Acetaminophen (ACE) is commonly used in analgesic and antipyretic drug, which is hardly removed by traditional wastewater treatment processes. Herein, amorphous Co(OH)2 nanocages were explored as peroxymonosulfate (PMS) activator for efficient degradation of ACE. In the presence of amorphous Co(OH)2 nanocages, 100% of ACE removal was reached within 2 min with a reaction rate constant k1 = 3.68 min−1 at optimum pH 5, which was much better than that of crystalline β-Co(OH)2 and Co3O4. Amorphous materials (disorder atom arrangement) with hollow structures possess large specific surface area, more reactive sites, and abundant vacancies structures, which could efficiently facilitate the catalytic redox reactions. The radicals quenching experiment demonstrated that SO4− radicals dominated the ACE degradation rather than OH radicals. The mechanism of ACE degradation was elucidated by the analysis of degradation intermediates and theoretical calculation, indicating that the electrophilic SO4− and OH tend to attack the atoms of ACE with high Fukui index (f −). Our finding highlights the remarkable advantages of amorphous materials as heterogeneous catalysts in sulfate radicals-based AOPs and sheds new lights on water treatment for the degradation of emerging organic contaminants.
Mo and W in the bulk silicate Earth and their partitioning behavior between molten metal and silicate can be used to constrain the thermochemical conditions during Earth's core-mantle differentiation. In order to improve our understanding of core-forming conditions, we performed a series of superliquidus metal-silicate partitioning experiments on Mo and W at 40–93 GPa and 3000–4700 K in laser-heated diamond anvil cells. Under the extended P-T conditions directly relevant to terrestrial core formation in a deep magma ocean, we find that pressure and temperature have profound yet opposing effects on their partitioning, and a significant amount of O dissolved in the metal. Based on an activity model for liquid Fe-rich metal, it is observed that O enhances the solubility of both Mo and W in the metal, whereas S makes W significantly less siderophile than Mo. Combining our new data with those of the literature, we modeled the effects of pressure, temperature and metal composition on partitioning, and applied them to a multi-stage accretion model. While our model with homogeneous S accretion successfully explains the abundance of Mo, it underestimates that of W and therefore overestimates Mo/W ratio in Earth's mantle, regardless of the oxidation conditions prevailing during core formation. On the other hand, mantle observables (Mo and W abundances, Mo/W ratio) can be reproduced simultaneously if S is supplied to the Earth towards the end of accretion. This corroborates previous work at lower pressures, and agrees with heterogeneous accretion models where the late volatile-rich delivery was envisaged to explain various isotopic signatures of terrestrial bodies. Nonetheless, this conclusion does not discriminate between reducing and oxidizing conditions.
A highly solar active AgBr/h-MoO3 composite was constructed by a facile precipitation method, and the charge separation tuning was achieved by photoreduction of AgBr. The photoreduced Ag0 on AgBr/h-MoO3 acted as charge transfer bridge to form Z-scheme heterostructure, while the high degree of Ag reduction converted the material into type-II heterostructure. The synthesized optimal material promoted charge separation and visible light activity due to the incorporation of highly solar active AgBr, which showed ca. 2 times activity on trimethoprim (TMP) degradation than h-MoO3. The contribution of reactive species on TMP degradation followed the order of O2− > 1O2 > h+, which agree well with the proposed charge separation mechanism. The photocatalytic degradation mechanism of TMP was proposed based on the radical quenching, intermediate analysis and DFT calculation. The toxicity analysis based on QSAR calculation showed that part of the degradation intermediates are more toxic than TMP, thus sufficient mineralization are required to eliminate the potential risks of treated water. Moreover, the material showed high stability and activity after four reusing cycles, and it is applicable to treat contaminants in various water matrix. This work is expected to provide new insight into the charge separation tuning mechanism for the AgX based heterojunction, and rational design of highly efficient photocatalysts for organic contaminants degradation by solar irradiation.
Time spent in residences substantially contributes to human exposure to volatile organic compounds (VOCs). Such exposures have been difficult to study deeply, in part because VOC concentrations and indoor occupancy vary rapidly. Using a fast-response online mass spectrometer, we report time-resolved exposures from multi-season sampling of more than 200 VOCs in two California residences. Chemical-specific source apportionment revealed that time-averaged exposures for most VOCs were mainly attributable to continuous indoor emissions from buildings and their static contents. Also contributing to exposures were occupant-related activities, such as cooking, and outdoor-to-indoor transport. Health risk assessments are possible for a subset of observed VOCs. Acrolein, acetaldehyde, and acrylic acid concentrations were above chronic advisory health guidelines, whereas exposures for other assessable species were typically well below the guideline levels. Studied residences were built in the mid-20th century, indicating that VOC emissions even from older buildings and their contents can substantially contribute to occupant exposures.
