Morphology, of calcium carbonate

The final examples, taken from a range of possibilities, illustrate first the use of nanoparticles (in Fig. 29, dendrimers of two generations) on the morphology of calcium carbonate particles prepared in their presence. The larger dendrimer has a greater effect on the product whose particles size is much smaller than that prepared with the lower generation dendrimer. 

Corrales LR (1999) Dissociative model of water clusters. J Chemical Physics 110 9071-9080 Curtiss LA, Halley JW, Hautman J, Rahman A (1987) Nonadditivity of ab-initio pair potentials for molecular dynamics of multivalent transition metal ions in water. J Chem Phys 86 2319-2327 de Leeuw NH, Parker SC, Catlow CRA, Price GD (2000) Proton-containing defects at forsterite (010) tilt grain boundaries and stepped surfaces. Am Min 85 1143-1154 de Leeuw NH, Parker SC (1998) Surface stracture and morphology of calcium carbonate polymorphs calcite, aragonite, andvaterite An atomistic approach. JPhys ChemB 102 2914-2922... 

Differences in river basin morphology, soil characteristics, rainfall, and land use in a watershed Influence phosphorus transport in a fluvial system. However, the dominance of iron oxides as an inorganic phosphate sink and the discharge dependent behavior of calcium carbonate-phosphate minerals found in this study would be expected to exist in other calcareous agricultural regions of New York State as well. Mountainous terrain and areas of sand and muck soil would probably not exhibit the same behavior. It would seem that the results of this study could also apply to other agricultural watersheds adjacent to the North American Great Lakes. 

While the presence of a filler affects the way a matrix crystallizes, the opposite is also true. In studies of in situ formation of calcium carbonate in different copolymers, different crystalline forms of calcium carbonate were found. Calcium carbonate crystallized without a polymer had a rhombohedral morphology. When crystallized in the presence of polyethylene oxide its morphology remained rhombohedral because the polymer does not interact with the crystal of calcium carbonate as it... 

The dramatic inhibitory effect of even trace amounts of PMA on the precipitation of calcium carbonate has long been recognised [249] and it has thus found considerable commercial application as an inhibitor of the formation of scale in hard water systems [251]. However, the mechanism by which this species inhibits the precipitation reaction remains unclear. Furthermore, to our knowledge, there have been no kinetic or morphological studies on the effect of polymaleic acid on the dissolution process. 

In this section, we briefly provide preliminary results on the morphology of etch pits obtained on cleaved calcite crystals by dissolution in unbuffered aqueous solutions of maleic acid (3 mM) under both stationary conditions and through channel electrode experiments. Kinetic and morphological studies on the effect of maleic acid on the dissolution of calcium carbonate... 

The process is complex and involves simultaneous dissolution of calcium hydroxide and carbon dioxide, and crystallisation of calcium carbonate. Carbonation is generally carried out in a series of reactors under closely controlled pH, temperature and degree of supersaturation, to produce the required PCC morphology and particle size distribution (see section 31.2.3). Crystallisation can occur on the surface of the calcium hydroxide particles (producing scalenohedral crystals), in the aqueous phase (producing rhombohedral crystals) and at the gas-liquid interface. 

These experiments show the effect of inhibition of calcite precipitation by the organics at pH 8. At pH 10 (Figure 7.30) the inhibition is less effective because the solubility of calcium carbonate is lower and no difference in flux can be seen. Further studies of the deposit morphologies are illustrated in section 7.8. 

Although it seems that the calcite surface in these fillers is often covered by either organic materials or silicate minerals, their chemistry is determined by the basic nature of calcium carbonate and its reactivity towards acids. This is of considerable importance. In particular, their reaction with fatty or other organic acids, but especially stearic acid, has been used for many years [7, 8] to improve compatibility with, and dispersion in, polymers. The coated fillers are much more hydrophobic than uncoated ones, reducing water pick-up, and they have also been shown to have an effect on polymer morphology, and hence modifying properties (see Chapter 1). 

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