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

Abstract

This article reports on the formation of pyrolytic carbon/TiO 2 nanocomposite (p-C/TiO 2 ) by pyrolysis of a mixture of the P25 TiO 2 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/TiO 2 nanocomposite is a strong phisisorbent of both MB and RhB nearly twofold with respect to neat TiO 2 . 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 TiO 2 was far more effective than p-C/TiO 2 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.

Innovative chitin-glucan based material obtained from mycelium of wood decay fungal strains

“…Thermogravimetric analyses were performed using a Mettler Toledo TGA1 XP1 thermogravimetric analyzer by heating the samples having the weight of 8–10 mg were inserted in an alumina crucible with a perforated lid at the temperature from 25 °C to 800 °C by the heating rate of 20 °C/min under N 2 atmospheric condition with a mass flow rate of 100 mL/min. A blank performed with an empty crucible together with a perforated lid was subtracted from the curves [ [37] , [38] , [39] , [40] , [41] , [42] , [43] ]. Standards of β-glucan and chitin (both from Sigma Aldrich) were analyzed in the same conditions, allowing the comparison with the fungal mass loss at different temperatures.…”

Copper tungstate assisted photocatalytic degradation of Industrial (dye and pharmaceutical) products in water

“…These energetic charge carriers initiate the degradation of dye molecules. The photocatalyst surface develops reactive oxygen species (ROS) such as hydroxyl radicals (•OH) and superoxide ions when electron-hole pairs react with water and oxygen molecules or adsorbed substances [53][54][55][56]. ROS with strong oxidative potential break chemical bonds and transform dye molecules into simpler chemicals.…”

Advancements in Materials Science and Photocatalysts for Sustainable Development

“…Titania can be efficiently layered with pyrolytic carbon by employing a low-cost recyclable resource such as kraft lignin. The crystalline structure of the P25 TiO 2 photocatalyst was unaffected by the 600 • C pyrolytic procedure (p-C/TiO 2 ) [49]. The photocatalytic performance of p-C/TiO 2 was assessed for the degradation of a fluoroquinolone antimicrobial drug in tap water under simulated sunlight.…”