frequency at maximum amplitude) and the hits with duration show a consistent trend with that of calibration. The change of tensile to shear cracking ratio in reloading illustrates a self-healing effect of cracks. Meanwhile, X-ray diffraction analysis indicates more calcite formed in the crack of self-healing specimens. The pretreated ceramsite-containing specimens exhibit the predominate self-healing effect due to the internally available CO32– and sufficient Ca2+ as compared to the others.

Development and Research of Inorganic Energy Conversion Materials and Devices —The Effect of Carbonate Ions on the Ionic Conduction of B-type Carbonated Apatite—

Development and Research of Inorganic Energy Conversion Materials and Devices —The Effect of Carbonate Ions on the Ionic Conduction of B-type Carbonated Apatite—

Advanced Oxidation Processes for Degradation of Water Pollutants—Ambivalent Impact of Carbonate Species: A Review

Advanced oxidation processes (AOPs) hold great promise in the removal of organic contaminants. Reactive oxygen species (ROS) produced in AOPs react with target pollutants to initially form several intermediate compounds that finally undergo complete mineralization. Such observations are reported, especially for laboratory-scale experiments performed in pure water. On the other hand, while considering real contaminated wastewater matrices, particularly industrial effluents, there are many co-existing ions. Carbonate ions are one of the major inorganic ions commonly existing in water resources. Hence, these ions have a significant impact on the respective water treatment processes. This review focused on the effect of carbonate ions on the degradation of pollutants in AOPs. In AOPs, carbonate radicals are formed by the scavenging reaction of the respective ions with ROS. The reactivity of these radicals towards the pollutant varies with respect to the structure and functionality. Therefore, depending on the functionalities of the contaminants, these ions show both positive and negative effects. Thus, this review aims to summarize the effects of carbonate species on the degradation of organic contaminants during AOPs and their environmental impacts. The carbonates enhanced the degradation of several emerging organic pollutants, including aniline, bisphenol A, rhodamine B, acid orange 7, naphthalene, and phenol derivatives. Carbonate presence was also revealed to have a positive contribution in cases of drug degradation, including sulfamethoxazole, propranolol, sulfamethazine, salbutamol, trimethoprim, azithromycin, naproxen, oxcarbazepine, and oxytetracycline.

Role of carbonate on the crystallization and processing of amorphous calcium phosphates

The dominating effect of carbonate ions on regulating the properties of apatite drives further inquiry about its influence on amorphous calcium phosphate (ACP). To date, the maximum carbonate inclusion, and the influence on the densification of amorphous powders have not been reported. Carbonate-substituted ACP was synthesized and then crystallized by heating in a furnace (in air) or a pressure vessel (in water or steam). Characterization by X-ray diffraction showed a 21 wt.% carbonate (Ca/P = 2.6) solid solubility limit in ACP. Steam processing crystallized a monophasic apatite at the highest carbonate content: up to Ca/P of 2.4 (18 wt.% of carbonate). FTIR spectra showed carbonate absorption characteristic of the non-apatitic environment for the amorphous phase, but after crystallization showed carbonate, like in a phosphate site. Thermal analysis revealed that higher carbonate content amorphous powders are less thermally stable and crystallize at lower temperatures. Cold sintering of higher carbonate content amorphous powders produced a lower density and lower hardness. A significant decrease in hardness occurs after a Ca/P of 1.74 (8 wt.% carbonate). This is the first report on such wide carbonate content amorphous calcium phosphate (ACP) powders showing the solid solubility of carbonate, and the influence on the processability.

Effect of CO32- and Ca2+ on self-healing of cementitious materials due to “build-in” carbonation

