Influence of foreign salts on the CaCO3 pre-nucleation stage: application of the conductometric method

Calcium carbonate crystallization process has been studied for more than a century. Nevertheless, little is known about the early stages of nucleation since the in situ observations are difficult at...

Efficiency of one scale inhibitor on calcium carbonate precipitation from hot water sanitary: effect of temperature and concentration

The scaling of hot water transport pipes has become one of the major problems encountered in Agadir's region, which exploits water of underground origin with very high hardness (40°F). Several methods can be used to prevent this phenomenon. Among these methods, the use of chemical inhibitors remains one of the processes to stop or retard the formation of scale deposits.

In this study, we tested the inhibitor with the trade name “Aquatreat601” at different temperatures such as 30, 40 and 60 °C. This inhibitor was tested at different concentrations for each temperature in order to find the efficiency concentration to prevent the precipitation of scale, which consists mainly of calcium carbonate CaCO₃ of the aragonite variety with a percentage of 88 %, and also the Mg-calcite Mg_0.06Ca_0.94(CO₃) with a percentage of 12 %. These results obtained by method X-ray diffraction (XRD) analysis.

We carried out this study on pure calco-carbonic water, of hardness equal to 40°F, using the “LCGE” method. The quantity of inhibitor is added before the research gas is introduced. In all cases, the presence of chemical inhibitors does not alter the initial pH of the solution or the concentration of calcium (TCa) value measured before the experiment begins.

The results obtained show that the ‘‘Aquatreat 601″ contents of 100, 180 and 300 ppm allowed total inhibition of calcium carbonate precipitation at temperatures of 30, 40 and 60 °C respectively.

Inhibition of calcium carbonate deposition on stainless steel using olive leaf extract as a green inhibitor

The antiscale properties of the aqueous extract of olive (Olea europaea L.) leaves as a natural scale inhibitor for stainless steel surface in Hammam raw water were investigated using chronoamperometry (CA) and electrochemical impedance spectroscopy techniques in conjunction with a microscopic examination. The X-ray diffraction analysis reveals that the scale deposited over the pipe walls consists of pure CaCO₃ calcite. The CA, in accordance with electrochemical impedance spectra and scanning electron microscopy, shows that the inhibition efficiency increases with increasing extract concentration. This efficiency is considerably reduced as the temperature is increased.

In situ probing calcium carbonate formation by combining fast controlled precipitation method and small-angle X-ray scattering

The initial stage of calcium carbonate nucleation and growth, found usually in "natural" precipitation conditions, is still not well understood. The calcium carbonate formation for moderate supersaturation level could be achieved by an original method called the fast controlled precipitation (FCP) method. FCP was coupled with SAXS (small-angle X-ray scattering) measurements to get insight into the nucleation and growth mechanisms of calcium carbonate particles in Ca(HCO3)2 aqueous solutions. Two size distributions of particles were observed. The particle size evolutions of these two distributions were obtained by analyzing the SAXS data. A nice agreement was obtained between the total volume fractions of CaCO3 obtained by SAXS analysis and by pH-resistivity curve modeling (from FCP tests).