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Franca Jones - One of the best experts on this subject based on the ideXlab platform.

  • Can macrocyclic phosphonate molecules inhibit Barium Sulfate crystallization
    CrystEngComm, 2019
    Co-Authors: Tomoko Radomirovic, Andrew L. Rohl, Mark I. Ogden, Franca Jones
    Abstract:

    Macrocyclic compounds such as DOTP (1,4,7,10-tetraazacyclododecanetetrakis(methylenephosphonic acid)) and NOTP (1,4,7,-triazacyclononanetri(methylenephosphonic acid)) are found to inhibit precipitation of Barium Sulfate just as potently as their non-cyclic counterparts depending on the ionisation state of the molecule. Morphologically, DOTP has a more significant influence on the shape of Barium Sulfate particles formed than NOTP while turbidity results show that NOTP does not significantly affect the induction time observed, unlike DOTP, which does impact the induction time at higher concentrations. Overall, the inhibition of these macrocyclic compounds can be explained by the number of de-protonated phosphonate groups and is not significantly impacted by the presence of the ring. The presence of calcium ions during Barium Sulfate crystallization lowers the degree of inhibition for both NOTP and DOTP. Molecular modelling showed that an uncomplexed DOTP molecule could lattice match to the Barium Sulfate lattice but had fewer Ba⋯Ophos interactions than the equivalent non-macrocyclic molecule. The comparison of uncomplexed with complexed DOTP shows that the final configuration is similar for these two situations, thus in this case it is not the Ba⋯Ophos interactions but the overall replacement energy that is important.

  • The impact of oxalate ions on Barium Sulfate crystallization
    Journal of Crystal Growth, 2018
    Co-Authors: Franca Jones, Mark I. Ogden, Tomoko Radomirovic
    Abstract:

    Abstract In this manuscript we investigate the impact of oxalate ions on the crystallization of Barium Sulfate. The organic anion, oxalate, was found to inhibit both nucleation and growth according to atomic force microscopy measurements and dynamic light scattering data. Raman confocal imaging was used to try and determine how the oxalate interacts with the Barium Sulfate surface. It was found that Barium oxalate is only seen at very high oxalate concentrations. At lower concentrations no direct evidence for the presence of oxalate was observed, however, the most probable mode of action for oxalate is via adsorption onto the Barium Sulfate surface including into key kink or step sites, impacting growth.

  • Effect of Solution Silicate on the Precipitation of Barium Sulfate
    Crystal Growth & Design, 2012
    Co-Authors: Franca Jones, Tomoko Radomirovic, Mark I. Ogden
    Abstract:

    The presence of silicate during Barium Sulfate crystallization has different impacts depending on the pH of the solution. At pH 7 the dominance of the protonated form (H4SiO4) and possible polymerization of the silicate impacts mainly on the aggregation state and on twinning of the Barium Sulfate formed. At higher pH values (∼10), the silicate ion present is able to influence both morphology and partially substitute for Sulfate in the lattice. Interesting fibrous particles are formed under these conditions, but this is not due to mesocrystal formation as the particles are observed to be single crystalline in nature. These fibrous sections are found to be dominant on the surface and are highly porous. These particles are different, however, to the biomorphs formed when crystallization of Barium carbonate occurs in the presence of silicate. This is because the speciation of Sulfate does not change over a large pH range. The impact of silicate on Barium Sulfate particles is similar to the impact on calcium c...

  • Understanding Barium Sulfate precipitation onto stainless steel
    Applied Surface Science, 2008
    Co-Authors: Franca Jones, Phillip Jones, Roland De Marco, Bobby Pejcic, Andrew L. Rohl
    Abstract:

    This paper investigates the influence of Barium Sulfate scaling and scaling inhibitors on the electrochemical behaviour of stainless steel. The results of a synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) and electrochemical impedance spectroscopy (EIS) study on stainless steel shows that different scaling inhibitors interact uniquely with the substrate when Barium Sulfate is precipitated on the electrode surface. The main effect of the substrate in the presence of inhibitor is a tendency to form smaller Barium Sulfate particles. The SR-GIXRD patterns obtained in the presence of the two inhibitors were different to each other and to the control, with the carboxylate showing greater amounts of barite solids precipitated together with iron(III) and (II) Sulfate, while the phosphonate showed low amounts of barite solid were precipitated. The presence of iron Sulfates on the electrode surface as detected by SR-GIXRD, in the case of NTA, suggests that scaling inhibitors are not always benign, and can promote the dissolution of iron species from the substrate.

