In this study, natural chalcopyrite (NCP) was employed in the activation of peroxymonosulfate (PMS) for bisphenol S (BPS) degradation. Firstly, the NCP catalyst was characterized via X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) techniques. Then, several key parameters such as catalyst dosage, PMS dosage and initial pH were investigated in NCP/PMS system. Furthermore, the transformation of various free radicals (SO4•−, •OH and O2•−) with the changes of initial pH were investigated by quenching experiments and electron spin resonance (ESR) study. Also, sulfur species cycling of copper and iron species were investigated via exogenous Cu2+ and Fe3+ addition experiments and X-ray photoelectron spectroscopy (XPS) analysis, the result indicated that sulfur species promoted Fe3+/Fe2+ and Cu2+/Cu+ cycles on the NCP surface. Furthermore, thirteen major degradation intermediates of BPS were detected by UPLC-QTOF-MS/MS and density functional theory (DFT) method was used to illustrate possible reaction pathways of BPS. Finally, a reasonable reaction mechanism of NCP/PMS system for BPS degradation was proposed on the basis of the comprehensive analysis. In brief, this work helps to provide useful information for the application of natural metallic sulfide minerals in treatment of contaminated waters.
Organic Matter (OM) with different molecular weight and functional groups can impact the adsorptive removal of metal ions, and the influence trend can be facilitated, inhibited or unchanged. However, the association capabilities of different ligands were superficially expounded. Based on the sorption behavior of Cr(III) onto titanate nanotubes (TNTs) with coexisting citric acid (CA), humic acid (HA) and fulvic acid (FA), this study highlighted differential absorbance and DFT simulations to quantitatively detect the mutual effect. As results, adsorption capacities of Cr(III) obviously enhanced from ca. 60 mg/g to 85 mg/g with CA or FA; while HA can slightly promote Cr(III) adsorption. UV spectra scanning proved that FA and HA led to the remarkable red shift of peak A1 (232 nm), A2 (262 nm), A3 (295 nm), A4 (431 nm) of Cr(III), and the area ratio of A2/A3 followed the order Cr-HA > Cr-FA > Cr-CA ≈ Cr. DFT calculations further confirmed that the simultaneous formation of ligand-metal-adsorbents complex and electrostatic effect promoted Cr(III) adsorption, with binding energies of −202.9 −420.8 kJ/mol and − 3958 kJ/mol, respectively. Meanwhile, the bridge connection of OM mainly appeared in the outer sphere of TNTs, as the larger molecular scale prevented their insertion into the inner spacing of TNTs, especially for HA and FA. Therefore, the adsorption mechanism was the combined actions of electrostatic attraction, bridge connection of OM and steric effect. This study can give insights into OM effects on metal adsorption, and quantificationally describe the junction state of ternary complex.
Sulfachloropyridazine (SCP) was commonly used as a broad-spectrum sulfonamide antibiotic and hard to be removed through traditional sewage treatment process. In this study, we developed a simple and controllable strategy to realize in-situ construction of Co(OH)2 nanoparticles decorated urchin-like WO3 (Co(OH)2/WO3), which could efficiently remove SCP through peroxymonosulfate (PMS) activation. Some tiny nanoparticles of Co(OH)2 decorated on the spines/nanorods or surfaces of urchin-like WO3 by transmission electron microscopy (TEM) analysis. The obtained 10 wt% Co(OH)2/WO3 realized completely removal of SCP (degradation efficiency 100%) with a high reaction rate constant (k1) of 0.88 min−1 within 3 min at optimal pH 7. That was because the urchin-like WO3 with numerous adsorption functional groups on its surface (e.g., W = O and –OH bonds) could adsorb the Co2+ easily to form CoOH+, which was perceived the rate-limiting step for PMS activation and generating radicals. Radical quenching experiments indicated that SO4•− played a more significant role than HO• radicals. Density functional theory (DFT) calculation revealed that the atoms of SCP with high Fukui index (f−) were active sites, which preferred to be attacked by the electrophilic SO4•− and HO• radicals. The toxicity of the intermediates by SCP degradation was evaluated by quantitative structure–activity relationship (QSAR) prediction through Toxicity Estimation Software Tool (T.E.S.T.). The possible degradation pathway and catalytic mechanism for SCP removal were proposed. Considering the good catalytic properties of Co(OH)2/WO3-PMS, the material will show great application potential in the removal of emerging contaminants in water.
China submitted the Greenhouse gas emission reduction target in the form of Nationally Determined Contributions (NDC) to the Paris Agreement. To reduce the negative impact of global warming, a tighter target is needed, such as the 2-degree target. This study investigated how China could reach its emissions peak and decarbonize its economy through different key countermeasures in various sectors in line with the NDC and 2 degrees C targets by 2030. A dynamic CGE model is used to develop ten scenarios that contain two dimensions consisting of two stringency levels of carbon emission limitation and the availability of different low-carbon options. We found that in the baseline scenario, China's total CO2 emissions in 2030 would reach 14.7 Gt. To meet China's NDC target, it is essential to develop non-fossil fuel energy, restrict the over-expansion of energy-intensive industries and improve end-use efficiency. Meanwhile, the global 2 degrees C target poses higher requirements for China to develop various non-fossil technologies both in electricity production and demand sectors, and vigorously promote low-carbon consumption pattern. Furthermore, we estimated the economic impacts and found that if low-carbon measures are adopted properly, the mitigation cost in 2030 could decline by 92 and 226 USD/ton-CO2 under the NDC target and 2 degrees C target, respectively. Accordingly, GDP loss could fall from 3.8% to barely 0.004% under the NDC target, and from 11.6% to 1.6% under the 2 degrees C target. The welfare will almost not be affected significantly under all scenarios. Moreover, carbon reduction will also bring co-benefits on the air pollution improvement in China. (c) 2020 Elsevier Ltd. All rights reserved.
