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CeO 2 nanoparticles are successfully loaded on carbonate doped Bi 2 O 2 CO 3 (CBOC) nanosheets by a facile hydrothermal and low-temperature calcination method. CeO 2 /CBOC heterojunction shows significantly enhanced photocatalytic activity, when 35 mg of CeO 2 /CBOC photocatalyst is added to tetracycline (TC) solution (20 mg/L, 100 mL), about 79.5% TC is degraded within 90 min under visible light irradiation, which is much higher than that of original CeO 2 and CBOC. According to photoelectrochemical characterization and active radical capture experiments, the Z-scheme electron transfer mechanism is the reason for the significant enhancement of photocatalytic activity. Besides, the XPS results indicate that Ce4+/Ce3+ redox pairs are formed at the contact interface between CeO 2 and CBOC, which is conducive to the transfer of photoexcited electrons and production of superoxide radicals. Additionally, the photocatalytic mechanism and possible degradation pathway of TC is proposed through free radical trapping experiments and liquid chromatography-mass (LC-MS) analysis. This study will accumulate experience for the combination of CeO 2 and bismuth-based nanomaterials, and provide a feasible way to design wide band-gap bismuth-based photocatalysts, thereby achieving efficient visible light degradation of environmental pollutants. [ABSTRACT FROM AUTHOR]

The increasingly serious pollution of antibiotics brings an enormous threat to the ecological environment and human health. Graphite phase carbon nitride (g-C 3 N 4), as a popular photocatalytic material, is widely used in photocatalytic degradation of antibiotics in water. In order to make up for the shortage of g-C 3 N 4 monomer, CeO 2 /N-doped g-C 3 N 4 (CeNCN) composite photocatalysts co-modified with nitrogen doping and CeO 2 loading were designed and synthesized with the idea of expanding visible light absorption and promoting photogenerated carrier separation. CeNCN exhibits excellent photodegradation performance, the removal rate of tetracycline reached 80.09% within 60 min, which is much higher than that of g-C 3 N 4 (CN) and N-doped g-C 3 N 4 (NCN); and the quasi-first-order degradation rate constant is 0.0291, which is 7.86 and 2.29 times higher than CN and NCN. Electron spin resonance and free radical trapping experiments confirmed that h+, O 2 − and OH are the active substances in the photocatalytic system. After 5 cycles, the degradation efficiency of tetracycline still exceeds 75%, which indicates that CeNCN has good stability. This work proves that N-doping and CeO 2 loading can effectively broaden the photoresponse range of g-C 3 N 4 , facilitate the separation of photogenerated electron-hole pairs, and provide a reference for the construction of g–C 3 N 4 –based photocatalyst with high-efficiency photodegradation activity. [Display omitted] • CeO 2 /N-doped g-C 3 N 4 (CeNCN) photocatalyst was successfully first synthesized. • CeNCN exhibits excellent light response and the separation of charge carriers. • CeNCN exhibits significantly enhanced photocatalytic activity for TC degradation. • The proposed photocatalytic mechanism toward CeNCN photocatalyst is illustrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coordinative Fe-N x improved the catalytic ability of FeOCN for photo-Fenton process. • The consumption of H 2 O 2 was reduced in the photo-Fenton process over FeOCN. • FeOCN showed high catalytic performance for tetracycline degradation. • The improved charge separation favored Fe(III)/Fe(II) conversion. • FeOCN exhibited wide applicable pH range and anti-interference ability to anions. Tetracycline (TC) antibiotics have been widely used over the past decades, and their massive discharge led to serious water pollution. Photo-Fenton process has gained ever-increasing attention for its excellent oxidizing ability and friendly solar energy utilization ability in TC polluted water treatment. This work introduced coordinative Fe into oxygen-enriched graphite carbon nitride (OCN) to form FeOCN composites for efficient photo-Fenton process. Hemin was chosen as the source to provide