Showing papers on "Carbonic acid published in 2019"

Mass Transport Analysis of Bicarbonate Buffer: Effect of the CO2-H2CO3 Hydration-Dehydration Kinetics in the Fluid Boundary Layer and the Apparent Effective p Ka Controlling Dissolution of Acids and Bases.

Abstract: The main buffering system influencing ionizable drug dissolution in the human intestinal fluid is bicarbonate-based; however, it is rarely used in routine pharmaceutical practice due to the volatility of dissolved CO2. The typical pharmaceutical buffers used fail to capture the unique aspects of the hydration-dehydration kinetics of the bicarbonate-CO2 system. In particular, CO2 is involved in a reversible interconversion with carbonic acid (H2CO3), which is the actual conjugate acid of the system, as follows CO2 + H2O ⇌ H2CO3. In contrast to ionization reactions, this interconversion does not equilibrate very rapidly compared to the diffusional processes through a typical fluid diffusion boundary layer at a solid-liquid interface. In this report, a mathematical mass transport analysis was developed for ionizable drug dissolution in bicarbonate using the rules of conservation of mass and electric charge in addition to accounting for the diffusional times and reaction rate constants of the CO2-H2CO3 interconversion. This model, which includes both the hydration reaction rate and dehydration reaction rate, we called the "reversible non-equilibrium" (RNE) model. The predictions made by this RNE approach for ionizable drug dissolution rates were compared to the experimental data generated by an intrinsic dissolution method for three ionizable drugs, indomethacin, ibuprofen, and haloperidol. The results demonstrate the superiority of predictions for the RNE approach compared to the predictions of a model assuming equilibrium between CO2 and H2CO3, as well as models ignoring reactions. The analysis also shows that bicarbonate buffer can be viewed as having an effective p Ka in the boundary layer that is different from that in bulk and is hydrodynamics-dependent.

A New Narrative for CO 2 Corrosion of Mild Steel

Abstract: The conventionally accepted mechanism of CO2 corrosion considers the direct reduction of carbonic acid as the main process that results in the higher corrosion rates as compared to that observed in strong acid solutions with the same pH. The present study is an attempt to further elucidate the underlying electrochemical mechanisms of CO2 corrosion. In this regard, the mechanism of CO2 corrosion was investigated based on the cathodic and anodic polarization behavior of mild steel in CO2-saturated solutions at elevated pressures. The examination of charge transfer controlled cathodic currents showed that the direct reduction of carbonic acid is insignificant at the condition of the present study. Additionally, the iron dissolution reaction was found to be significantly affected by the presence of CO2, particularly over the transition and pre-passivation ranges. A comprehensive mathematical model based on the presented mechanistic understanding of the system was developed and used for further quantitative examinations. The present mechanistic model was shown to be able to represent the main mechanistic features of polarization curves and predict the corrosion rates with reasonable accuracy.

Surface-Catalyzed Oxygen Exchange during Mineral Carbonation in Nanoscale Water Films

Abstract: Properties of nanoconfined adsorbed H2O on mineral surfaces are distinct from those of bulk H2O, and this can lead to significant differences in reactivity. Here, we investigate how O-exchange between H2O and CO2 depends on the thickness of H2O films on the mineral, forsterite (Mg2SiO4), which at sufficient adsorbed H2O is highly reactive toward carbonation. Rates of O-exchange measured using O-isotopic tracers and infrared spectroscopy increase with adsorbed H2O concentration and are two orders of magnitude faster than those for inert substrates such as fumed silica (SiO2). Quantum chemical calculations demonstrate that O-exchange can be catalyzed through interactions with active Mg2+ sites that lower the barrier for carbonic acid formation. These active metal centers exist as ≡Mg–bicarbonate surface complexes or dissolved Mg2+ with predominantly bicarbonate counterions, as evidenced by infrared and nuclear magnetic resonance spectroscopies. Intermolecular proton hopping to bicarbonate can form a carboni...