In this study, the self-healing efficiency of mortar due to “build-in” carbonation was investigated. Sodium carbonate was selected as the healing agent to be carried by porous ceramsites to carry carbonate ions in the mortar as the healing components (HCs). The coating efficiency of the HCs and its effect on the fresh and hardened properties of the mortar were investigated. To investigate the effect of carbonate and calcium ions on formation of carbonates, the healing efficiency of mortars in the presence of an external calcium source only (P), an external carbonate source only (N), and an internal carbonate source combined with an external calcium source (C), was evaluated based on the mechanical property and pore structure by characterization of water absorption, mercury intrusion porosimetry (MIP) and backscattered electron imaging (BSE) measurements. The results showed that the incorporated HCs triggered “build-in” carbonation to heal the cracks. The mechanical regains and water absorption results demonstrated that the incorporated coated HCs significantly improved the self-healing capability of the pre-cracked mortars. The specimen containing 7.5 wt% of HCs showed the maximum compressive strength recovery rate of 1.35 and the greatest value of rate of water absorption was 64%. The MIP results showed a greatest reduction of pores in 100–1800 nm for the self-healing specimens after curing. The BSE results indicated that the main healing product for specimens with HCs was CaCO3. All the results by different measurements are consistent with each other and the best healing efficiency is seen for C, followed by N and P. The availability of carbonate ions is more critical in formation of calcite than the calcium source, particularly when the carbonate ions were provided internally. The optimum HCs dosage and environment for enhancing the self-healing capability of the mortars were 7.5 wt% and a saturated Ca(OH)2 solution, respectively.

Effects of carbonate ions in phosphate solution on the fabrication of carbonate apatite through a dissolution–precipitation reaction

Carbonate apatite (CO3Ap) artificial bone has attracted much attention due to its high osteoconductivity and replacement to bone. CO3Ap is an inorganic component of bone, and has been fabricated by compositional transformation through a dissolution–precipitation reaction in Na2HPO4 solution using calcium carbonate as a precursor. In this study, the effects of the CO32− concentration in the Na2HPO4 solution on the CO3Ap fabrication reaction and the properties of the fabricated CO3Ap were investigated. The rate of the compositional transformation became faster, and more CO3 containing CO3Ap was fabricated using CO32− concentrated in Na2HPO4 solution. The crystal shape of CO3Ap changed from scale-like to hexagonal crystals. In addition, the crystallite size increased with increasing CO32− concentration in the Na2HPO4 solution. These changes lead to larger pores (≥0.02 μm) and decreased number of small pores (<0.02 μm) according to the CO3 content in CO3Ap, even though the total pore volume remained the same. These findings indicate that the CO32− concentration in Na2HPO4 solution is an important factor for the CO3Ap fabrication reaction and affects the properties of the fabricated CO3Ap.

The Effect of Sulphate and Carbonate Ions on Lithium Carbonate Precipitation from a Low Concentration Lithium Containing Solution

The Effect of Sulphate and Carbonate Ions on Lithium Carbonate Precipitation from a Low Concentration Lithium Containing Solution

Inhibitive effect of sodium carbonate on corrosion of AZ31 magnesium alloy in NaCl solution

Magnesium is the world’s lightest structural metal, with a significant growth potential in view of the accelerating demand for light-weighting portable devices and transportation (aerospace, automotive), amongst other. The effect of carbonate ions on corrosion protection of AZ31 magnesium alloy was studied in 0.1 M NaCl solution saturated in Mg(OH)2 using Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization measurements, hydrogen evolution tests and SEM-EDX analysis. X-ray Photoelectron Spectroscopy (XPS) was used in order to investigate the top-surface composition. The inhibitive effect of CO32− ions on corrosion of AZ31 magnesium alloy was highlighted and the underlying mechanisms discussed.

A Comparative Study on Cure Kinetics of Layered Double Hydroxide (LDH)/Epoxy Nanocomposites

Layered double hydroxide (LDH) minerals are promising candidates for developing polymer nanocomposites and the exchange of intercalating anions and metal ions in the LDH structure considerably affects their ultimate properties. Despite the fact that the synthesis of various kinds of LDHs has been the subject of numerous studies, the cure kinetics of LDH-based thermoset polymer composites has rarely been investigated. Herein, binary and ternary structures, including [Mg0.75 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, [Mg0.75 Al0.25 (OH)2]0.25+ [(NO3−)0.25∙m H2O]0.25− and [Mg0.64 Zn0.11 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, have been incorporated into epoxy to study the cure kinetics of the resulting nanocomposites by differential scanning calorimetry (DSC). Both integral and differential isoconversional methods serve to study the non-isothermal curing reactions of epoxy nanocomposites. The effects of carbonate and nitrate ions as intercalating agents on the cure kinetics are also discussed. The activation energy of cure (Eα) was calculated based on the Friedman and Kissinger–Akahira–Sunose (KAS) methods for epoxy/LDH nanocomposites. The order of autocatalytic reaction (m) for the epoxy/Mg-Al-NO3 (0.30 and 0.254 calculated by the Friedman and KAS methods, respectively) was smaller than that of the neat epoxy, which suggested a shift of the curing mechanism from an autocatalytic to noncatalytic reaction. Moreover, a higher frequency factor for the aforementioned nanocomposite suggests that the incorporation of Mg-Al-NO3 in the epoxy composite improved the curability of the epoxy. The results elucidate that the intercalating anions and the metal constituent of LDH significantly govern the cure kinetics of epoxy by the participation of nitrate anions in the epoxide ring-opening reaction.

