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Heavy metal pollution stems from the modern industry is a severe environmental problem. In this work, a highly efficient adsorbent based on starch-graphene oxide architecture (SGO) was fabricated, characterized and employed to scavenge aqueous Pb(Π). The scavenging performance was evaluated, and the interaction mechanism between SGO and Pb(Π) was elucidated. Results indicate, the starch introduction brought performance enhancement, consequently made SGO outperform both single starch and GO in terms of adsorption efficiency. SGO adsorbs 95.83 % of Pb(Π) in 16 min, with adsorption capacity 383.32 mg•g− 1, manifesting some advantages over other analogous adsorbents, such as higher capacity and faster kinetics. The chemical interaction between Pb(OH)+ and C = O, C-O related groups in SGO supported the adsorption, which was a spontaneous, exothermic and entropy increasing process. The adsorption was well described by the Freundlich, pseudo-second-order model and Intra-particle diffusion models, both intra-particle diffusion and chemical interaction were the rate controlling steps. Based on its high adsorption efficiency, SGO may have promising application in heavy metal scavenging from water.

Heavy metal contamination caused by industrial discharge is a challenging environmental issue. Herein, an efficient adsorbent based on few-layered magnetic graphene oxide (FLMGO) was fabricated, characterized, and utilized to remove aqueous Cd(II) and Cu(II). Results present that the two components graphene oxide (GO) and Fe3O4 of FLMGO promote mutually, enabling FLMGO to outperform either GO or Fe3O4. Specifically, FLMGO adsorbs Cd(II) and Cu(II) with adsorption quantities of 401.14 and 1114.22 mg·g-1 in 5 and 7 min, respectively. Moreover, FLMGO can be readily recovered via magnetic separation using a hand-held magnet. Adsorptions are spontaneous, endothermic, and entropy increasing, which are the best described by the Freundlich and pseudo-second-order model. The interaction mechanism is as follows: lone pair electrons in C=O- and C-O-related groups were coordinated toward Cd(II) and Cu(II) to induce chemical interaction. The high adsorption efficiency endows FLMGO with encouraging application potential in heavy metal remediation.

Water pollution caused by heavy metals is a severe environmental issue. In this work, a graphene oxide–starch composite (GO/WS) was facilely prepared via hydrothermal process. The as-prepared GO/WS was characterized and employed as adsorbent to remove Cu(II). The removal performance was evaluated, and the adsorption mechanism was analyzed. Result shows that GO/WS outperforms either single graphene oxide (GO) or water soluble starch (WS) in terms of adsorption capacity. Specifically, GO/WS (D = 500 mg L−1) adsorbs 542.01 mg g−1 of Cu(II) (C0 = 300 mg L−1) in 24 min, exhibiting some advantages as higher capacity and shorter equilibrium time over other similar adsorbents. Adsorption complies with the Freundlich model and PSO model and is controlled by surface reaction, exhibiting favorable and chemical feature. Moreover, adsorption is thermodynamically spontaneous and exothermic. The chemical bonding of C=O, C–O-related groups in both GO and starch with Cu(II) serves as the main adsorption mechanism. Owing to its high adsorption efficiency, GO/WS may be a promising adsorbent for heavy metal scavenging.

Sediment deposition carried by flood flow is the main cause of reservoir sedimentation. This can be reduced by an appropriate operational strategy of flood flow and sediment in the reservoir. High-precision and large-scale hydrodynamic models to predict flood propagation and sediment transport in reservoirs are extremely important for an efficient flood forecasting and real-time joint regulation of water and sediment in reservoirs. In the present study, the three-dimensional (3D) numerical semi-implicit cross-scale hydroscience integrated system model (SCHISM) was adopted to model the flood propagation and sediment transport in the approximately 280-km-long reach in the Three Gorges Reservoir. This model is mainly focused on analysing the asynchronous movement characteristics of flood propagation and sediment transport and the operational strategy of sediment peak regulation. The flood event in July 2013 was reproduced by the numerical model, which was validated by a comparison with the measured data. The results indicated that the numerical model has the ability to accurately simulate the flood propagation and sediment transport processes. The time that the sediment peak lags behind the flow discharge peak increases as the flood waves propagate downstream, reaching 8.1 days at the dam site. During the rising period of the flood, the discharged flow is lowered to reduce the flood peak, and when the sediment peak reaches the dam, the discharged flow is increased to release high concentration sediment during the flood recession period so as to reduce sedimentation in the reservoir. The model results agreed well with the measured results. The 3D numerical model can be used for the real-time prediction of the arrival time of the flow discharge and sediment peaks for the joint regulation of water and sediment in the Three Gorges Reservoir.

