Influence of Surface Modifiers on the Structure of Precipitated Calcium Carbonate

Abstract

A calcium carbonate (CaCO 3 ) sorbent synthesized in the presence of surface modifiers has recently been developed in this laboratory for the purpose of enhancing the reactivity toward SO 2 at high temperatures (800-1150 °C). The calcium carbonate particles are produced by precipitation from an aqueous suspension of calcium hydroxide by bubbling pure CO 2 . The operating parameters such as suspension concentration, gas flow rate, and concentration of surface modifiers are varied to study their influence on the particle size, surface area, and pore volume. The synthesized CaCO 3 particles exhibit dramatically high SO 2 reactivity and sorbent utilization. The increased reactivity is primarily due to the development of an open initial pore structure of the sorbent brought about by the action of surface-active agents, compared to the conventional calcium-based sorbents. ζ-potential measurements indicate that addition and subsequent adsorption of anionic surfactants neutralize the high positive surface charge (30 mV) on the precipitated calcium carbonate and facilitate particle agglomeration and pore structure development. High surface area (>55 m 2 /g) and pore volume (>0.175 cm 3 /g) are obtained for particles with neutral or near-neutral surface changes.

Stability of CaCO3 in Ca(OH)2 solution

“…Nano-calcite can be produced by recrystallization methods utilizing calcium hydroxide (Ca(OH) 2 ) and carbon dioxide (CO 2 ) as in the carbonization method, and calcium chloride (CaCl 2 ) and sodium carbonate (NaCO 3 ) as in the chemical method (Carmona et al, 2003a(Carmona et al, , 2004Chen et al, 2000;Ukrainczyk et al, 2007). However, obtaining CaCO 3 particles in nano-sizes with homogeneous size distribution, and different morphologies is difficult due to agglomeration of newly synthesized clusters (Gebauer et al, 2008;Kellermeier et al, 2012;Kilic and Ozdemir, 2015;Pouget et al, 2009), which is related to the surface potential of the colloidal CaCO 3 particles (Agnihotri et al, 1999;Holysz et al, 2003;Moulin and Roques, 2003;Pourchet et al, 2013). CaCO 3 is also one of the principal constituents of hard scale formed in many industrial and heating installations.…”

“…It is the reason why newly formed particles in the literature with the chemical or carbonization methods were aggregated and formed micron sized particles (Carmona et al, 2003a(Carmona et al, , 2003bKilic and Ozdemir, 2015;Kitamura et al, 2002;Rodriguez-Blanco et al, 2011;Tai and Chen, 1998;Yan et al, 2008). It was understood that the surface potential for CaCO 3 is affected by various parameters such as aging (Chibowski et al, 2003b), additives (Yuan et al, 2008), surface modifiers (Agnihotri et al, 1999), and ions (Holysz et al, 2003;Pourchet et al, 2013). For instance, the zeta potential for CaCO 3 was positive when Ca ++ ions were in excess in the solution, and it was negative when CO 3 = ions were in excess in the solution (Chibowski et al, 2003b;Holysz et al, 2003;Pourchet et al, 2013).…”

Rice-like hollow nano-CaCO 3 synthesis

“…Therefore, production of nano calcite can be achieved by recrystallization; such that the mineral CaCO 3 is converted to calcium oxide (CaO) by calcination, hydrated to calcium hydroxide (Ca(OH) 2 ) and recrystallize by carbon dioxide (CO 2 ) [3][4][5][6]. Obtaining CaCO 3 particles in nano sizes with homogeneous size distribution and different morphologies is difficult due to agglomeration of newly synthesized clusters [7][8][9][10], which is related to the surface potential of the colloidal CaCO 3 particles [11][12][13][14]. Also, there is a huge effort to produce hollow nano-CaCO 3 particles with homogenous size distribution and different morphologies, which is rare in the literature.…”

“…It is the reason why newly formed particles were aggregated and formed micron sized particles [3,9,[23][24][25][26][27]. It was understood that the surface potential for CaCO 3 is affected by various parameters such as aging [22], additives [28], surface modifiers [11], and ions [12,14]. For instance, the zeta potential for CaCO 3 was positive when Ca þ þ ions were in excess in the solution, and it was negative when highly important for the production of stable nano-CaCO 3 particles.…”

Green silica scale inhibitors for Alkaline-Surfactant-Polymer flooding: a review

“…), these phosphorus-containing inhibitors frequently react stoichiometrically with calcium ions leading to calciumpolyphosphate/phosphonate precipitation (Wohlever et al 2001). This is because the amorphous nature of silica renders crystal modifiers phosphonates or mixed phosphonates/carboxylates ineffective (Agnihotri et al 1999). Therefore, to overcome this problem, Arensdorf et al (2010) and (2011) have developed new scale inhibitors in mitigating silicate scale during ASP flooding (Arensdorf et al 2010(Arensdorf et al , 2011.…”