Pyrolytic Formation of TiO2/Carbon Nanocomposite from Kraft Lignin: Characterization and Photoactivities

Catalysts

DiegoSavio Branciforti¹  Daniele Dondi¹  Ilanchelian Malaichamy²  Dhanalakshmi Vadivel²  Andrea Speltini³  Michela Sturini³  Vittorio Bellani⁴ 

[1] Department of Chemistry and INFN, University of Pavia, via Taramelli 12, 27100 Pavia, Italy;Department of Chemistry, Bharathiar University, Coimbatore 641046, India;Department of Drug Sciences, University of Pavia, via Taramelli 12, 27100 Pavia, Italy;Department of Physics, University of Pavia, via Bassi 6, 27100 Pavia, Italy;

关键词: kraft lignin;    pyrolytic carbon;    nanocomposite;    dyes photodegradation;    phenol;    fluoroquinolone;    photocatalytic activity;   

DOI  :  10.3390/catal10030270

来源: DOAJ

【 摘 要 】

This article reports on the formation of pyrolytic carbon/TiO₂ nanocomposite (p-C/TiO₂) by pyrolysis of a mixture of the P25 TiO₂ and kraft lignin at 600 °C. The result was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-visible spectroscopy, electron paramagnetic resonance spectrometry (EPR), thermogravimetry (TGA) and SEM microscopy. Its photocatalytic activity was ascertained using three classes of chemical probes, namely (i) degradation of methylene blue (MB) and rhodamine-B (RhB) dyes in UV light-irradiated aqueous suspensions, (ii) depletion of phenol and (iii) degradation of antibiotics. The p-C/TiO₂ nanocomposite is a strong phisisorbent of both MB and RhB nearly twofold with respect to neat TiO₂. Although it is nearly twofold more photoactive toward the degradation of MB (0.091 min⁻¹ versus 0.047 min⁻¹), it is not with regard to RhB degradation (0.064 min⁻¹ versus 0.060 min⁻¹). For the degradation of phenol in aqueous media (pH 3), pristine TiO₂ was far more effective than p-C/TiO₂ for oxygenated suspensions (17.6 × 10⁻³ mM min⁻¹ versus 4.3 × 10⁻³ mM min⁻¹). Under an argon atmosphere, the kinetics were otherwise identical. The activity of the material was tested also for a real application in the degradation of a fluoroquinolone antibiotic such as enrofloxacin (ENR) in tap water. It is evident that the photoactivity of a semiconductor photocatalyst is not a constant, but it does depend on the nature of the substrate used and on the experimental conditions. It is also argued that the use of dyes to assess photocatalytic activities when suspensions are subjected to visible light irradiation is to be discouraged as the dyes act as electron transfer photosensitizers and or can undergo photodegradation from their excited states.

【 授权许可】

Unknown