The functionalization of self-supporting graphene (SSG) which in-situ grows on a flexible graphite sheet is performed by an electrochemical exfoliation in a HCl solution and then a diazonium reacti...

In this work, a dual-emission ratiometric fluorescent probe of carbon dots–copper nanoclusters (CDs–Cu NCs) nanohybrids with bifunctional features was successfully assembled through mechanical mixing. The CDs were synthesized using ascorbic acid as a carbon source, and Cu NCs were prepared using D-penicillamine as the stabilizer and reducing agent. The as-prepared CDs–Cu NCs displayed two emission peaks (blue at 424 nm and red at 624 nm) when excited at 360 nm, and showed great stability. Interestingly, trace amount of Fe3+ could lead to the aggregation of Cu NCs, and induce a drastic static fluorescence quenching at 624 nm because of the electrostatic combination between them, while the fluorescence of the emission peak at 424 nm remained constant. Moreover, an attractive fluorescence enhancement phenomenon at 424 nm was observed when trace Tb3+ was added to the above system, which may due to the combination of fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET) mechanisms. Thus, CDs–Cu NCs were applied for the ratiometric detection of Fe3+ and Tb3+ in aqueous solution, and the detection limit (3σ/slope) was 45 nM and 62 nM with the linear range from 0.01 to 40 μM and 0.1 to 50 μM, respectively. Furthermore, the developed sensor was successfully applied for the detection of Fe3+ and Tb3+ in real-water samples.

The processes of sediment particle movement were studied through numerical simulation using a coupled method with focus on discussing the characteristics of sliding or rolling and saltation sediment particles, respectively. Turbulent flow was simulated using large eddy simulation (LES). The sediment particle was simulated using the combined finite-discrete element method (FDEM). The interaction forces of turbulent flow and sediment particle were calculated using the immersed boundary method (IBM). It indicated that the collisions of saltating particle with low concentration increase the saltation length and flight time. In response, sediment particle velocity also increases. The particle angular velocity is largest at the takeoff moment, and decreases gradually in the saltation progress. The drag and lift forces near the bed are large, and away from the bed decrease and trend to be a stable value, gradually. From the relative magnitudes of the drag and lift forces, the lift force plays a more important role than the drag force in the sediment saltation. The relative magnitudes of drag and lift forces influence the incident and takeoff angles. The sediment transport rate calculated based on the characteristics of saltation sediment particles is overestimated, ignoring the effect of sliding or rolling sediment particles and inter-particle collisions.

The processes of sediment transport in high flow intensity are studied through numerical simulation using a coupled CFD (computational fluid dynamics)-DPM (discrete particle method) model with a fo...

Bismuth halide oxide with three halogen elements (P-BiOXs) catalyst was prepared by a facile precipitation method at room temperature only for 30 min. Several measurement technologies were employed to characterise the structures and morphologies of the obtained samples. Coloured Rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and colourless bisphenol A (BPA) were selected to evaluate the photocatalytic activity of the samples. The experimental results showed the P-BiOXs thin nanoplates exhibited the most excellent photocatalytic activity among the prepared samples for the degradation of MO under visible light illumination. More importantly, the catalyst P-BiOXs could effectively degradate RhB, MB and BPA. The P-BiOXs catalyst displayed good photocatalytic stability by the recycling tests. The highly efficient visible light catalytic properties of P-BiOXs could be due to the high specific surface area, enhanced light-harvesting ability, the suitable bandgap energy and the lower recombination rate of the photogenerated electrons and holes.

