Facile Fabrication of Durable Biochar/H₂-TiO₂ for Highly Efficient Solar-Driven Degradation of Enrofloxacin: Properties, Degradation Pathways, and Mechanism

Abstract

Widespread application of TiO 2 for degradation of antibiotics is restricted by mainly the low photodegradation efficiency under solar irradiation. To expand the application of TiO 2 , the key factors that should be improved are visible-light response, yield of electrons and holes, and durability. Herein, we report a visible-light responsive and durable sugarcane-bagasse-derived biochar supported hydrogenated TiO 2 (HSCB/H 2 -TiO 2 ) photocatalyst with higher electron production fabricated by a facile one-pot hydrogenation. Mild hydrogenation temperature preserved the lotus-stem-like structure of sugarcane bagasse and gave the photocatalyst great separability. The superior durability of HSCB/H 2 -TiO 2 was demonstrated by 12 rounds of repeated degradation of methylene blue (MB). In addition, the electron paramagnetic resonance (EPR) results demonstrated that the biochar skeleton contains abundant persistent free radicals (PFRs), which can provide excess electrons to form more • O 2 – . Meanwhile, radical quenching experiment and EPR radical trapping results also revealed that • O 2 – was the most dominant species for enrofloxacin (ENR) degradation. Thus, the as-fabricated photocatalyst shows excellent solar-driven degradation of ENR, and 95.6% of ENR was degraded in 180 min under simulated solar irradiation. Possible ENR degradation pathways and mechanism are also proposed based on the identified intermediates.

Spent-coffee grounds-derived biochar-supported heterogeneous photocatalyst: a performance evaluation and mechanistic approach for the degradation of pentachlorophenol

“…In CGB, the two deconvoluted peak at ∼531.4 eV and ∼533.2 eV are assigned to –COOH and C–O bond. 9 Compared with CGB, a new peak appeared at ∼532.6 eV in the CGBT composite, which is assigned to Ti–O bond from the TiO 2 lattice. 39,40 The existence of this peak in the composite material further demonstrated the successful deposition of TiO 2 nanoparticles onto the coffee-ground biochar surface via an oxygen atom, which is also consistent with the FT-IR and TEM results.…”

“…4b and c, respectively. In the CGB, four peaks can be assigned to C n (∼284.9 eV), 9,39 C–OH (∼286.4 eV), CO (∼287.9 eV), and O–CO (∼289.5 eV). 40 Similar peaks were observed for the CGBT composite, except the O–CO (∼289.5 eV) peak was missing, and other characteristic peaks C–O (from 286.4 to 286.8 eV) and CO (from 287.9 to 289 eV) shifted towards higher binding energies.…”

“…2b), which generally signies mesoporous structure. 9 The pore-size distributions (Fig. 2b, inset) conrmed the presence of meso/microporous structures for all the prepared materials.…”

“…46 Similar trends have been observed for radical trapping experiments with biochar/hydrocharderived catalysts used in the photocatalytic degradation of organic pollutants. 9,44,47 To further support the inuence of CGBT nanocomposite on the mineralization of PCP, the COD removal efficiency of PCP was assessed during the photocatalytic reaction process. It can be observed from Fig.…”

“…6 However, TiO 2 has a relatively large bandgap (∼3.0 and ∼3.2 eV for rutile and anatase TiO 2 , respectively) 7 and absorbs a small portion of the solar spectrum. 8 The photogenerated e − −h + pair undergo fast recombination which limits the reaction rates 9 and it has low reactivity towards pollutants with lower concentrations. 10 Combining TiO 2 with carbon-rich material that is low cost and non-toxic and derived from the valorization of waste biomass could provide an optimal solution for designing stable and versatile heterogenous TiO 2 photocatalysts.…”