Barium Sulfate Crystals Research Articles

Adsorption Behavior of Polyelectrolytes on Barium Sulfate Crystals

For two polyphosphinoacrylates, PPAA-I and PPAA-II, and a random copolymer of maleic acid and vinyl sulfonic acid, PMA-PVS, the levels of adsorption equilibrium on BaSO4 crystals were determined as a function of their concentration and related to the formerly established growth-inhibiting effect of these compounds on BaSO4 crystallization. The best growth retarder of the two polyphosphinoacrylates, PPAA-II, reaches a higher surface coverage than PPAA-I which has a lower molecular weight. Such a relationship between inhibitor effect, maximal surface coverage, and molecular weight is only valid for structurally identical compounds. For the better growth retarder, PMA-PVS, a lower maximal surface coverage was found than for the structurally different PPAA-II. From the adsorption isotherms of PMA-PVA and PPAA-II, the equilibrium surface coverages at the PMA-PVS and PPAA-II concentrations which cause total growth blockage (0.2 ppm and 0.5 ppm, respectively) could be derived. This resulted in equilibrium surface coverages of ≈3.8 × 10-3 mg m-2 for PMA-PVS and ≈6.6 × 10-3 mg m-2 for PPAA-II.To determine whether matching between the inhibitor molecules and the crystal surface layer of BaSO4 plays a role in its performance, the shape and morphology of BaSO4 crystals were examined after long-term growth experiments in the presence of PMA-PVS and PPAA-II. The development of the {011} and {101} faces in the presence of PMA-PVS points at an easy replacement of the lattice sulfate ions with one S-O bond orientated perpendicular to the crystal surface by sulfonate ions of PMA-PVS. In the presence of PPAA-II, striations were observed in the 〈010〉 directions which might be related to a good fitting between the interatomic lattice distances in these directions and the mutual distances of the functional carboxylate groups of the inhibitor.

The statolith compartment inChararhizoids contains carbohydrate and protein

In contrast to higher plants, the alga Chara has rhizoids with single membrane-bound compartments that function as statoliths in gravity perception. Previous work has demonstrated that these statoliths contain barium sulfate crystals. In this study, we show that statoliths in Chara rhizoids react with a Coomassie Brilliant Blue cytochemical stain for proteins. While statoliths did not react with silver methenamine carbohydrate cytochemistry, the monoclonal antibody CCRC-M2, which is against a carbohydrate (sycamore-maple rhamnogalacturonan I), labeled the statolith compartment. These results demonstrate that in addition to barium sulfate, statoliths in Chara rhizoids have an organic matrix that consists of protein and carbohydrate moieties. Since the statoliths were silver methenamine negative, the carbohydrate in this compartment could be a 3-linked polysaccharide. CCRC-M2 also labeled Golgi cisternae, Golgi-associated vesicles, apical vesicles, and cell walls in the rhizoids. The specificity of CCRC-M2 immunolabeling was verified by several control experiments, including the demonstration that labeling was abolished when the antibody was preabsorbed with its antigen. Since in this and a previous study (John Z. Kiss and L. Andrew Staehelin, American Journal of Botany 80: 273-282, 1993) antibodies against higher plant carbohydrates crossreacted with cell walls of Chara in a specific manner, Characean algae may be a useful model system in biochemical and molecular studies of cell walls.

Barium and Calcium Sulfate Precipitation and Migration Inside Sandpacks

Summary This paper is an experimental and theoretical study of permeability reduction of sandpacks caused by solids generation and migration. Two solids, calcium and barium sulfate crystals, were injected into and generated within the sandpacks by chemical reaction. We found that we could simulate the effluent concentrations, including the produced solids, with a fractional flow model for solids migration.

Molecular design based on recognition at inorganic surfaces

MOLECULAR recognition at inorganic surfaces has the potential to provide control over crystal growth processes. For organic surfaces, molecules that influence crystallization1–3 can be derived by rational modification of host molecules to give the stereochemistry required by the surface structure. This approach is of little use for inorganic systems, however, because the relatively simple stereochemistries of the surfaces and ions concerned allow little scope for similar manipulation. Previous work4–6, therefore, has been essentially phenomenological. Here we show that a detailed understanding of recognition processes at inorganic surfaces can nevertheless lead to the rational design of surface-active molecules. We have used crystal morphological characteristics to deduce the nature of the surface binding sites of diphosphonates on barium sulphate crystals, and have thereby been able to design new surface-active molecules with improved efficacy.