Decontamination of aqueous heavy metal is a challenging task of environmental remediation. Herein, we demonstrated an adsorptive method for efficient removal of aqueous Hg(II) using a magnetic nanocomposite Fe3O4/graphene oxide (Fe3O4/GO). Adsorption of Hg(II) onto Fe3O4/GO equilibrated in 4 min, with the adsorption percent and quantity of 91.17% and 547.01 mg g−1, respectively. Fe3O4/GO can be easily recovered from solution via magnetic separation for reuse, and retaining 73.5% of its original capacity after five consecutive cycles. The Temkin model and PSO model were most suitable for describing adsorption in equilibrium and non-equilibrium state, respectively. Both GO and Fe3O4 adsorbed Hg(II) via donating electrons in oxygen atoms toward Hg(II). Moreover, GO made a major contribution, while Fe3O4 made a minor one to adsorption. The facile preparation, high adsorption efficiency, easy recovery, and reusability may enable Fe3O4/GO to be a promising adsorbent for aqueous Hg(II).

Graphene with low oxygen content via an electrochemically anode exfoliation is desired. Here, an electrochemical exfoliation method to realize the simultaneous electrochemical preparation and reduction of graphene with low oxygen content is proposed using a flexible graphite sheet (FGS). Under water bath, the FGS is soaked into a NaBH4 solution under an electric field of 3 V/cm for 3, 9, 15 or 21 h (Gr-3/Gr-9/Gr-15/Gr-21). The C/O ratios of the FGS, Gr-3, Gr-9, Gr-15 and Gr-21 increase in turn by the X-ray photoelectron spectroscopy. The comparison between the electrochemical properties of the FGS, Gr-3, Gr-9, Gr-15 and Gr-21 indicates that the Gr-15 possesses a specific capacitance of 181 F/g and capacitance retention of 93.8% over 3000 cycles, which shows better electrochemical performances than the FGS, Gr-3, Gr-9 and Gr-21. The symmetric supercapacitor based on the Gr-15 achieves an energy density as high as 22.56 Wh/kg at a power density of 0.85 kW/kg.

Sensitivity analysis is necessary in numerical models to establish the optimal model configuration and simulate turbidity currents accurately. The sensitivity of turbidity currents simulated by a three-dimensional numerical model named the semi-implicit cross-scale hydroscience integrated system model (SCHISM) was assessed using domain discretization, the turbulence closure model, and the transport scheme. The results show that a higher horizontal resolution with an appropriate aspect ratio, localized sigma coordinates with shaved cells (LSC2) grid with sufficient layers, a two-phase mixture turbulence closure model, and transport schemes with critical depth ratio lower than 1 could improve the model performance on the turbidity currents. The study can provide helpful guidance to establish accurate turbidity current simulations in complex water environments.

In this work, a dual-emission ratiometric fluorescent probe of carbon dots-copper nanoclusters (CDs-Cu NCs) nanohybrids with bifunctional features was successfully assembled through mechanical mixing. The CDs were synthesized using ascorbic acid as a carbon source, and Cu NCs were prepared using d-penicillamine as the stabilizer and reducing agent. The as-prepared CDs-Cu NCs displayed two emission peaks (blue at 424 nm and red at 624 nm) when excited at 360 nm, and showed great stability. Interestingly, trace amount of Fe

MoS2 nanosheets have been widely explored as LIB anode materials due to higher theoretical capacity and weak interlayer interactions, but limited by their low conductivity and ease of stacking. Herein, we reported a novel Fe doped MoS2/reduced graphene oxide (Fe-MoS2/rGO) composite as LIB anode material and its one-step synthesis method. The results show that the synthesized Fe-MoS2/rGO composite has unique porous heterostructure, where networked Fe-MoS2 nanosheets of several nm thickness grow upon crumpled rGO sheets with high specific area. Due to the Fe doping as well as the mild synthesis conditions, the resulting Fe-MoS2 upon rGO sheets has wide interlayer spacing, abundant lattice defects and lower inner resistance. As a result, the Fe-MoS2/rGO electrode exhibits significant improvement in electrochemical performance relative to the non-doped MoS2/rGO electrode. The reversible capacities of Fe-MoS2/rGO electrode reach 1255 mAh/g (2nd circle) and 946 mAh g−1 (100th circle) with a retention of 75.4%. By comparison, the reversible capacities of MoS2/rGO electrode are only 654.1 mAh g−1 (2nd circle) and 429 mAh g−1 (100th circle) with a low retention of 64.1%.

