In situ preparation of TiO2/f-MWCNT catalyst using Pluronic F127 assisted sol-gel process for sonocatalytic degradation of methylene blue

Abstract

In this study, titanium dioxide- Pluronics @F127/functionalized -multi walled carbon nanotubes (TiO2–F127f-/MWCNT) nanocatalysts were prepared, characterized, and used in methylene blue (MB) degradation under ultrasonic conditions. The characterization studies were performed using TEM, SEM, and XRD analyses to reveal the morphological and chemical properties of TiO2–F127/MWCNT nanocatalysts. To detect the optimum parameters for MB degradation using TiO2–F127/f-MWCNT nanocatalysts, several experimental parameters were conducted at various conditions such as different temperatures, pH, catalyst amount, hydrogen peroxide (H2O2) concentration, and various reaction contents. Transmission electron microscopy (TEM) analyses showed that TiO2–F127/f-MWCNT nanocatalysts consisted of a homogenous structure and have a 12.23 nm particle size. The crystalline particle size of TiO2–F127/MWCNT nanocatalysts was found to be 13.31 nm. Scanning electron microscope (SEM) analyses revealed the surface structure of TiO2–F127/f-MWCNT nanocatalysts turned to be modified after TiO2 loaded on MWCNT. Under the optimum conditions; pH: 4, MB concentration: 25 mg/L, H2O2 concentration: 30 mol/L, reaction time: and catalyst dose: 24 mg/L, chemical oxygen demand (COD) removal efficiency reached a maximum of 92%. To detect the radical effectiveness, three scavenger solvents were tested. Reuse experiments revealed that TiO2–F127/f-MWCNT nanocatalysts retained 84.2% catalytical activity after 5 cycles. Gas chromatography–mass spectrometry (GC–MS) was successfully used to identify the generated intermediates. Based on the experimental results, it has been suggested that •OH radicals are the main active species responsible for the degradation reaction in the presence of the TiO2–F127/f-MWCNT nanocatalysts.