Search

To develop a convenient method for simultaneous detection of As(III/V), Cr(III/VI), and Fe(II/III), three morphologies of CeO2 oxidase have been prepared. Based on the difference in oxidase activity and binding ability with substrate TMB of CeO2 of different morphologies, a 3 (Signal unit) × 6 (Target number) × 5 (Repetition) sensor array was constructed to realize simultaneous detection of six variable valence metal ions As(III/V), Cr(III/VI), and Fe(II/III). The lowest detection limit of the array for metal ions was 1.68 µg/L. The analysis of environmental samples with multiple metal ions (binary and ternary mixtures) co-existing has confirmed that the sensor array can achieve simultaneous qualitative and quantitative results for composite samples. This study not only revealed the influencing factors of crystal morphology regulation on oxidase activity, but also provided a scheme for the morphology detection of easily convertible metal ions in the field through the construction of the sensor array. [ABSTRACT FROM AUTHOR]

To develop simultaneous and in-situ detection techniques towards Cr(VI) and Mn(II), Eu/Tb@CDs with white fluorescence were prepared by a one-step hydrothermal method. With the increase of Cr(VI), all fluorescence channels of Eu/Tb@CDs exhibited obvious quenching, and the detection limit (LOD) was 0.10 μM. In the presence of Mn(II), only the fluorescence from Tb and Eu was quenched, while the fluorescence of CDs was not effected. The LOD for Mn(II) was 0.16 μM. More importantly, in the actual water samples where Cr(VI) and Mn(II) coexist, Eu/Tb@CDs can realize their rapid and simultaneous detection by simple spectral calculation. The selective and competitive experiments have also confirmed that the detection of Cr(VI) and Mn(II) was not interfered by common pollutants in groundwater. It is undeniable that the simultaneous detection of multiple targets by one probe not only greatly improves the detection efficiency, but also has important significance for the field monitoring of water quality parameters. [ABSTRACT FROM AUTHOR]

Sulfur quantum dots are promising alternatives for traditional heavy metal-containing quantum dots due to their benign chemical properties and low cytotoxicity. Herein, cysteine-decorated sulfur dots were prepared from facile modification of pristine sulfur dots and can be acted as a chemosensor for the fluorometric and colorimetric dual-channel detection of cobalt (Co2+) with high sensitivity and selectivity. Visual colors of the as-prepared chemosensor in the presence of Co2+ changed from blue to colorless under UV light and also can transform from colorless to yellow under sunlight based on the photoinduced electron transfer effect. The detection limit of cysteine-decorated sulfur dots toward Co2+ was determined as low as 0.16 μM with a wide detection range, which is lower than the permitted guideline level by Department of Environmental Protection for drinking water (1.7 μM). Furthermore, portable paper sensor-based cysteine-decorated sulfur dots were fabricated for Co2+ detection and showed superior detection ability. Aided by a common smartphone as detector, the rapid, on-site and accurate quantification of Co2+ in real water samples can be accomplished. Our research has provided a novel chemosensor based on sulfur dots for dual-channel detection of Co2+, which would expand applications of sulfur dots in environmental monitoring, diseases diagnosis, cell imaging, light-emitting diodes, etc. Cysteine-decorated sulfur dots were acted as a chemosensor for fluorometric and colorimetric dual channel detection of Co2+ based on the photoinduced electron transfer effect. [ABSTRACT FROM AUTHOR]

The effects of food to microorganism (F/M) ratio and alcohol ethoxylate (AE) dosage on the methane production potential were investigated in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor (SAnMBR). The fate of AE and its acute and/or chronic impact on the anaerobic microbes were also analyzed. The results indicated that AE had an inhibitory effect to methane production potential (lag-time depends on the AE dosage) and the negative effect attenuated subsequently and methane production could recover at F/M ratio of 0.088-0.357. VFA measurement proved that AE was degraded into small molecular organic acids and then converted into methane at lower F/M ratio (F/M<0.158). After long-term acclimation, anaerobic microbe could cope with the stress of AE by producing more EPS (extracellular polymeric substances) and SMP (soluble microbial products) due to its self-protection behavior and then enhance its tolerance ability. However, the methane production potential was considerably decreased when AE was present in wastewater at a higher F/M ratio of 1.054. Higher AE amount and F/M ratio may destroy the cell structure of microbe, which lead to the decrease of methane production activity of sludge and methane production potential. [ABSTRACT FROM AUTHOR]

FeO was supported on mesoporous AlO or SiO (50 wt.%) using an incipient wetness impregnation method, and FeO/AlO exhibited higher catalytic efficiency for the degradation of 2,4-dichlorophenoxyacetic acid and para-chlorobenzoic acid aqueous solution with ozone. The effect and morphology of supported FeO on catalytic ozonation performance were investigated based on the characterization results of X-ray diffraction, X-ray photoelectron spectroscopy, BET analysis and Fourier transform infrared spectroscopy. The results indicated that the physical and chemical properties of the catalyst supports especially their Lewis acid sites had a significant influence on the catalytic activity. In comparison with SiO, more Lewis acid sites existed on the surface of AlO, resulting in higher catalytic ozonation activity. During the reaction process, no significant Fe ions release was observed. Moreover, FeO/AlO exhibited stable structure and activity after successive cyclic experiments. The results indicated that the catalyst is a promising ozonation catalyst with magnetic separation in drinking water treatment. [ABSTRACT FROM AUTHOR]

Fe-Co bimetallic oxides supported on mesoporous zirconia (Fe-Co/ZrO) was prepared using incipient wetness co-impregnation method and characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectra. Compared with individual component Fe or Co catalysts, Fe-Co/ZrO exhibited higher ozonation efficiency for the degradation of the tested toxic pollutants, as demonstrated with the herbicides 2,4-dichlorophenoxyacetic acid and pharmaceutical phenazone, diphenhydramine hydrochloride in aqueous solution. Furthermore, the characterization studies indicated that Fe-Co oxides were highly dispersed on the surface of mesoporous zirconia with multivalent oxidation states. The interfacial electron transfer process was greatly enhanced due to the presence of two redox couples (Fe/Fe and Co/Co) in Fe-Co/ZrO, which caused the higher catalytic reactivity for ozone decomposition into OH radicals, leading to the efficient removal of toxic pollutants in aqueous solution. The catalytic mechanism of pollutants degradation over Fe-Co/ZrO with ozone was proposed on the basis of all information obtained under different experimental conditions. Graphical Abstract: The multivalent oxidation states, high dispersion and the synergistic effect of Fe-Co oxides in Fe-Co/ZrO enhanced the interfacial electron transfer process, which caused the higher catalytic reactivity for the degradation of toxic pollutants in aqueous solution.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]