A novel high-performance electrode material based on fluoro-functionalized graphene oxide (GOF)/polyaniline (PANI) composites was synthesized via in situ polymerization of monomer in the presence of GOF. The composite was characterized by Fourier transform infrared spectrometry, X-ray diffraction (XRD), and the field emission scanning electron micrographs. The electrochemical properties of the composites were measured based on cyclic voltammetry, galvanostatic charge/discharge, and AC impedance spectroscopy. When the obtained composites with a mass ratio is 3% GOF/PANI, the results showed that GOF as a support material provides additional electron transfer paths, as well as active sites, for the electrochemical redox reaction of PANI, which helps to increase its pseudocapacitance. A specific capacitance of 502 F·g−1 was obtained at a current density of 1.0 A·g−1 in 1 mol·L−1 H2SO4, as well as excellent cycling stability with 95% of its initial capacitance after 600 cycles. These encouraging results illustrate the exciting potential for high-performance, electrical energy storage devices based on this new class of carbon material.

The N,S co-doped carbon nanospheres with/without hierarchical pores (N,S-HPCNs/N,S-CNs) are prepared by the pyrolysis of polypyrrole and (NH4)2S2O8 with/without F127 as the pore-foaming agent in flowing N2. The results show that the combination of the hierarchical pores and N,S co-doping improves the electrochemical properties of carbon materials. As a result, the specific capacitance of N,S-HPCNs is as high as 416 F g−1 at a current density of 0.2 A g−1, which is much higher than that of N,S-CNs (138 F g−1). At a current density of 10 A g−1, the specific capacitance of 313 F g−1 for N,S-HPCNs is obtained, which keeps a capacitance retention of 75.2%, while the N,S-CNs has only the capacitance retention of 44.2%. After 5000 cycles, the retention ratio of N,S-HPCNs as high as 95.8% is obtained and the columbic efficiency of N,S-HPCNs is close to 100%. The symmetric supercapacitor device assembled using N,S-HPCNs exhibited a high energy density of 18.1 Wh kg−1 at a power density of 100 W kg−1. The exhibited excellent electrochemical performances of N,S-HPCNs are attributed to a high content of doped heteroatoms N and S and the hierarchical pore structure.

The influences of the catalysts of CoS2 and MoS2 nano-particles on microstructure and hydrogen storage behaviors of as-milled Sm5Mg41 alloy have been compared in this work. The Sm5Mg41 + 5 wt.% M (M = CoS2, MoS2) alloys were prepared by milling the mechanical ground as-cast Sm5Mg41 alloy powders (particle size ≤ 75 μm) with 5 wt.% CoS2 or MoS2 nano-particles (particle size ≤ 30 nm), respectively. The results demonstrate that the CoS2 and MoS2 nanoparticles are embedded into the alloy surface, which is nanostructure containing some crystal defects, such as dislocation, grain boundary and twin etc. Those microstructures play a beneficial role in reducing the total potential barrier that the hydrogen absorption or desorption reactions must overcome, hence improving the hydrogen storage kinetics of the alloys. The as-milled alloys are composed of Sm5Mg41 and SmMg3 phases, and ball milling refines their crystal grains. The MgH2 and Sm3H7 phases appear after hydrogenation, while Mg and Sm3H7 phases exist after dehydrogenation. The dehydriding activation energy of M = CoS2 and MoS2 alloys are 101.67 and 68.25 kJ/mol H2 respectively. The initial hydrogen desorption of M = CoS2 and MoS2 alloys are 252.9 °C and 247.8 °C. The hydrogenation and dehydrogenation enthalpy changes of M = MoS2 alloy are a little smaller than that of M = CoS2 alloy. Therefore, the catalyst MoS2 can improve the as-milled Sm5Mg41 alloy in hydrogen storage property more effectively than CoS2.

