Developing new methods to improve the photocatalytic activity of graphitic carbon nitride (g-C₃N₄) for hydrogen (H₂) evolution has attracted intensive research interests. Here, we report that the ...g-C₃N₄ exhibits photocatalytic activity for H₂ evolution from pure water. And, the activity is dramatically improved by loading highly dispersed conductive polymer nanoparticles. The H₂ evolution rate increases up to 50 times for g-C₃N₄ with 1.5 wt% polypyrrole (PPy) nanoparticles on the surface. The reaction proceeding in a pure water system excludes the need for sacrificial agents. The role of the highly conductive PPy in enhancing H₂ evolution is as a surface junction to increase the number of photoinduced electrons, and to facilitate electron transfer to the interface.
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•Two supported microporous carbons on sepiolite was synthesized to activate PMS.•KOH was more effective than ZnCl2 in enhancing PMS activation performance.•TC degradation in SMC-K/PMS ...system follows a non-radical mechanism.•The role of SMC-K in PMS activation for efficient TC degradation was discussed.•TC degradation pathway by non-radical involved oxidation process was proposed.
Carbon-based peroxymonosulfate (PMS) activator as a promising candidate for substituting metal-based heterogeneous catalysts has drawn increasing concerns. In this study, we reported two supported microporous carbon based PMS activators after treatment by KOH and ZnCl2 (denoted as SMC-K and SMC-Z). Their catalytic activity was evaluated and compared by the degradation efficiency of a typical antibiotics of tetracycline (TC). The results indicated that SMC-K exhibited a higher PMS activation performance than SMC-Z. TC degradation data followed the pseudo-first-order kinetics with reaction rate constants of 0.0818 and 0.0392 min−1, respectively. Based on the characterization results, SMC-K had an extensive microporous structure with abundant vacancy defects and catalytic active sites, accompanied by more basic site distribution. The PMS activation mechanism was further explored via quenching tests, electron paramagnetic resonance (EPR) and electrochemical impedance spectroscopy (EIS). TC degradation occurred via a non-radical oxidation mechanism: (1) direct oxidation by activated PMS where SMC-K acted as the electron transfer shuttle, (2) oxidized by 1O2 instead of SO4− or OH generated from PMS self-decomposition. Furthermore, a reasonable degradation pathway of TC based on the non-radical oxidation has been proposed. This work benefits to develop new treatment technologies for organic pollutants removal in practical application.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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 (Co
2+
) with high sensitivity and selectivity. Visual colors of the as-prepared chemosensor in the presence of Co
2+
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 Co
2+
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 Co
2+
detection and showed superior detection ability. Aided by a common smartphone as detector, the rapid, on-site and accurate quantification of Co
2+
in real water samples can be accomplished. Our research has provided a novel chemosensor based on sulfur dots for dual-channel detection of Co
2+
, which would expand applications of sulfur dots in environmental monitoring, diseases diagnosis, cell imaging, light-emitting diodes, etc.
Graphical Abstract
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.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Electrolytic manganese residue (EMR) was used as filler in sulfur concrete.•Sulfur concrete with EMR showed good mechanical strength and corrosion resistance.•This study establishes EMR as a ...suitable raw material for sulfur cement concrete.
Utilization of sulfate-rich industrial residue building materials can reduce both the production cost and the environmental impact of the solid wastes. In this paper, the possibility of using electrolytic manganese residues filler for sulfur cement concrete has been investigated and compared with those of the relevant mortar samples. Mechanical properties, microstructure and durability of the sulfur concrete samples prepared with the above mentioned waste filler has been discussed. The microstructure results indicate that electrolytic manganese residue and aggregates were tightly wrapped by hydrophobic modified sulfur forming particle packing structure. The new sulfur concrete samples showed high mechanical strength and excellent environmental durability. Leaching test showed that the leaching concentrations of the heavy metal ions were far below the regulatory limits of National Integrated Waste water Discharge Standards in China (GB 8978-1996). Therefore, the results obtained in this study established a technical suitability of electrolytic manganese residue as raw material for sulfur cement concrete.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A method has been developed to quantify PET and PBT microplastics (MPs) based on depolymerization and detection of depolymerization products by gas chromatography-tandem mass spectrometry (GC–MS/MS) ...without a complex separation process from environmental samples. Under the optimal depolymerization conditions, PET and PBT were efficiently converted to ethylene glycol (78%) and 1,4-butanediol (87%), respectively. Subsequently, the linear curves were constructed between signal intensities of depolymerization products and polymer masses by GC–MS/MS, and the correlation coefficients of PET and PBT were 0.996 and 0.997, respectively. The spiking and recovery experiments of PET and PBT in the environmental samples showed that the recovery was stable in the range 89–100%, and the limit of detection was 4.95 μg and 1.39 μg of PET and PBT, respectively. The method has been proven to be capable of simultaneous identification and quantification of PBT and PET MPs in real environmental water samples without complex separation process, which provided a scheme for the determination of microplastics.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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•Highly ordered mesoporous aluminas are highly efficient for fluoride ion removal.•Ordered mesoporous alumina has high fluoride uptake because of large surface area.•Crystalline ...mesoporous alumina has high selectivity for fluoride and recyclability.