To explore an effective approach of simultaneous nitrification and denitrification in wastewater with low C/N ratios, integrated packed bed bioreactors based on poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) with different dosing methods were designed. The removal efficiency of NH4+-N in bioreactor with aeration was 88.62%, and higher NO3–N removal efficiency was observed in bioreactor filled with grainy PHBV (95.21%) than bioreactor filled with strip PHBV (93.34%). Microbial study indicated that microbes harboring amoA and nirS genes preferred to attach on the surface of ceramsite, and significant differences in microbial community compositions at phylum and genus levels were observed. To summarize, it is feasible to utilize grainy PHBV for simultaneous and efficient removal of NH4+-N and NO3–N from wastewater with low C/N ratios.
The majority of neurons in the neuronal systems of the brain have a complex structure of the morphology, which diversifies the dynamics of neurons. In the granule layer of the cerebellum, there exists a unique cell type, unipolar brush cell (UBC), serving as an important relay cell to transfer information from outside mossy fibers to downstream granule cells. The distinguishing feature of UBC is that it has a simple morphology with only one short dendritic brush connected its soma. Based on experimental evidence showing that UBCs exhibit a variety of dynamic behaviors, here we develop two simple models, one with a few detailed ion channels for simulation, and the other one as a two-variable dynamical system for theoretical analysis, to characterize the intrinsic dynamics of UBCs. The reasonable values of the key channel parameters of the models can be determined by analysis of the stability of the resting membrane potential and the rebound firing properties of UBCs. Together with a large variety of synaptic dynamics installed on UBCs, we show the simple structured UBCs, as relay cells, can extend the range of dynamics and information from input mossy fibers to granular cells with low-frequency resonance, and transfer the stereotyped input to diverse amplitudes and phases of the output for downstream granule cells. These results suggest that neuronal computation, embedded with intrinsic ion channels and diverse synaptic properties on single neurons without sophisticated morphology, can shape a large variety of dynamic behaviors to enhance the computational ability of local neuronal circuits.
We theoretically investigate strong-filed electron vortices in time-delayed circularly polarized laser pulses by a generalized quantum-trajectory Monte Carlo (GQTMC) model. Vortex interference patterns in photoelectron momentum distributions (PMDs) with various laser parameters can be well reproduced by the semiclassical simulation. The phase difference responsible for the interference structures is analytically identified through trajectory-based analysis and simple-man theory, which reveal the underlying mechanism of electron vortex phenomena for both co-rotating and counter-rotating component. This semiclassical analysis can also demonstrate the influences of laser intensity and wavelength on the number of arms of vortices. Furthermore, we show the influence of the Coulomb effect on the PMDs. Finally, the controlling of the ionization time intervals in the tens to hundreds of attosecond magnitude is qualitatively discussed.
Ferrihydrite (Fh) is a major Fe(III)-(oxyhydr)oxide nanomineral distinguished by its poor crystallinity and thermodynamic metastability. While it is well known that in suboxic conditions aqueous Fe(II) rapidly catalyzes Fh transformation to more stable crystalline Fe(III) phases such as lepidocrocite (Lp) and goethite (Gt), because of the low solubility of Fe(III) the mass transfer pathways enabling these rapid transformations have remained unclear for decades. Here, using a selective extractant, we isolated and quantified a critical labile Fe(III) species, one that is more reactive than Fe(III) in Fh, formed by the oxidation of aqueous Fe(II) on the Fh surface. Experiments that compared time-dependent concentrations of solid-associated Fe(II) and this labile Fe(III) against the kinetics of phase transformation showed that its accumulation is directly related to Lp/Gt formation in a manner consistent with the classical nucleation theory. 57Fe isotope tracer experiments confirm the oxidized Fe(II) origin of labile Fe(III). The transformation pathway as well as the accelerating effect of Fe(II) can now all be explained on a unified basis of the kinetics of Fe(III) olation and oxolation reactions necessary to nucleate and sustain growth of Lp/Gt products, rates of which are greatly accelerated by labile Fe(III).
espite successful modeling of graphene as a 0.34-nm-thick optical film synthesized by exfoliation or chemical vapor deposition (CVD), graphene-induced shift of surface-plasmon resonance (SPR) of gold films has remained controversial. Here we report the resolution of this controversy by developing a clean CVD graphene transfer method and extending Maxwell-Garnett effective-medium theory (EMT) to two-dimensional (2D) materials. A SPR shift of 0.24° is obtained and it agrees well with 2D EMT in which wrinkled graphene is treated as a 3-nm graphene/air layered composite, in agreement with the average roughness measured by atomic force microscopy. Because the anisotropic built-in boundary condition of 2D EMT is compatible with graphene's optical anisotropy, graphene can be modeled as a film thicker than 0.34 nm without changing its optical property; however, its actual roughness, i.e., effective thickness, will significantly alter its response to strong out-of-plane fields, leading to a larger SPR shift.