The influences of bentonite and different silane coupling agents (SCA) on the viscoelastic properties of nitrile butadiene rubber were studied in this work. The silane coupling agents compatibilized bentonite/nitrile butadiene rubber nanocomposites were fabricated by a novel green method. The viscoelastic behaviors of the nanocomposites and their vulcanizates were explored using a rubber processing analyzer (RPA) in the modes of strain sweep and frequency sweep. Storage modulus (G′) and elastic torque (S′) of nitrile butadiene rubber increased significantly with the incorporation of bentonite. In the SCA applied in this work, mercaptopropyltrimethoxysilane (MPTMS) contributed to high storage modulus (G′) of the nanocomposites because of thorough exfoliation of bentonite and short sulfur bonds formed during curing process. Meanwhile, multi-sulfur bonds in bis-[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) and reversible interactions from [3-(2-aminoethylamino)propyl] trimethoxysilane (AEAPTMS) resulted in lower storage modulus of the cured nanocomposites.

Silicon is one of the most promising candidates for next-generation anode of Lithium-ion batteries. However, poor electrical conductivity and large volume change during alloying/dealloying hinder its practical use. Here we reported a three-dimensional (3D) nitrogen and sulfur codoped graphene supported silicon nanoparticles composite (SN-G/Si) through one-step hydrothermal self-assembly. The obtained SN-G/Si was investigated in term of instrumental characterizations and electrochemical properties. The results show that SN-G/Si as a freestanding anode in LIBs delivers a reversible capacity of 2020 mAh g −1 after 100 cycles with coulombic efficiency of nearly 97%. The excellent electrochemical performance is associated with the unique structure and the synergistic effect of SN-G/Si, in which SN-G provides volume buffer for nano Si as the flexible loader, short paths/fast channels for electron/Li ion transport as porous skeleton, and low charge-transfer resistance.

There are ever increasing interests in three dimensional (3D) graphene for the construction of wearable electrics and flexible energy storage devices. Herein, we report a 3D porous graphene supported polyaniline (PANI) nanoarrays composite with enhanced interface bonding and high load fraction of PANI for supercapacitor application. We demonstrate that by utilizing benzenesulfonic acid functionalization followed by a pre-immersion treatment, surface chemistry and permeability of the porous graphene can be improved significantly, which favors the controllable growth of high-quality PANI nanoarrays. The resulting composite used as a freestanding electrode exhibits excellent electrochemical performance, hence a maximum specific capacitance of 752 F/g with retention of 90.8% over 10000 cycles was achieved.

A novel 1,3-dicarbonyl-functionalized reduced graphene oxide (rDGO) was prepared by N-(4-aminophenyl)-3-oxobutanamide interacting with the epoxy and carboxyl groups of graphene oxide. The high-performance composite supercapacitor electrode material based on MnO2 nanoparticles deposited onto the rDGO sheet (DGM) was fabricated by a hydrothermal method. The morphology and microstructure of the composites were characterized by field-emission scanning electron microscopy, transmission electron microscopy, Raman microscopy and X-ray photoelectron spectroscopy. The obtained results indicated that MnO2 was successfully deposited on rDGO surfaces. The formed composite electrode materials exhibit excellent electrochemical properties. A specific capacitance of 267.4 F g−1 was obtained at a current density of 0.5 A g−1 in 1 mol L−1 H2SO4, while maintaining high cycling stability with 97.7% of its initial capacitance after 1000 cycles at a current density of 3 A g−1. These encouraging results are useful for potential energy storage device applications in high-performance supercapacitors.

At present, the development of science and technology in our country is very fast and quickly occupied the larger economic market, at the same time, it also draws great attention in the communication industry. With the development of science and technology, computer technology has attracted the attention of the majority of people in the society with the major concern that whether it can truly keep customers’ privacy. Network information security, for national enterprises or the government, is crucial, but it is difficult to use information in the process of absolute confidentiality. Therefore, in today’s network research and development, it is necessary to carry out more rigorous processing of information to ensure that the information is not leaked during the use of the network. In the actual application process, the information should also be privatized. We can apply the computer security monitoring information network technology to protect information security, reduce virus invasion in order to ensure the green and healthy network. This paper mainly studies the security of the network based on the monitoring technology research while application and development prospects of the current situation of computer information security monitoring technology are described, which can be a good reference for the future construction of security information network.

