Porous Geopolymer/ZnTiO3/TiO2 Composite for Adsorption and Photocatalytic Degradation of Methylene Blue Dye

Abstract

In this study, GP (geopolymer) and GTA (geopolymer/ZnTiO3/TiO2) geopolymeric materials were prepared from metakaolin (MK) and characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive X-rays (EDX), specific surface area (SSA), and point of zero charge (PZC). The adsorption capacity and photocatalytic activity of the compounds prepared in the form of pellets was determined by degradation of the methylene blue (MB) dye in batch reactors, at pH = 7.0 ± 0.2 and room temperature (20 °C). The results indicate that both compounds are highly efficient at adsorbing MB, with an average efficiency value of 98.5%. The Langmuir isotherm model and the pseudo second order kinetic model provided the best fits to the experimental data for both compounds. In the MB photodegradation experiments under UVB irradiation, GTA reached an efficiency of 93%, being higher than that achieved by GP (4%). Therefore, the incorporation of ZnTiO3/TiO2 in the geopolymeric matrix allowed GTA to achieve higher overall efficiency, by combining adsorption and photocatalysis, compared to the GP compound. The results indicate that the synthesized compounds could be used for up to five consecutive cycles for the removal of MB from wastewater through adsorption and/or photocatalysis processes.

Green route to fabrication of Semal-ZnO nanoparticles for efficient solar-driven catalysis of noxious dyes in diverse aquatic environments

“…Adsorption kinetics studies help to determine a suitable adsorbent material, predict the required contact time, and optimize the operating conditions to achieve efficient dye degradation ( Ghaffar et al, 2023 ; Usman et al, 2023 ). The kinetics of dye degradation through adsorption involves understanding the rates at which dye molecules are adsorbed onto the adsorbent materials and can be described using various mathematical models, with the most commonly used types being the pseudo-first-order and pseudo-second-order kinetics ( Borah et al, 2023 ; Jaramillo-Fierro et al, 2023 ; Singh et al, 2023 ; Usman et al, 2023 ).…”

Development of an Antimicrobial Inorganic Polymer Based on Fly Ash and Metakaolin Incorporated by Nano-TiO 2 for Reactive Dye Removal

“…From all the adsorption test results, we observed that the FM-TiO2 has a larger adsorption capacity than the FM, which suggests that applying TiO2 to the geopolymer may enhance its adsorption capacity [58]. As a result of their porous structures and the presence of active sites on their surfaces, the FM and FM-TiO2 composites both exhibit adsorption capabilities [58]. In our previous study [13], we modified a metakaolin /cement kiln dust -based geopolymer composite to remove organic reactive dye effluent from wastewater by two different methods: adsorption and solidification of organic pollutants inside the geopolymer matrix.…”

“…The decolorization rate for the FM geopolymer composite at 120 minutes is 80.22%, while it is 89.56% for the FM-TiO2 geopolymer composite. From all the adsorption test results, we observed that the FM-TiO2 has a larger adsorption capacity than the FM, which suggests that applying TiO2 to the geopolymer may enhance its adsorption capacity [58]. As a result of their porous structures and the presence of active sites on their surfaces, the FM and FM-TiO2 composites both exhibit adsorption capabilities [58].…”