Nanopillars TiO2 thin film photocatalyst application in the remediation of aquatic environment

Noble metal-doped TiO2 thin films in the efficient removal of Mordant Orange-1: insights of degradation process

Nanocomposite Ag⁰(NPs)/TiO₂ is synthesised in a facile template method enabling nanoparticles of reduced Ag evenly distributed within the titania network. The morphological studies of nanocomposites were extensively performed employing SEM/EDX (scanning electron microscopy/energy dispersive X-ray), TEM (transmission electron microscopy) and AFM (atomic force microscopy). Moreover, the bandgap energies of materials were obtained using the diffuse reflectance spectrometer (DRS). The newer insights in the photocatalytic elimination of Mordant Orange-1 (MO1) was obtained using the nanocomposite thin film for various parametric studies utilising the UV-A and LED illuminations. The kinetics of degradation of MO1 was performed, and the rate constant was favoured at lower concentrations of MO1. Moreover, the elimination efficiency of MO1 was favoured with a decrease in solution pH. The NPOC results inferred that a fairly good extent of MO1 was mineralised using a thin-film catalyst for both the UV-A and LED illuminations. The minimal effect of several co-ions demonstrated the applicability of thin films in the elimination of MO1, and the stability of the thin film has shown the potential applicability of thin-film catalysts. Further, the mechanism of photocatalytic degradation was demonstrated with the radical scavenger studies and ascertained the reaction pathways.

Improving Photocatalytic Performance Using Nanopillars and Micropillars

A recent research emphasis has been placed on the development of highly crystallized nanostructures as a useful technology for many photocatalytic applications. With the unique construction of semiconductor transition metal oxide nanostructures in the form of nanopillars—artificially designed pillar-shaped structures grouped together in lattice-type arrays—the surface area for photocatalytic potential is increased and further enhanced through the introduction of dopants. This short review summarizes the work on improving the efficiency of photocatalyst nanopillars through increased surface area and doping within the applications of water splitting, removal of organic pollutants from the environment, photoswitching, soot oxidation, and photothermalization.

Synthesis and characterization of Ag0(NPs)/TiO2 nanocomposite: insight studies of triclosan removal from aqueous solutions

Nanocomposite mesoporous Ag⁰(NPs)/TiO₂ thin film materials were synthesized and assessed for its efficient application in the elimination of potentially important drug triclosan from aqueous solutions. A template synthesis using the polyethylene glycol was enabled to obtain Ag⁰(NPs)/TiO₂ nanocomposite materials where zerovalent Ag was in situ doped to the titania network. The nanocomposite materials were characterized by the scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), EDX elemental mapping, X-ray diffraction (XRD) analyses and Brunauer-Emmett-Teller (BET) methods. Further, the diffuse reflectance spectroscopy (DRS) was introduced to estimate the band gap of these solids. The thin film materials were subjected to the remediation of water contaminated with triclosan using the UV-A light. The oxidative elimination of triclosan was demonstrated as a function of pH, concentration of triclosan and presence of several co-existing ions. Increase in pH (4.0-10.0) and triclosan concentrations (0.5-15.0 mg/L) had decreased significantly the percentage degradation of triclosan. The pseudo-first-order kinetics was shown in the degradation of triclosan and rate constant was significantly decreased with the increase in pollutant concentration (0.5-15.0 mg/L) and pH (4.0-10.0). The 1000 times presence of scavengers showed that ^•OH were, predominantly, caused the oxidation of triclosan. Moreover, multiple application of nanocomposite Ag⁰(NPs)/TiO₂(B) revealed that the thin film was fairly intact since the photocatalytic efficiency of triclosan removal was almost unaffected.

Nanocomposite thin films Ag0(NP)/TiO2 in the efficient removal of micro-pollutants from aqueous solutions: A case study of tetracycline and sulfamethoxazole removal

The aim of this communication is to synthesize novel Nanocomposite thin film materials (Ag⁰(NP)/TiO₂) using the template process. Surface morphology of materials was obtained by the Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses. The presence of doped Ag-nanoparticles was confirmed by the TEM images along with the SEM-EDX analyses. The Atomic Force Microscopic images were demonstrated the surface roughness and thickness of Nanocomposite thin films. X-ray diffraction analysis confirmed that TiO₂ was predominantly present to its anatase mineral phase. The Fourier Transform Infra-red analysis conducted to obtain the functional groups present with the solid. The specific surface area and pore sizes of Nanocomposites were obtained by the BET (Brunauer, Emmett, and Teller) analysis. Further, the Nanocomposite thin film photocatalysts were successfully employed in the degradation of emerging micro-pollutants viz., the antibiotics tetracycline and sulfamethoxazole from aqueous solutions using less harmful UV-A light (λ_max 330 nm). The effect of solution pH (pH 4.0-8.0) and pollutant concentrations (1.0 mg/L-20.0 mg/L (for tetracycline) and (0.5 mg/L-15.0 mg/L (for sulfamethoxazole)) was extensively studied in the photocatalytic removal of these antibiotics. A significant decrease in percentage of non-purgeable organic carbon removal indicated that the micro-pollutants was substantially mineralized by the photocatalytic treatment. The stability of thin film was assessed by the repeated use of Nanocomposite thin films and results were indicated that the degradation of tetracycline or sulfamethoxazole was almost unaffected at least for six cycles of photocatalytic operations. The presence of several cations and anions in the degradation of these antibiotics was studied. Additionally, the presence of 2-propanol and EDTA inhibited significantly the degradation of these micro-pollutants i.e., the percentage of degradation was decreased by 31.8 and 24.2% (for tetracycline) and 42.8 and 39.9% (for sulfamethoxazole), respectively. This indicated that the degradation of tetracycline or sulfamethoxazole was predominantly proceeded by the OH radicals; generated at the valance and conduction band of semiconductor. Similarly, the presence of sodium azide inhibited the percentage removal of these antibiotics.