Characterization of a trans-trans Carbonic Acid-Fluoride Complex by Infrared Action Spectroscopy in Helium Nanodroplets.

Abstract: The high Lewis basicity and small ionic radius of fluoride promote the formation of strong ionic hydrogen bonds in the complexation of fluoride with protic molecules. Herein, we report that carbonic acid, a thermodynamically disfavored species that is challenging to investigate experimentally, forms a complex with fluoride in the gas phase. Intriguingly, this complex is highly stable and is observed in abundance upon nanoelectrospray ionization of an aqueous sodium fluoride solution in the presence of gas-phase carbon dioxide. We characterize the structure and properties of the carbonic acid–fluoride complex, F–(H2CO3), and its deuterated isotopologue, F–(D2CO3), by helium nanodroplet infrared action spectroscopy in the photon energy range of 390–2800 cm–1. The complex adopts a C2v symmetry structure with the carbonic acid in a planar trans–trans conformation and both OH groups forming ionic hydrogen bonds with the fluoride. Substantial vibrational anharmonic effects are observed in the infrared spectra, ...

Experimental Study of Pyrite Oxidation at 100 °C: Implications for Deep Geological Radwaste Repository in Claystone

Abstract: The oxidation of pyrite is one of the near field processes of the chemical evolution of clay rock planned to host a deep geological radioactive waste repository during operation. Indeed, this process can lead to transitory acidic conditions in the medium (i.e., production of sulphuric acid, carbonic acid) which may influence the corrosion kinetics of the carbon steel components of some disposal cells. In order to improve the geochemical modelling of the long-term disposal, the oxidation of pyrite in contact with clays and carbonates at 100 °C must be evaluated. In this study, special attention was paid to the pyrite oxidation rate thanks to an original experimental set-up, involving several pyrite/mineral mixtures and a reactor coupled to a micro gas chromatograph (PO2 and PCO2 monitoring). Although thermodynamic modelling expects that hematite is the most stable phase in a pure pyrite heated system (low pH), experiments show the formation of native sulfur as an intermediate product of the reaction. In the presence of calcite, the pH is neutralized and drives the lower reactivity of pyrite in the absence of native sulfur. The addition of clay phases or other detrital silicates from the claystone had no impact on pyrite oxidation rate. The discrepancies between experiments and thermodynamic modelling are explained by kinetic effects. Two laws were deduced at 100 °C. The first concerns a pure pyrite system, with the following law: r P y = 10 − 4.8 · P O 2 0.5 · t − 0.5 . The second concerns a pyrite/carbonates system: r P y + C a = 10 − 5.1 · P O 2 0.5 · t − 0.5 where PO2 corresponds to the partial pressure of O2 (in bar) and t is time in seconds. Different mechanisms are proposed to explain the evolution with time of the O2 consumption during pyrite oxidation: (i) decrease of the specific or reactive surface area after oxidation of fine grains of pyrite, (ii) decrease of O2 pressure, (iii) growing up of secondary minerals (Fe-oxides or anhydrite in the presence of calcium in the system) on the surface of pyrite limiting the access of O2 to the fresh surface of pyrite, and (iv) change in the pH of the solution.

Molecular Hydration of Carbonic Acid: Ab Initio Quantum Chemical and Density Functional Theory Investigation.

Abstract: Molecular hydration of carbonic acid (H2CO3) is investigated in terms of bonding patterns in H2CO3···(H2O) n [ n = 1-4] hydrogen-bonded clusters within ab initio quantum chemical and density functional theory (DFT) frameworks. Successive addition of water molecules to H2CO3···H2O entails elongation of O-H (hydroxyl) bond as well as contraction of specific intermolecular hydrogen bonds signifying hydration of carbonic acid; these structural features get markedly enhanced under the continuum solvation framework. A comparison between the structurally similar clusters H2CO3···(H2O) n and HCOOH···(H2O) n [ n = 1-3] brings out the structural stability of the former. The present investigation in conjunction with the binding energy behavior of approaching water molecule(s) should serve as a precursor for pathways exploring aqueous dissociation of H2CO3 for larger clusters, as well as development of force-field potentials for acid dissociation process.

