Photocatalytic transfer of aqueous nitrogen into ammonia using nickel-titanium-layered double hydroxide.

The development of solar-driven transfer of atmospheric nitrogen into ammonia is one of the green and sustainable strategies in industrial ammonia production. Nickel-titanium-layered double hydroxide (NiTi-LDH) was synthesised using the soft-chemical process for atmospheric nitrogen fixation application under photocatalysis in an aqueous system. NiTi-LDH was investigated using advanced characterisation techniques and confirmed the potential oxygen vacancies and/or surface defects owing to better photocatalytic activity under the solar spectrum. It also exhibited a bandgap of 2.8 eV that revealed its promising visible-light catalytic activities. A maximum of 33.52 µmol L-1 aqueous NH3 was obtained by continuous nitrogen (99.9% purity) supply into the photoreactor under an LED light source. Atmospheric nitrogen supply (≈78%) yielded 14.67 µmol L-1 aqueous NH3 within 60 min but gradually reduced to 3.6 µmol L-1 at 330 min. Interestingly, in weak acidic pH, 20.90 µmol L-1 NH3 was produced compared to 11.51 µmol L-1 NH3 in basic pH. The application of NiTi-LDH for visible-light harvesting capability and photoreduction of atmospheric N2 into NH3 thereby opens a new horizon of eco-friendly NH3 production using natural sunlight as alternative driving energy.

Novel gC3N4/MgZnAl-MMO derived from LDH for solar-based photocatalytic ammonia production using atmospheric nitrogen.

The development of catalysis technologies for sustainable environmental applications, especially an alternative to ammonia (NH3) production under the Haber-Bosch process, has gained a lot of scope in recent days. The current work demonstrated a green synthesis of graphitic carbon nitride (gC3N4) containing magnesium-zinc-aluminium mixed metal oxides (MgZnAl-MMO) derived from layered double hydroxide (LDH) for visible light aided catalytic production of ammonia. Pyrolysis-hydrothermal techniques were adopted for the synthesis and fabrication of the gC3N4/MgZnAl-MMO catalytic composite. Characterization results of field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV-visible spectroscopy, photoluminescence (PL), etc. showed the desired properties and functionalities like semi-crystalline structure with rough surface morphology that enhance the sorption reactions. Catalytic composite gC3N4/MgZnAl-MMO showed a bandgap energy of 2.16 eV that is considerably shifted toward the visible range when compared to gC3N4 (2.39 eV) and MgZnAl-MMO (2.93 eV). The results were also well complied with XPS results obtained that promote solar-based photocatalysis. The gC3N4/MgZnAl-MMO assisted photocatalytic production of NH3 in an aqueous media proved to be acceptable by the production of a maximum 47.56 µmol/L NH3 under visible spectrum employing a light emitting diode (LED) source. The results showed that the advancement of catalyst for desired functionalities and NH3 production using LED simulating solar light-aided catalysis would be an alternative to the Haber-Bosch process and solar-based sustainable processes for NH3 production.

Photocatalytic degradation of lomefloxacin antibiotics using hydrothermally synthesized magnesium titanate under visible light-driven energy sources.

Antibiotics in water system pose a human health risk due to the rise of antibacterial activity in the environmental web. Advanced oxidation processes are the potential to become an effective treatment technology for targeting antibiotics. This study demonstrates the visible light photocatalysis of lomefloxacin using magnesium titanate (MgTiO3). The nanomaterial was subjected to computational analysis to study morphology, functional, and optical characteristics through FESEM, XRD, FTIR, BET, UV-Vis, etc. Importantly, MgTiO3 had band gap energy of 3.09 eV. The photocatalytic studies were performed to observe different parameters affecting lomefloxacin degradation such as initial concentration, catalyst dosage, and pH. The nanomaterial exhibited the maximum lomefloxacin degradation. The study revealed that 30 mg/L of catalyst was optimum to degrade 10 mg/L of lomefloxacin with 30-W LED irradiation up to 150 min. Reactive species, namely, electron, hole, hydroxyl, and superoxide radicals, comprised the primary photocatalytic mechanism for lomefloxacin degradation. Ultimately, the summative result from this study highlights the suitability of the photocatalytic system to treat persistent antibiotics in aqueous environment.

Degradation of doxycycline antibiotics using lanthanum copper oxide microspheres under simulated sunlight.

In this study, lanthanum copper oxide was synthesized under hydrothermal techniques and characterized for doxycycline degradation. The catalyst exhibited enhanced photocatalytic doxycycline degradation under visible light owing to its compatible bandgap energy (1.7 eV). The XRD data revealed high crystallinity of the material with no noticeable impurities. Three-dimensional microspheres of varying sizes (average diameter of 2.52 µm) were observed from SEM. EDX confirms the successful synthesis of La2CuO4. The effect of DC concentration, catalyst dosage, and initial pH on the degradation rate of DC was studied methodically. Interestingly, about 85% of doxycycline (10 mg/L) was degraded within 120 min of light-emitting diode irradiation at pH 10. Oxygen vacancies and surface defects were determined through photoluminescence spectra. The recyclability experiments suggested that the catalyst is capable of degrading DC for three consecutive runs. Radical trapping trials suggested that holes (h+), superoxide radicals (●O2-), and hydroxyl radicals (●OH) are involved in the photodegradation of DC. Herein, the novel approach of La2CuO4 synthesis and the efficient visible-light harvesting capability of as-prepared catalyst reveal the potentiality for DC degradation thereby opening a new horizon of research employing La2CuO4 used for various environmental applications.