Porous Layered Double Hydroxide/TiO2 Photocatalysts for the Photocatalytic Degradation of Orange II

Abstract

Layered Double Hydroxide (LDH)/TiO2 nanocomposites with photocatalytic properties were synthesized by both impregnation and the direct coprecipitation of LDH matrices using a colloidal suspension of TiO2 nanoparticles. While the two methods led to an efficient TiO2 nanoparticle immobilization, the direct coprecipitation allowed us to tune the amount of immobilized TiO2 within the materials. The LDH/TiO2 nanocomposites obtained were deeply characterized by chemical analysis (ICP-AES), Powder X-ray diffraction (XRD), Fourier Transformed Infra-Red (FTIR), Thermogravimetric analysis (TGA), and High-Resolution Transmission Electron Microscopy (HRTEM). Clearly, the immobilization of TiO2 by direct coprecipitation promoted a modification of the textural properties and a net increase in the surface area. The crystallized TiO2 nanoparticles can be distinctly visualized by HRTEM at the surface of the layered material. Several parameters, such as the nature of the chemical composition of LDH (ZnAl and MgAl), the method of immobilization and the amount of TiO2, were shown to play a crucial role in the physicochemical and photocatalytic properties of the nanocomposites. The photocatalytic efficiency of the different LDH/TiO2 nanocomposites was investigated using the photodegradation of a model pollutant, the Orange II (OII), and was compared to a pure TiO2 colloidal solution. The degradation tests revealed that the nanocomposite obtained from MgAl LDH at a low MgAl LDH/TiO2 ratio was the most efficient for the photodegradation of OII leading to complete mineralization in 48 h.

Application of M²⁺ (Magnesium, Zinc)/Alumina-Metal Oxide Composites as Photocatalysts for the Degradation of Cationic Dyes

“…Titanium dioxide is dispersed in a mixture with a weight ratio of 1:1 between the resulting LDH and titanium dioxide, then stirred for 3 hours. This ratio is in accordance with the research results of Djeda et al (2020). The mixture was added with sodium hydroxide again with a concentration of 0.37 M with a stirrer for 10 hours at a temperature of 70 °C.…”

“…Synthetic dyes often become pollutants because they have a complex aromatic molecular structure that is difficult to degrade. These characteristics can be harmful to human health and aquatic life (Djeda et al, 2020;An et al, 2015). About 10-15% of the dyes that have been used in the dyeing process can be released into the wastewater stream (Singh et al, 2017).…”

“…Composite is written as M 2+ /M 3+metal oxide. This is done in addition to increasing the structural strength, but also composites can be used as photocatalysts in degrading dyestuff s (Djeda et al, 2020). The use of LDH containing metal oxides titanium dioxide (TiO 2 ) and zinc oxide (ZnO) will inhibit electron recombination, besides that the LDH layer facilitates electron transfer (Jaerger et al, 2021;Bhuvaneswari et al, 2019).…”

LDH-TiO2 Composite for Selenocyanate (SeCN−) Photocatalytic Degradation: Characterization, Treatment Efficiency, Reaction Intermediates and Modeling

“…Furthermore, Paredes et al (2011) [34] report that a TiO 2 /LDH matrix produced a synergistic effect causing both higher •OH radical production and higher degradation of phenol than TiO 2 alone. Similarly, the application of an LDH-TiO 2 matrix for dimethyl phthalate and methylene blue pollutant removal has also been reported [35,36], as well as the use of an LDH-TiO 2 matrix for the removal of 2,4-dichlorophenoxyacetic acid and orange II [37,38]. This clearly indicates improvement in both adsorption and photocatalysis of several aqueous pollutants when using a combined LDH-TiO 2 system.…”

Layered Double Hydroxide (MgFeAl-LDH)-Based Polypropylene (PP) Nanocomposite: Mechanical Properties and Thermal Degradation

“…LDHs have been used as acid scavengers [ 17 ], in the pharmaceutical industry [ 18 ], as antioxidants [ 19 ], in biomedical applications [ 20 , 21 , 22 , 23 ], as UV-Vis absorption materials [ 12 , 24 , 25 , 26 ], in photovoltaic and solar cells [ 26 ], in supercapacitors [ 27 ], in sensors [ 28 ], in wastewater treatments [ 29 ], as precursors for photocatalytic materials [ 30 , 31 ], as catalysts [ 18 , 32 ], as stabilizers in polymers [ 33 , 34 ] and as flame retardants for polymers [ 35 , 36 , 37 , 38 ]. LDHs can be used for different purposes—as coolants and in producing diluents for flammable gas [ 39 ], as flame retardants providing resistance to ignition [ 40 ], or they can provide an alternate way of combustion with a slower rate of flame spread and can reduce the quantity of smoke [ 18 , 40 ].…”