High-energy ion impacts into the sulfur-bearing ice surface of Europa: an atomistic study of chemical transformations

Abstract: Context. The ice surface of Europa is unique due to its high concentration of sulfur compounds such as SO4 , SO2 , and H2 S. Energetic ion impacts originating from the magnetosphere of Jupiter may alter the composition of the ice surface.Aims. We explore the chemical alteration of the surface due to a 20 MeV sulfur ion impact, for which the most pronounced effects are expected, and monitor the chemical transformations occurring inside the ice.Methods. Molecular dynamics simulations are used based on a reactive (REAX) potential, which allows for the molecular breakups and the ensuing reactions to be followed on an atomistic scale.Results. We observe dissociation of SO4 and also a loss of SO2 , while SO3 is created; this is in qualitative agreement with laboratory experiments. Hydrolysis of water leads to abundant formation of H+ , H3 O+ and OH− ; in addition, we predict the presence of both sulfurous acid, H2 SO3 , and sulfuric acid, H2 SO4 , as well as traces of carbonic acid, H2 CO3 . The irradiation produces H2 and O2 , which are free to escape from the surface, in agreement with the tenuous Europa atmosphere detected.Conclusions. Since magnetospheric sulfur ions have a high mass and may possess large energies, they provide a unique source of high energy deposition in the ice surface of Europa leading to abundant radiolysis fragments and products. In addition, sulfur compounds existing in the ice are chemically transformed, for example, by sulfite formation.

Carbonic Acid Eluent Ion Chromatography

Abstract: Alkali metals, amines and alkanolamines are separated on a poly(butadiene)-maleic acid on silica stationary phase using a carbonic acid (H2CO3*) eluent with and without a mineral acid. The H2CO3* eluent is prepared in situ by high pressure permeative introduction of gaseous CO2 through thin membranes supported upon a porous steel disk. The permeation flux and thus the eluent concentration is controlled by varying the applied CO2 pressure. This novel frit-supported membrane device tolerates much higher liquid and gas pressures than Teflon AF capillaries, permitting [H2CO3*] exceeding 0.53 M and attaining a pH of 3.3. Silicone was presently preferred over Teflon AF, both as planar membranes, as mechanical properties of the latter change as large amounts of CO2 dissolve in it. After separation, the CO2 can be efficiently removed via another gas permeable membrane device permitting detection of the eluting bicarbonate salt conductometrically in a background of nearly pure water. Most analytes are more sensiti...

Understanding the nature of bonding interactions in the carbonic acid dimers

Abstract: Carbonic acid dimer, (CA)2, (H2CO3)2, helps to explain the existence of this acid as a stable species, different to a simple sum between carbon dioxide and water. Five distinct, well characterized types of intermolecular interactions contribute to the stabilization of the dimers, namely, C=O⋯H–O, H–O⋯H–O, C=O⋯C=O, C=O⋯O–H, and C–O⋯O–H. In many cases, the stabilizing hydrogen bonds are of at least the same strength as in the water dimer. We dissect the nature of intermolecular interactions and assess their influence on stability. For a set of 40 (H2CO3)2 isomers, C=O⋯H–O hydrogen bonds between the carbonyl oxygen in one CA molecule and the acidic hydrogen in the hydroxyl group at a second CA molecule are the major stabilizing factors because they exhibit the shortest interaction distances, the largest orbital interaction energies, and the largest accumulation of electron densities around the corresponding bond critical points. In most cases, these are closed-shell hydrogen bonds, however, in a few instances, some covalent character is induced. Bifurcated hydrogen bonds are a common occurrence in the dimers of carbonic acid, resulting in a complex picture with multiple orbital interactions of various strengths. Two anti–anti monomers interacting via the strongest C=O⋯H–O hydrogen bonds are the ingredients for the formation of the lowest energy dimers.

