Crystal growth of lead fluoride using constant composition method I. The effect of Pb/F activity ratio on the solubility of solid phase

2007 ◽  
pp. 201-206 ◽  
Author(s):  
N. Stubičar ◽  
M. Ćavar ◽  
D. Škrtić
Keyword(s):  
Crystal Growth ◽  
Activity Ratio ◽  
Solid Phase ◽  
Lead Fluoride ◽  
Constant Composition ◽  
Composition Method

Crystal growth of lead fluoride phases using the constant composition method III. Effect of pH and ionic strength

1993 ◽  
Vol 130 (1-2) ◽  
pp. 300-304 ◽  
Author(s):  
Nada Stubičar ◽  
Berislav Marković ◽  
Anton Tonejc ◽  
Mirko Stubičar
Keyword(s):  
Crystal Growth ◽  
Ionic Strength ◽  
Lead Fluoride ◽  
Constant Composition ◽  
Effect Of Ph ◽  
Composition Method

A Controlled Composition Study of Calcium Carbonate Crystal Growth: The Influence of Scale Inhibitors

CORROSION ◽  
1981 ◽  
Vol 37 (2) ◽  
pp. 76-81 ◽  
Author(s):  
George H. Nancollas ◽  
Thomas F. Kazmierczak ◽  
Eric Schuttringer
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Solid Phase ◽  
Ionic Species ◽  
Constant Composition ◽  
Rotating Disc ◽  
Active Growth ◽  
Ambient Temperatures ◽  
Composition Method ◽  
Wide Range

Abstract The precipitation of calcium carbonate is of considerable importance in a wide variety of scale forming situations since carbonate concentrations in the environment are usually quite appreciable. As a first-formed solid phase, calcium carbonate may induce the growth of other scale minerals on its surface. Since the solubility of calcium carbonate polymorphs decreases with increasing temperature, the problem is also aggravated by the relatively high ambient temperatures in many processes. This paper describes a new highly reproducible, seeded crystal growth method in which the activity of ion species is automatically maintained constant during the crystal growth reaction so that the kinetics can be studied over a wide range of supersaturation. The rate of calcite growth, over a 30X range of ionic strength, is proportional to the square of the relative supersaturation ([{Ca2+}{CO32−}]1/2−Kso1/2)2 expressed in terms of the activities of the ionic species. The rate is directly proportional to the seed concentration over a 3X range of the latter. The constant composition method has also been used to investigate the mineralization rate of a rotating disc of calcite (∼ 1 cm2 area) having very well defined hydrodynamic parameters. The rate of reaction (per m seed surface) is in striking agreement with that obtained using seed crystals (typically 500 cm2) despite the large difference in available growth sites. The evidence points to a surface controlled crystallization mechanism. Traces of orthophosphate and typical phosphonate scale inhibitors markedly inhibit the rate of calcium carbonate scale formation. Even with the sustained driving force provided by the constant composition method, a concentration of 9.1×10−8 M hydroxyethylidene-1, 1-diphosphonic acid completely inhibits the crystallization of calcite for more than 100 hours. The effectiveness of this scale inhibitor is clearly due to adsorption at active growth sites on the developing crystal surfaces.

scholarly journals Inhibition of calcium carbonate crystal growth by organic additives using the constant composition method in conditions of recirculating cooling circuits

2017 ◽  
Vol 472 ◽  
pp. 35-45 ◽  
Author(s):  
Norinda Chhim ◽  
Chams Kharbachi ◽  
Thibaut Neveux ◽  
Céline Bouteleux ◽  
Sébastien Teychené ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Organic Additives ◽  
Constant Composition ◽  
Composition Method

Molecular-Dynamics Simulations of Recrystallization Processes in Silicon: Nucleation and Crystal Growth in the Solid-Phase and Melt

2019 ◽  
Vol 3 (8) ◽  
pp. 207-213
Author(s):  
Teruaki Motooka ◽  
Shinji Munetoh ◽  
Ryuzo Kishikawa ◽  
Takahide Kuranaga ◽  
Tomohiko Ogata ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Crystal Growth ◽  
Molecular Dynamics Simulations ◽  
Solid Phase ◽  
Dynamics Simulations

Constant composition study of crystal growth of dicalcium phosphate dihydrate. The influence of polyphosphates, phosphonates, and phytate

1988 ◽  
Vol 66 (9) ◽  
pp. 2181-2187 ◽  
Author(s):  
Zahid Amjad
Keyword(s):  
Crystal Growth ◽  
Phosphonic Acid ◽  
Structural Features ◽  
Dicalcium Phosphate Dihydrate ◽  
Constant Composition ◽  
Seed Crystals ◽  
Langmuir Adsorption ◽  
Inhibitor Complex ◽  
Phosphate Dihydrate ◽  
Mechanism Of Inhibition

The influence of inhibitors of varying functional groups on the crystal growth of calcium phosphate dihydrate (CaHPO4•2H2O, DCPD) on DCPD seed crystals at pH 6.00, 37 °C, has been studied using the constant composition technique. The inhibitors studied include: (a) polyphosphate (sodium pyrophosphate, sodium hexametaphosphate, SHMP), (b) phosphonates (nitrilotris(methylene phosphonic acid), NTMP; 1-hydroxyethylidene-1,1-diphosphonic acid, HEDP; ethylenediaminetetra (methylene phosphonic acid), ETMP; hexamethylenediaminetetra(methylene phosphonic acid), HMDP); and (c) myoinositol hexaphosphoric acid (phytic acid). The effect of these inhibitors on the growth kinetics have been studied at several inhibitor concentrations. The retarding effect of these inhibitors is discussed in relation to calcium–inhibitor complex formation on the DCPD seed crystals and the structural features of the inhibitor molecules. The fit of the Langmuir adsorption to experimental data supports a mechanism of inhibition through molecular adsorption of the inhibitor ions on the surface of growing crystals. Based upon the kinetic data, the overall order of inhibitors effectiveness is[Formula: see text]

The Growth of Hydroxyapatite from Solution. A New Constant Composition Method

1978 ◽  
Vol 57 (9-10) ◽  
pp. 909-909 ◽  
Author(s):  
Z. Amjad ◽  
P. Koutsoukos ◽  
M.B. Tomson ◽  
G.H. Nancollas
Keyword(s):  
Constant Composition ◽  
Composition Method
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