The rapid development of plastic industrials has created a variety of plastic products, causing revolutionary progress in chemistry, physics, biology, and medicine. Large-scale production and ...applications of plastics increase their possibility of entering the environment. Previous environmental impact studies typically focused on the toxicity, behavior and fate; limited attention was paid on greenhouse gas emissions and climate change. With the increase of plastic waste, the threat of plastic pollution to the earth’s climate has been gradually taken seriously. Evidence showed that greenhouse gas emissions occur at every stage of the plastic life cycle, including extraction and transportation of plastic raw materials, plastic manufacturing, waste treatment and entering the environment. The oil and gas industries used to make plastics are the main sources of greenhouse gas emissions (from the extraction of raw materials to the manufacture of plastics). Emissions of greenhouse gases during manufacture are mainly controlled by the production facilities themselves, usually depending on the efficiency, configuration and service life of equipment. Additionally, there are some unintended impacts, including transport requirements, pipeline leakage, land use, as well as impeding forests as natural carbons sinks. Recycling of plastic waste energy seems to be a good way to deal with waste plastics, but this process will release a lot of greenhouse gases. With this energy conversion occurring, the incineration of plastic packing waste will become one of the main sources of greenhouse gas emissions. Furthermore, plastics released into the environment also slowly release greenhouse gases, and the presence of (micro)plastics in the ocean will seriously interfere with the carbon fixation capacity of the ocean. In its current form, greenhouse gas emissions from cradle to grave of plastics will reach 1.34 gigatons per year by 2030 and 2.8 gigatons per year by 2050. This will seriously consume the global remaining carbon budgets, thereby threatening the ability of the global community to keep global temperatures rising by below 1.5 °C even 2 °C by 2100. In order to achieve this goal, the total global greenhouse gas emissions must be kept within the remaining carbon budget of 420–570 gigatons. The accumulative greenhouse gas emissions from cradle to grave of plastics may exceed 56 gigatons by 2050 (approximately accounting for 10%–13% of the total remaining carbon budget). As the plastic industry plans to expand production on a large scale, the problem will worsen further. The World Economic Forum forecasted that by 2030, the production and use of plastics will grow at an annual rate of 3.8%, and this growth rate will fall to 3.5% per year from 2030 to 2050. However, there are significant challenges and uncertainties in this estimation, and challenge and uncertainty factors come from all aspects. Recently, several organizations and researchers have started to discern the relationship between greenhouse gas emissions and plastic industrials, but relevant research on these impacts is still in its infancy. Consequently, the contribution of plastic pollution to greenhouse gas emissions and climate change should be given immediate attention and it needs to further explore the impact of plastic pollution on greenhouse gas emission and climate change. The implementation of measures to solve or alleviate the (micro)plastic crisis was critical necessary and proposed: (1) production control of global plastics; (2) improving the treatment and disposal of plastic waste; and (3) assessment of the impact of global environmental (micro)plastics on climate.
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•A crisis that plastic life cycle affects GHG emission and climate change is raised.•GHG emissions from cradle to grave of plastics will reach 1.34 Gt per year by 2030.•Accumulative GHG emission from cradle to grave of plastics may exceed 56 Gt by 2050.•GHG emissions from plastic life cycle seriously threaten remaining carbon budget.•Perspectives and challenges on plastic industry and policy are put forward.
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•Impact of surfactant on adsorption performance of Pb2+ on MPs was studied.•Surfactant caused a higher hydrophilicity of MPs and improved the adsorption ability of MPs for Pb2+.•SDBS ...significantly enhanced adsorption of Pb2+ on MPs compared with other two surfactants.•The presence of Cu2+ affected the adsorption behavior of PP for Pb2+.•Surfactant could promote the migration and stabilization of Pb2+ in the environment.
