Study of the influence of the supersaturation coefficient on scaling rate using the pre-calcified surface of a quartz crystal microbalance

International audienceScale deposition is a common issue in industrial plants, which creates technical problems, i.e. reduction of heat transfer, decrease of flow rate due to an obstruction of pipes. Therefore, the development of some appropriate methods based on well suitable in situ sensors to evaluate and predict the scaling propensity of water is a major concern in current research. This would be a good strategy for the optimization of anti-scaling treatments.In this study, scaling tests were carried out using a sensitive sensor, which has been developed using a quartz crystal microbalance with a pre-calcified electrode surface (SQCM). This technique allowed studying the influence of the supersaturation on the scaling rate. The set-up was tested with different water samples which were brought to a given supersaturation coefficient by degassing the dissolved CO2. The prediction of the scaling propensity of water was then possible through the relationship between the scaling rate on a pre-calcified surface and the supersaturation coefficient. In addition, the kinetics of CaCO3 deposit on the pre-calcified SQCM surface was found to be slower for natural water than for synthetic water (same calcium concentration). Furthermore, the activation energy for scale deposit, in synthetic water, was found to be 22 kJ.mol−1, which may be related to the diffusion of ions and/or CaCO3 nuclei in solution

Effects of Magnetic Field on Homogeneous and Heterogeneous Precipitation of Calcium Carbonate

Abstract In this study, fast controlled precipitation (FCP) and chronoamperometry (CA) methods were performed to evaluate the influence of the magnetic treatment at 0.70 T, upon the scale formation in synthetic solutions (hardness 25 °F), exposed to a static magnetic field for different exposure times. According to FCP results, homogeneous CaCO3 precipitation rates in treated solution were lower than those in the absence of the magnetic field. It has been found that the memory effect can last up to 24 h after the magnetic treatment even if it decreases over time. As purpose of comparison, CA method was applied to investigate the influence of the magnetic treatment on heterogeneous CaCO3 precipitation. The magnetic field effect increased with the increasing exposure time. The obtained scale, characterized by scanning electronic microscopy and X‐ray diffraction, was formed by a mixture of calcite and aragonite in the presence of magnetic field

State of art of natural inhibitors of calcium carbonate scaling. A review article

International audienceThe formation of calcium carbonate in water has some important implications in geoscience researches, oceanchemistry studies, CO2 emission issues and biology. In industry, the scaling phenomenon may cause technicalproblems such as reduction of heat transfer efficiency in cooling systems and obstruction of pipes.The use of chemicalswhich act as antiscalant is a common approach in the control of scale deposition. However,inorganic nitrogen and phosphorous compounds are involved in eutrophication process. Therefore, it is of primeimportance to find alternative solutions, i.e. green inhibitors of scale formation. This last decade, several newscaleinhibitors, that are more ecological compared with conventional inhibitors, have been reported in the literature.Plant extracts have been also recently used as newgreen antiscalants. Indeed, as they can be easily extracted andare environmentally friendly, they represent an interesting alternative source of "natural" organic molecules.In this review, a focus of some green antiscalants derived frompetrochemicals has been reported. Then the effortsdone those last years to obtain green inhibitors, either by using “natural” organic molecules or extracted fromplants were summarized. Such green inhibitors might be used in various technical areas, i.e. energy, water,food and beverages industries

Antiscalant properties of Herniaria glabra aqueous solution

International audienceChemical antiscalants are usually used to control scale depositions, a major concern in industry. Some of these products may be harmful towards environment or toxic for humans, so environmentally friendly antiscalant are needed. In this respect, plant extracts can be used as new green antiscalant agents. In this work, stock aqueous solution of Herniaria glabra (H. glabra) was obtained by infusion. H. glabra is used in traditional medicine to treat or prevent urolithiasis; it could be an interesting candidate as a green antiscaling agent. The properties of H. glabra towards CaCO3 formation were tested by using chronoamperometry and Fast Controlled Precipitation methods. An n-butanol solution was used to partition the aqueous solution of H. glabra, yielding a polar compounds-free fraction. This fraction was also studied by chronoamperometry and Fast Controlled Precipitation methods. The results showed a better inhibition efficiency towards CaCO3 precipitation for the n-butanol fraction compared to the crude H. glabra solution

Antiscalant properties of Spergularia rubra and Parietaria officinalis aqueous solutions

International audienceThe formation of calcium carbonate in water has important implications in industry. Chemical antiscalant is usually used to control scale depositions. Plant extracts have been recently used as new green antiscalant agents, as they can be easily prepared and are environmentally friendly. In this study, stock aqueous solutions of Spergularia rubra and Parietaria officinalis, two plants used in traditional medicine to treat or prevent urolithiasis, were obtained by infusion. The antiscaling properties of these extracts towards CaCO3 formation were tested by using chronoamperometry and Fast Controlled Precipitation methods. The aqueous solution of S. rubra was further fractionated to isolate compounds of lower polarity. Their efficiency towards CaCO3 precipitation was characterized by Fast Controlled Precipitation method. The inhibiting efficiency of this fractionated solution was greater than that of the stock aqueous solution