Excessive discharge of heavy metals by industrial activities has caused severe environmental problem. In this work, a magnetic graphene oxide nanocomposite (MGON) based on graphene oxide-Fe3O4 framework was prepared, characterized and employed as adsorbent to remove aqueous Mn(Ⅱ), Zn(Ⅱ) efficiently. The adsorption performance and mechanism were investigated carefully. Results suggest, the mutual enhancement between GO and Fe3O4 brings synergistic effect on adsorption performance, which enables MGON to outperform either of the two single phase. In particular, MGON efficiently adsorbs 399.67 mg g−1, 372.98 mg g−1 of Mn(Ⅱ), Zn(Ⅱ) in 4 min, 6 min, respectively. What is more, MGON can be readily recovered via magnetic separation for further recycling. The thermodynamic parameters of the adsorptions under 298.15 K are: ΔH = 20.86 kJ mol−1, ΔS = 108.84 J K−1 mol−1, ΔG = −11.59 kJ mol−1 for Mn(Ⅱ) and ΔH = 20.99 kJ mol−1, ΔS = 96.04 J K−1 mol−1, ΔG = −7.64 kJ mol−1 for Zn(Ⅱ), respectively, indicating spontaneous, endothermic and entropy increasing features. Both adsorptions fit well by the Freundlich, pseudo second order, and intra-particle diffusion models. Furthermore, adsorption mechanism is based on the chemical interaction of the oxygen atoms in C O, C-O related groups with Mn(Ⅱ), Zn(Ⅱ). The high adsorption efficiency suggests that MGON has promising application in heavy metal treatment.

Partially reduced graphene oxide-Fe3O4 composite was prepared through in situ co-precipitation and used as an efficient adsorbent for removing Pb(II) from water. The composites were characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectra, Fourier transformation infrared, Raman spectrometer, N2 adsorption–desorption, vibrating sample magnetometer, and zeta potential analyses. The impacts of pH, contact time, adsorbent dosage, temperature, and foreign substances on Pb(II) adsorption performance were investigated. The adsorption mechanism, kinetics, and thermodynamics were analyzed. The results indicate that Fe3O4 is homogeneously anchored inside the thin graphene sheets, with a particle size of 15–20 nm, resulting in a very low remanence and coercivity. The composite shows excellent and efficient adsorption performance toward aqueous Pb(II): adsorption equilibrium was reached in 10 min with the adsorption percent and quantity of 95.77% and 373.14 mgċg−1, respectively, under a condition of pH = 6, adsorbent dosage 250 mgċL−1, and Pb(II) initial concentration 97.68 mgċL−1, with the subsequent magnetic separation taking only 10 s. The adsorption performance is dependent on adsorbent dosage. A lower dosage favors a higher adsorption quantity, implying a strong adsorptive potential for partially reduced graphene oxide-Fe3O4. The adsorption quantity reached 777.28 mgċg−1, given the dosage 100 mgċL−1. The adsorption is monolayer chemisorption, the whole process of which is controlled by chemisorption and liquid film diffusion. In terms of thermodynamics, the adsorption is an exothermic and spontaneous process.

Herein we reported a novel routine to easily access graphene/polyaniline paper (GPp) as supercapacitor electrodes through controlled in-situ polymerization followed by roll coating. According to this routine, the load fraction of PANI can be easily controlled by feed ratio of aniline to GO. In the resulting GPp, PANI nanoarrays anchored graphene nanosheets and PANI nanofibers throughout the bulk coexist, and the former construct a three-dimensional network. As a result, the GPp as a freestanding electrode exhibits excellent electrochemical properties. It can deliver a high capacitance up to 838 F/g at a current density of 1 A/g, while keeps high retention of 93.7% at 10 A/g over 5000 cycles. Kinetics analysis shows that the GPp stores both surface capacitance and diffusion capacitance, but the former dominates the latter.

As one of the simple and efficient routes to access two-dimensional materials, liquid exfoliation has received considerable interest in recent years. Here, we reported on high-efficient liquid exfoliation of hexagonal boron nitride nanosheets (BNNSs) using monoethanolamine (MEA) aqueous solution. The resulting BNNSs were evaluated in terms of the yield and structure characterizations. The results show that the MEA solution can exfoliate BNNSs more efficiently than the currently known solvents and a high yield up to 42% is obtained by ultrasonic exfoliation in MEA-30 wt% H2O solution. Finally, the BNNS-filled epoxy resin with enhanced performance was demonstrated. Electronic supplementary material The online version of this article (10.1186/s11671-017-2366-4) contains supplementary material, which is available to authorized users.

