Microplastics (MPs), the appearance of which has gained considerable interest, can act as vectors to transport other pollutants such as metals into organisms. In this study, the sorption isotherms of ...three model heavy metals (i.e., Cu2+, Cd2+, and Pb2+) on four virgin plastic particles including chlorinated polyethylene (CPE), PVC, and two polyethylene plastic particles (i.e., LPE and HPE). HPE and LPE were investigated. The results showed that MPs can load high amounts of Pb2+, Cu2+ and Cd2+. The sorption affinity of the three metals to the model MPs followed the sequence of CPE > PVC > HPE > LPE. The adsorption process was affected by the chemical structure and electronegativity of the sorbents, and seemed irrelevant to the crystallinity of MPs. For the three metals, Pb2+ exhibited significantly stronger sorption than did Cu2+ and Cd2+ due to the strong electrostatic interaction. Moreover, pH can significantly affect the sorption of metals on MPs, but ionic strength exerted a relatively slight effect on this process. In brief, the electrostatic interaction played an important role in the sorption of Pb2+ to model MPs. For Cd2+ and Cu2+, sorption was determined by electrostatic interaction together with surface complexation onto the plastic surface. This study indicates that depending on the surface physicochemical properties of MPs the adsorption behavior can vary significantly. Therefore, the adsorption process of metals on MPs should be readily affected by other environmental mediums in the environment. The study provides additional insight into the behavior of MPs as a vector of metals.
•Sorption of Cu2+, Cd2+, and Pb2+ on four virgin plastic particles was investigated.•The sorption strength followed the order of Pb2+>Cu2+>Cd2+.•PH and ionic strength can affect the sorption of metals on MPs.•Electrostatic interaction played an important role in the sorption of Pb2+ to MPs.•Electrostatic interaction and complexation determined the sorption of Cd2+ and Cu2+.
Oxidative C–H/N–H cross-coupling has emerged as an atom-economical method for the construction of C–N bonds. Conventional oxidative C–H/N–H coupling requires at least one of the following: high ...temperatures, strong oxidizers, transition metal catalysts, organic solvents, light, and electrochemical cells. In this study, by merely spraying the water solutions of the substrates into microdroplets at room temperature, we show a series of oxidative C–H/N–H coupling products that are strikingly produced in a spontaneous and ultrafast manner. The reactions are accelerated by six orders of magnitude compared to the same reactions in the bulk. It has been previously proposed by fluorescence microscopy and theory that the spontaneously generated electric field at the microdroplets peripheries can be in the ∼109 V/m range. Based on mass spectrometric analysis of key radical intermediates, we opine that the ultrahigh electric field catalytically oxidizes the substrates by removing an electron, which further promotes C/N coupling. Taken together, we anticipate that microdroplet chemistry will be an avenue rich in green opportunities of constructing C-heteroatom bonds.
This paper studies the massive MIMO full-duplex relaying (MM-FDR), where multiple source-destination pairs communicate simultaneously with the help of a common full-duplex relay equipped with very ...large antenna arrays. Different from the traditional MM-FDR protocol, a general model where sources/destinations are allowed to equip with multiple antennas is considered. In contrast to the conventional MIMO system, massive MIMO must be built with low-cost components which are prone to hardware impairments. In this paper, the effect of hardware impairments is taken into consideration, and is modeled using transmit-receive distortion noises. We propose a low complexity hardware impairments aware transceiver scheme (named as HIA scheme) to mitigate the distortion noises by exploiting the statistical knowledge of channels and antenna arrays at sources and destinations. A joint degree of freedom and power optimization algorithm is presented to further optimize the spectral efficiency of HIA based MM-FDR. The results show that the HIA scheme can mitigate the "ceiling effect" appears in traditional MM-FDR protocol, if the numbers of antennas at sources and destinations can scale with that at the relay.
A high performance all-vanadate-based Li-ion full cell Xu, Jie; Zhang, Dongmei; Zhang, Zongping ...
