TiO2/MgAl layered double hydroxides mechanical mixtures as efficient photocatalysts in phenol degradation

Abstract MgAl layered double hydroxides (MgAl LDH) were synthesized by the sol–gel method using ultrasound irradiation in the crystallization step. The interlayer anions were nitrate and acetylacetonate-ethoxide. The solids were characterized by XRD, N 2 -physisorption and TEM. TiO 2 /MgAl LDH mixtures were prepared by mixing the MgAl LDH (as prepared) or the calcined sample with TiO 2 (Aldrich, 99.9% anatase) in different weight ratios. Photocatalytic activities of the TiO 2 /MgAl LDH mixtures were evaluated through the degradation of phenol as model pollutant. TiO 2 /MgAl LDH mixture (1:1) was more photocatalytically active for the degradation of phenol than pure TiO 2 . The synergy effect was attributed to a higher production of • OH radicals, which were formed from the structural hydroxides. Also, the hydrotalcite phase enhanced the phenol adsorption and transfer to the TiO 2 sites where the phenol was photocatalytically degradated.

[1]  Fabrizio Cavani,et al.  Hydrotalcite-type anionic clays: Preparation, properties and applications. , 1991 .

[2]  J. Raulin,et al.  Heterogeneous photocatalysis: state of the art and present applications In honor of Pr. R.L. Burwell Jr. (1912–2003), Former Head of Ipatieff Laboratories, Northwestern University, Evanston (Ill). , 2005 .

[3]  T. Engelhardt,et al.  ZnAl-layer double hydroxides as photocatalysts for oxidation of phenol in aqueous solution , 2005 .

[4]  H. Lasa,et al.  Photocatalytic conversion of phenolic compounds in slurry reactors , 2004 .

[5]  Angelo Vaccari,et al.  Preparation and catalytic properties of cationic and anionic clays , 1998 .

[6]  A. Dombi,et al.  Investigation of the photodecomposition of phenol in near-UV-irradiated aqueous TiO2 suspensions. II. Effect of charge-trapping species on product distribution , 1999 .

[7]  Changwen Hu,et al.  Preparation and photocatalytic behavior of Zn/Al/W(Mn) mixed oxides via polyoxometalates intercalated layered double hydroxides , 2002 .

[8]  Andrzej Sobczynski,et al.  Phenol destruction by photocatalysis on TiO2: an attempt to solve the reaction mechanism , 2004 .

[9]  C. Taviot‐Gueho,et al.  Microstructural study of different LDH morphologies obtained via different synthesis routes , 2010 .

[10]  M. Bellotto,et al.  A Reexamination of Hydrotalcite Crystal Chemistry , 1996 .

[11]  M. Bellotto,et al.  Hydrotalcite Decomposition Mechanism: A Clue to the Structure and Reactivity of Spinel-like Mixed Oxides , 1996 .

[12]  G. Fetter,et al.  Sorption of131I− by hydrotalcites , 1997 .

[13]  Andrew Mills,et al.  An overview of semiconductor photocatalysis , 1997 .

[14]  Changwen Hu,et al.  Photocatalytic degradation of aqueous organocholorine pesticide on the layered double hydroxide pillared by Paratungstate A ion, Mg12Al6(OH)36(W7O24)·4H2O , 2001 .

[15]  A. Mills,et al.  A web-based overview of semiconductor photochemistry-based current commercial applications , 2002 .

[16]  J. Yvon,et al.  Competition between monovalent and divalent anions for calcined and uncalcined hydrotalcite: anion exchange and adsorption sites , 1996 .

[17]  F. Najafi,et al.  Synthesis, amine functionalization and dye removal ability of titania/silica nano-hybrid , 2012 .

[18]  A. Reller,et al.  Photoinduced reactivity of titanium dioxide , 2004 .

[19]  L. Latterini,et al.  Use of anionic clays for photoprotection and sunscreen photostability: Hydrotalcites and phenylbenzimidazole sulfonic acid , 2006 .

[20]  Carlo Rossi,et al.  Anionic clays for sunscreen agent safe use: photoprotection, photostability and prevention of their skin penetration. , 2006, European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V.

[21]  G. Fetter,et al.  Sol-gel synthesis of hydrotalcite — like compounds , 2006 .

[22]  A. Vaccari.  Clays and catalysis: a promising future , 1999 .

[23]  K. Domen,et al.  Visible light-induced photocatalytic behavior of a layered perovskite-type rubidium lead niobate, RbPb2Nb3O10 , 1993 .

[24]  Jiaguo Yu,et al.  Effect of phase structures on the formation rate of hydroxyl radicals on the surface of TiO2 , 2010 .

[25]  José Antonio Ayllón,et al.  TIO2-photocatalyzed degradation of phenol and ortho-substituted phenolic compounds , 2001 .