Synthesis, characterization and formation mechanism of friedel’s salt (FS: 3CaO·Al₂O₃·CaCl₂·10H₂O) by the reaction of calcium chloride with sodium aluminate

Abstract

The synthesis of Friedel’s salt (FS: 3CaO·A1₂O₃·CaCl₂·10H₂O) by the reaction of calcium chloride with sodium aluminate was investigated. Factors affecting the preparation of Friedel’s salt, such as reaction temperature, initial concentration, titration speed, aging time and molar Ca/Al ratio were studied in detail. XRD, SEM images and particle size distribution show that the reaction temperature, aging time and molar Ca/Al ratio have significant effect on the composition, crystal morphology, and average particle size of the obtained samples. In addition, the initial CaCl₂ concentration and NaAlO₂ titration speed do not significantly influence the morphology and particle size distribution of Friedel’s salt. With the optimization of the operating conditions, the crystals can grow up to a average size of about 28 μm, showing flat hexagonal (or pseudo-hexagonal) crystal morphology. Moreover, two potential mechanisms of Friedel’s salt formation including adsorption mechanism and anion-exchange mechanism were discussed. In the adsorption mechanism, Friedel’s salt forms due to the adsorption of the bulk Cl⁻ ions present in the solution into the interlayers of the principal layers, [Ca₂Al(OH⁻)₆·2H₂O]⁺, in order to balance the charge. In the anion-exchange mechanism, the free-chloride ions bind with the AFm (a family of hydrated compounds found in cement) hydrates to form Friedel’s salt by anion-exchange with the ions present in the interlayers of the principal layer, [Ca₂Al(OH⁻)₆·2H₂O]⁺-OH⁻.

Keywords

synthesis / characterization / formation mechanism / Friedel’s salt

References

[1] de Roy A Lamellar Double Hydroxides[J]. Mol. Cryst. Liq. Cryst., 1998, 311(1): 173-193.

[2] Vaccari A Clays and Catalysis: a Promising Future [J]. Appl. Clay Sci., 1999, 14(4): 161-198.

[3] Rives V, Ulibarri M A Layered Double Hydroxides (LDH) Intercalated with Metal Coordination Compounds and Oxometalates [J]. Coord. Chem. Rev., 1999, 181(1): 61-120.

[4] Inacio J, Forano C, Besse J P Adsorption of MCPA Pesticide by Mg-Al Layered Double Hydroxides [J]. Appl. Clay Sci., 2001, 18(5–6): 255-264.

[5] Rousselot I, Palvadeau P, Besse J P Insights on the Structural Chemistry of Hydrocalumite and Hydrotalcite-Like Materials: Investigation of the Series Ca₂M³⁺(OH)₆Cl·2H₂O (M³⁺: Al³⁺, Ga³⁺, Fe³⁺, and Sc³⁺) by X-ray Powder Diffraction[J]. J. Solid State Chem., 2002, 167(1): 137-144.

[6] Roussel H, Briois V, Elkaim E, . Cationic Order and Structure of [Zn-Cr-Cl] and [Cu-Cr-Cl] Layered Double Hydroxides: a XRD and EXAFS Study [J]. J. Phys. Chem. B, 2000, 104(25): 5 915-5 923.

[7] Roussel H, Briois V, Elkaim E, . Study of the Formation of the Layered Double Hydroxide [Zn-Cr-Cl] [J]. Chem. Mater., 2001, 13(2): 329-337.

[8] Friedel P M Surunchloro-Aluminate de Calcium Hydrate Semaclantpar Compression [J]. Bull. Soc. Fr. Mineral, 1897, 19(20): 122-136.

[9] Filippakis S, Terzis A, Burzlaff H The Crystal Structure of Ca₂Al(OH)₆Cl·2H₂O[J]. Zeit. Kris., 1987, 181(1–4): 29-34.

[10] Suryavanshi A K, Scantlebury J D, Lyon S B Mechanism of Friedel’s Salt Formation in Cements Rich in Tricalcium Aluminate [J]. Cem. Concr. Res., 1996, 26(5): 717-727.

[11] Birnin-Yauri U A, Glasser F P Friedel’s Salt, Ca₂Al(OH)₆(Cl, OH): Its Solid Solutions and Their Role in Chloride Binding[J]. Cem. Concr. Res., 1998, 28(2): 1 713-1 723.

