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To degrade the antiviral and antimalarial drug chloroquine phosphate (CQP), an oxygen doping MoS 2 nanoflower (O-MoS 2 -230) co-catalyst was prepared by a hydrothermal method to construct an O-MoS 2 -230 co-catalytic Fenton system (O-MoS 2 -230/Fenton) without pH adjustment (initial pH 5.4). Remarkable CQP degradation efficiency (99.5 %) could be achieved in 10 min under suitable conditions ([co-catalyst] = 0.2 g L–1, [Fe2+] 0 = 70 μM, [H 2 O 2 ] 0 = 0.4 mM) with a reaction rate constant of 0.24 min–1, which was 4.8 times that of MoS 2 co-catalytic Fenton system (MoS 2 /Fenton). Compared to MoS 2 /Fenton, the system had 1.5 times more Fe2+ (28.4 μM) and showed a 24.0 % increase in H 2 O 2 activation efficiency, reaching 50.0 %. The electron paramagnetic resonance (EPR) determinations and active species trapping experimental data revealed that •OH and 1O 2 were responsible for CQP degradation. The combination of experiments and density functional theory (DFT) calculation demonstrates that O doping in MoS 2 modifies the surface charge distribution, leading to an increase in its conductivity, thus accelerating the Fe3+/Fe2+ cycle and promoting reactive oxygen species (ROS) generation. Furthermore, O-MoS 2 -230/Fenton system exhibited excellent stability. This work reveals the degradation mechanism of accelerated Fe3+/Fe2+ cycle and abundant ROS in the O-MoS 2 -230/Fenton system and provides a promising technology for antibiotic pollutant degradation. [Display omitted] • Oxygen doping MoS 2 nanoflowers are prepared by self-assembly route. • O doping in MoS 2 facilitated the cycle of Fe3+/Fe2+ to enhance CQP degradation. • O-MoS 2 -X/Fenton system provides excellent CQP degradation without pH adjustment. • Abundant ROS such as •OH and 1O 2 are generated in O-MoS 2 -230/Fenton system. [ABSTRACT FROM AUTHOR]

A novel visible light emitting diode (LED) photocatalysis combined ultrafiltration (UF) system driven by metal-free O-doped C 3 N 4 was established for sulfamethazine (SMZ) removal in environmental remediation. Among different O-doping ratios, 8%O-C 3 N 4 exhibited the optimal SMZ degradation efficiency (89.36%) and the flux of 8%O-C 3 N 4 /LED/UF system could reach up to 38.92 L/m2/h. Benefitting from the O-doping, the synergetic effect of the expansion of visible-light absorption, enhancement of electron redox capacity, and improvement of e--h+ separation efficiency could produce the intensified photoactivity. Superoxide radical (O 2 •-) and single oxygen (1O 2) were proved to be the primary active species by EPR and quenching tests. Moreover, the influence of several parameters such as photocatalyst dosage, SMZ concentration, raw turbidity and humic acid concentration in 8%O-C 3 N 4 /LED/UF system on SMZ removal were systematically studied. Under simulated surface water matrix, 8%O-C 3 N 4 /LED/UF system could also remove 96.88% SMZ and stable membrane flux stabilized as high as 33.36 L/m2/h. This study makes a demonstration for applying highly-effective powdery photocatalysts in the actual wastewater treatment and designing future photocatalytic reactors. [Display omitted] • 2D ultrathin O-doped C 3 N 4 was synthesized via a two-step thermal polymerization process. • 8%O-C 3 N 4 /LED/UF system achieved optimal SMZ removal (~90%) and highest permeation flux (~39 L/m2/h). • Raw turbidity and humic acid exhibited a marginal impact to the O-C 3 N 4 /LED/UF system. • In surface water matrix, the combined system could remove 96.88% SMZ and membrane flux stabilized at 33.36 L/m2/h. • Superoxide radical and single oxygen were the primary active species for SMZ elimination. [ABSTRACT FROM AUTHOR]

Bifunctional oxygen-doped graphitic carbon nitride (OCN) was fabricated to activate peroxymonosulfate (PMS) for degrading imidacloprid (IMD). The modulated electronic structure of OCN promoted the adsorption, electron transfer, and formation of the redox site of PMS. The light absorption capacity, and the separation and migration speed of photogenerated carriers of OCN were increased. Consequently, 94.5% of IMD (3.0 mg/L) was removed by OCN-10/PMS process in 2.0 h. Compared with g-C 3 N 4 /PMS (0.048 h−1), the IMD degradation rate constant of OCN-10/Vis/PMS system (1.501 h−1) was increased by 30.3 times. The PMS oxidation on electron-deficient C atoms and holes, the PMS reduction around electron-rich O atoms and photogenerated electrons, and the multiple reactions of superoxide radical were the sources of the main active species singlet oxygen. Moreover, even under different pH conditions, coexisting anions, humic acid, and other neonicotinoid pesticides, the OCN-10/Vis/PMS system still showed acceptable applicability. Finally, mass spectrometry identified that hydroxylation and N-dealkylation of amines were the primary degradation pathways of IMD. This paper demonstrates an environmental-friendly combined activation strategy of PMS that can be operated day and night with low energy consumption, aiming to pave the way for developing metal-free photocatalysts for high-efficient environmental purification based on advanced oxidation coupling technology. [Display omitted] • The OCN/Vis/PMS system was first applied for pesticide degradation. • OCN activated PMS via non-photochemical and photocatalytic pathways. • The joint action mechanism of the two activation pathways was first revealed. • The system had good applicability under various environmental factors. [ABSTRACT FROM AUTHOR]