Response to the letter to the editor

Arsenite is a highly toxic compound present in many water sources around the world. The removal of arsenite from water requires its oxidation to arsenate which is much more amenable to treatment using well attested technologies. Prior research has shown that the oxidation of arsenite by hydroxyl radicals is significantly accelerated in the presence of carbonate ions but the intrinsic mechanisms of the acceleration have not yet been established. The main goal of the present work was to examine the oxidation of arsenite in the framework of the density functional theory, to establish a detailed microscopic level mechanism of interactions between arsenite and hydroxyl radicals and to elucidate the nature of the catalytic effect of carbonate ions. Results of this study demonstrate that the [As(OH)2CO3]- complex is the thermodynamically most stable species formed in the system H3AsO3–CO32–/HCO3−–H2O. Interactions of the hydroxyl radical with the [As(OH)2CO3]- complex yield the pre-reaction complex [As(OH)3CO3]-∗ in the reaction of subsequent oxidation of arsenite. The structures of the reactants, products and transition states, as well as pre- and post-reaction complexes corresponding to several possible mechanisms of the first stage of As(III) oxidation to As(IV) intermediate using hydroxyl radicals in the absence and in the presence of [As(OH)2CO3]-, were determined in this study. The data demonstrate that the arsenite-carbonate complexes [As(OH)2CO3]- are characterized by a significantly lower activation energy of the first oxidation stage under the action of a hydroxyl radical (2.8 kcal/mol) compared to that for the free arsenite H3AsO3 (13.6 kcal/mol).

The intrinsic mechanism of catalytic oxidation of arsenite by hydroxyl-radicals in the H3AsO3–CO32–/HCO3−–H2O system: A quantum-chemical examination

Arsenite is a highly toxic compound present in many water sources around the world. The removal of arsenite from water requires its oxidation to arsenate which is much more amenable to treatment using well attested technologies. Prior research has shown that the oxidation of arsenite by hydroxyl radicals is significantly accelerated in the presence of carbonate ions but the intrinsic mechanisms of the acceleration have not yet been established. The main goal of the present work was to examine the oxidation of arsenite in the framework of the density functional theory, to establish a detailed microscopic level mechanism of interactions between arsenite and hydroxyl radicals and to elucidate the nature of the catalytic effect of carbonate ions. Results of this study demonstrate that the [As(OH)2CO3]- complex is the thermodynamically most stable species formed in the system H3AsO3–CO32–/HCO3−–H2O. Interactions of the hydroxyl radical with the [As(OH)2CO3]- complex yield the pre-reaction complex [As(OH)3CO3]-∗ in the reaction of subsequent oxidation of arsenite. The structures of the reactants, products and transition states, as well as pre- and post-reaction complexes corresponding to several possible mechanisms of the first stage of As(III) oxidation to As(IV) intermediate using hydroxyl radicals in the absence and in the presence of [As(OH)2CO3]-, were determined in this study. The data demonstrate that the arsenite-carbonate complexes [As(OH)2CO3]- are characterized by a significantly lower activation energy of the first oxidation stage under the action of a hydroxyl radical (2.8 kcal/mol) compared to that for the free arsenite H3AsO3 (13.6 kcal/mol).