[12] Gougar M L D, Scheetz B E, Roy D M Ettringite and C-S-H Portland Cement for Waste Ion Immobilization: a Review[J]. Waste Manage., 1996, 16(4): 295-303.

[13] Miyata S Anion-Exchange Properties of Hydrotalcite-Like Compounds [J]. Clays Clay Miner., 1983, 31(4): 305-311.

[14] Walcarius A, Lefevre G, Rapin J P Voltammetric Detection of Iodide after Accumulation by Friedel’s Salt [J]. Electroanalysis, 2001, 13(4): 313-320.

[15] Liu Q, Li Y, Zhang J, . Effective Removal of Zinc from Aqueous Solution by Hydrocalumite [J]. Chem. Eng. J., 2011, 175: 33-38.

[16] Zhang J J, Zhao H, Cao H B, . Adsorption Kinetics of Friedel’s Salt for Removal of Cd²⁺ from Low Concentration Wastewater [J]. The Chinese Journal of Process Engineering, 2012, 12(4): 590-595.

[17] Ma J Y, Li Z B, Zhang Y, . Desilication of Sodium Aluminate Solution by Friedel’s Salt (FS: 3CaO·Al₂O₃·CaCl₂·10H₂O) [J]. Hydrometallurgy, 2009, 99(3–4): 225-230.

[18] Dai Y C, Qian G R, Cao Y L, . Effective Removal and Fixation of Cr(VI) from Aqueous Solution with Friedel’s Salt [J]. J. Hazard. Mater., 2009, 170(2–3): 1 086-1 092.

[19] Zhang D N, Jia Y F, Ma J Y, . Removal of Arsenic from Water by Friedel’s Salt (FS: 3CaO·Al₂O₃·CaCl₂·10H₂O) [J]. J. Hazard. Mater., 2011, 195(15): 398-404.

[20] Kuzel H J Suryavanshi AK, Hager WH X-ray Investigations of Some Complex Calcium Aluminum Hydrates and Related Compounds[C]. Proceedings of the Fifth International Congress on Chemistry of Cements, 1969 Tokyo: Cement Association of Japan

[21] Goni S, Guerrero A Accelerated Carbonation of Friedel’s Salt in Calcium Aluminate Cement Paste [J]. Cem. Concr. Res., 2003, 33(1): 21-26.

[22] Mersmann A Crystallization Technology Handbook [M], 2001 New York: Marcel Dekker Inc. 342-351.

[23] Cheng W T, Li Z B Precipitation of Nesquehonite from Homogeneous Supersaturated Solutions[J]. Cryst. Res. Technol., 2009, 44(9): 937-947.

[24] Mersmann A Supersaturation and Nucleation [J]. Chem. Eng. Res. Des., 1996, 74(7): 812-820.

[25] Wang Y, Li Z B, Demopoulos G P Controlled Precipitation of Nesquehonite (MgCO₃·3H₂O) by the Reaction of MgCl₂ with (NH₄)₂CO₃[J]. J. Cryst. Growth., 2007, 310(5): 1 220-1 227.

[26] Boistelle R, Astier J P Crystallization Mechanisms in Solution [J]. J. Cryst. Growth, 1988, 90(1–3): 14-30.

[27] Girgin S Crystallization of Alpha-Calcium Sulphate Hemihydrate by Aqueous Reaction of Calcium Chloride with Sulphuric Acid [D], 2006 Montreal: McGill University

[28] Brown P, Bothe J The System CaO-Al₂O₃-CaCl₂-H₂O at 23±2 °C and the Mechanisms of Chloride Binding in Concrete [J]. Cem. Concr. Res., 2004, 34(9): 1 549-1 553.

[29] Jones M R, Macphee D E, Chudek J A Studies Using ²⁷Al MAS NMR of AF_m and AF_t Phases and the Formation of Friedel’s Salt [J]. Cem. Concr. Res., 2003, 33(2): 177-182.

[30] Dosch W, Keller H Idom GM, Fordos Z Phase Equilibria and Cement Hydration[C]. Proceedings of the Sixth International Congress on Chemistry of Cements, 1976 Moscow: Cement Association of Russia

[31] Daimdot D, Glasser F P Thermodynamic Investigation of the CaOAl₂O₃-CaSO₄-H₂O System at 25 °C[J]. Cem. Concr. Res., 1993, 23(1): 221-238.