Intact carbonic acid is a viable protonating agent for biological bases.

Abstract: Carbonic acid H2CO3 (CA) is a key constituent of the universal CA/bicarbonate/CO2 buffer maintaining the pH of both blood and the oceans. Here we demonstrate the ability of intact CA to quantitatively protonate bases with biologically-relevant pKas and argue that CA has a previously unappreciated function as a major source of protons in blood plasma. We determine with high precision the temperature dependence of pKa(CA), pKa(T) = -373.604 + 16,500/T + 56.478 ln T. At physiological-like conditions pKa(CA) = 3.45 (I = 0.15 M, 37 °C), making CA stronger than lactic acid. We further demonstrate experimentally that CA decomposition to H2O and CO2 does not impair its ability to act as an ordinary carboxylic acid and to efficiently protonate physiological-like bases. The consequences of this conclusion are far reaching for human physiology and marine biology. While CA is somewhat less reactive than (H+)aq, it is more than 1 order of magnitude more abundant than (H+)aq in the blood plasma and in the oceans. In particular, CA is about 70× more abundant than (H+)aq in the blood plasma, where we argue that its overall protonation efficiency is 10 to 20× greater than that of (H+)aq, often considered to be the major protonating agent there. CA should thus function as a major source for fast in vivo acid-base reactivity in the blood plasma, possibly penetrating intact into membranes and significantly helping to compensate for (H+)aq's kinetic deficiency in sustaining the large proton fluxes that are vital for metabolic processes and rapid enzymatic reactions.

Large Presence of Carbonic Acid in CO2 -Rich Aqueous Fluids under Earth's Mantle Conditions

Abstract: The chemistry of carbon in aqueous fluids at extreme pressure and temperature conditions is of great importance to Earth's deep carbon cycle, which substantially affects the carbon budget at Earth's surface and global climate change. At ambient conditions, the concentration of carbonic acid in water is negligible; therefore, aqueous carbonic acid was simply ignored in previous geochemical models. However, by applying extensive ab initio molecular dynamics simulations at pressure and temperature conditions similar to those in Earth's upper mantle, we found that carbonic acid can be the most abundant carbon species in aqueous CO2 solutions at ∼10 GPa and 1000 K. The mole percent of carbonic acid in total dissolved carbon species increases with increasing pressure along an isotherm, while its mole percent decreases with increasing temperature along an isobar. In CO2-rich solutions, we found significant proton transfer between carbonic acid molecules and bicarbonate ions, which may enhance the conductivity of the solutions. The effects of pH buffering by carbonic acid may play an important role in water-rock interactions in Earth's interior. Our findings suggest that carbonic acid is an important carbon carrier in the deep carbon cycle.

Carbonic Acid Resistance of Hydroxyapatite Based Cement

Abstract: With the current applications of CO2 in oil wells for enhanced oil recovery (EOR) and sequestration purposes, the dissolution of CO2 in the formation brine and the formation of carbonic acid is a major cause of cement damage. This degradation can lead to non-compliance with the functions of the cement as it changes compressive and shear bond strengths and porosity and permeability of cement. It becomes imperative to understand the degradation mechanism of cement and methods to reduce the damage such as the addition of special additives to improve the resistance of cement against acid attack. Hence, the primary objective of this study is to investigate the effects of hydroxyapatite on cement degradation. To investigate the impacts of hydroxyapatite additive on oil well cement performance, two Class H cement slurry formulations (baseline/HS and hydroxyapatite containing cement/HHO) were compared after exposure to acidic environments. To evaluate the performance of the formulations, samples were prepared and aged in high-pressure high-temperature (HPHT) autoclave containing 2% brine saturated with mixed gas containing methane and carbon dioxide. Tests were performed at different temperatures (38 to 221°C), pressures (21 to 63 MPa) and CO2 concentrations (10 to 100%). After aging for 14 days at constant pressure and temperature, the samples were recovered and their bond and compressive strength, porosity and permeability were measured and compared with those of unaged samples. The results demonstrated that adding hydroxyapatite limits carbonation. Baseline samples that do not contain hydroxyapatite carbonated and consequently their compressive strength, porosity, permeability, and shear bond strength significantly changed after aging while hydroxyapatite-containing samples displayed a limited change in their properties. However, hydroxyapatite-containing samples exhibit high permeability due to the formation of microcracks after exposure to carbonic acid at high temperature (221°C). The formation of microcracks could be attributed to thermal retrogression or other phenomena that cause the expansion of the cement. This article sheds light on the application of hydroxyapatite as a cement additive to improve the carbonic acid resistance of oil well cement. It presents hydroxyapatite containing cement formulation that has acceptable slurry properties for field applications and better carbonic acid resistance compared to conventional cement.

