Influence of clay suspensions on the precipitation of CaCO₃ in seawater

Abstract

The effect of montmorillonite and kaolinite, most common clay in marine water, on nucleation and growth of calcium carbonate in standard sea water was studied. Crystallization was induced by the degasification of the dissolved carbonic gas. It was shown by XRD and SEM analysis that CaCO 3 crystallize under its aragonite polymorph some either the clay concentration or type. It was also found that tested clays inhibited significantly the crystallization of calcium carbonate, especially for concentrations higher than 25 mgL -1. From the fine analyses of the formed solid, it was suggested that the tested clays have an indirect effect on nucleation and growth of aragonite by increasing the Mg ions concentration, strong inhibitor of CaCO 3 formation, in the neighbourhood of clay particles where supersaturation is the higher and than crystallization can occur. In addition to its indirect role, kaolinite can interact with aragonite by adsorbing on their faces and blocking growth sites.

Speciation of Fe(II) and Fe(III) effect on CaCO3 crystallization

“…However, nucleation pH and then the solution thermodynamic state were not influenced. This inhibiting effect of Fe(II) is similar to the one of other divalent metallic ions such as Mg 2+ ,Zn 2+ , Cu 2+ , .…”

“…Kinetically, Fe(II) seems has a similar effect as that of SO 4 2− and Mg 2+ known by their inhibitory effect in prolonging the nucleation time and decelerating the growth rate of CaCO 3 crystallization . Nevertheless, for iron (II), the most published works were interested on its effect on the growth of calcite and no on its nucleation.…”

“…water composition . It was shown that Mg 2+ and SO 4 2− , abundant ions in natural water, delay the nucleation of CaCO 3 and decelerate its growth rate by adsorption onto the growing CaCO 3 lattice and/or their incorporation into the structure .…”

State of art bio-materials as scale inhibitors in recirculating cooling water system: a review article

“…The Fast Controlled Precipitation (FCP) method (Also known as CO 2 degasification method) was first developed in 1994 (Martin-Dominguez 1994) and has been used in many studies (Tlili et al 2001;Fathi et al 2006;Karoui et al 2010), the principle of this technique is based on the motivation of the calco-carbonic equilibrium in the direction of CaCO 3 precipitation with dissolved-CO 2 continually degassing, which can be achieved by either agitation or nitrogen sparge, the reaction is basing on the following equation (Menzri et al 2017):…”

Formation of Aragonitic Layered Structures from Kaolinite and Amorphous Calcium Carbonate Precursors

“…Furthermore, even after these dehydration processes, the constituent clay materials continue to be reactive and interact with various compounds in the environment because of their innate electrostatic surface behaviors and intermolecular organization. These are the characteristic behaviors that many groups have attempted to utilize to capture heavy metal pollutants in aquafiers and recently for use in carbon capture strategies. − …”