  • The interaction of EDTA with Barium Sulfate
    Journal of colloid and interface science, 2007
    Co-Authors: Franca Jones, Phillip Jones, Mark I. Ogden, William R. Richmond, Andrew L. Rohl, Martin Saunders
    Abstract:

    Ethylenediaminetetraacetic acid (EDTA) is a known complexing agent that interacts with a host of cations. In this paper, various techniques are used to elucidate the mechanism of interaction between EDTA and Barium Sulfate surfaces. It is shown that complexation with metal ions is not sufficient to explain the inhibition of barite crystallization but that other processes such as chemisorption must also occur. EDTA is shown to always adsorb as the mono-protonated species - suggesting that the molecule is able to lose a proton when it adsorbs at lower pH. Molecular modelling shows that the interaction of the surface Barium ions with the carboxylate group is an important one. Finally, in situ turbidity measurements provide information about the mechanism of nucleation/growth modification. It is found that the EDTA molecule inhibits Barium Sulfate nucleation and that this could be its primary means of inhibiting precipitation of Barium Sulfate.

Andrew L. Rohl - One of the best experts on this subject based on the ideXlab platform.

  • Can macrocyclic phosphonate molecules inhibit Barium Sulfate crystallization
    CrystEngComm, 2019
    Co-Authors: Tomoko Radomirovic, Andrew L. Rohl, Mark I. Ogden, Franca Jones
    Abstract:

    Macrocyclic compounds such as DOTP (1,4,7,10-tetraazacyclododecanetetrakis(methylenephosphonic acid)) and NOTP (1,4,7,-triazacyclononanetri(methylenephosphonic acid)) are found to inhibit precipitation of Barium Sulfate just as potently as their non-cyclic counterparts depending on the ionisation state of the molecule. Morphologically, DOTP has a more significant influence on the shape of Barium Sulfate particles formed than NOTP while turbidity results show that NOTP does not significantly affect the induction time observed, unlike DOTP, which does impact the induction time at higher concentrations. Overall, the inhibition of these macrocyclic compounds can be explained by the number of de-protonated phosphonate groups and is not significantly impacted by the presence of the ring. The presence of calcium ions during Barium Sulfate crystallization lowers the degree of inhibition for both NOTP and DOTP. Molecular modelling showed that an uncomplexed DOTP molecule could lattice match to the Barium Sulfate lattice but had fewer Ba⋯Ophos interactions than the equivalent non-macrocyclic molecule. The comparison of uncomplexed with complexed DOTP shows that the final configuration is similar for these two situations, thus in this case it is not the Ba⋯Ophos interactions but the overall replacement energy that is important.

  • Understanding Barium Sulfate precipitation onto stainless steel
    Applied Surface Science, 2008
    Co-Authors: Franca Jones, Phillip Jones, Roland De Marco, Bobby Pejcic, Andrew L. Rohl
    Abstract:

    This paper investigates the influence of Barium Sulfate scaling and scaling inhibitors on the electrochemical behaviour of stainless steel. The results of a synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) and electrochemical impedance spectroscopy (EIS) study on stainless steel shows that different scaling inhibitors interact uniquely with the substrate when Barium Sulfate is precipitated on the electrode surface. The main effect of the substrate in the presence of inhibitor is a tendency to form smaller Barium Sulfate particles. The SR-GIXRD patterns obtained in the presence of the two inhibitors were different to each other and to the control, with the carboxylate showing greater amounts of barite solids precipitated together with iron(III) and (II) Sulfate, while the phosphonate showed low amounts of barite solid were precipitated. The presence of iron Sulfates on the electrode surface as detected by SR-GIXRD, in the case of NTA, suggests that scaling inhibitors are not always benign, and can promote the dissolution of iron species from the substrate.

  • The interaction of EDTA with Barium Sulfate
    Journal of colloid and interface science, 2007
    Co-Authors: Franca Jones, Phillip Jones, Mark I. Ogden, William R. Richmond, Andrew L. Rohl, Martin Saunders
    Abstract:

    Ethylenediaminetetraacetic acid (EDTA) is a known complexing agent that interacts with a host of cations. In this paper, various techniques are used to elucidate the mechanism of interaction between EDTA and Barium Sulfate surfaces. It is shown that complexation with metal ions is not sufficient to explain the inhibition of barite crystallization but that other processes such as chemisorption must also occur. EDTA is shown to always adsorb as the mono-protonated species - suggesting that the molecule is able to lose a proton when it adsorbs at lower pH. Molecular modelling shows that the interaction of the surface Barium ions with the carboxylate group is an important one. Finally, in situ turbidity measurements provide information about the mechanism of nucleation/growth modification. It is found that the EDTA molecule inhibits Barium Sulfate nucleation and that this could be its primary means of inhibiting precipitation of Barium Sulfate.