The impact of surfactant addition on the adsorption performance of lead ion (Pb2+) as a typical heavy metal ion on three microplastics was investigated. The types of microplastics (polyethylene (PE), polypropylene (PP) and polymethylmethacrylate (PMMA)) and surfactants (triton X-100 (TX-100), 1-hexadecylpyridinium bromide (HDPB), and sodium dodecyl benzenesulfonate (SDBS)), adsorption time, concentration of Pb2+, and coexisting ions was systematically investigated, and the characteristics of adsorption of Pb2+ by microplastics were analyzed. The experimental results showed that the adsorption capacity of Pb2+ on three micropalstics was different. The adsorption capacity of Pb2+ on the three microplastics without surfactants was: 4.21 (PMMA) > 2.01 (PE) > 1.57 mg g−1 (PP). The addition of surfactants resulted in a higher hydrophilicity of microplastics, and obviously improved the adsorption ability of microplastics for lead ions. SDBS can significantly enhance the adsorption of Pb2+ on three microplastics compared with other two surfactants (TX100 and HDPB). The highest adsorption capacity of Pb2+ on the three microplastics with addition of SDBS solution was: 7.87 (PMMA) > 7.20 (PE) > 7.02 mg g−1 (PP). With the increase of adsorption time and Pb2+ concentration, the adsorption efficiency of microplastics for Pb2+ first increased and then decreased. The pH of solution had a great influence on the adsorption of Pb2+ by microplastics. The results of coexisting ion experiments demonstrated that when lead ion and copper ion coexist, the two ions have competitive adsorption phenomenon on PP. This research explored the adsorption characteristics of lead ions by microplastics with addition of surfactants, which can provide theoretical basis for further study of heavy metal enrichment and environmental behavior of microplastics in the environment.
•Recent advances of g-C3N4-based catalysts in AOPs beyond photocatalysis are reviewed.•Catalytic performance and involved mechanism are summarized.•Effect of water chemistry on catalytic performance ...is discussed.•Reusability and stability in water treatment are mentioned.•Future prospects in real environmental applications are proposed.
Advanced oxidation processes (AOPs) have attracted much interest in the field of water treatment owing to their high removal efficiency for refractory organic contaminants. Graphitic carbon nitride (g-C3N4)-based catalysts with high performance and cost effectiveness are promising heterogeneous catalysts for AOPs. Most research on g-C3N4-based catalysts focuses on photocatalytic oxidation, but increasingly researchers are paying attention to the application of g-C3N4-based catalysts in other AOPs beyond photocatalysis. This review aims to concisely highlight recent state-of-the-art progress of g-C3N4-based catalysts in AOPs beyond photocatalysis. Emphasis is made on the application of g-C3N4-based catalysts in three classical AOPs including Fenton-based processes, catalytic ozonation and persulfates activation. The catalytic performance and involved mechanism of g-C3N4-based catalysts in these AOPs are discussed in detail. Meanwhile, the effect of water chemistry including pH, water temperature, natural organic matter, inorganic anions and dissolved oxygen on the catalytic performance of g-C3N4-based catalysts are summarized. Moreover, the reusability, stability and toxicity of g-C3N4-based catalysts in water treatment are also mentioned. Lastly, perspectives on the major challenges and opportunities of g-C3N4-based catalysts in these AOPs are proposed for better developments in the future research.
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The wide use of perfluorooctane sulfonate (PFOS) has led to increasing concern about its human health risks over the past decade. In vivo and in vitro studies are important and effective means to ...ascertain the toxic effects of PFOS on humans and its toxic mechanisms. This article systematically reviews the human health risks of PFOS based on the currently known facts found by in vivo and in vitro studies from 2008 to 2018. Exposure to PFOS has caused hepatotoxicity, neurotoxicity, reproductive toxicity, immunotoxicity, thyroid disruption, cardiovascular toxicity, pulmonary toxicity, and renal toxicity in laboratory animals and many in vitro human systems. These results and related epidemiological studies confirmed the human health risks of PFOS, especially for exposure via food and drinking water. Oxidative stress and physiological process disruption based on fatty acid similarity were widely studied mechanisms of PFOS toxicity. Future research for assessing the human health risks of PFOS is recommended in the chronic toxicity and molecular mechanisms, the application of various omics, and the integration of toxicological and epidemiological data.