Biological minerals formed from strontium and barium sulphates. II. Crystallography and control of mineral morphology in desmids

The crystallography and morphology of barium sulphate crystals produced by a range of desmid species have been examined by electron microscopy and electron diffraction. The morphology of the BaSO 4 crystals varies between desmid species and water chemistry. Tabular, rhombic crystals are commonly produced by Closterium lunula and hexagonal or elliptical crystals by Micrasterias thomasiana . High-resolution transmission electron microscopy (hrtem) has confirmed the single-crystal nature of the biological precipitates. The crystals all lie with their tabular faces perpendicular to the [001] zone axis and are comparable with the typical crystal habit of geological and synthetic barium sulphates, suggesting a limited degree of biological control over precipitation. M 2+ (Ba 2+ or Sr 2+ ) : SO 2- 4 ion ratios in vivo and in vitro have been shown to affect the morphology of the crystals produced. For Closterium lunula an M 2+ : SO 2- 4 ion ratio of less than 1:1 produces rhombic crystals and an ion ratio of more than 10:1 produces hexagonal crystals. For Micrasterias thomasiana , an ion ratio of 0.01:1 produces hexagonal crystals; an ion ratio of 1:1 produces a mixture of hexagonal and elliptical crystals, and an ion ratio of more than 10:1 produces elliptical crystals. Crystal morphologies produced by desmids have been compared with those of synthetic crystals produced at similar ion ratios. The apparently limited extent of biological control and the importance of the ionic environment on the development of crystal morphology are discussed. It is proposed that desmid crystal morphology may provide a diagnostic for the local environment of crystal formation in the cell.

The pallial organ of Atrina pectinata (Bivalvia: Pinnidae): its structure and function

Hitherto, the unique pallial organ of the Pinnidae has been considered to fulfil a cleansing role, removing sediment and shell fragments from the mantle cavity. This study of the pallial organ of Atrina pectinata describes structure in greater detail than before but was unable to demonstrate a cleansing function. Rather, the organ is thigmotropic and massively secretory. Study of the pallial organ head demonstrates it to have a pH of between 2 and 4 and that tall, apparently empty cells in the head epithelium contain sulphuric acid which can be precipitated as barium sulphate crystals following irrigation with barium chloride.Acid‐secreting cells are recorded from a number of animal groups, notably opisthobranch gastropods, where they are concluded to possess a defensive function. Such a structure has not hitherto been recorded from the Bivalvia.

Barium sulfate crystals in parenteral solutions of aminoglycoside antibiotics.

Barium sulfate crystals in parenteral solutions of aminoglycoside antibiotics.

Electron microscopic study of nucleation and growth of highly dispersed solid phase

Crystallization of barium carbonate and barium sulfate at fast mixing of reagents solutions was investigated. The method of high resolution electron microscopy showed that during crystallization ultramicrocrystals of 1- to 5-nm size are formed which have an oriented aggregation and are further transformed into polyhedrons not different in their outer appearance from the single crystals. The change of ultramicrocrystals size distribution is described by the Fokker-Planck equation. Ultramicrocrystal nucleation and growth at large supersaturation interval obey the kinetic reaction equations of the third and the second order, respectively. It is possible to consider nucleation as ion triplet associate formation with further rearrangement requiring activation energy of approximately 70 kJ mole −1.

ChemInform Abstract: CRYSTAL GROWTH IN AQUEOUS SOLUTION AT ELEVATED TEMPERATURES. BARIUM SULFATE GROWTH KINETICS

AbstractDie Löslichkeit sowie die Kristallisation nach Animpfen von Baryt (BaSO4) werden bei 105‐150°C in wäßrigen NaCl‐Lösungen bei Ionenstärken zwischen 0.1 und 1.0 M im Hinblick auf BaSO4‐Ablagerungen in Öl‐ und Gasquellen sowie in geothermischen Wässern untersucht.

The adsorption of polyelectrolytes on barium sulfate crystals

The adsorption isotherms of sodium carboxymethyl cellulose and poly(acrylic acid) on barium sulfate from aqueous solution have been determined using both spin-labeled and radiolabeled molecules. The influence of pH, ionic strength, and strongly adsorbing competing ions on the amount adsorbed and the adsorbed polymers' configuration was investigated. At alkaline pH, increased ionic strength allowed more polymer to adsorb, demonstrating the importance of the osmotic repulsion between unattached segments of adsorbed polymers. In water, the configuration of the adsorbed polymers was flat, having more than 90% of segments associated with the surface whereas in the presence of electrolyte as many as 30–40% of the segments will be in tails or loops. The presence of phosphate ions causes less polymer to be adsorbed and for the adsorbed polymer to contain more tails or loops than in the presence of simple electrolytes. From IR, ESCA, and 35SO 4 2− measurements, it is likely that the carboxylate ions are not closely associated with barium ions in the surface but are rather loosely attracted to those positive sites. Adsorption of poly(acrylic acid) is accompanied by desorption of SO 4 2− from the surface.

