Semi‐Batch Precipitation of Calcium Oxalate Monohydrate

Millán, Ángel; Gráses, F.; Söhnel, O.; Křivánková, I.

doi:10.1002/crat.2170270105

Cited by 15 publications

(15 citation statements)

References 14 publications

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“…This smoothed procedure allows to decrease a mistake at calculation of K a . Starting with the measurement 7 to the measurement 12 the aggregation constant can be calculated with expression (6). The results of these calculations of K a and C in run 22 are also presented in table 1.…”

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confidence: 99%

Spontaneous crystallization of sodium chloride from aqueous‐ethanol solutions – Part 2: Mechanism of aggregation and coalescence of crystals

Linnikov¹

2006

Cryst. Res. Technol.

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Published data on aggregation kinetics of sodium chloride crystals at its spontaneous crystallization from supersaturated aqueous-ethanol solutions were analysed. It was found that the crystals coalesced through contact nucleus-bridges between them according to the mechanism proposed by Polak. The kinetics of aggregation were described by the Smoluchowski equation for coagulation of colloidal particles. The kinetic coefficient of aggregation process depended on supersaturation, temperature of solution and other characteristics of the system. The specific surface energy of sodium chloride 0.95 mJ/m 2 was found.Investigations of last years showed that at spontaneous crystallization from solutions there is always aggregation of crystals [1][2][3][4][5][6][7]. But at present theoretical models of the crystallization describe this process only on a quality level [8][9][10][11][12][13]. Earlier [14] it was shown that kinetics of aggregation of potassium chloride crystals at spontaneous crystallization from aqueous and aqueous-ethanol solutions in sympathy with coagulation of colloidal particles were describes by the famous Smoluchowski equation [15]. That equation for this case was transformed into [7,14]:where τ is the time (s); K a is the aggregation constant; τ 0 is the length of the induction period of crystallization (s); N 0 , N are the total numbers of crystals of salt in solution at the end of the induction period of crystallization and at time τ , respectively. During the crystallization of potassium chloride the aggregation constant K a decreased as result of drop in supersaturation of solution, and was determined by expression [7,14]:where K 0 is the hydrodynamic constant depending on the fluid dynamics conditions of crystallization process and determining the probability of collision of crystals in solution; P is the orientation factor, it is equal to probability of suitable coalescence orientation of crystals at the moment of the collision; V is the volume of solution (m 3 ); W 1 is the probability of the event that the formed nucleus-bridges between crystals will not be destroyed at the next collisions ; K 1 =K 0 PV -1 W 1 is the coefficient of proportionality; D 1 , D 2 , D 3 are constants; С, С 0 are the concentrations of supersaturated and saturated solutions of salt, respectively. It was shown earlier [14] that the hydrodynamic constant K 0 did not change and was a constant value during the crystallization process when a mixer speed was also constant. This is in agreement with [12].

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Spontaneous crystallization of sodium chloride from aqueous‐ethanol solutions – Part 2: Mechanism of aggregation and coalescence of crystals

Linnikov¹

2006

Cryst. Res. Technol.

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“…The majority of physicochemical studies on urolithiasis to date (e.g. [3,7,8]) have dealt with this stage, and undoubtedly their results are of importance for evaluating oxalocalcic stone growth. Nevertheless, recent data clearly indicate that heterogeneous nucleation of calcium oxalate on foreign particles retained at the boundary of the papilla and subsequent primary aggregation prevail during the early stages of stone formation and represent the principal stage in calcium oxalate urolithiasis.…”

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confidence: 99%

Experimental technique simulating oxalocalcic renal stone generation

1993

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A new technique simulating some of the conditions experienced by papillar and caliceal oxalocalcic stones during the early stages of their generation was developed. This technique enables the study of how conditions prevailing at calculogenesis, such as pH, composition of urine and presence of admixtures, influence the rate of formation and development, the crystalline texture and the composition of the concretion formed. Results achieved with this technique demonstrate that: (1) an appropriate substrate always gives rise to a crystalline concretion if it is in contact with supersaturated urine; (2) primary agglomeration plays a significant role in concretion development whereas secondary agglomeration is of minor importance; and (3) citrate and pyrophosphate exert a considerable influence on the shape and composition of particles constituting the concretion.

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“…C O M ag glomerates with a structure similar to this described above are also formed under reaction conditions widely differing from those employed in the present study (7,8].…”

Section: Resultsmentioning

confidence: 63%

Role of Agglomeration in Calcium Oxalate Monohydrate Urolith Development

Gráses¹,

Millán²,

Söhnel³

1992

Nephron

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Formation of agglomerates of calcium oxalate monohydrate (COM) crystals on semi-batch precipitation peformed at conditions relevant to urolithiasis (37°C, pH = 6, initial ratio [Ca]/[Ox] = 10), but without any specific admixture, was followed by both optical and electron microscopy. COM crystals formed on precipitation developed into large agglomerates consisting of intergrown crystals by a mechanism of primary agglomeration. Primary agglomeration of COM crystals represents an important mechanism of COM renal calculi growth.

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Semi‐Batch Precipitation of Calcium Oxalate Monohydrate

Cited by 15 publications

References 14 publications

Spontaneous crystallization of sodium chloride from aqueous‐ethanol solutions – Part 2: Mechanism of aggregation and coalescence of crystals

Spontaneous crystallization of sodium chloride from aqueous‐ethanol solutions – Part 2: Mechanism of aggregation and coalescence of crystals

Experimental technique simulating oxalocalcic renal stone generation

Role of Agglomeration in Calcium Oxalate Monohydrate Urolith Development

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