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•Assessing human health risks of PFOS by in vivo and in vitro studies are reviewed.•Exposure to PFOS can cause significant human health risks.•The chronic toxicity and molecular mechanisms need further study.•Integration of the toxicological and epidemiological data is recommended.
The excellent properties of plastics make them widely used all over the world. However, when plastics enter the environmental medium, microplastics will inevitably be produced due to physical, ...chemical and biological factors. Studies have shown that microplastics have been detected in terrestrial, aquatic and atmospheric environments. In addition, the presence of microplastics will provide a new artificial adhesion substrate for biofilms. It has been proved that the formation of biofilms could significantly change some properties of microplastics. Some studies have found that microplastics attached with biofilms have higher environmental risks and eco-toxicity. Therefore, considering the widespread existence of microplastics and the ecological risks of microplastic biofilms, the physical and chemical properties of biofilms on microplastics and their impact on microplastics in aqueous environment are worth reviewing. In this paper, we comprehensively reviewed representative studies in this area. Firstly, this study reviews that the existence of biofilms could change the transport and deposition of microplastics. Subsequently, the presence of biofilms would enhance the ability of microplastics to accumulate pollutant, such as persistent organic pollutants, heavy metals and antibiotics. Moreover, the effect of biofilms on microplastics enrichment of harmful microorganisms is summarized. Finally, some future research needs and strategies are proposed to better understand the problem of biofilms on microplastics.
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•Microplastics enter terrestrial, aquatic and atmospheric environment through a variety of pathways.•Microplastics have impacts on creatures and humans.•Biofilms on microplastics have unique physicochemical properties.•The existence of biofilm affects microplastics in aqueous environment.
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•A novel silicate-hydrochar composite was synthesized for environmental remediation.•Heavy metal and tetracycline could be removed simultaneously by MgSi-HC.•The maximum adsorption ...capacity of MgSi-HC exceeded 200 mg/g.•MgSi-HC had stable performance in deionized water, tap water, and lake water.•Different concentrations of coexisting ions had different effects on coadsorption.
A novel cost-effective hydrochar composite (MgSi-HC) prepared by a simple one-step process using waste sawdust, inexpensive silicate and magnesium salts as raw materials was used to remove Cu(II), Zn(II), and tetracycline (TC) from aqueous solution. The novel hydrochar material was characterized by SEM, TEM, XRD, BET specific surface area, ATR-FTIR spectra, and X-ray photoelectron spectroscopy. The values of surface area (107.7 m2/g) and pore volume (0.489 cc/g) of MgSi-HC indicated that it had a large specific surface area and well-developed pore structure. Adsorption isotherm showed that the maximum adsorption capacity of MgSi-HC for Cu(II), Zn(II), and TC was 214.7 mg/g, 227.3 mg/g, and 361.7 mg/g, respectively. In addition, the effects of heavy metals and tetracycline on each other in binary adsorption systems were different. Meanwhile, the study of mechanism indicated that various interactions might be involved in the adsorption process, and the adsorption mechanisms of heavy metal and TC were different. The potential of MgSi-HC for practical environmental remediation was evaluated, the result demonstrated that MgSi-HC still had high performance after 5 adsorption-desorption cycles, and it had stable adsorption ability in different water samples (150.2–156.2 mg/g for Cu, 159.6–167.4 mg/g for Zn, and 183.9–189.8 mg/g for TC), implying that the novel hydrochar could be a promising adsorbent for removal of heavy metal and antibiotics from real wastewater. This work provided a reference on the coadsorption of heavy metal and antibiotics, and indicated the potential application of MgSi-HC in complex pollutant adsorption.