Quantitative Description of the Influence of the Inhibitor Concentration on the Growth Rate of Barium Sulfate Crystals in Suspension (III)

AbstractTo describe quantitatively the effect of a growth inhibitor on the growth rate of barium sulfate crystals, suspended in a supersaturated solution, the “strength of inhibition” has been introduced. The strength of inhibition is defined as the ratio of the mean linear growth rates without and with inhibitor at the same value of the growth affinity. It has been shown that the strength of inhibition, exerted by 1‐hydroxyethylidene‐1, 1‐bisphosphonic acid (HEDP) and aminomethylene‐bisphosphonic acid (AMDP) on the growth process, not only depends on its concentration, but also on the growth affinity, or probably even on both the growth affinity and the changes in the geometry of the crystals due to their growth in the presence of an inhibitor.

Identification of subvisible barium sulfate crystals in parenteral solutions

Identification of subvisible barium sulfate crystals in parenteral solutions

The influence of inhibitors on the growth of barium sulfate crystals in suspension: Scale prevention (II)

AbstractThe inhibiting influence of four organic bisphosphonates with different substituents on the growth rate of barium sulfate crystals, suspended in a supersaturated solution, has been investigated. The growth process has been studied conductometrically. Plots of both the relative supersaturation versus time and the mean linear rate versus the growth affinity have been given. — The results have been interpreted using a hypothesis, stating that growth inhibition occurs due to simultaneous coordination of the cations and hydrogen bonding of the anions at the active growth spots on the crystal surface.

The growth kinetics of barium sulphate crystals in suspension: Scale prevention (I)

AbstractThe growth process of barium of sulfate crystals suspended in a supersaturated solution has been studied conductometrically. The mean linear rate R̄ has been plotted as a function of the growth affinity — Δμ/RT. A first attempt has been made to fit the experimental growth data in the highest supersaturation range with surface nucleation models.

Nitrilotri (methylenephosphonic acid) adsorption on barium sulfate crystals and its influence on crystal growth

The crystallization of barium sulfate has been studied, at 25°C, by conductimetric and radiochemical methods both in the absence and presence of nitrilotri (methylenephosphonic acid) NTMP. The marked reduction in rate constant for crystal growth in the presence of NTMP is interpreted in terms of a Langmuir adsorption isotherm reflecting the blocking of active growth sites on the barium sulfate crystals. The results of a carbon-14 study of the adsorption of NTMP on barium sulfate crystals, clearly demonstrate the heterogeneity of the surface sites. At an additive concentration corresponding to complete inhibition of crystal growth, it is estimated that less than 5% of the crystal surface is covered by adsorbed NTMP molecules.

A kinetic study of the seeded growth of barium sulfate in the presence of additives

The crystallization of barium sulfate seed crystals in supersaturated solutions has been studied conductometrically and radiochemically at 25°C. After an initial surge reflecting secondary nucleation, the crystal growth follows a rate law second-order in relative supersaturation, both in the absence and presence of additives. Organic polyphosphonates and polymeric molecules such as polygalacturonic acid and ethylenemaleic anhydride co-polymer are effective inhibitors of crystallization. The inhibiting influence of benzene polycarboxylic acids can be related to the tendency for complex formation with barium ions and to the pH of the supersaturated solutions.

Scanning electron microscopic and kinetic studies of the crystallization and dissolution of barium sulfate crystals

The kinetics of crystallization and of dissolution of well-characterized seed crystals of barium sulfate in stable supersaturated and undersaturated solutions, respectively, of this salt, have been studied at 25°C using a highly reproducible conductance technique. Seed crystals of three distinctly different morphologies have been used and the crystal growth has also been followed by parallel scanning electron microscopic experiments. Following an initial growth surge reflecting some secondary nucleation, the rate of crystallization is proportional to the square of the supersaturation indicating a surface controlled reaction. The rate of dissolution is also controlled by a surface reaction being proportional to the square of the undersaturation and independent of fluid dynamics. In spontaneous precipitation experiments crystals have been obtained of widely differing morphologies depending upon the nature and concentration of the reactants and the fluid dynamics of mixing. Different shaped crystals have different densities of active growth sites, monitored kinetically, on their surfaces. The rate of growth of all the crystals, however, varies linearly with the square of the barium sulfate supersaturation.