the source of coordinative Fe-N x groups. The degradation efficiency of TC reached 82.1 % within 40 min of irradiation, and remained 76.9 % after five runs of reaction. The degradation intermediates of TC were detected and the possible degradation pathways were gained. It was found that h+, OH, and O 2 − played major roles in TC degradation. Notably, the photo-Fenton performance of FeOCN was stable in highly saline water or strong acid/base environment (pH 3.0–9.0). Besides, H 2 O 2 can be generated in-situ in this photo-Fenton process, which is favorable for practical application. It can be anticipated that the coordinative FeOCN composites will promote the application of photo-Fenton oxidation process in TC polluted water treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • UiO-66-SO 3 H/Fe(1:1)-800 exhibited high tetracycline degradation efficiency. • The influence of operating parameters on tetracycline degradation was analyzed. • It exhibited good stability and potential for wastewater treatment applications. • Mechanism of TC degradation by heterogeneous electro-Fenton process was proposed. Designing efficient heterogeneous electro-Fenton (HEF) catalysts for in-situ H 2 O 2 generation and organic pollutant degradation in water has become a hot research topic. In this study, a series of novel UiO-66-SO 3 H/Fe(x)-800 materials were successfully prepared by carbonizing sulfonic acid metal-organic frameworks (UiO-66-SO 3 H) doped with iron for tetracycline (TC) HEF degradation. The catalytic performance of UiO-66-SO 3 H/Fe(x)-800 was evaluated by comparing different HEF systems, and the effects of different operating parameters and co-existing substances were investigated. The results indicated that UiO-66-SO 3 H/Fe(1:1)-800 displayed excellent performance for TC degradation over a broad pH range, with an optimal TC degradation efficiency of 90.10% in 90 min and a low energy consumption of 4.39 kWh/kg/TOC. Furthermore, the superior stability and reusability of this catalyst were proved in continuous cycling experiments with low iron leaching (<1.000 ug/L). The mechanism exploration demonstrated that TC was mainly oxidized by ‧OH and 1O 2. In addition, iron-doped porous carbon carrier improved the utilization rate of H 2 O 2 and accelerated the regeneration of Fe2+, which played an important role in the HEF process. The HEF system based on UiO-66-SO 3 H/Fe(1:1)-800 also exhibited satisfactory performance when treating actual water samples, presenting broad application prospects. [ABSTRACT FROM AUTHOR]

Recently, photo-Fenton technology has been widely used to degrade tetracycline (TC) because of its great efficiency and wide application range. Herein, Fe–Ni layered double hydroxides (FeNi-LDH)/Ti 3 C 2 photo-Fenton system was constructed in this study. The results showed the introduction of Ti 3 C 2 solved some problems of FeNi-LDH such as poor conductivity, easy aggregation, and high recombination rate of photoelectron. Benefiting from these advantages, FeNi-LDH/Ti 3 C 2 exhibited excellent TC removal rate of 94.7% while pure FeNi-LDH was only 54%. Besides, FeNi-LDH/Ti 3 C 2 possessed strong pH tolerance (2–11) and the removal efficiency was still up to 82% after the four-cycle experiment. Furthermore, the quenching experiments revealed the reaction mechanism, where ∙OH and ·O 2 − were the primary active radicals for degrading TC. Last, the results of the simulated wastewater treatment and the inorganic ion interference tests showed that FeNi-LDH/Ti 3 C 2 possessed practical application potential. In brief, this study shows that FeNi-LDH/Ti 3 C 2 can offer a certain theoretical basis for the actual development of hydrotalcite in heterogeneous photo-Fenton systems. [Display omitted] • A novel material FeNi-LDH/Ti 3 C 2 was successfully prepared by a facile method. • The incorporation of Ti 3 C 2 enhanced the photogenerated carrier separation. • The degradation efficiency of TC increased by 40% after introduce Ti 3 C 2. • FeNi-LDH/Ti 3 C 2 photo-Fenton system possessed great application prospect. • The possible mechanism and degradation pathways of TC were illustrated. [ABSTRACT FROM AUTHOR]