Reagent-Free Electromembrane Process for Decarbonization of Natural Water

Abstract: The reagent-free electromembrane process of removing carbonates, bicarbonates, and carbonic acid from softened natural carbonate water using an electrodialysis synthesizer EDS-01 with a two-cell unit cell formed by a bipolar membrane and a cation-exchange membrane has been studied. MB-2M membranes modified with an ionopolymer containing phosphoric acid groups catalytically active in a water-splitting reaction have been used as bipolar membranes, while heterogeneous membranes Ralex CMH (Mega a.s., Czech Republic) have been used as cation-exchange membranes. The decarbonization process has been carried out in two stages. At the first stage, a reagent-free correction of pH of the solution treated has been carried out. The value of pH in acid compartments has been adjusted to be 2.5–4.0. At the second stage, this solution has been deaerated with air purified from carbon dioxide. For a quantitative description of the process, a previously developed model has been adapted to describe the electrodialysis process with bipolar and cation-exchange membranes. It is shown that the electrodiffusion transfer of anions through the cation-exchange membrane and bipolar membrane is practically absent, and the change in the concentrations of carbonate ions, bicarbonates, and carbonic acid is due to the quasi-equilibrium chemical reactions. The deaeration of acidified softened water reduces the total carbon content from 5 to 1 mmol/L. The decarbonization of softened water is accompanied by a decrease in the concentration of sodium cations and total mineralization. With an EDS-01 electrodialysis synthesizer performance of 100 L/h, the specific energy consumption is in the range from 0.16 to 6.12 kW h/m3 depending on the current density.

The pH value control in air plasma-liquid system by sodium bicarbonate

Abstract: The pH value of an aqueous solution usually decreases when treated by air discharge plasma due to the formation of HNO2 and HNO3 in solution. Herein, we found that the existence of a pH-buffer material, sodium bicarbonate (NaHCO3), can maintain or even increase the solution pH value in an air plasma–liquid system depending on the discharge conditions such as the temperature and the voltage polarity of the liquid. When acidic compounds (for instance, HNO2 and HNO3) are produced by the plasma–liquid interactions, the bicarbonate ions (HCO3) existing in the solution can combine with the produced hydrogen ions (H+) to form carbonic acid molecules (H2CO3−), resulting in the maintaining of the solution pH value. However, the formed H2CO3 might be decomposed to produce water (H2O) and carbon dioxide (CO2) by the discharge plasma-induced heat, leading to a continuous consumption of H+ ions in the solution. As the quantity of H+ ions consumed by the decomposition of H2CO3 is greater than the quantity of H+ ions produced by air discharge plasma, the solution pH value will increase.

