The rapid growth in nuclear industries such as uranium ores mining, nuclear energy generation, spent-fuel treatment and nuclear weapon manufacture has caused a legacy of uranium contamination in the ...aquatic environment, which poses a potential threat to the ecological environment and human health. The safe and effective disposal of uranium-contaminated water has thus been an urgent requirement. For decades, various materials have been shown to be capable for removing uranium from aqueous solution by adsorption technique, namely inorganic materials (e.g., clay minerals, metal oxides, mesoporous silica), organic polymers (e.g., resins, cellulose, chitosan), carbon family materials (e.g., mesoporous carbon, carbon nanotubes, graphene oxides), and porous framework materials (e.g., covalent organic frameworks, metal-organic frameworks). In this review, we provide a systematic and comprehensive overview of the researches conducted from 2005 to 2018 for uranium removal from aqueous solution by these emerging materials. The different approaches in the determination of the adsorption mechanisms between uranium and adsorbents are also briefly summarized, involving macroscopic experimental approaches, microscopic spectroscopic and computational approaches. Finally, we discuss the current limitations and propose future research perspectives in hopes of inspiring more dramatic advancements in the material and environment remediation fields.
Various kind of organics are toxic and detrimental, resulting in eutrophication, black, odorous water and so on. Photocatalysis has been deemed to be a promising technology which can decompose ...different kinds of organic pollutants under visible light irradiation, finally achieving non-poisonous, harmless CO2, water and other inorganic materials. Bismuth oxychloride (BiOCl) is considered as a promising photocatalyst for the efficient degradation of organic pollutants due to its high chemical stability, unique layered structure, resistance to corrosion and favorable photocatalytic property. However, BiOCl can only absorb UV irradiation because of its wide band gap of 3.2 eV–3.5 eV that limits its photocatalytic performance. Herein, a lot of methods have been reviewed to improve its photocatalytic activity. We introduced the unique and special layered structure of BiOCl, the typical and common synthesis methods that can control the morphology, and the most important part is varies of modification routes of BiOCl and the application of BiOCl-based materials for photocatalytic degradation of organic pollutants. Besides, we summarized the crucial issues and perspectives about the application of BiOCl in pollution management.
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•The synthesis methods of BiOCl-based composites are reviewed.•Metal-doping, nonmetal-doping and OVs introduction functions are summarized.•Recent catalytic applications of BiOCl-based photocatalysts are discussed.•The mechanisms of BiOCl-based photocatalysts are analyzed in catalysis.
Adsorption of 4-n-nonylphenol (4-n-NP) and bisphenol A (BPA) on magnetic reduced graphene oxides (rGOs) as a function of contact time, pH, ionic strength and humic acid were investigated by batch ...techniques. Adsorption of 4-n-NP and BPA were independent of pH at 3.0- 8.0, whereas the slightly decreased adsorption was observed at pH 8.0–11.0. Adsorption kinetics and isotherms of 4-n-NP and BPA on magnetic rGOs can be satisfactorily fitted by pseudo-second-order kinetic and Freundlich model, respectively. The maximum adsorption capacities of magnetic rGOs at pH 6.5 and 293 K were 63.96 and 48.74 mg/g for 4-n-NP and BPA, respectively, which were significantly higher than that of activated carbon. Based on theoretical calculations, the higher adsorption energy of rGOs + 4-n-NP was mainly due to π–π stacking and flexible long alkyl chain of 4-n-NP, whereas adsorption of BPA on rGOs was energetically favored by a lying-down configuration due to π–π stacking and dispersion forces, which was further demonstrated by FTIR analysis. These findings indicate that magnetic rGOs is a promising adsorbent for the efficient elimination of 4-n-NP/BPA from aqueous solutions due to its excellent adsorption performance and simple magnetic separation, which are of great significance for the remediation of endocrine-disrupting chemicals in environmental cleanup.
