Morphological control of Ca3Al2(OH)12

Abstract

The effect of a range of inorganic and organic crystal growth modifiers on the morphology of Ca 3 Al 2 (OH) 12 has been studied. It has been found that some additives show a strong preference for a single crystal face forming polyhedral crystals whilst others are less selective, producing crystals with a less well defined morphology. In this way sulphite and dithionite preferentially interact with the {111} face producing octahedral crystals and nitrilotriacetic acid stabilises the {110} face forming rhombic dodecahedral crystals. Phosphate, however, leads to the formation of small needle-like crystals and the organic acids, N(CH 2 CO 2 H) 2 (CH 2 PO 3 H 2), N(CH 2 CO 2 H)(CH 2 PO 3 H 2) 2 , HN(CH 2 PO 3 H 2) 2 , and H 3 CN(CH 2 PO 3 H 2) 2 , produce near spherical crystals. The ability to be able to control the morphology of a material is of great importance in a variety of fields. This control is brought about by varying the crystallising conditions, typically by the addition of a crystal growth modifier to the solution. For molecular crystals, morphological modification has been brought about by the use of stereospecific inhibition of the growth of particular crystal faces. [1,2]

New method for carbon dioxide mineralization based on phosphogypsum and aluminium-rich industrial wastes resulting in valuable carbonated by-products

“…In Fig. 4, micron-sized octahedral habit of the katoite was easily recognised, as reported previously [41,42]. In addition, elongated-shaped thenardite crystals could be readily observed.…”

A Computer Modeling Study of the Inhibiting Effect of Organic Adsorbates on Calcite Crystal Growth

“…61 Furthermore, we have shown in earlier work 62 that the effect of adsorption of methanoic acid to calcium carbonate surfaces is to stabilize the surfaces to the same extent, leading to a calculated spherical morphology of the crystal, which finding was confirmed to some extent by the work of Fogg et al, who obtained spherical crystals of a calcium-aluminum salt when grown in the presence of organic acids. 63 When investigating the competitive adsorption of water and methanoic acid at calcite and fluorite surfaces, we successfully calculated the relative strengths of adsorption of the two adsorbates compared to experiment, 60,64 and based upon these preliminary studies we are now confident that the potential model is reliable for the quantitative comparison of the adsorption behavior of these organic molecules to calcite surfaces.…”

A Computer Modeling Study of the Competitive Adsorption of Water and Organic Surfactants at Surfaces of the Mineral Scheelite

“…For example, we found in a combined DFT and interatomic potential study of the adsorption of water in the scheelite material that both techniques were in good agreement as to the mode of adsorption and the hydration energies, and the experimental morphology of the scheelite crystal was accurately reproduced, indicating that the relative stabilities of the surfaces are calculated correctly . In addition, simulations of water adsorption at surfaces of calcium carbonate, a similar mineral to scheelite, predicted geometries for the adsorbed water molecules, which were later confirmed by experimental surface science techniques. , Furthermore, in addition to numerous computational studies of the sorption of a range of organic molecules in complex oxide systems such as zeolites, for example, − we have shown in earlier work that the effect of adsorption of methanoic acid to calcium carbonate surfaces is to stabilize the surfaces to the same extent, leading to a calculated spherical morphology of the crystal, which finding was confirmed to some extent by the work of Fogg et al who obtained spherical crystals of a calcium−aluminum salt when grown in the presence of organic acids . When investigating the competitive adsorption of water and methanoic acid at calcite and fluorite surfaces, we successfully calculated the relative strengths of adsorption of the two adsorbates compared to experiment. , On the basis of these preliminary studies, we are now confident that the potential model is reliable for the quantitative comparison of the adsorption behavior of these organic molecules to scheelite surfaces.…”