Method for preparing polycarbonate through ionic liquid catalyzing and fusing ester exchange method

Abstract: The invention discloses a method for using imidazole amino acid ionic liquid to efficiently catalyze carbonic acid ester and dyhydroxy compound fusing ester exchange to synthesize polycarbonate. The method is characterized in that the ionic liquid prepared from imidazolium salt serving as cations and amino acid radical serving as anions is taken as a catalyst to efficiently catalyze the reaction with the raw materials being dyhydroxy compound and carbonic acid ester so as to prepare aromatic or aliphatic polycarbonate. The using amount of the ionic liquid catalyst is 1*10 -3% of the mass ofthe dyhydroxy compound, the reaction temperature in the pre-polyester exchange stage is 100-200 DEG C, the pressure is 15kPa to the normal pressure, and the reaction time is 0.5-6 hours; and in the polycondensation stage, the reaction temperature is 220-280 DEG C, the pressure is 20-300 Pa, and the reaction time is 0.1-6 hours. Compared with traditional alkali metal salt, alkaline-earth metal salt and a quaternary ammonium catalyst, the imidazole amino acid ionic liquid has the characteristics that the catalyst has the good compatibility with the raw materials, the activity is high, the product glossiness is good, and the molecular weight of polycarbonate is high.

Preparation method of carbonic acid containing cosmetic using ice having high content of co2

Abstract: To provide a gas generation agent for applying easily and inexpensively, carbonic acid foam to a cosmetic having specific viscosity (viscosity at 25°C is 5-6500 mPa s) without using a pressure proof container, a propellant and carbonate, a kit for carbonic acid foam containing cosmetic preparation comprising the gas generation agent and the cosmetic having the specific viscosity, and a preparation method of the carbonic acid foam containing cosmetic including a step for applying such a gas generation agent to the cosmetic having specific viscosity.SOLUTION: The invention is configured so that, the gas generation agent including ice having COpercentage content of 3 mass% or more, is used as the gas generation agent for applying carbonic acid foam in use time of the cosmetic having viscosity at 25°C of 5-6500 mPa s.SELECTED DRAWING: None

PH value neutralization method of mercerized dyed shell fabric

Abstract: The invention discloses a pH value neutralization method of a mercerized dyed shell fabric. The method comprises the following steps of firstly, charging water with carbon dioxide at the rate of 15m /h to 30m /h so as to subject carbon dioxide and water to a reaction in a high-pressure environment of 1MPa to 4MPa to produce carbonic acid and enable a pH value of the produced carbonic acid to be 4 to 6, then, charging a rinsing bath with the carbonic acid so as to completely submerge a fabric into the carbonic acid for neutralization, thereby obtaining the finished fabric, wherein the temperature of the carbonic acid during neutralization is 25 DEG C to 40 DEG C, and the neutralization time is 25 to 35 seconds. According to the method, the neutralization cost of the fabric can be reduced while surface off odors are removed from the fabric.

A carboxy mask set

Abstract: The present invention relates to a carboxy mask set in which carbonic acid generated during a cosmetic procedure penetrates the skin and enlarges blood vessels to obtain effects of waste discharge, metabolism promotion, and skin detoxification. The carboxy mask set according to the present invention comprises: a first agent comprising carbonic acid powder, sugar powder, and sodium bicarbonate powder mixed with olive oil; and a second agent packaged separately from the first agent and formed by impregnating a fiber fabric with an organic acid and a moisturizing component.

δ-Carbonic anhydrases

Abstract: One-third of the CO2 released in the atmosphere by anthropogenic activities is absorbed by the oceans determining a dramatic change in seawater chemistry. In fact, CO2 reacts with water to form carbonic acid (H2CO3), which being unstable dissociates into hydrogen ions (H+) and bicarbonate ( H C O 3 − ) . Diatoms are a crucial component of the biological carbon pump that exports carbon into the ocean, contributing significantly to the long-term sequestration of atmospheric CO2. Diatom genome sequencing reveals the presence of different systems for H C O 3 − uptake, most of which are phylogenetically affiliated with those found in metazoans. In Phaeodactylum tricornutum, a plastid-targeted β-CA suggests that the localization and the role of carbonic anhydrases in diatoms are central to primary carbon metabolism. This chapter focuses on the δ-CAs (TweCA) identified in the genome of the marine diatom Thalassiosira weissflogii, demonstrating that TweCA is catalytically active for the hydration of CO2 but not for the hydrolysis of p-nitrophenyl acetate. Besides, the phylogenetic analysis showed that the δ-CAs are phylogenetically correlated more with the α-CAs than the other CA classes. Moreover, inhibition profiles of sulfonamides, inorganic anions, and the mono- and dithiocarbamates showed distinctive features for this enzyme providing new insights into the role of δ-CA in the algal carbon-concentrating mechanism.

