Preparation, Characterization, and Formation Mechanism of Calcium Sulfate Hemihydrate Whiskers

Abstract

Calcium sulfate hemihydrate whiskers were synthesized successfully via one-step hydrothermal crystallization method using phosphogypsum at 130 °C for 240 min with an initial slurry mass fraction of 2.5wt%. The phase compositions, microstructures, thermal properties and molecular structures of asprepared samples were analyzed by XRD, ESEM, EDS, TG-DTA, and FT-IR. The influence of raw materials’ ball-milling time on the morphologies of whiskers was investigated. The effects of impurities on crystallization morphologies and length to diameter ratio (L/D) of calcium sulfate hemihydrate whiskers were studied. The results indicated that the calcium sulfate dihydrate crystalline could be translated directly into fibrous calcium sulfate hemihydrate whiskers. It was beneficial to form fine fiber structure when the ball-milling time of the raw material was 15 min. Aspect ratio of calcium sulfate hemihydrate whiskers decreased with increasing content of impurities. Moreover, the relative growth mechanism of whisker crystals via one-step hydrothermal crystallization method was discussed in detail.

Keywords

calcium sulfate / whiskers / phosphogypsum / hydrothermal crystallization

References

[1] Canut MMC, Jacomino VMF, Bratveit K, et al. Microstructural Analyses of Phosphogypsum Generated by Brazilian Fertilizer Industries[J]. Mater. Charact., 2008, 59: 365-373.

[2] Al–Hwaiti MS, Ranville JF, Ross PE. Bioavailability and Mobility of Trace Metals in Phosphogypsum from Aqaba and Eshidiy[J]. Jordan. Chem. Erde., 2010, 70: 283-291.

[3] Bituha T, Vuci Z, Marovic G, et al. A New Approach to Determine the Phosphogypsum Spread from the Deposition Site into the Environment [J]. J. Hazard. Mater., 2013, 261: 584-592.

[4] Contreras M, Pérez–López R, Bolívar JP, et al. Fractionation and Fluxes of Metals and Radionuclides During the Recycling Process of Phosphogypsum Wastes Applied to Mineral CO₂ Sequestration[J]. Waste Manage., 2015, 45: 412-419.

[5] Sahu SK, Ajmal PY, Bhangare RC, et al. Natural Radioactivity Assessment of a Phosphate Fertilizer Plant Area[J]. J. Radiat. Res. Appl. Sci., 2014, 7: 123-128.

[6] Bituha T, Vuci Z, Marovic Tayibi H, et al. Environmental Impact and Management of Phosphogypsum[J]. J. Env. Man., 2009, 90: 2 377-2 386.

[7] Yang JK, Liu WC, Zhang LL, et al. Preparation of Load–bearing Building Materials from Autoclaved Phosphogypsum[J]. Constr. Build. Mater., 2009, 23(2): 687-693.

[8] Kadirova ZC, Hojamberdiev M, Bo L, et al. Ion Uptake Properties of Low–cost Inorganic Sorption Materials in the CaO–Al₂O₃–SiO₂ System Prepared from Phosphogypsum and Kaolin[J]. J. Clean. Prod., 2014, 83: 483-490.

[9] El–Afifi EM, Hilal MA, Attallah MF, et al. Characterization of Phosphogypsum Wastes Associated with Phosphoric Acid and Fertilizers Production[J]. J. Environ. Radioactiv., 2009, 100: 407-412.

[10] He H, Dong FQ, He P, et al. Effect of Glycerol on the Preparation of Phosphogypsum–based CaSO₄·0.5H₂O Whiskers[J]. J. Mater. Sci., 2014, 49: 1 957-1 963.

[11] Zhu ZC, Xu L, Chen G, et al. Optimization on Tribological Properties of Aramid Fibre and CaSO4 Whisker Reinfored Non–metallic Friction Material with Analytic Hierarchy Process and Preference Ranking Organization Method for Enrichment Evaluations[J]. Mater. Des., 2010, 31: 551-555.

[12] Mwaba MG, Gu JJ, Golriz MR. Effect of Magnetic Field on Calcium Sulfate Crystal Morphology[J]. J. Cryst. Growth, 2007, 303: 381-386.

[13] Xu A, Li H, Luo K, et al. Formation of Calcium Sulfate Whiskers from CaCO₃–bearing Desulfurization Gypsum[J]. Res. Chem. Intermed., 2011, 37: 449-455.

[14] Zhu ZC, Xu L, Chen G, et al. Effect of Different Whiskers on the Physical and Tribological Properties of Non–metallic Friction Materials [J]. Mater. Des., 2011, 32: 54-61.

[15] Zhu XF, Wang YB, Wang X, et al. Integration of Preparation and Stabilization for Hemihydrate Calcium Sulfate Whiskers[J]. Adv. Mater. Res, 2011, 239–242: 047-3 077.

[16] Hamdona SK, Al–Hadad UA. Crystallization of Calcicalcium Sulfate Dihydrate in the Presence of Some Metal Ions[J]. J. Cryst. Growth, 2007, 299: 146-151.

[17] Liu J, Reni L, Wei Q, et al. Fabrication and Characterization of Polycaprolactone/Calcium Sulfate Whisker Composites[J]. Express Polym. Lett., 2011, 5: 742-752.

[18] Capadona JR, Shanmuganathan K, Trittschuh S, et al. Polymer Nanocomposites with Nanowhiskers Isolated from Microcrystalline Cellulose [J]. Biomacromolecules, 2009, 10: 712-716.

[19] Zhao W, Wu Y, Xu J, et al. Effect of Ethylene Glycol on Hydrothermal Formation of Calcium Sulfate Hemihydrate Whiskers with High Aspect Ratios[J]. RSC. Adv., 2015, 5: 50 544-50 548.

[20] Wang YQ, Li YC, Yuan A, et al. Preparation of Calcium Sulfate Whiskers by Carbide Slag through Hydrothermal Method[J]. Cryst. Res. Technol., 2014, 49: 800-807.

[21] Wang X, Jin B, Yang LS, et al. Effct of CuCl₂ on Hydrothermal Crystallization of Calcium Sulfate Whiskers Prepared from FGD Gypsum [J]. Cryst. Res. Technol., 2015, 50: 633-640.

[22] Luo KB, Xiang CM, Li HP, et al. Influence of Temperature and Solution Composition on the Formation of Calcium Sulfates[J]. Particuology, 2010, 8: 240-244.

[23] Anto PL, Anto RJ, Varhhese HT, et al. FT–Raman and SERS Spectra of Anilinium Sulfate[J]. Ramac. Spectrosc., 2009, 40: 1 810-1 815.