It is well-known that chemical functionalization of graphene has the great significance. We report the development of a new synthesis method of chloro-functionalized reduced graphene oxide (rGOCl). The rGOCl was prepared by radical reaction, and treatment of carboxyl graphene oxide (GOCOOH) with N-chlorosuccinimide (NCS) at 90 °C for 10 h under an atmosphere of nitrogen, using silver nitrate as catalyst. The morphologies and structures of the prepared materials were investigated by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and the thermal gravimetric. Results indicated that the rGOCl can be readily obtained from graphene oxide (GO) in three steps.

Graphene aerogel (GA) has wide applications in energy storage, catalysis, and adsorption. However, as a candidate for supercapacitor electrode, it suffers from low specific capacitance. In this paper, we conceived and conducted a two-step strategy to improve the electrochemical properties of GA: First, GA was selective functionalized with p-phenylenediamine. Then PANI was grafted onto GA by in situ polymerization. The results suggest that surface functionalization enhances the interface bonding between GA and PANI and charge transfer during electrode redox. As a result, the obtained GAp/PANI composites, applied as the freestanding electrodes for supercapacitor, exhibit high specific capacitance (810 F/g at 1 A/g, 2.4 times of GA), good rate capability, and extraordinary cycling stability (83.2% of retention at 10 A/g after 10,000 cycles, 1.25 times of PANI/GA), indicating its great potential in the construction of high-performance energy-storage systems.

A weakly compressible smoothed particle hydrodynamics (WCSPH) method was developed to model open-channel flow over rough bed. An improved boundary treatment is proposed to quantitatively characterize bed roughness based on the ghost boundary particles (GBPs). In this model, the velocities of GBPs are explicitly calculated by using evolutionary polynomial regression with a multiobjective genetic algorithm. The simulation results show that the proposed boundary treatment can well reflect the influence of wall roughness on the vertical flow structure. A fully developed open channel is established, and its flume length, processing time, and turbulent model are discussed. The mixed-length-based subparticle scale (SPS) turbulence model is adopted to simulate uniform flow in open channel, and this model is compared with the Smagorinsky-based one. For the modified WCSPH model, the results show that the calculated vertical velocity and turbulent shear stress distribution are in good agreement with experimental data and fit better than the calculations obtained from the traditional Smagorinsky-based model.

Massive disposal of various heavy metals by industrial activities gives rise to serious environmental contamination. Herein, a magnetite nanoparticles decorated graphene oxide composite (MNGO) was facilely prepared via simple co-precipitation. The as fabricated MNGO was characterized and used as adsorbent to remove aqueous Ni(Π) and Pb(Π) with high efficiency. The removal performance was investigated, and the interaction mechanism between adsorbent and adsorbate was analyzed. Control experiment presents, MNGO outperforms either single Fe3O4 or graphene oxide (GO), which is owing to the mutual positive effects between the two phases. Concretely, MNGO efficiently adsorbs 391.63 mg·g–1, 373.59 mg·g–1 of Ni(Π), Pb(Π) in 5 min, respectively. In addition, Fe3O4 introduction brings magnetic separability, which make MNGO recoverable. Adsorptions are spontaneous, exothermic and randomness decreasing, which conform well to the Freundlich and pseudo second order models. The interaction mechanism is clarified as: oxygen atoms in C=O, C–O related groups chemically interact with Ni(Ⅱ), Pb(Ⅱ). The high efficiency performance of MNGO entails inspiring application in heavy metal scavenging.

