A simple and novel synthetic route to prepare anatase TiO₂ nanopowders from natural ilmenite via the H₃PO₄/NH₃ process

Abstract

A simple and novel technique for the preparation of anatase TiO₂ nanopowders using natural ilmenite (FeTiO₃) as the starting material is reported. Digesting ilmenite with concentrated H₃PO₄ under refluxing conditions yields a white α-titanium bismonohydrogen orthophosphate monohydrate (TOP), Ti(HPO₄)₂·H₂O, which can be easily isolated via gravity separation from unreacted ilmenite. The addition of ammonia to the separated TOP followed by calcination at 500°C completes the preparation of anatase TiO₂. Calcination at temperatures above 800°C converts the anatase form of TiO₂ to the stable rutile phase. The removal of iron from ilmenite during the commercial production of synthetic TiO₂ is problematic and environmentally unfriendly. In the present study, the removal of iron was found to be markedly simple due to the high solubility of iron phosphate species in concentrated H₃PO₄ with the precipitation of TOP. The titanium content of the prepared samples on metal basis with silica and phosphorous as major impurities was over 90%. Prepared TiO₂ samples were characterized using X-ray fluorescence, Fourier-transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, and X-ray diffraction analyses. The photocatalytic potentials of the commercial and as-prepared TiO₂ samples were assessed by the photodegradation of rhodamine B dye.

Keywords

ilmenite / phosphoric acid / titanium phosphates / titanium dioxide / anatase / rutile

References

[1] Wells AF. Structural Inorganic Chemistry, 2012, Oxford, Oxford University Press

[2] Greenwood NN, Earnshaw A. Chemistry of the Elements, 2012, Amsterdam, Elsevier Science

[3] Ding XZ, Liu XH, He YZ. Grain size dependence of anatase-to-rutile structural transformation in gel-derived nanocrystalline titania powders. J. Mater. Sci. Lett, 1996, 15(20): 1789.

[4] Sabyrov K, Burrows ND, Penn RL. Size-dependent anatase to rutile phase transformation and particle growth. Chem. Mater., 2013, 25(8): 1408.

[5] Li JG, Ishigaki T, Sun XD. Anatase, brookite, and rutile nanocrystals via redox reactions under mild hydrothermal conditions: Phase-selective synthesis and physicochemical properties. J. Phys. Chem. C, 2007, 111(13): 4969.

[6] Hanaor DAH, Sorrell CC. Review of the anatase to rutile phase transformation. J. Mater. Sci, 2011, 46(4): 855.

[7] Tompsett GA, Bowmaker GA, Cooney RP, Metson JB, Rodgers KA, Seakins JM. The Raman spectrum of brookite, TiO₂ (Pbca, Z = 8). J. Raman Spectrosc, 1995, 26(1): 57.

[8] Chen JS, Tan YL, Li CM, Cheah YL, Luan DY, Madhavi S, Boey FYC, Archer LA, Lou XW. Constructing hierarchical spheres from large ultrathin anatase TiO₂ nanosheets with nearly 100% exposed (001) facets for fast reversible lithium storage. J. Am. Chem. Soc, 2010, 132(17): 6124.

[9] Chen X, Mao SS. Titanium dioxide nanomaterials: Synthesis, properties, modifications, and applications. Chem. Rev, 2007, 107(7): 2891.

[10] Linsebigler AL, Lu G, Yates JTJ. Photocatalysis on TiO₂ surfaces: Principles, mechanisms, and selected results. Chem. Rev, 1995, 95(3): 735.

[11] Hoffmann MR, Martin ST, Choi WY, Bahnemann DW. Environmental applications of semiconductor photocatalysis. Chem. Rev, 1995, 95(1): 69.

[12] Yang HG, Liu G, Qiao SZ, Sun CH, Jin YG, Smith SC, Zou J, Cheng HM, Lu GQ. Solvothermal synthesis and photoreactivity of anatase TiO₂ nanosheets with dominant {001} facets. J. Am. Chem. Soc, 2009, 131(11): 4078.

[13] Macwan DP, Dave PN, Chaturvedi S. A review on nano-TiO₂ sol-gel type syntheses and its applications. J. Mater. Sci, 2011, 46(11): 3669.

[14] Bosc F, Ayral A, Albouy PA, Guizard CF. A simple route for low-temperature synthesis of mesoporous and nanocrystalline anatase thin films. Chem. Mater, 2003, 15(12): 2463.

[15] Sullivan WF, Cole SS. Thermal chemistry of colloidal titanium dioxide. J. Am. Ceram. Soc, 1959, 42(3): 127.

[16] Cheng HM, Ma JM, Zhao ZG, Qi LM. Hydrothermal preparation of uniform nanosize rutile and anatase particles. Chem. Mater, 1995, 7(4): 663.

