Formation of Stable Vaterite with Poly(acrylic acid) by the Delayed Addition Method

Abstract

The crystallization of CaCO3 was examined by changing the addition time of poly(acrylic acid) (PAA) to an aqueous solution of calcium carbonate by selectively interacting with the crystal at different stages during the crystal-forming process. The precipitation of CaCO3 was carried out by a double jet method to prevent heterogeneous nucleation on glass walls, and the sodium salt of PAA was added by a delayed addition method. In the initial presence of PAA in an aqueous solution of calcium carbonate, PAA acted as an inhibitor for the nucleation and growth of crystallization. However, it was found that stable vaterite particles were successfully obtained by delaying the addition of PAA from 1 to 60 min. The vaterite particles were stable in the aqueous solution for more than 30 days, and the CaCO3 particles were formed by a spherulitic growth mechanism. It is suggested that PAA strongly binds with the Ca2+ ion on the surface of CaCO3 particles to stabilize the unstable vaterite form effectively. Upon changing the addition time of PAA, we found that CaCO3 particles were formed through different formation mechanisms in selectively controlled crystallization at different stages during the crystallization process.

Effect of Molecular Weights of Poly(acrylic acid) on Crystallization of Calcium Carbonate by the Delayed Addition Method

“…This is because the high concentration of calcium reagents exhibits a fast rate of the crystallization, in which the critical point of the sudden increase in the turbidity of the solution was observed before incubation for 1 min. 33 The crystal phase of the obtained products was confirmed by XRD analysis. 35,36 The XRD patterns exhibit the characteristic reflections of vaterite for all the samples except for the product of run 20 in Table I e The adsorbed amount of PAA-Na was measured by TGA (heating rate: 10 C/min under an air atmosphere).…”

“…33 In this work, we further investigated the influence of the molecular weights of PAA-Na on the crystallization of CaCO 3 by the delayed addition method. The precipitation of CaCO 3 was carried out by the double jet method.…”

“…15,32,33 In our previous work, the sodium salt of poly(acrylic acid) (PAA-Na) (PAA5k, M w ¼ 5000) for selectively interacting with the crystallization of calcium carbonate at different stages was studied by a delayed addition method. 33 Although PAA5k-Na acted as an inhibitor for the crystallization in the initial presence of PAA5k-Na, stable vaterite particles were successfully obtained by delaying the addition of PAA5k-Na from 1 to 60 min. The vaterite particles were stable in an aqueous solution for more than 30 d. We also found a different particle-formation mechanism of the CaCO 3 products.…”

Calcium promotes cadmium elimination as vaterite grains by tobacco trichomes

“…It can be stabilized by organic molecules (Colfen and Antonietti, 1998;Naka and Chujo, 2001;Falini et al, 2005;Rodriguez-Navarro et al, 2007;Qiao et al, 2008), such as proteins (Kanakis and Dalas, 2000;Rautaray et al, 2005), exopolysaccharides and carboxylic molecules (Dalas et al, 1999;Manoli and Dalas, 2001;Braissant et al, 2003;Malkaj and Dalas, 2004;Naka et al, 2006), and amino acids (Manoli et al, 2002;Lakshminarayanan et al, 2005;Xie et al, 2005). Consequently, abiotic vaterite is rare in nature (Rowlands and Webster, 1971;Lucas and Andrews, 1996), and more common in biota (Lowenstam and Weiner, 1989;Mann, 2001).…”

A Novel Approach to Controlling CaCO3Crystalline Assembly by Changing the Concentration of Poly(aspartic acid)

“…[9][10][11][12][13][14][15][16][17][18][19][20][21] Owing to the remarkable progress in the research on biomimetic mineralization, the mechanisms underlying the formation of biominerals have been established, on the basis of which a number of novel designs and high-performance structures have been developed. 22,23 Much effort has been focused on exploring the interaction between additives and certain crystal faces and the relationship between primary and secondary structures of organic additives and crystal morphology.…”