Highly ordered and disordered (MA-n) mesoporous aluminas with excellent fluoride adsorption performance have been successfully developed. The physicochemical and adsorption properties were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption isotherms and fluoride removal experiments. Highly ordered mesoporous structure (OMA) was produced by using aluminum metal organic as precursor and wormlike disordered mesoporous structure (MA-n, MA-cl) was synthesized from inorganic aluminum salt precursors. The synthesized mesoporous alumina with a large pore size distribution of 7–14nm and large surface areas in the range of 163–338m2/g are beneficial for transport of solution in interconnected mesoporous channels and the fluoride ion was anchored on plenty of surface hydroxyl groups which provide high fluoride adsorption capacity and efficiency. Adsorption kinetics was described by pseudo-second-order, pseudo-first-order and intra-particle pore diffusion models, while, their adsorption equilibrium isotherms were described reasonably well by Langmuir model. Maximum fluoride adsorption capacities of OMA-400, OMA-850 and MA-n were 135, 91 and 95mg/g, respectively, which are higher than many reported alumina based adsorbents. Due to the ordered mesoporous structure which decreases the liquid transfer resistance, the OMA-400 showed extremely faster adsorption kinetics with a removal of 90% of F− within 20min at an optimal pH of 6. Presence of other anions like SO42−, NO3−, Cl− and HCO3− effect on fluoride removal efficiency and desorption study of OMA-400 and OMA-850 were also determined and compared.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
To develop a convenient method for simultaneous detection of As(III/V), Cr(III/VI), and Fe(II/III), three morphologies of CeO
2
oxidase have been prepared. Based on the difference in oxidase activity ...and binding ability with substrate TMB of CeO
2
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.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study focuses on the feasibility of boron nitride as a catalyst for ozonation of ketoprofen. The defective boron nitride was prepared by calcination of boric acid and melamine and characterized ...by XRD, SEM, FT-IR, XPS, temperature programmed desorption, Raman and UV–Vis diffuse reflectance spectra. The apparent rate constant and removal efficiency of chemical oxygen demand in the boron nitride catalyzed system were 2.7 times and 1.6 times higher than those of the ozonation alone at the pH of 7, respectively. The catalytic active sites were found to be acidic BOH and could be generated by manufacturing defects during preparation.
•A defective BN was obtained by a simple calcination method.•The BN was active towards both catalytic ozonation and adsorption of ketoprofen.•The BN benefited the generation of hydroxyl radical from ozonation.•The BOH acidic groups were catalytic active sites.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Effect of wastewater characteristics on bioenergy recovery in sewage treatment by anaerobic membrane bioreactor (AnMBR) was investigated. Based on COD removal, sludge concentration change and COD ...mass balance, nonionic surfactant or operation at 20–25 °C had no effect on the energy recovery with COD conversion of 72–79%. The anaerobic microbes can cope with the characteristic by releasing more SMP/EPS or changing its community structure. Compared with Control (6.99 × 107 kJ/d, HRT 12 h), with suspended solid or operation at 15 °C and 10 °C, the captured energy was only 5.90 × 107 kJ/d, 6.0 × 107 kJ/d and 3.10 × 107 kJ/d, respectively while the energy in dissolved methane was 1.08 × 107 kJ/d, 0.98 × 107 kJ/d and 1.26 × 107 kJ/d. Hence, the recovery efficiency was decreased by 15.6%, 14.2% and 55.7%. The recovery also decreased by 26% (5.17 × 107 kJ/d) in the presence of anionic surfactant. The toxicity of anionic surfactant to the anaerobic microbes and lower growth rate of microorganism at psychrophilic temperatures were responsible to the decrease of bioenergy recovery efficiency. SS accumulation will finally increase the loading rate of sludge and decrease the bioenergy recovery from the long-term view.
•Effect of water characteristics on bioenergy recovery in sewage by AnMBR was studied.•Recovery efficiency was inhibited by 15.6% if suspended solid was present in sewage.•Anionic surfactant caused a decreased efficiency by 26% due to toxicity to microbe.•55.7% of decreased energy recovery at 10 °C was due to lower growth rate of microbe.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