  • Investigation into the effect of phosphonate inhibitors on Barium Sulfate precipitation
    Journal of Crystal Growth, 2001
    Co-Authors: Franca Jones, Mark I. Ogden, Andrew L. Rohl, Allan Oliveira, Gordon Parkinson, Manijeh M. Reyhani
    Abstract:

    The effect of a series of phosphonate molecules on Barium Sulfate precipitation was tested. While an increase in the number of phosphonate groups generally resulted in increased inhibition of Barium Sulfate precipitation, two notable exceptions showed that a relatively high number of phosphonate groups does not guarantee inhibition while a relatively low number of phosphonate groups does not imply no inhibition. Increasing the pH showed an increased effect of additives on Barium Sulfate precipitation up to pH 8. However, on increasing from pH 8 to 12, a loss of inhibition in the additives was observed which appears to be due to the Barium Sulfate surface changing with pH. r 2002 Elsevier Science B.V. All rights reserved.

Mark I. Ogden - One of the best experts on this subject based on the ideXlab platform.

  • Can macrocyclic phosphonate molecules inhibit Barium Sulfate crystallization
    CrystEngComm, 2019
    Co-Authors: Tomoko Radomirovic, Andrew L. Rohl, Mark I. Ogden, Franca Jones
    Abstract:

    Macrocyclic compounds such as DOTP (1,4,7,10-tetraazacyclododecanetetrakis(methylenephosphonic acid)) and NOTP (1,4,7,-triazacyclononanetri(methylenephosphonic acid)) are found to inhibit precipitation of Barium Sulfate just as potently as their non-cyclic counterparts depending on the ionisation state of the molecule. Morphologically, DOTP has a more significant influence on the shape of Barium Sulfate particles formed than NOTP while turbidity results show that NOTP does not significantly affect the induction time observed, unlike DOTP, which does impact the induction time at higher concentrations. Overall, the inhibition of these macrocyclic compounds can be explained by the number of de-protonated phosphonate groups and is not significantly impacted by the presence of the ring. The presence of calcium ions during Barium Sulfate crystallization lowers the degree of inhibition for both NOTP and DOTP. Molecular modelling showed that an uncomplexed DOTP molecule could lattice match to the Barium Sulfate lattice but had fewer Ba⋯Ophos interactions than the equivalent non-macrocyclic molecule. The comparison of uncomplexed with complexed DOTP shows that the final configuration is similar for these two situations, thus in this case it is not the Ba⋯Ophos interactions but the overall replacement energy that is important.

  • The impact of oxalate ions on Barium Sulfate crystallization
    Journal of Crystal Growth, 2018
    Co-Authors: Franca Jones, Mark I. Ogden, Tomoko Radomirovic
    Abstract:

    Abstract In this manuscript we investigate the impact of oxalate ions on the crystallization of Barium Sulfate. The organic anion, oxalate, was found to inhibit both nucleation and growth according to atomic force microscopy measurements and dynamic light scattering data. Raman confocal imaging was used to try and determine how the oxalate interacts with the Barium Sulfate surface. It was found that Barium oxalate is only seen at very high oxalate concentrations. At lower concentrations no direct evidence for the presence of oxalate was observed, however, the most probable mode of action for oxalate is via adsorption onto the Barium Sulfate surface including into key kink or step sites, impacting growth.

  • Effect of Solution Silicate on the Precipitation of Barium Sulfate
    Crystal Growth & Design, 2012
    Co-Authors: Franca Jones, Tomoko Radomirovic, Mark I. Ogden
    Abstract:

    The presence of silicate during Barium Sulfate crystallization has different impacts depending on the pH of the solution. At pH 7 the dominance of the protonated form (H4SiO4) and possible polymerization of the silicate impacts mainly on the aggregation state and on twinning of the Barium Sulfate formed. At higher pH values (∼10), the silicate ion present is able to influence both morphology and partially substitute for Sulfate in the lattice. Interesting fibrous particles are formed under these conditions, but this is not due to mesocrystal formation as the particles are observed to be single crystalline in nature. These fibrous sections are found to be dominant on the surface and are highly porous. These particles are different, however, to the biomorphs formed when crystallization of Barium carbonate occurs in the presence of silicate. This is because the speciation of Sulfate does not change over a large pH range. The impact of silicate on Barium Sulfate particles is similar to the impact on calcium c...