Fovea, located in the centre of the retina, is specialized for high-acuity vision. Mimicking the sampling mechanism of the fovea, a retina-inspired camera, named spiking camera, is developed to record the external information with a sampling rate of 40,000 Hz, and outputs asynchronous binary spike streams. Although the temporal resolution of visual information is improved, how to reconstruct the scenes is still a challenging problem. In this paper, we present a novel high-speed image reconstruction model through the short-term plasticity (STP) mechanism of the brain. We derive the relationship between postsynaptic potential regulated by STP and the firing frequency of each pixel. By setting up the STP model at each pixel of the spiking camera, we can infer the scene radiance with the temporal regularity of the spike stream. Moreover, we show that STP can be used to distinguish the static and motion areas and further enhance the reconstruction results. The experimental results show that our methods achieve state-of-the-art performance in both image quality and computing time.
Given that long-term treated wastewater discharge may alter the microbial community of the recipient coast, it is important to evaluate whether and how the community's stability is impacted. We constructed microcosms using coastal sediments with (near-coast) and without (far-coast) a wastewater disposal history and compared the communities’ responses to p-chloroaniline (PCAN, a typical organic pollutant) in low (10 mg/L) and high (100 mg/L) concentrations. Compared to the far-coast community, the near-coast community drove faster PCAN attenuation and nitrate generation. More significant negative correlations were observed between the alpha-diversity indices and PCAN concentrations in the far-coast communities than the near-coast ones. The community turnover rate, represented by the slopes of the time–decay curves, was slower for the near-coast community (−0.187) than that for the far-coast community (−0.233), but only when the PCAN was added in low concentration. Our study revealed that the long-term wastewater disposal may cause the sediment bacterial community to be less sensitive and more stable in response to a future disturbance, demonstrating a significant historical effect of environmental context on the coastal microbial community's stability.
The petroleum refining industry in China is a major contributor to the national economy and a significant source of ambient volatile organic compounds (VOCs). The development history of China’s refineries was investigated for the period 1949–2018, and future development trends were predicted until 2030. The historical VOC emissions from 1949 to 2018 were estimated based on source-specific emission factors, and the emissions in 2025 and 2030 were predicted under the business-as-usual (BAU), alternative control (AC), and accelerated control (ACC) scenarios. Each scenario consisted of a policy and a technical scenario. VOC emissions from refineries increased from 0.53 Gg in 1949 to 1.12 Tg in 2018; fugitive emissions were always the most significant sources of VOCs (40.0–43.9%), followed by end-of-pipe (28.4–31.3%), tank storage (18.3–25.3%), and wastewater treatment (5.8–6.6%) emissions. Provinces in the coastal area have experienced more VOC emissions than inland areas, and Eastern China currently has the highest VOC emissions from refineries. By 2030, China could reduce its current VOC emissions by 5.4%, 35.7%, and 62.5% under the BAU, AC, and ACC scenarios, respectively. The main pressure for reducing VOC emission from China’s refineries will come predominantly from Northeastern China, followed by Eastern and Northern China. The improvement of the production processes, enhancing the airtightness of equipment and containers, and implementation of improved leak detection and repair system are the more effective measures in reducing VOC emissions, accounting for more than 40% of the total reduction. In addition, the penetration and removal rate of control measures for end-of-pipe sources should be further strengthened.
CO2 enhanced oil recovery (EOR) has proven its capability to explore unconventional tight oil reservoirs and the potential for geological carbon storage. Meanwhile, the extremely low permeability pores increase the difficulty of CO2 EOR and geological storage processing in the actual field. This paper initiates the ultrasonic-assisted approach to facilitate oil–gas miscibility development and finally contributes to excavating more tight oils. Firstly, the physical properties of crude oil with and without ultrasonic treatments were experimentally analyzed through gas chromatography (GC), Fourier-transform infrared spectroscopy (FTIR) and viscometer. Secondly, the oil–gas minimum miscibility pressures (MMPs) were measured from the slim-tube test and the miscibility developments with and without ultrasonic treatments were interpreted from the mixing-cell method. Thirdly, the nuclear-magnetic resonance (NMR) assisted coreflood tests were conducted to physically model the recovery process in porous media and directly obtain the recovery factor. Basically, the ultrasonic treatment (40 KHz and 200 W for 8 h) was found to substantially change the oil properties, with viscosity (at 60 °C) reduced from 4.1 to 2.8 mPa·s, contents of resin and asphaltene decreased from 27.94% and 6.03% to 14.2% and 3.79%, respectively. The FTIR spectrum showed that the unsaturated C-H bond, C-O bond and C≡C bond in macromolecules were broken from the ultrasonic, which caused the macromolecules (e.g., resin and asphaltenes) to be decomposed into smaller carbon-number molecules. Accordingly, the MMP was determined to be reduced from 15.8 to 14.9 MPa from the slim-tube test and the oil recovery factor increased by an additional 11.7%. This study reveals the mechanisms of ultrasonic-assisted CO2 miscible EOR in producing tight oils.