Tetracycline removal from aqueous solution by visible-light-driven photocatalytic degradation with low cost red mud wastes

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BACKGROUND The formation of heterojunction is an effective mean for increasing the photocatalytic activity of single‐phase semiconductor photocatalyst. RESULTS In this report, KNbO3/N‐defected g‐C3N4 (KNO/CNx) composites were prepared by an impregnation heat method. The optimized photocatalyst 3% KNO/CNx possesses excellent photocatalytic activity (100 mL, 10 mg/L; 84% degradation within 120 min) in the degradation of tetracycline (TC) under visible light (λ > 420 nm), and it can reach about 125, 10.71 and 3.75 times the degradation kinetic constants, compared with KNO, CN, and CNx, respectively. Furthermore, 3% KNO/CNx possesses relatively high stability during the entire photoreaction process. CONCLUSION This enhanced photocatalytic activity of KNO/CNx is mainly ascribed to the synergistic effect between the heterojunction and defect engineering, which expand the visible‐light adsorption and accelerate the separation efficiency of photo‐induced electron–hole pairs. The research is expected to be used to improve the structure and properties of KNO‐based composites, which provides a possibility for practical application of environmental restoration. © 2020 Society of Chemical Industry

Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Enhancement of visible‐light photocatalytic degradation performance over nitrogen‐deficient g‐C₃N₄/KNbO₃ heterojunction photocatalyst

Shi

Shu

Huang

et al. 2020

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“…(a)). As for BiOI, the negative slope suggests that BOI is a p‐type semiconductor . The flat potential of ZnWO 4 and BiOI are about −1.06 and 2.0 V [ versus saturated calomel electrode (SCE)], respectively.…”

Section: Resultsmentioning

confidence: 99%

Constructing 1D/2D BiOI/ZnWO₄p‐n heterojunction photocatalyst with enhanced photocatalytic removal of NO

Gong

Zhu

Bello

et al. 2020

BACKGROUND: Photocatalysis technology based on green renewable solar energy has broad prospects in environmental protection and new energy utilization. The energy of the light can be utilized to convert the pollutants in the environment into non-toxic substances even available products. Due to its low cost and environmental protection, photocatalysis technology has been further developed in the fields of water splitting, sewage treatment and nitrogen oxides (NO x ) removal.RESULTS: In this study, zinc tungstate (ZnWO 4 ) nanorods loaded on bismuth oxyiodide (BiOI) nanosheets with exposed {001} facet forming a 1D/2D BiOI/ZnWO 4 p-n heterojunction photocatalysts were synthesized and their photocatalytic activities for nitric oxide (NO) removal were investigated. The 20% BOI/ZWO composite exhibited the most excellent photocatalytic NO removal performance, which were 32.32% and 48.24% under visible light and simulated sunlight irradiation, respectively. CONCLUSION: A novel 1D/2D BiOI/ZnWO 4 p-n heterojunction was successfully synthesized by a two-step procedure. Compared to the pure ZnWO 4 and BiOI, the 20% BOI/ZWO composite has a significant increase in photocatalytic activity which is attributed to the enhanced visible light absorption and the improved separation of charge carriers. Trapping experiments and electron spin resonance results indicate that the hole (h + ), super oxygen radical (·O 2 − ) and hydroxyl radical (·OH) play minor roles, while the electron (e − ) has a major contribution to the NO removal process. Therefore, the BiOI/ZnWO 4 p-n heterojunction is a promising material for NO removal.

“…In recent years, heterogeneous photocatalysis using solar energy has become a hot research topic because of its low-cost, low-pollution and time-saving abilities in removing natural environmental pollutants and acquiring energy. [9][10][11] Photocatalysts such as titanium oxide (TiO 2 ) are at the heart of photocatalysis technology. Since Fujishima and Honda discovered its photocatalytic performance to produce H 2 from water in 1972, 12 TiO 2 has been one of the most promising semiconductor photocatalytic materials due to the advantages including high stability, nontoxicity and low cost, notwithstanding its limitations.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of TiO₂/high‐crystalline g‐C₃N₄ composite with enhanced visible‐light photocatalytic performance for tetracycline degradation

Guo

Sun

Huang

et al. 2020

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BACKGROUND The construction of heterojunction between two‐phase semiconductors is a crucial tactic to enhance photocatalytic activity due to its efficient charge separation. RESULT In this work, a novel TiO2/high‐crystalline g‐C3N4 (HCCN) heterojunction photocatalyst was synthesized successfully via a simply hydrothermal method, which was composed of TiO2 nanoparticles distributed on the surface of the HCCN nanosheets. The microstructure and morphology of TiO2/HCCN heterojunction were investigated by various characteristic techniques (such as X‐ray diffraction, transmission electron microscopy and Fourier transform infrared). The photocatalytic performance of as‐prepared photocatalysts was tested though the degradation of tetracycline (10 mg L−1) under visible light irradiation (λ > 420 nm). Significantly, the 50% TiO2/HCCN composite photocatalyst (mass fraction of TiO2 is 50%) exhibited the optimum photocatalytic activity (90%, 120 min), and the corresponding reaction rate constant was around 12 times and 54 times higher than those of pristine HCCN and TiO2, respectively. CONCLUSION The excellent photocatalytic performance was attributed mainly to the synergistic effect of the TiO2/HCCN heterojunction as follows: (i) enhanced light absorption capacity; (ii) improved separation and migration of electron–hole pairs; (iii) extended lifetime of photogenerated carriers. This current study extends our knowledge towards constructing other HCCN‐based nanocomposites with extraordinary photocatalytic performance for addressing environmental problems. © 2020 Society of Chemical Industry