La Loaded TiO2 Encapsulated Zeolite Y Catalysts: Investigating the Characterization and Decolorization Process of Amaranth Dye

Lanthanide ions loaded TiO2 encapsulated into Y zeolite catalysts were synthesized and used in sonocatalytic degradation of Amaranth dye in aqueous solution. The support zeolite Y was modified by different loading of Ti and La species using ion exchange method. The sonocatalytic reaction condition was carried out at 10？mg/L initial dye concentration, original pH, 1.5？g/L of catalyst loading with low ultrasonic frequency of 40？KHz. Different characterization techniques were used to reveal the physicochemical characteristics of the catalysts. Successful loading of TiO2 and La/TiO2 into zeolite Y was achieved. The framework of zeolite Y remained unchanged after the loading of TiO2. Titanium species was bound to the framework of zeolite through Ti–O–Si bonds through isomorphous substitution of Si in the zeolite. The ultrasonic degradation of Amaranth dye was enhanced by the TiO2 encapsulation with a maximum degradation efficiency of 50% after 120？min of reaction. However, the activity of the catalyst decreased after the loading of lanthanum. This decrease was attributed to the poor contact between the metal crystallites located on the external surface and the titanium encapsulated into cages of zeolite Y. 1. Introduction Titanium dioxide is generally considered to be a very efficient photo- or sonocatalyst that is nontoxic, stable, and cheap [1]. It exhibits high durability, corrosion resistance, and high oxidation potential of the valence band that ensures its general applicability to a wide range of substrates [2]. On the other hand, fast charge carrier recombination, low interfacial charge-transfer rates, and recycling difficulties were the main drawbacks of using bare TiO2 [3]. In order to overcome these problems, two methods have been suggested to increase its activity. The first one is through doping of the transition metal ions into titanium dioxide to suppress the recombination of electrons holes. Song et al. [4], Jamalluddin and Abdullah [5], Wang et al. [6], and many other researches have reported the differences in the catalytic activity of titanium oxide with different types of doping metals. Secondly, loading of titanium dioxide onto suitable supports could reduce the problem of catalyst separation after the reaction. Loading of TiO2 nanoparticles on porous supports has been attempted using activated carbon [7, 8], fiber glass [9], clay [10], and zeolites [11] as the support materials. Zeolites are good adsorbents and eco-friendly materials possessing high surface area and high thermal stability. Additionally, these materials possess amphoteric