The presence of heavy metals in the industrial effluents has recently been a challenging issue for human health. Efficient removal of heavy metal ions from environment is one of the most important ...issues from biological and environmental point of view, and many studies have been devoted to investigate the environmental behavior of nanoscale zerovalent iron (NZVI) for the removal of toxic heavy metal ions, present both in the surface and underground wastewater. The aim of this review is to show the excellent removal capacity and environmental remediation of NZVI-based materials for various heavy metal ions. A new look on NZVI-based materials (e.g., modified or matrix-supported NZVI materials) and possible interaction mechanism (e.g., adsorption, reduction and oxidation) and the latest environmental application. The effects of various environmental conditions (e.g., pH, temperature, coexisting oxy-anions and cations) and potential problems for the removal of heavy metal ions on NZVI-based materials with the DFT theoretical calculations and EXAFS technology are discussed. Research shows that NZVI-based materials have satisfactory removal capacities for heavy metal ions and play an important role in the environmental pollution cleanup. Possible improvement of NZVI-based materials and potential areas for future applications in environment remediation are also proposed.
Graphene with atomic layer of sp2-hybridized carbon atoms in a hexagonal structure has attracted multidisciplinary attention since its discovery. Due to the inherent advantages of large specific ...surface area and abundant functional groups, its derivative graphene oxide (GO) nanomaterials have achieved large-scale development in effective pollution treatment. In the past few years, novel GO-based nanomaterials through coupling with other nanomaterials have been synthesized with significant process and applied for efficient elimination of different kinds of pollutants. This paper aims to summarize recent research results on the excellent removal ability of GO-based nanomaterials for various heavy metal ions in aqueous solutions. The synthesis, adsorption process characteristics and interaction mechanism of the adsorbent are emphasized and discussed. The effects of various environmental conditions are outlined. At last, a brief summary, perspective and outlook are presented. This review is intended to provide some thrilling information for the design and manufacture of GO-based nanomaterials for the elimination of heavy metal ions from wastewater in environmental pollution management.
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•Synthesis and surface modification of GO-based composites are reviewed.•Applications of different GO-based composites for metal ions elimination are reviewed.•Interaction mechanism of metal ions with GO-based composites is discussed.•Sorption capacities of metal ions on GO-based composites and other materials are compared.•Perspective of GO-based composites in pollution management is summarized.
The synthesis of graphene oxide-based materials and their application in the efficient elimination of different metal ions are summarized and compared with other materials. The interaction mechanism is discussed in detail.
A bimetallic‐structured ternary phosphide (NiCo2Px) as a novel pH‐universal electrocatalyst for hydrogen evolution reaction is presented. It exhibits both high activity and long‐term stability in all ...the tested alkaline, neutral, and acidic media. The excellent catalytic performance endows it with a bright future in the large‐scale electrochemical water splitting industry.
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•The BN-based nanomaterials present the outstanding removal percentage of organic pollutants.•The BN-based nanomaterials have satisfactory sorption capacities for heavy metal ...ions.•The removal processes of heavy metal ions were mainly attributed to surface complexation.•The interaction mechanism between BN and organic compounds was π-π interaction.
Water pollution, a worldwide issue for the human society, has raised global concerns on environmental sustainability, calling for high-performance materials in effective pollution treatments. Boron nitride (BN) with a structure similar to graphene possesses many extraordinary properties such as high surface areas, high oxidization resistance at high temperature, and high chemical stability. This review presents the outstanding removal percentage and environmental restoration of BN-based nanomaterials for the elimination of various pollutants from the last ten years. Notably, recent advances in the removal of organic/inorganic pollutants and interaction mechanism are outlined. BN-based materials can not only preferably remove contaminants, but also can be directly regenerated by burning in air. The BN-based materials have satisfactory sorption capacities for inorganic pollutants (e.g. heavy metal ions) and organic pollutants (e.g. dyes and pharmaceutical molecules). The interaction mechanisms between pollutants and BN-based materials are mainly surface complexation, π-π stacking, and electrostatic interactions. This paper is beneficial to further comprehend the interactions of pollutants with BN-based materials, which is also helpful for the improvement of BN-based materials and potential areas for future applications in environment remediation.