Can carbonic acid protonate biological bases? Support from base protonation in methanol solvent

Abstract: In separate contributions, we have focussed on demonstrating that carbonic acid (CA) - historically considered too unstable to be a viable protonating agent - is able to protonate several types of pH indicators while behaving as a regular, moderately strong, carboxylic acid. Together with the experimental support we found for considering CA as a regular carboxylic acid are theoretical calculations demonstrating CA’s ability to protonate methylamine within 25 fs when forming with it a contact reactive complex. Here we briefly discuss a further aspect of this focus, involving the measurement of the lifetime and pKa of CA in pure methanol. The lifetime in methanol was found to be about 12-fold longer than in water, showing that the decomposition reaction of CA is solvent-dependent. The pKa change upon transferring CA from water to methanol was found to be 4.7 ± 0.1 pKa units, changing from 3.49 ± 0.03 to 8.16 ± 0.05: this change is similar to the pKa change observed for common stable carboxylic acids when these are transferred from water to methanol. These results add further support of our earlier proposal that CA can be an important protonating agent of biological bases in the blood plasma.

Method of producing carbonates of rare-earth elements

Abstract: FIELD: chemistry.SUBSTANCE: invention can be used in production of catalysts, individual rare-earth oxides and polishing powders. Method of producing carbonates of rare-earth elements (REE) involves feeding a solution of a lanthanum or cerium salt and a solution of a salt of carbonic acid, stirring at temperature of 20–45 °C to obtain a pulp of carbonates, filtration, washing and drying the lanthanum or cerium carbonate precipitate. Solution supply is controlled by pH change in process steps. At the first stage, the pH of the rare-earth carbonates pulp is fed in range of 4.1–5.5 by feeding the solution of the carbonic acid salt. At the second stage, the pH of the lanthanum or cerium salt solution is set in range of 3.7–4.5. At the third stage, the pH of the pulp is fed in range of 6.5–7.0 by feeding the solution of the carbonic acid salt. After reaching the preset value of pH, the pulp is agitated under mixer for 20–25 minutes at the first stage and for 20–30 minutes at the second and third stages. After that, mixer is switched off and pulp is left for 20–30 minutes to mature precipitate of carbonates. Then the pulp is filtered on a vacuum filter. Mixing is performed at agitator rotation speed 800–900 rpm.EFFECT: invention allows to enhance the product quality and efficiency of the process due to the possibility of obtaining homogeneous crystals of a regular plate-like or acicular shape of controlled size.2 cl, 5 dwg, 3 tbl, 3 ex

Acrylate carbonate and homopolymer and copolymer material thereof

Abstract: The invention discloses styrene carbonate and a homopolymer and a copolymer material thereof. The styrene carbonate is prepared by the following method: 1) in a high-pressure reaction kettle, an alcohol compound and a strong alkali catalyst are uniformly mixed in no solvent or an organic solvent, and carbon dioxide is introduced for reacting to obtain a carbonic acid monoester intermediate; and 2)vinylbenzyl chloride is added into the high-pressure reaction kettle in the step 1), carbon dioxide is introduced for reacting, and separating and the styrene carbonate is separated and purified after the reaction is ended. The method has the characteristics of simple and feasible process operation, low cost and suitability for industrial production, and the preparation process of the styrene carbonate is simple and efficient, the styrene carbonate structure can be regulated and controlled by selecting different alcohol compounds; the homopolymer and the copolymer of the styrene carbonate have fluorescent groups and can be used as fluorescent materials.