[17] Li GS, Li LP, Boerio-Goates J, Woodfield BF. High purity anatase TiO₂ nanocrystals: Near room-temperature synthesis, grain growth kinetics, and surface hydration chemistry. J. Am. Chem. Soc, 2005, 127(24): 8659.

[18] Wang CC, Ying JY. Sol-gel synthesis and hydrothermal processing of anatase and rutile titania nanocrystals. Chem. Mater, 1999, 11(11): 3113.

[19] Cassaignon S, Koelsch M, Jolivet JP. Selective synthesis of brookite, anatase and rutile nanoparticles: Thermolysis of TiCl₄ in aqueous nitric acid. J. Mater. Sci, 2007, 42(16): 6689.

[20] Parra R, Góes MS, Castro MS, Longo E, Bueno PR, Varela JA. Reaction pathway to the synthesis of anatase via the chemical modification of titanium isopropoxide with acetic acid. Chem. Mater, 2008, 20(1): 143.

[21] Zhang WS, Zhu ZW, Cheng CY. A literature review of titanium metallurgical processes. Hydrometallurgy, 2011, 108(3): 177.

[22] Sahu KK, Alex TC, Mishra D, Agrawal A. An overview on the production of pigment grade titania from titaniarich slag. Waste Manage. Res, 2006, 24(1): 74.

[23] Palliyaguru L, Arachchi NDH, Jayaweera CD, Jayaweera PM. Production of synthetic rutile from ilmenite via anion-exchange. Miner. Process. Extr. Metall, 2018, 127(3): 169.

[24] Lasheen TA. Sulfate digestion process for high purity TiO₂ from titania slag. Front. Chem. Eng. China, 2009, 3(2): 155.

[25] Hisashi T, Eiichi N, Hitoshi T, Masahiro A, Taijiro O. Manufacture of high pure titanium(IV) oxide by the chloride Process. I. Kinetic study on leaching of ilmenite ore in concentrated hydrochloric acid solution. Bull. Chem. Soc. Jpn, 1982, 55(6): 1934.

[26] Sariman S, Krisnandi YK, Setiawan B. Anatase TiO₂ enrichment from bangka ilmenite (FeTiO₃) and its photocatalytic test on degradation of congo red. Adv. Mater. Res, 2013, 789, 538.

[27] AIP Conf. Proc., 2016, 1710(1) art. No. 030023

[28] Palliyaguru L, Kulathunga MUS, Kumarasinghe KGUR, Jayaweera CD, Jayaweera PM. Facile synthesis of titanium phosphates from ilmenite mineral sand: Potential white pigments for cosmetic applications. J. Cosmet. Sci, 2019, 70(3): 149.

[29] Cullity BD. Elements of X-ray Diffraction, 1978, 3rd ed., New Jersey, Addison-Wesley Publishing Company

[30] Spurr RA, Myers H. Quantitative analysis of anatase-rutile mixtures with an X-ray diffractometer. Anal. Chem, 1957, 29(5): 760.

[31] Kubelka P. New contributions to the optics of intensely light-scattering materials. Part I. J. Opt. Soc. Am, 1948, 38(5): 448.

[32] Stoch A, Jastrzębski W, Brożek A, Stoch J, Szaraniec J, Trybalska B, Kmita G. FTIR absorption-reflection study of biomimetic growth of phosphates on titanium implants. J. Mol. Struct., 2000, 555(1–3): 375.

[33] Sysoeva TS, Asabina EA, Pet’kov VI, Kurazhkovskaya VS. Alkali (alkaline-earth) metal, aluminum, and titanium complex orthophosphates: Synthesis and characterization. Russ. J. Inorg. Chem, 2009, 54(6): 829.

[34] Ratanatamskul C, Chintitanun S, Masomboon N, Lu MC. Inhibitory effect of inorganic ions on nitrobenzene oxidation by fluidized-bed Fenton process. J. Mol. Catal. A: Chem, 2010, 331(1): 101.

[35] Zhang TB, Lu YC, Luo GS. Effects of temperature and phosphoric acid addition on the solubility of iron phosphate dihydrate in aqueous solutions. Chin. J. Chem. Eng, 2017, 25(2): 211.

[36] Beltrán JJ, Novegil FJ, García KE, Barrero CA. On the reaction of iron oxides and oxyhydroxides with tannic and phosphoric acid and their mixtures. Hyperfine Interact, 2010, 195(1): 133.

[37] Iuliano M, Ciavatta L, De Tommaso G. On the solubility constant of strengite. Soil Sci. Soc. Am. J, 2007, 71(4): 1137.

[38] Zhou WJ, He W, Zhang XD, Liu JA, Du Y, Yan SP, Tian XY, Sun XA, Han XX, Yue YZ. Simple and rapid synthesis of Fe(PO₃)₃ by microwave sintering. J. Chem. Eng. Data, 2009, 54(7): 2073.