Journal of materials chemistry. A, Materials for energy and sustainability,
04/2021, Letnik:
9, Številka:
16
Journal Article
Recenzirano
Li
3
VO
4
is regarded as a promising anode material for Li-ion batteries due to its advantages of safety and low volumetric variation. However, unscalable synthesis makes the practical application of ...Li
3
VO
4
challenging. Herein, state-of-the-art Li
3
VO
4
/N doped C porous microspheres comprising Li
3
VO
4
nanoparticles encapsulated in interconnected N doped C networks (LVO/NC PMSs) are designed and synthesized
via
a scalable spray drying approach. Ultra-high capacity, ultra-long cycle life and prominent rate capability are achieved in the LVO/NC PMS electrode. When cycling at 0.1 A g
−1
, it delivers a reversible capacity of 610 mA h g
−1
after 200 cycles. At a high constant charge current of 2.0 A g
−1
, it delivers stable cycling over 5000 cycles at a high discharge current of 4.0 A g
−1
, and the reversible capacity is completely restored after 150 cycles of rate performance testing with discharge current from 0.2 to 4.0 A g
−1
. Moreover, Li
3
V
2
(PO
4
)
3
microspheres (LVP MSs) are also prepared using the scalable spray drying approach, and a new all-vanadate-based LVO//LVP full cell is designed for the first time. The full cell delivers a high energy density of 300 W h kg
−1
which is higher than that of most of the Li
4
Ti
5
O
12
and LVO-based full cells, and a long lifespan (340.7 mA h g
−1
after 1000 cycles at 1.0 A g
−1
) which meets the requirements of commercialization. The scalable synthesis of LVO/NC PMSs and LVP MSs with excellent performance and the configuration of the LVO//LVP full cell with high energy density and long cycle life may pave the way for LVO for practical applications.
An all-vanadate-based Li-ion full cell with high energy density and long lifespan is constructed for the first time based on the design of Li
3
VO
4
/N doped C porous microspheres with excellent electrochemical performance.
Water serves as an inert environment for the dispersion and application of many kinds of herbicides. Viologen compounds, a type of widely used but highly toxic herbicide, are stable in bulk water, ...whose half-life can be up to 23 weeks in natural water, imposing a severe health risk to mammals. In this study, we present the striking results of the spontaneous and ultrafast reduction-induced degradation of three viologen compounds in water microdroplets and provide the concentration, time, temperature dependence, mechanism, and scale-up of the reactions. We postulate that the electrons existing at the air–water interface of the microdroplets due to the unique redox potential therein initiate the reduction, from which further degradation occurs. The host–guest complexation between cucurbit7uril and viologens only slightly changes the redox potential of viologens in the bulk but completely inhibits the reactions in microdroplets, adding to the uniqueness of the redox potentials at the air–water interfaces of microdroplets. Taken together, microdroplets might have been functioning as naturally occurring ubiquitous tiny electrochemical cells for a plethora of unique redox reactions that were thought to be impossible in the bulk water.
New strategies that can simultaneously detect and remove highly toxic environmental pollutants such as heavy metal ions are still in urgent need. Herein, through supramolecular host–guest ...interactions, a fluorescent supramolecular polymer has been facilely constructed from a newly designed 2biphenyl-extended pillar6arene equipped with two thymine sites as arms (H) and a tetraphenylethylene (TPE)-bridged bis(quaternary ammonium) guest (G) with aggregation-induced emission (AIE) property. Interestingly, supramolecular assembly-induced emission enhancement (SAIEE) could be switched on upon addition of Hg2+ into the above-mentioned supramolecular polymer system to generate spherical-like supramolecular nanoparticles, due to the restriction of intramolecular rotation (RIR)-related AIE feature of G. Significantly, this supramolecular polymer with integrated modalities has been successfully used for real-time detection and removal of toxic heavy metal Hg2+ ions from water with quick response, high selectivity, and rapid adsorption rates, which could be efficiently regenerated and recycled without any loss via a simple treatment with Na2S. The newly developed supramolecular polymer system combines the inherent rigid and spacious cavity of novel extended-pillarene host with the AIE characteristics of TPE-based guest, suggesting a great potential in the treatment of heavy metal pollution and environmental sustainability.