Photo-Fenton degradation of methylene blue in the presence of Au-Fe3O4/graphene composites under UV and visible light at near neutral pH: Effect of coexisting inorganic anion

Herein, Fe3O4 nanocatalyst composited with Au and graphene (Au-Fe3O4/graphene) has been applied for the photo-Fenton degradation of methylene blue in solution at a near neutral pH value under UV and visible light. The synthesized catalyst was successfully prepared by hydrothermal method and showed a good catalytic performance on H2O2 activation to degrade methylene blue at neutral pH. The Au concentration was set as 15 and 25 wt percentage (wt.%). The degradation efficiency of methylene blue reached 99% and 100% within 2 h under UV light irradiation using Au-Fe3O4/graphene with Au concentrations of 15% and 25 wt.%, respectively, whereas the corresponding percentage under visible light was 60% and 80%, respectively. The Au-Fe3O4/graphene maintained its stability during the repeated batch experiments. Furthermore, the effect of inorganic anions, including chloride, sulfate, nitrate, dihydrogen phosphate, and carbonate ions, on the photo-Fenton degradation of methylene blue was investigated. Results showed that under different concentrations of various inorganic anions, carbonate ions have a significant effect in inhibiting the photo-Fenton process, whereas nitrate and sulfate ions have a negligible effect to inhibit the photo-Fenton activity. The degradation efficiency of methylene blue decreased from 78% to 53% under visible light irradiation and from 100% to 73% under UV light irradiation in the presence of carbonate. The inhibition effect was in the following order: sodium carbonate (vis =32% and UV = 27%) > dihydrogen phosphate (vis =28% and UV = 24%) > chloride (vis =15% and UV = 18%) > nitrate (vis = 6% and UV = 3%) > sulfate (vis = 4% and UV = 3%).

The roles carbonate and bicarbonate ions play on pre‐passive HRB400 rebars in simulated pore solutions of deteriorating concrete

To evaluate the corrosion behavior of HRB400 rebars during the aging process of concrete, corresponding simulated concrete pore solutions were proposed. Using electrochemical measurements and XPS analysis, the depassivation conditions, properties of the pre‐passive films, and rebars corrosion rate were discussed. The effects of carbonate and bicarbonate ions, pH and chloride on the corrosion behavior of pre‐passive HRB400 rebars were investigated. Results show that the influence of carbonate and bicarbonate ions on the pre‐passive HRB400 rebars is reversed before and after its depassivation: before depassivation, carbonate and bicarbonate ions are detrimental to the stability of passive film, but beneficial after depassivation.

Effect of inorganic ions on the ultrasound initiated degradation and product formation of triphenylmethane dyes

Triphenylmethane (TPM) dyes are an important category of dyes with a variety of industrial applications and consequently, these are found in the aquatic environment at relatively higher concentrations. Here, we report the degradation of two important TPM dyes (para rosaniline (PRA) and ethyl violet (EV)) in an aqueous medium by ultrasound which is one among the Advanced Oxidation Processes (AOPs). The main objective of this work is to study the effect of various inorganic ions on the degradation and the product formation of TPM dyes from the sonochemical reactions. Using a typical concentration of 10 ppm dyes and an ultrasonic frequency of 350 kHz and power of 60 W, a complete degradation of EV and PRA was observed with a pseudo first order rate constant of 0.2339 min−1 and 0.1956 min−1, respectively. The product analyses using high-resolution mass spectrometry (LC-Q-TOF-MS) revealed the formation of hydroxylated, de-alkylated, and other collapsed conjugated structure destructed products. The evolution of these products in the presence of various inorganic ions (Cl−, SO42−, NO3−, and CO3−) showed that only carbonate ions had a significant impact on the product evolution. The carbonate ions facilitated the formation of conjugated structure destructed product for both the dyes. This is attributed to the reactivity of carbonate radical, which facilitated the formation of carbon-centered radicals. This carbon-centered radical further undergoes reaction to cause the destruction of conjugated structures. This is confirmed by the identification of the corresponding product peaks in the mass spectra. The scavenging effect of carbonate ions was also reflected in the product study where there is a reduction in the formation of most of the hydroxylated products. One of the major inorganic species in any wastewater is carbonate ions and therefore the present result is very relevant to the understanding of oxidation based treatment protocol.

Effect of Carbonate Ions on the Adsorption of Phosphorus by Diopside in Aqueous Solution

Effect of Carbonate Ions on the Adsorption of Phosphorus by Diopside in Aqueous Solution