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The residues of tetracycline in environment have raised increasing concern for the deleterious impact on ecological and human health. Natural organic matter (NOM), ubiquitous in natural waters, is unavoidable to encounter tetracycline, which might affect the fate of tetracycline in aquatic environment. In this study, we investigated the effect of natural organic matter (NOM) on the photolytic fate of tetracycline (TC). The photolysis kinetics of TC were evaluated with two representative NOM, tannic acid (TA) and gallic acid (GA). The presence of TA and GA obviously inhibited the removal of TC under UV irradiation with photolysis rate constant at 0.067 h−1 and 0.071 h−1, respectively, which were 32.3% and 28.3% less than that without TA and GA (0.099 h−1). Furthermore, NOM exhibited different impacts on both indirect photolysis and direct photolysis. NOM promoted the formation of hydroxyl radical, induced the generation of triplet-excited state NOM and thus greatly enhanced the indirect photolysis of TC. However, direct photolysis was almost completely inhibited by NOM via inner filter effect and interacting with TC to form ground-state complex with low photoreactive. Moreover, similar intermediates were detected in the presence and absence of NOM, indicating that NOM exhibited limited influence on the degradation pathways of TC. This study reveals the multiple roles of NOM on tetracycline photolysis, contributing to better understand the photolytic fate of antibiotics in natural waters. Image 1 • The presence of NOM would slow the photolysis of tetracycline. • NOM greatly enhanced the indirect photolysis of tetracycline and almost completely inhibited the direct photolysis of tetracycline. • NOM exhibited limited influence on the degradation pathways of tetracycline. [ABSTRACT FROM AUTHOR]

• The Fe doping BiOCl with higher utilization efficiency in the sulfate radical-based photo-Fenton system. • LVX degradation pathway was put forward based on the experimental results in the Fe-BiOCl/PS/LED process. • Low iron leaching and high catalytic stability are achieved for Fe-BiOCl. In this research, Fe-doped BiOCl nanosheets were successfully synthesized through controlled hydrothermal method and applied in the degradation of levofloxacin (LVX) by sulfate radical-based photo-Fenton process. The conduction band of Fe-doped BiOCl was calculated as 2.77 eV compared to BiOCl (3.24 eV), and showed remarkable visible-LED-light driven photocatalytic activity with the expanded visible light absorption. Certain parameters were studied, with the addition persulfate (1 mM) and catalyst dosage (0.5 g L−1) at natural pH, the LVX reached over 95% degradation efficiency in 60 min during at least five successive experiments which displayed excellent catalytic activity and stability. LVX degradation was confirmed to depend on the formation of free reactive oxidant species through radical scavenger reagents and EPR analysis. On the basis of the experimental results and density functional theory calculations, the role of photocatalytic degradation mechanism of LVX degradation by the Fe-BiOCl sample was investigated. Moreover, the LVX degradation pathway was induced according to the intermediates detected by LC-MS. The results of this research demonstrated the good feasibility of Fe-doped BiOCl nanosheets which would enhance the utilization of photocatalysts under visible light irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Herein, functionalized PEDOT films were prepared by incorporation of two electroactive species, ferrocenecarboxylic acid (Fc−) and ferricyanide (Fe(CN)6 4−) as doping anions during the electropolymerization of PEDOT at glassy carbon electrodes (GCEs) from aqueous solution. The electrochemically synthesized electroactive species-doped PEDOT films have been carefully characterized by scanning electron microscopy (SEM), FTIR and UV/Vis spectra and various electrochemical techniques. Such nanostructured films combined the advantages of PEDOT (high conductivity and stability) together with electroactive species (good electrochemical activity) and were applied as electrochemical sensors for simultaneous determination of vitamin B2 (VB2), vitamin B6 (VB6) and vitamin C (VC). The results showed that the oxidation peak currents of vitamins obtained at the GCEs modified with electroactive species-doped PEDOT films were much higher than those at the ClO4 −-doped PEDOT films and bare GCEs. The experiment results also illustrated that the sensors possessed high selectivity with no interference from other potential competing species. Moreover, the proposed sensors were successfully employed for the determination of vitamins in orange juice samples with satisfactory results. [Copyright &y& Elsevier]