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•Photodegradation of POPs by GR-based composites was comprehensively reviewed.•Recent developments in the synthesis of GR-based photocatalysts were summarized.•Catalytic mechanisms ...and roles of GR species in composites were elucidated in depth.•Challenges and future research needs in this field were insightfully suggested.
Over the last decade, two-dimensional graphene (2D GR) has brought new impetus in environmental photocatalysis, mainly benefiting from their unique physicochemical and photoelectric structural properties. Numbers of researchers have spared no effort to utilize visible-light-induced GR-based composites as catalyst platform to generate reactive species in photocatalytic oxidation technology. Herein, a comprehensive overview is presented on recent achievements of the construction and water-related applications of these photocatalysts for persistent organic pollutants (POPs) removal. A brief introduction of synthesis strategies is introduced for GR and its derivatives. Roles of GR as supports, flexible substrates and co-catalysts in composites are specifically pointed out with experimental studies. Most importantly, shortcomings (e.g., fast carrier recombination and serious photocorrosion) appeared in visible light photocatalysis and relative solutions by using GR species are clearly investigated. Based on the current research status, special attention has been paid to their promising applications on removing typical POPs, such as phenols, antibiotics, pharmaceuticals and dyes. Also, challenges (e.g., biotoxicity) and prospects are discussed for future developments in this field. This paper enriches the knowledge to deeply understand the catalytic performances and mechanisms of GR-based photocatalysts, and bring better perspectives for researchers in this field.
A short-term traffic flow prediction framework is proposed for urban road networks based on data-driven methods that mainly include two modules. The first module contains a set of algorithms to ...process traffic flow data. After analysis and repair, a complete data set without outliers is provided as well as a data set containing pairs of road segments that are the most similar to each other in regard to their trends. The second module focuses on multiple time-step short-term forecasting. With a good understanding of the periodicity and randomness of traffic flow, the time series is first decomposed into a trend series and residual series. After reconstructing the two time series, model training and prediction based on a long short-term memory-recurrent neural network (LSTM-RNN) are performed. Finally, the two results are combined together to form the final prediction. A model evaluation is performed using two urban road networks. The results show that the data processing module can effectively improve the data quality, reduce the training time and enhance the model robustness. The LSTM-RNN correctly identifies the time trend and spatial similarity of traffic flow and obtains a more accurate multiple time-step prediction. The proposed framework outperforms other deep learning algorithms and has better accuracy and stability.
Graphene oxide (GO) has attracted considerable attention because of its remarkable enhanced adsorption and multifunctional properties. However, the toxic properties of GO nanosheets released into the ...environment could lead to the instability of biological system. In aqueous phase, GO may interact with fine mineral particles, such as chloridion intercalated nanocrystallined Mg/Al layered double hydroxides (LDH–Cl) and nanocrystallined Mg/Al LDHs (LDH–CO3), which are considered as coagulant molecules for the coagulation and removal of GO from aqueous solutions. Herein the coagulation of GO on LDHs were studied as a function of solution pH, ionic strength, contact time, temperature and coagulant concentration. The presence of LDH–Cl and LDH–CO3 improved the coagulation of GO in solution efficiently, which was mainly attributed to the surface oxygen-containing functional groups of LDH–Cl and LDH–CO3 occupying the binding sites of GO. The coagulation of GO by LDH–Cl and LDH–CO3 was strongly dependent on pH and ionic strength. Results of theoretical DFT calculations indicated that the coagulation of GO on LDHs was energetically favored by electrostatic interactions and hydrogen bonds, which was further evidenced by FTIR and XPS analysis. By integrating the experimental results, it was clear that LDH–Cl could be potentially used as a cost-effective coagulant for the elimination of GO from aqueous solutions, which could efficiently decrease the potential toxicity of GO in the natural environment.