Crystal Growth and Dissolution of Barium Sulfate

Abstract The kinetics of crystallization and dissolution of barium sulfate seed crystals were investigated conductimetrically. Growth is characterized by an initial surge caused by secondary nucleation, followed by a rate that is proportional to The square of the supersaturation. Studies were made using seed material of differing morphology; in all cases, the crystallization was surface controlled. A surface reaction also appears to be rate-determining for the corresponding dissolution process, but the over-all rate constant is considerably greater than that for growth. Crystallization and dissolution were studied in the presence of potential phosphonate and polyphosphate scaling inhibitors phosphonate and polyphosphate scaling inhibitors in some cases, both processes were markedly inhibited. The incorporation of the antiscalant into the developing crystals may pose problems in down-hole application. Introduction The state of knowledge of adsorption and desorption phenomena and of reactions at the solid-liquid interfaces under wellbore conditions is extremely limited. Consequently, the procedures used for eliminating scale by the chemical treatment of surface waters that are frequently injected into an oil-bearing formation are often based on empirical considerations. In the absence of knowledge of the mechanism of scale formation and its inhibition, the choice of additive is usually made on the basis of the results of spontaneous precipitation experiments made in the laboratory. precipitation experiments made in the laboratory. Although attempts are made to reproduce such experimental data, extreme sensitivity to factors such as the methods used to mix reagents, rates of stirring, and concentrations of reactants make it impossible to do so. Also, it is difficult to avoid heterogeneous nucleation in such systems, and this process also may be influenced by the presence of the additive. Interpretations of the course of the precipitation reactions solely in terms of the precipitation reactions solely in terms of the thermodynamic solubility products of the precipitating minerals also is questionable. Such precipitating minerals also is questionable. Such treatments assume that, at all stages of the scaling process, the systems are effectively at equilibrium process, the systems are effectively at equilibrium and are amenable to treatment using experimental solubility products. It has been shown that kinetic factors often are considerably more important in determining the course of a precipitation process. Thus, in the case of calcium phosphate crystal growth, an amorphous precursor is formed rapidly at the beginning of the reaction and undergoes a slow transformation to the thermodynamically stable phase, hydroxyapatite. Significant changes with phase, hydroxyapatite. Significant changes with time are observed in such factors as chemical composition, crystallinity, and the specific surface areas of the solid phases. The nature of the initially precipitated phases and the course of the subsequent precipitated phases and the course of the subsequent crystal growth reaction is markedly dependent not only on the degree of supersaturation of the solution, but also on the ionic strength of the solution and the type of neutral or inert electrolyte present. Simple equilibrium solubility studies reveal nothing of these factors that may be important in determining whether scale will form in the field. Not only is the growth of crystals important for studies of scale formation, but a knowledge of the mechanism of the reverse process, dissolution, also is essential if the results of laboratory experiments are to be used to predict the behavior in actual scaling situations. At first, the growth and dissolution of crystals may be considered to be exactly reciprocal processes. The dissolution process usually has been considered to be a simple process usually has been considered to be a simple diffusion-controlled process, with the transport of lattice ions away from the crystal surface as the slow step in the reaction. in terms of diffusion following Fick's law, the rate of reaction would be expected to be proportional to the subsaturation, mo - m, where m is the molar concentration of electrolyte in the solution and mo is the equilibrium (solubility) value. Although a number of salts follow this kinetic path, there is now appreciable evidence that the dissolution of many slightly soluble salts is controlled by a process other than film diffusion of the crystal lattice ions. Whereas scale inhibitors would be expected to have little influence on a dissolution process that depends on the diffusion of crystal lattice ions away from the surface, a surface-controlled process may be markedly retarded in their presence. SPEJ P. 509

The crystal growth and dissolution of barium sulfate in the presence of additives

The crystallization and dissolution of barium sulfate in the presence of N,N,N′,N′ triethylenediaminetetra(methylene phosphonic acid) (TENTMP), sodium tetrametaphosphate, and sodium tripolyphosphate have been studied conductimetrically at 25°C. Quadratic equations, second order with respect to relative supersaturation and subsaturation, have been satisfactorily used to interpret the kinetic data for the growth and dissolution reactions, respectively. Delay periods in the growth of barium sulfate crystals in the presence of sodium tripolyphosphate strongly suggest that this additive is incorporated into the crystals during growth. In the corresponding dissolution reactions, the presence of polyphosphates results in an initial surge indicating that the adsorption of the polyphosphates on the surface of the barium sulfate seed crystals is not an instantaneous process. The marked inhibition of dissolution in the presence of 4.4 × 10 −8 M sodium tripolyphosphate adds strong support to the suggested surface control for this reaction. For all the additives, the relative effectiveness as inhibitors both for crystal growth and dissolution is sodium tripolyphosphate > sodium tetrametaphosphate > TENTMP.

Defect formation in crystals grown from aqueous solutions. Growth rate of barium sulphate crystals and its influence on their defect content

Crystal defect generation dependence on growth rate is shown to be adequately represented by the Planck–Fokker equation, under widely different supersaturations (0.1–400 fold). The experimental results indicate that the bulk crystal defects are a reflection of the steady state surface defect situation. Rearrangement and migration of trapped solvent molecules, subsequent to growth, leads to formation of micro-inclusions.