Low cost, eco-friendly, and easily scaled-up processes are needed to fabricate efficient oil/water separation materials, especially those useful in harsh environments such as highly acidic, alkaline, ...and salty environments, to deal with serious oil spills and industrial organic pollutants. Herein, a highly efficient oil/water separation mesh with durable chemical stability was fabricated by simply scratching and pricking a conventional polyethylene (PE) film. Multiscaled morphologies were obtained by this scratching and pricking process and provided the mesh with a special wettability performance termed superhydrophobicity, superoleophilicity, and low water adhesion, while the inert chemical properties of PE delivered chemical etching resistance to the fabricated mesh. In addition to a highly efficient oil/corrosive liquid separation, the fabricated PE mesh was also reusable and exhibited ultrafast oil/water separation solely by gravity. The easy operation, chemical durability, reusability, and efficiency of the novel PE mesh give it high potential for use in industrial and consumer applications.
Polyaniline has been widely used in high-performance pseudocapacitors, due to its low cost, easy synthesis, and high theoretical specific capacitance. However, the poor mechanical properties of ...polyaniline restrict its further development. Compared with polyaniline, functionalized carbon materials have excellent physical and chemical properties, such as porous structures, excellent specific surface area, good conductivity, and accessibility to active sites. However, it should not be neglected that the specific capacity of carbon materials is usually unsatisfactory. There is an effective strategy to combine carbon materials with polyaniline by a hybridization approach to achieve a positive synergistic effect. After that, the energy storage performance of carbon/polyaniline hybridization material has been significantly improved, making it a promising and important electrode material for supercapacitors. To date, significant progress has been made in the synthesis of various carbon/polyaniline binary composite electrode materials. In this review, the corresponding properties and applications of polyaniline and carbon hybrid materials in the energy storage field are briefly reviewed. According to the classification of different types of functionalized carbon materials, this article focuses on the recent progress in carbon/polyaniline hybrid materials, and further analyzes their corresponding properties to provide guidance for the design, synthesis, and component optimization for high-performance supercapacitors.
Co-time co-frequency uplink and downlink (CCUD) transmission was considered challenging in the cellular system due to the strong self-interference (SI) between the transmitter and receiver of base ...station (BS). In this paper, by investigating the beam-domain representation of channels based on the basis expansion model, we propose a beam-domain full-duplex (BDFD) massive multiple-input multiple-output (MIMO) scheme to make the CCUD transmission possible. The key idea of the BDFD scheme lies in intelligently scheduling the uplink and downlink user equipment (UE) based on the beam-domain distributions of their associated channels to mitigate SI and enhance transmission efficiency. We show that the BDFD scheme achieves significant savings in uplink/downlink training resource and achieves uplink and downlink sum capacities simultaneously as the number of BS antennas approaches infinity. The superiority of the BDFD scheme over the traditional time-division duplex (TDD)/frequency-division duplex (FDD) massive MIMO is evaluated through simulation for the macrocell environment. The results show that the spectral efficiency gain can even exceed 2× in the specific scenarios, since the BDFD scheme utilizes the time-frequency resource more efficiently in both the training and data transmission phases.
Seepage erosion around the underground pipelines will produce various adverse influences on the stratum stability and the structural safety. It involves behaviours at three scales, that is, ...particle-scale, cell-scale and engineering-scale. The problem relies on the fact that finding general equations for the granular media is difficult due to the changing nature of how solids flow, so that the continuous approach is unavailable to directly describe the phenomenon. Hence, DEM simulations are firstly conducted in this study to quantify the relationship between the fine particle loss (ΔFC = 0, 5%, 10%, 15%, 20%, 25%, 30%) and the mechanical properties of soil elements, upscaling particle to cell. Considering two initial fine grain contents (S6:4, S3:7), the empirical equations of soil mechanical parameters εve, E0, φ and c changing with the fine particle loss ΔFC are obtained by regression analysis. Then, based on the corresponding constitutive parameters of different erosional stages, FEM simulations at the engineering scale are conducted to analyse the structural mechanical response to the seepage erosion, upscaling cell to engineering. This study reveals the multiscale response of the seepage erosion in the sandy strata, and helps in providing the practical guidance for engineering application and the reference for the next multiscale parallel computation on this issue.
•The erosional influence on soil mechanical properties is quantitatively characterized by DEM simulations.•Regression equations of soil mechanical parameters with erosion are fitted according to the DEM simulation result.•Varying degrees of eroded stratum are modelled by FEM based on the result of DEM simulations.•The mechanical response of pipe structure to seepage erosion is analysed by using the FEM model.
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