Providing clean and affordable drinking water without harmful disinfection byproducts generated by conventional chemical disinfectants gives rise to the need for technological innovation. ...Nanotechnology has great potential in purifying water and wastewater treatment. A graphene oxide-silver (GO-Ag) nanocomposite with excellent antibacterial activity was prepared and characterized by transmission electron microscope and X-ray photoelectron spectroscopy. The tests were carried out using Escherichia coli and Staphylococcus aureus as model strains of Gram-negative and Gram-positive bacteria, respectively. The effect of bactericide dosage and pH on antibacterial activity of GO-Ag was examined. Morphological observation of bacterial cells by scanning electron microscope showed that GO-Ag was much more destructive to cell membrane of Escherichia coli than that of Staphylococcus aureus. Experiments were carried out using catalase, superoxide dismutase and sodium thioglycollate to investigate the formation of reactive oxygen species and free silver ions in the bactericidal process. The activity of intracellular antioxidant enzymes was measured to investigate the potential role of oxidative stress. According to the consequence, synergetic mechanism including destruction of cell membranes and oxidative stress accounted for the antibacterial activity of GO-Ag nanocomposites. All the results suggested that GO-Ag nanocomposites displayed a good potential for application in water disinfection.
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•Graphene oxide-silver (GO-Ag) nanocomposites with excellent antibacterial activity in aqueous solutions were prepared.•The antibacterial activity relied on the concentration of GO-Ag.•GO-Ag nanocomposites were much more destructive to cell membrane of Escherichia coli than that of Staphylococcus aureus.•Silver ions dissolved form silver nanoparticles were the main substance to directly kill bacteria.•Synergetic mechanism accounted for the antibacterial activity of GO-Ag nanocomposites.
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•This paper reviews recent findings on pollutants removal from water using NAGOs.•Characterization and properties of NAGOs suggest that can be promising adsorbents.•Adsorption ...mechanisms depend on NAGOs properties and target pollutants.•Outlook is proposed to close knowledge gaps before engineering application.
Nowadays, using graphene oxide (GO) as an adsorbent for removing pollutants from wastewater has attracted increasing attention due to its unique physic-chemical properties. Nitrogen-containing amino (NA) compounds have excellently complexing properties due to their abundant amino functional groups. In order to obtain an innovative adsorbent, functionalized GO (NAGO) has been developed by combining the properties of GO with the advantages of NA compounds. The obtained NAGO composites usually exhibit great improvement in adsorption properties and can be used as a promising adsorbent for decontamination of wastewater. This paper reviewed recent progress of synthetic technologies about fabricating various NAGOs, and their morphologies, structures and functional characteristics. Meanwhile, important applications of NAGOs for different kind of pollutants and theory of the adsorption phenomena are discussed based on the isothermal and kinetic adsorption models. Furthermore, the affecting factors, underlying mechanisms and comparison with other adsorbents for the removal of pollutants are reviewed. Conclusively, the perspectives and challenges involved in the application of NAGOs for decontamination of wastewater have also been proposed to promote sustainable development of this new exciting field.
Micro(nano)plastics, as emerging contaminants, have attracted worldwide attention. Nowadays, the environmental distribution, sources, and analysis methods and technologies of micro(nano)plastics have ...been well studied and recognized. Nevertheless, the role of micro(nano)plastic particles as vectors for attaching organisms is not fully understood. In this paper, the role of micro(nano)plastics as vectors, and their potential effects on the ecology are introduced. Micro(nano)plastics could 1) accelerate the diffusion of organisms in the environment, which may result in biological invasion; 2) increase the gene exchange between attached biofilm communities, causing the transfer of pathogenic and antibiotic resistance genes; 3) enhance the rate of energy, material and information flow in the environment. Accordingly, the role of microplastics as vectors for organisms should be further evaluated in the future research.
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•Questions of micro(nano)plastics as organism vectors have been raised.•Ecological effects of micro(nano)plastics as organism vectors are discussed.•Role of micro(nano)plastics as organism vectors need to be studied in future.
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