  • The interaction of EDTA with Barium Sulfate
    Journal of colloid and interface science, 2007
    Co-Authors: Franca Jones, Phillip Jones, Mark I. Ogden, William R. Richmond, Andrew L. Rohl, Martin Saunders
    Abstract:

    Ethylenediaminetetraacetic acid (EDTA) is a known complexing agent that interacts with a host of cations. In this paper, various techniques are used to elucidate the mechanism of interaction between EDTA and Barium Sulfate surfaces. It is shown that complexation with metal ions is not sufficient to explain the inhibition of barite crystallization but that other processes such as chemisorption must also occur. EDTA is shown to always adsorb as the mono-protonated species - suggesting that the molecule is able to lose a proton when it adsorbs at lower pH. Molecular modelling shows that the interaction of the surface Barium ions with the carboxylate group is an important one. Finally, in situ turbidity measurements provide information about the mechanism of nucleation/growth modification. It is found that the EDTA molecule inhibits Barium Sulfate nucleation and that this could be its primary means of inhibiting precipitation of Barium Sulfate.

  • Investigation into the effect of phosphonate inhibitors on Barium Sulfate precipitation
    Journal of Crystal Growth, 2001
    Co-Authors: Franca Jones, Mark I. Ogden, Andrew L. Rohl, Allan Oliveira, Gordon Parkinson, Manijeh M. Reyhani
    Abstract:

    The effect of a series of phosphonate molecules on Barium Sulfate precipitation was tested. While an increase in the number of phosphonate groups generally resulted in increased inhibition of Barium Sulfate precipitation, two notable exceptions showed that a relatively high number of phosphonate groups does not guarantee inhibition while a relatively low number of phosphonate groups does not imply no inhibition. Increasing the pH showed an increased effect of additives on Barium Sulfate precipitation up to pH 8. However, on increasing from pH 8 to 12, a loss of inhibition in the additives was observed which appears to be due to the Barium Sulfate surface changing with pH. r 2002 Elsevier Science B.V. All rights reserved.

Sana Mateen - One of the best experts on this subject based on the ideXlab platform.

Juan D. G. Durán - One of the best experts on this subject based on the ideXlab platform.

  • Interfacial Properties of Barium Sulfate Suspensions. Implications in Their Stability
    Journal of pharmaceutical sciences, 2000
    Co-Authors: Visitación Gallardo, L. Zurita, A. Ontiveros, Juan D. G. Durán
    Abstract:

    Abstract A surface characterization of Barium Sulfate particles in aqueous suspensions was carried out in this work. With the aim of predicting the stability conditions of these widely used suspensions, the electrical surface properties of the particles were first studied by electrophoretic mobility determinations. It was found that both H + and OH − ions can be considered as potential‐determining ions for the Barium Sulfate/water interface. The same conclusion was reached concerning the lattice ions, Ba 2+ (mainly) and SO 4 2− . It was also found that increasing the concentration of sodium chloride in the dispersion medium can even change the sign of the zeta (ζ) potential: it is suggested that this behavior is an indirect effect provoked by changes in the solubility of Barium Sulfate with the ionic strength. To compute the van der Waals (LW) attraction between the particles as well as the acid‐base contribution to the total energy of interaction, a thermodynamic characterization of the interface was also carried out by measuring the rate of penetration of selected liquids through plugs of the particles. It was found that Barium Sulfate particles are essentially monopolar in nature; that is, they show electron‐donor character as demonstrated by the essentially zero value of the electron‐acceptor component of their surface free energy. Pretreatment of the particles with 10 −2 M solutions of BaCl 2 and CaCl 2 significantly reduced the electron‐donor component, whereas both NaCl and Na 2 SO 4 provoked the opposite effect. This result is explained in terms of the acid–base character of the ions added. These data were used to calculate the interaction energy between the particles. The effect of electrolyte concentration on the stability of the suspensions was analyzed on the basis of the dependence with distance of the interaction energy between the particles. Our results suggest that more stable suspensions of Barium Sulfate are predicted if moderate amounts of SO 4 2− ions are added to the dispersion medium. © 2000 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 89: 1134–1142, 2000