[39] Zhang YH, Reller A. Phase transformation and grain growth of doped nanosized titania. Mater. Sci. Eng. C, 2002, 19(1): 323.

[40] Sullivan WF, Coleman JR. Effect of sulphur trioxide on the anatase-rutile transformation. J. Inorg. Nucl. Chem, 1962, 24(6): 645.

[41] Yang J, Ferreira JMF. On the titania phase transition by zirconia additive in a sol-gel-derived powder. Mater. Res. Bull, 1998, 33(3): 389.

[42] Gribb AA, Banfield JF. Particle size effects on transformation kinetics and phase stability in nanocrystalline TiO₂. Am. Mineral., 1997, 82(7–8): 717.

[43] Mackenzie KJD. The calcination of titania. VI. The effect of reaction atmosphere and electric fields on the anatase-rutile transformation. Trans. J. Brit. Ceram. Soc, 1975, 74(4): 121.

[44] Okada K, Yamamoto N, Kameshima Y, Yasumori A, MacKenzie KJD. Effect of silica additive on the anatase-to-rutile phase transition. J. Am. Ceram. Soc, 2001, 84(7): 1591.

[45] Zhang YH, Chan CK, Porter JF, Guo W. Micro-Raman spectroscopic characterization of nanosized TiO₂ powders prepared by vapor hydrolysis. J. Mater. Res, 2011, 13(9): 2602.

[46] Ohsaka T, Izumi F, Fujiki Y. Raman spectrum of anatase, TiO₂. J. Raman Spectrosc, 1978, 7(6): 321.

[47] Huffman EO, Cate WE, Deming ME, Elmore KL. Solubility of phosphates, rates of solution of calcium phosphates in phosphoric acid solutions. J. Agric. Food Chem, 1957, 5(4): 266.

[48] Cate WE, Deming ME. Effect of impurities on density and viscosity of simulated wet-process phosphoric acid. J. Chem. Eng. Data, 1970, 15(2): 290.

[49] Hagfeldt A, Graetzel M. Light-induced redox reactions in nanocrystalline systems. Chem. Rev, 1995, 95(1): 49.

[50] Zhang JF, Zhou P, Liu JJ, Yu JG. New understanding of the difference of photocatalytic activity among anatase, rutile and brookite TiO₂. Phys. Chem. Chem. Phys, 2014, 16(38): 20382.

[51] Serpone N. Is the band gap of pristine TiO₂ narrowed by anionand cation-doping of titanium dioxide in second-generation photocatalysts?. J. Phys. Chem. B, 2006, 110(48): 24287.

[52] Madhusudan Reddy K, Manorama SV, Ramachandra Reddy A. Bandgap studies on anatase titanium dioxide nanoparticles. Mater. Chem. Phys, 2003, 78(1): 239.

[53] Samsudin EM, Abd Hamid SB. Effect of band gap engineering in anionic-doped TiO₂ photocatalyst. Appl. Surf. Sci, 2017, 391, 326.

[54] Karbassi M, Nemati A, Zari MH, Ahadi K. Effect of iron oxide and silica doping on microstructure, bandgap and photocatalytic properties of titania by water-in-oil microemulsion technique. Trans. Indian Ceram. Soc, 2011, 70(4): 227.

[55] Schneider J, Matsuoka M, Takeuchi M, Zhang JL, Horiuchi Y, Anpo M, Bahnemann DW. Understanding TiO₂ photocatalysis: Mechanisms and materials. Chem. Rev, 2014, 114(19): 9919.

[56] Kumar SG, Devi LG. Review on modified TiO₂ photocatalysis under UV/visible light: Selected results and related mechanisms on interfacial charge carrier transfer dynamics. The J. Phys. Chem. A, 2011, 115(46): 13211.

[57] Turchi CS, Ollis DF. Photocatalytic degradation of organic water contaminants: Mechanisms involving hydroxyl radical attack. J. Catal, 1990, 122(1): 178.

[58] Naccache C, Meriaudeau P, Che M, Tench AJ. Identification of oxygen species adsorbed on reduced titanium dioxide. Trans. Faraday Soc, 1971, 67(67): 506.

[59] Tang WZ, Huren AN. UV/TiO₂ photocatalytic oxidation of commercial dyes in aqueous solutions. Chemosphere, 1995, 31(9): 4157.

[60] He J, Du YE, Bai Y, An J, Cai XM, Chen YQ, Wang PF, Yang XJ, Feng Q. Facile formation of anatase/rutile TiO₂ nanocomposites with enhanced photocatalytic activity. Molecules, 2019, 24(16): 2996.

[61] T. Luttrell, S. Halpegamage, J.G. Tao, A. Kramer, E. Sutter, and M. Batzill, Why is anatase a better photocatalyst than rutile? — Model studies on epitaxial TiO₂ films, Sci. Rep., 4(2014), art. No. 4043.