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[Display omitted] • Co 3 V 2 O 8 heterogeneous material is firstly used to active persulfate (PS). • Co 3 V 2 O 8 /PS system can effectively purify tetracycline (TC) wastewater. • The system produce a large number of SO 4 •−, •OH, •O 2 – and 1O 2 free radicals. • The •O 2 – contributed the most to TC degradation, followed by SO 4 •-, •OH and 1O 2. The persistence and wide dispersion of antibiotics have a severe impact on the ecological environment. Developing an effective method with universal applicability to remove pollutants is pretty necessary. Herein, a bimetallic oxides (Co 3 V 2 O 8) heterogeneous material was successfully prepared and used to activate the persulfate (PS) for purification of tetracycline (TC) wastewater. By exploring the reaction conditions and influencing factors, the removal rate of 50 mg⋅L-1 TC reached 87.1% by Co 3 V 2 O 8 /PS system, and the reaction rate constant was up to 0.0271 min−1. As a highly efficient catalyst for the activation of PS, Co 3 V 2 O 8 /PS system produces radicals of SO 4 •−, •OH, •O 2 – and 1O 2 in the reaction process due to the Co(II) and V(IV) exchange electrons with S 2 O 8 2- and O 2. Simultaneously, the internal electron exchange occurs between Co(II)/Co(III) and V(IV)/V(V), which stabilizes the content of Co(II) and V(IV). This work provides a novel activator for PS activation to degrade contaminants and contributes to a better understanding of the PS activation mechanism by transition compound. [ABSTRACT FROM AUTHOR]

Abstract: A simple, rapid, and effective photoelectrochemical method is proposed to quantitatively characterise photocatalytic degradation behaviour of organic compounds at nanoporous TiO2 film electrodes in a thin-layer photoelectrochemical cell. This method uses the charge obtained by integrating the photocurrent originating from the photocatalytic oxidation of organic compounds to quantify the extent of degradation. Complete mineralisation was observed for all organic compounds investigated. A double-exponential kinetic rate expression was acquired using a computer simulation method, indicating two simultaneous kinetic processes. Photocurrent profiles of different organic compounds complied well with the proposed theoretical model. Both pre-exponential and exponential constants were obtained. The rate of the fast kinetic component is 10–25 times faster than that of the slow kinetic component. It was found that the identities of organic compounds have no significant effect on the photocatalytic oxidation kinetics, whereas the availability of the organic compounds to capture photoholes plays a decisive role. [Copyright &y& Elsevier]

A unique transient photoelectrolysis technique was developed to study the photocatalytic oxidation kinetics of adsorbed organic compounds at particulate TiO2 film electrodes. The technique was employed to study the photocatalytic oxidation of a number of adsorbed dicarboxylic acids at TiO2 porous film electrodes. The adsorption of these compounds was found to be heterogeneous, with three major types of surface complexes identified—each having distinctive binding affinities to the TiO2 surface. The three thermodynamically distinctive types of surface complexes exhibit two measurable photocatalytic reaction kinetic characteristics, i.e., a fast process and a slow process. The fast kinetic process can be attributed to the photocatalytic degradation of the strongest adsorbed species at more active sites such as edge and corner titanium ions. The slow kinetic process can be attributed to the photocatalytic degradation of the medium-strength bound complexes and the weakest bound surface complexes. The rate constants for these processes were calculated by curve fitting the photocurrent transient response to a double exponential decay expression. For adsorbed oxalic acid both the fast and the slow processes were shown to be the first-order processes in which both rate constants were independent of surface coverage. For the larger dicarboxylic acids adsorbed, the rate constant for the fast photocatalytic process (kf) was found to decrease with an increase in the surface coverage. The rate constant for the slow photocatalytic process, however, was shown to be a true first-order process for all adsorbed dicarboxylic acids. The value of the rate constant (ks) was similar for all the adsorbates studied and was independent of the surface coverage. [Copyright &y& Elsevier]

Cuprous oxide (Cu 2 O) suffers from severe electron-hole pairs recombination, instability and low photocatalytic degradation efficiency, though it has been considered as an excellent visible light photocatalyst. The incorporation of the Cu 2 O with other photocatalysts can address these problems. Herein, unique Cu 2 O@ polydopamine (PDA) nanospheres are prepared by a simple photo-reduction approach. Due to the synergistic effects of the Cu 2 O and PDA semiconductors, the Cu 2 O@PDA nanospheres composite possesses enhanced photocatalytic activity and extended life time for the degradation of the methyl orange under visible light irradiation. [ABSTRACT FROM AUTHOR]

Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13 wt% g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2 ng mL −1 . In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5–1840 ng mL −1 . [ABSTRACT FROM AUTHOR]

Abstract: A bactericidal technique (PEC–Br) utilizing in situ photoelectrocatalytically generated photoholes (h+), long-lived di-bromide radical anions () and active oxygen species (AOS) for instant inactivation and rapid decomposition of Gram-negative bacteria such as Escherichia coli (E. coli) was proposed and experimentally validated. The method is capable of inactivating 99.90% and 100% of 9×106 CFU/mL E. coli within 0.40s and 1.57s, respectively. To achieve the same inactivation effect, the proposed method is 358 and 199 times faster than that of the photoelectrocatalytic method in the absence of Br−, and 2250 and 764 times faster than that of the photocatalytic method in the absence of Br−. The decomposition experimental results obtained from 600-s PEC–Br-treated samples demonstrated that over 90% of E. coli body mass was decomposed and 42% biological carbon contents in the sample was completely mineralized and converted into CO2. The mechanistic pathways of disinfection/decomposition by photocatalysis (PC), photoelectrocatalysis (PEC), and photoelectrocatalysis in presence of Br− (PEC–Br) were also illustrated based on experimental evidence. [ABSTRACT FROM AUTHOR]

Abstract: Titanium hydrate sols were prepared using different acid hydrolysis catalysts, i.e., acetic acid and hydrochloric acid. The platinum-doped TiO2 sol–gels were also synthesized by adding K2PtCl6 into the titanium hydrate sols. The hydrophobic montmorillonite clay, treated with organic cationic surfactant, i.e., hexadecyltrimethylammonium bromide, was used as a template to prepare TiO2 pillared photocatalyst with the above sols. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) were employed to characterize the resulting photocatalysts. The adsorption performance and photoactivity of prepared pillared clays were studied by using methyl orange as a model organic pollutant. The preliminary results indicated that the hydrophobic TiO2 pillared clay prepared with acetic acid as the acid hydrolysis catalysts possessed higher photocatalytic activity than that with hydrochloric acid. Due to the excellent sedimentation property of the clay, the resulting pillared photocatalyst is easily recovered and reused in the postrun treatment. Also the doping of platinum into the hydrophobic photocatalyst can increase the photocatalytic activity significantly. [Copyright &y& Elsevier]