The Three Gorges Dam (TGD), on the upper valley of the Yangtze River, China, is the largest water conservancy and power generation project in the world. Problematic sedimentation in the Three Gorges Reservoir (TGR) is related to the reservoir lifetime, hydropower generation, riverbed erosion, and sustainable development of ecosystems. In this study, measures to holistically and systematically address sedimentation in the TGR are -discussed and demonstrated, including upstream sediment trapping, regulatory optimisation with respect to sediment peaks and reservoir tail sedimentation reduction, and sediment dredging. Owing to upstream reservoir sediment trapping, the incoming sediment load of the TGR has decreased markedly. Results showed that the annual incoming sediment was only 164 million tons, nearly 70% lesser than the preliminary design value. By intercepting the sediment in the upstream reservoirs and conducting sediment peak regulation, the volume and rates of sedimentation in the TGR decreased significantly. Meanwhile, through sediment peak regulation during the flood season, increased volumes of sediment could be discharged downstream, thereby relieving sediment starvation downstream of the TGD. Overall, through adoption of the related sedimentation management strategies, sediment deposition decreased considerably, to approximately 33% of the preliminary design value, thereby successfully addressing the sediment problems in the TGR. Useful sedimentation management strategies learned from the TGR experience can be applied elsewhere to ensure the sustainable use and management of reservoirs.

The asynchronous propagation characteristics of flood and sediment peaks downstream (i.e., sediment peak lagging behind flood peak) are crucial for the operation of sediment peak release to reduce the sedimentation of the Three Gorges Reservoir (TGR). In the flood season of 2013, the sediment peak regulation was conducted in the TGR, based on the asynchronous propagation characteristics of flood and sediment peaks, and promising results were achieved towards reducing the reservoir sedimentation. In this study, the processes of flood propagation and sediment transport over a stretch of 280 km, upstream of the TGR on the Yangtze River were studied through a three-dimensional (3D) semi-implicit cross-scale hydroscience integrated system model (SCHISM), focussing on the asynchronous propagation characteristics of flood and sediment peaks downstream. It was demonstrated that firstly, the model efficiently and accurately reproduced the processes of flood propagation and sediment transport during the 2013 flood season compared with the measured results. The sensitivity analysis showed that the horizontal grid used in the numerical modelling had a greater influence on the model results than the vertical grid. The Manning coefficient was not sensitive to flood peaks propagation with a large flow discharge. Next, the validated model was adopted to investigate the asynchronous propagation characteristics of the flood and sediment peaks under different TGR operational scenarios. The results indicated that the impounded level ahead of the Three Gorges Dam (TGD) had an insignificant influence on the occurrence time and magnitude of the flood peak, but had a significant influence on the occurrence time and magnitude of the sediment peak. The time of sediment peak lagging behind flood peak increases as the impounded level in the TGR increased. The peak value of sediment concentration gradually decreased owing to the sediment deposition. The research results could provide a scientific basis for further optimising the sediment peak regulation, and the 3D numerical model could provide a reliable real-time tool to predict the arrival time of the flood and sediment peaks in the TGR.

A nanocomposite α-Fe2O3/graphene oxide (α-Fe2O3/GO) was prepared with a simple hydrothermal method. The as obtained α-Fe2O3/GO was used in removing aqueous Cr(Ⅵ). Batch adsorptions were conducted, the adsorption isotherms, kinetics, thermodynamics and removal mechanism were analyzed. The adsorption of an aqueous solution of Cr(Ⅵ) initial concentration 100 mg L−1 onto α-Fe2O3/GO of a dosage 500 mg L−1 reached equilibrium in 7 min, and the adsorption quantity and adsorption percent were 172.63 mg L−1 and 86.31%, respectively. No obvious performance fluctuations were observed under varying environmental factors such as pH and electrolyte. The fast adsorption kinetics was owing to the morphological feature: thin morphology enabled fast pore diffusion. The high adsorption capacity was owing to the structural feature: mesopores in α-Fe2O3/GO gave high specific surface area and pore volume, where accommodate abundant oxygen containing groups as adsorption sites. The good adaptability to environmental factors (pH, electrolyte) was owing to the strong chemical interactions between α-Fe2O3/GO and Cr(Ⅵ). The removal mechanism included physical adsorption, ion exchange, surface complexation, and reduction. 62.46% of the surface adsorbed Cr(Ⅵ) was reduced to Cr(Ⅲ). The facile preparation and good adsorption performance would make α-Fe2O3/GO a promising adsorbent for Cr(Ⅵ).