Ionic liquid/TiO2 nanoparticles doped with non-expensive metals: new active catalyst for phenol photodegradation

TiO2 nanoparticles were synthesized using 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI center dot BF4) ionic liquid and doped with non-expensive metals Cu2+ and Fe3+ by the sol-gel method. The new generated photocatalysts had their morphological, textural and structural characteristics analysed by scanning electron microscopy and dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller analysis (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). The results showed two phases by XRD analysis, anatase (majority) and rutile (minority). The SEM micrographs exposed spherical TiO2 NPs/BMI center dot BF4 IL and compact layers for Cu2+ and Fe3+-doped TiO2 NPs in BMI center dot BF4 IL, the EDX confirmed only the presence of Ti, O, Fe and Cu. The BET and BJH analyses exhibited high porous TiO2 NPs/BMI center dot BF4 IL. The BET and BJH analyses confirmed that the pore diameter of mesoporous materials was between 12 and 16 nm with similar values for surface area (55-63 m(2) g(-1)). The TEM images exhibited spherical shape nanoparticles with mean diameter of 20-22 nm. The DRS analysis and Tauc equation were applied to estimate the optical energy band gap of the photocatalysts. The energy band gap values of 3.1 eV, 3.32 eV, and 2.78 eV were obtained for TiO2 NPs/BMI center dot BF4 IL, 1% Fe3+-doped TiO2 NPs/BMI center dot BF4 IL and 1% Cu2+-doped TiO2 NPs/BMI center dot BF4 IL, respectively. Phenol photodegradation was realized using Cu2+ and Fe3+-doped TiO2 NPs/BMI center dot BF4 IL under UV/visible irradiation and quantified by HPLC-FLD. The phenol photodegradation was investigated by different concentrations of metal-doped TiO2 NPs/BMI center dot BF4 IL. The new active photocatalysts 1% Cu2+-doped TiO2 NPs and 1% Fe3+-doped TiO2 NPs/BMI center dot BF4 IL exhibited high catalytic activity (99.9% and 96.8%, respectively). The photocatalysts 1% Cu2+ and 1% Fe3+-doped TiO2 NPs/BMI center dot BF4 IL were also evaluated using industrial wastewater from the tobacco industry. The results showed 56.7% phenol photodegradation, due to the complexity of the tobacco matrix wastewater.

Automated summary

In this study, TiO2 nanoparticles doped with Cu2+ and Fe3+ were synthesized using 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI center dot BF4) ionic liquid. The new photocatalysts exhibited high catalytic activity in phenol photodegradation under UV/visible radiation, with 1% Cu2+-doped TiO2 NPs showing 99.9% degradation and 1% Fe3+-doped TiO2 NPs showing 96.8% degradation. Industrial wastewater from the tobacco industry was also evaluated, with 56.7% phenol photodegradation observed.