You do not have JavaScript enabled. Please enable JavaScript to access the full features of the site or access our non-JavaScript page. Issue 6, From the journal: CrystEngComm. This article is part of the themed collection: Crystal Growth. You have access to this article. Please wait while we load your content Something went wrong. Try again? Cited by. Download options Please wait Article type Paper. Submitted 28 Nov Accepted 10 Jan Calcium carbonate is a sparingly soluble salt, growing by a parabolic rate law.
Hence, the rate-limiting step of its crystal growth involves the dehydration of the growth units and the surface diffusion of these dehydrated growth units into the lattice from the adsorption site [ 31 ].
The effect of antiscalants on calcium carbonate scale formation has been investigated by using ATMP amino tris methylene phosphonic acid as a scale inhibitor. ATMP, commercially named as Hydrex , is one of the commonly used antiscalants used for calcium carbonate scale inhibition in water since it has an excellent chelating ability with calcium ions, low threshold inhibitory dosage, and powerful lattice distortion process.
Applying UV radiation dissociates the antiscalant into fragments that were unable to inhibit the scale formation. On the other hand, increasing pH to 9 had a drastic effect on the scale inhibition behavior, falling slowly in the first 15 minutes and then sharply decreasing in the next 15 minutes. This dramatic effect of pH can be interpreted based on the pH dependence of carbonate concentration in solution.
Bicarbonate ions were dissociated into carbonate according to the following equation:. According to the Henderson-Hasselbalch equation, as pH increases, the carbonate concentration increases as indicated in Table 1 :. By increasing sample pH, an increase in the carbonate concentration by two orders of magnitude was noticed.
An increase in sample pH also changes carbonate ions recombination, hence increasing the rate of calcium carbonate precipitation. The impact of radiation energy was studied in UV and visible regions. The effect of UV radiation can be explained through the calcium ion acid-base character. The calcium ion is a weak acid, and when excited, it becomes much more vulnerable.
When shifting from visible to UV region, the radiation energy increases, exciting more calcium ions, resulting in much more efficient scale inhibition.
Calcium carbonate scale formation involves supersaturation, nucleation, crystal growth, and precipitation. Thus, affecting any of these steps can retard the crystal growth rate. Table 2 shows the percentage of crystal growth of calcium carbonate for the untreated, chemically treated, and irradiated water samples.
The chemical antiscalant might be blocking some of the active sites of the calcium carbonate nuclei, therefore, decreasing the number of calcium carbonate crystals precipitated. When the calcium ions are subjected to UV radiation, some of the excited, energetic calcium ions become weakly acidic, and it reduces the recombination of calcium carbonate crystal growth. Hence, UV light treatment is much more efficient in calcium carbonate scale inhibition compared to commercial antiscalants.
The application of UV light has more advantages than chemical treatment. The UV radiation is commonly used in water treatment to get rid of pathogens without having any harmful effect when compared to chemical antiscalants. The amount of calcium carbonate deposited on polypropylene and polysulfone membranes was investigated by immersing the membrane separately inside the working solutions from 30 to 60 minutes.
The amount of scale deposited for UV-treated samples is very low compared to the untreated one Figure 6. This observation is precious for predicting the lifetime of the desalination membranes that are affected by the amount of scale deposited. Thus, using a UV light for scale inhibition increases the lifetime of the membrane due to the reduced membrane fouling. The untreated control sample produces calcite and vaterite form of crystals.
Interestingly, only calcite was formed in the case of the UV light treated samples. These crystals are less dense, less adherent, and easily removable when deposited compared to aragonite [ 11 ]. The SEM images reveal that calcite crystals with small particle sizes for the UV radiation samples and vaterite form control samples. In the reported work, we investigated the scale inhibition property of ultraviolet light on calcium carbonate.
An outcome is an excellent approach to the calcite scale problem that is bedeviling the oil and liquid-based industries over the years. The following are the conclusions drawn from this study. Hence, it is expected that UV treatment might increase the lifetime of the membrane. The manuscript is part of the M. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Guest Editor: Fada Feng. Received 04 Oct Revised 03 Jan Accepted 28 Feb Published 23 Mar Abstract Scale formation on surfaces in contact with water supersaturated with calcium carbonate creates technical problems, including heat transfer hindrance, energy consumption, and equipment shutdown.
Introduction Calcium carbonate scale formation is a major challenge in the transportation and operational oil pipelines in oil industries. The risk of scale deposition occurs during the course of injection operations mostly because of change in temperature that aid solution rapid supersaturation, the process that encourages the decomposition of according to the following reaction: The mineral scale can also be formed from the reaction of two chemicals that lead to precipitation: The calcite crystals are large, but, in the presence of impurities, they take the form of uniform, finely divided crystals.
Materials and Methods 2. Methods Synthetic seawater solution was prepared by mixing Figure 1. Figure 2. Figure 3. Figure 4. Effect of pH on calcium carbonate scale inhibition, as a function of time.
Table 1. Effect of pH on carbonate concentration in 9. Figure 5. Effect of radiation energy on calcium carbonate scale inhibition, as a function of time. Table 2. Rate of calcium carbonate crystal growth for UV-treated and UV-untreated water. Figure 6. Weight measurements of calcium carbonate deposits with and without UV light treatment. Figure 7. XRD spectra for a untreated case and b standard peaks of calcite and Vaterite and for c UV-treated case and d standard peaks of calcite and calcium carbonate.
Figure 8. SEM images for deposits of a untreated water and b UV-treated water. References C. Perdikouri, A. Kasioptas, C. Putnis, and A. Al Helal, A. Heteroagglomeration as a mechanism of retaining CaCO3 particles on the fibrils of cellulosic fines: A study by laser light diffraction and microscopy.
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