A comparison of the physical-chemical properties of precipitated calcium carbonate (PCC), prepared by batch and semicontinuous processes, is presented. In both processes, PCC, was synthesized by carbonation of slaked lime. In the batch process the experiments were performed by varying the initial mass concentration and temperature, and the semicontinuous process was conducted by varying the ini...

Fluid-inclusion measurements and textural relationships demonstrate that coarse-grained quartz and calcite from the upper part of The Geysers thermal system formed during the transition from liquid-dominated conditions to the modern vapor-dominated regime. The most diagnostic characteristics of these transition assemblages are: 1) evidence of quartz dissolution; 2) contemporaneous trapping of h...

The adsorption of selenite ions (SeO~-) from a dilute aqueous solution onto a freshly-cleaved calcite (1014) surface was studied with the X-ray standing wave (XSW) technique. The complex ion SeO zis found to selectively adsorb at the CO~ site via ionic exchange, forming a two-dimensional solid-solution of the form Ca(SeO3)x(CO3) 1 x at the interface. The calcite (1014), (0006) and (1120) Bragg ...

A microstructural investigation by electron microscopy on a travertine specimen collected from Munigou National Park, Sichuan Province, China revealed evidence of a non-classical reversed crystal growth route previously only discovered in synthetic materials. Examination of the travertine specimen suggests that the presence of organic matter initiates the oriented aggregation of calcite nanocry...

As crystallization processes are often rapid, it can be difficult to monitor their growth mechanisms. In this study, we made use of the fact that crystallization proceeds more slowly in small volumes than in bulk solution to investigate the effects of the soluble additives Mg2+ and poly(styrene sulfonate) (PSS) on the early stages of growth of calcite crystals. Using a "Crystal Hotel" microflui...

Calcium carbonate (CaCO3) in the presence of single-walled carbon nanotube (SWCNT) /fullerodendron supramolecular nanocomposites was crystallized with a CO2 diffusion method under ambient conditions and in aqueous environments to produce monodisperse spherical SWCNT/CaCO3 hybrids with a core-shell structure. The crystals nucleate at the carboxyl groups on the surface of the SWCNT/fullerodendron...

The growth kinetics of calcite crystals are studied in a batch-fluidized-bed crystallizer, which is maintained at a constant pH. The growth experiments are conducted in the metastable region explored as part of this research. The crystal growth rates are e®aluated from the consumption rates of calcium ions, using the cured natural calcite or silica sand as seeding materials. Se®eral operation ®...

We report on atomic force microscopy (AFM) in ambient and liquid environments with the qPlus sensor, a force sensor based on a quartz tuning fork with an all-electrical deflection measurement scheme. Small amplitudes, stiff sensors with bulk diamond tips and high Q values in air and liquid allow to obtain high resolution images. The noise sources in air and liquid are analyzed and compared for ...

Ž . At two caves Clamouse, S France and Ernesto, NE Italy , cave drip and pool waters were collected and sampled at intervals over a 2–3 year period. MgrCa and SrrCa concentration ratios, corrected for marine aerosols, are compared with those of bedrocks and, in some cases, aqueous leachates of soils and weathered bedrocks. Cave waters do not lie along mixing lines between calcite and dolomite ...

Stable isotope analyses of discrete seasonal layers from a 108-yr annually laminated freeze-core from Baldeggersee, a small, eutrophic lake in central Switzerland, provide information on the climatological and environmental factors, including lake eutrophication, that control oxygen and carbon isotopic composition of epilimnic biologically induced calcite precipitate. During the last 100 yr, Ba...