•Triclosan is a potential contaminant that is widely found in natural environment and human body.•TCS can be effectively removed by adsorption, redox, biological and hybrid techniques.•TCS removal ...mechanisms and parameters of various technologies are provided.•The advantages and disadvantages of various removal techniques are discussed.•Recommendations for the development of TCS removal technologies are proposed.
Triclosan (TCS) is a broad-spectrum antibacterial agent that has been widely used as addition ingredient in personal cares and medical antibacterial products. It has been ubiquitously detected in the human body and environment due to its higher bioaccumulation character. Toxicological studies have demonstrated it does serious harm to plants and animals, and it is speculated to have strong potential toxicity to human. Thus, it has been widely concerned by researchers in recent years. Nowadays many TCS removal methods have been developed, but no review has been critically summarized its removal technologies, mechanisms and influencing factors. Here, we classify the main TCS removal technologies into adsorption, redox, biodegradation and hybrid technique, summarize the removal mechanisms of various technologies and provide their technical parameters. In addition, the influencing factors of various removal technologies are also discussed. Among them, adsorption is mainly affected by pH, ionic strength and natural organic matter (NOM); Redox method varies with the type of oxidant and reducing agent; biodegradation is not only affected by the type of microorganisms, but also affected by their living environment. Finally, we present the shortcomings of different TCS removal technology and future research recommendations.
Cadmium (Cd) contamination in river sediments becomes increasingly serious, and phytoremediation has been used to remediate Cd contaminated sediments, but the remediation efficiency needs to be ...improved. In this study, tea waste derived biochar (TB) was used to facilitate the phytoremediation of Cd contaminated sediments. Results showed that TB at 100, 500 and 1000 mg kg−1 increased Cd accumulation and translocation in ramie seedlings by changing Cd speciation in sediments and altering the subcellular distribution of Cd in plant cells. TB at low contents alleviated Cd induced toxicity in ramie seedlings by promoting plant growth and mitigating the oxidative stress. In addition, the activities of urease-, phosphatase-, and catalase-producing microbes in the Cd contaminated sediments were promoted by the application of TB. These findings demonstrated that biochar at low concentrations could improve the phytoremediation efficiency and mitigating Cd-induced toxicity to plants and microbes in Cd contaminated sediments. This study herein provides a novel technological application of waste biomass in controlling and mitigating risks of heavy metals.
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•TB was prepared according to the pyrolysis of tea waste.•TB changed Cd speciation in river sediments.•TB increased Cd accumulation and translocation in the plants.•TB alleviated Cd induced toxicity to plants and microbes.•TB enhanced the phytoremediation efficiency and reduced the risks of heavy metals.
Soil mineral depletion is a major issue due mainly to soil erosion and nutrient leaching. The addition of biochar is a solution because biochar has been shown to improve soil fertility, to promote ...plant growth, to increase crop yield, and to reduce contaminations. We review here biochar potential to improve soil fertility. The main properties of biochar are the following: high surface area with many functional groups, high nutrient content, and slow-release fertilizer. We discuss the influence of feedstock, pyrolysis temperature, pH, application rates, and soil types. We review the mechanisms ruling the adsorption of nutrients by biochar.
The ubiquitous problems of microplastics in waters are receiving global attention as microplastics can harm aquatic organisms, and finally can accumulate in the human body through biological chain ...amplification. In addition, microplastics act as a carrier capable of carrying heavy metals, organics, which form complex pollutants. These new combinations of pollutants, once ingested by aquatic organisms, are amplified through the food chain and can have unpredictable ramifications for aquatic organisms and human beings. Therefore, human beings are not only the source of plastic pollution, but also the sink of microplastic pollution. Therefore, this study reviews the source and distribution of microplastics, and their combined ability with heavy metals, antibiotics, and persistent organic pollutants in aquatic environments. Furthermore, it describes the interaction between aquatic organisms and microplastics. Finally, some suggestions are put forward to promote the sustainable application of microplastics. This work provides theoretical guidance for combining microplastics with other pollutants in water, and the accumulation of microplastics in food chain.
Source and confluence of microplastics in the biosphere. Display omitted
•Composition and adsorption ability of microplastics in aquatic environments studied•Potention for microplastic accumulation in aquatic organisms•Microplastics were accumulated and amplificated in the food chain.•Microplastics may increase the health risk for the biosphere.
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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.
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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.
The application of iron-based nanoparticles in environmental remediation.
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•Typical core–shell structure of bare iron nanoparticles with Fe0 as core.•Superior properties of different ...modified iron nanoparticles.•The pathway of removing pollutants by iron nanoparticles through adsorption, redox and coprecipitation.•The environmental effects caused by the application of iron nanoparticles.•Risk assessment and green-sustainable development of iron nanoparticles in ecosystems.
Two decades ago, iron nanoparticles have been widely studied in environmental protection due to their particular characters. Compared with traditional absorbents, iron nanoparticles not only have higher specific surface area, but also can oxidize and reduce multiple pollutants. Iron nanoparticles have been employed for the remediation of organic and inorganic pollutants in polluted water, soil and sediments. With in-depth research, various modified iron nanoparticles have been prepared to further overcome the original defects of aggregation or oxidation, and improve the reaction efficiency. Based on the properties of iron-based nanoparticles, this review summarizes different synthesis methods of iron nanoparticles and the removal mechanism of various pollutants. We also systematically classified the unstable and stable iron nanoparticles. At present, stable iron nanoparticles are possible to overcome the aggregation and retention of bare iron nanoparticles so as to achieve higher efficiency for the removal of pollutants. The application of iron nanoparticles in environmental remediation has significant effect on the environmental pH value, the pollutant morphology and the toxicity to microorganisms. Subsequently, some suggestions and conclusions are put forward for the application of iron nanoparticles.
•Revisit the relationship between population and energy in the late stage of demographic dividend.•Consider the relationship between population and energy from the perspective of metabolism.•Measure ...metabolic efficiency by combining emergy analysis and the Index-DEA.•Explore the multi-scale response of metabolism to population quality.•Provide a reference for other developing countries with population and energy issues.
China's population and carbon emissions will reach two peaks in 2030. Especially in the late stage of demographic dividend, it is necessary to revisit the relationship between population and energy. Metabolism is a critical perspective to help understand the population-energy relationship. This paper establishes a new paradigm for assessing the impact of population quality change on regional metabolism based on panel data from 2003 to 2019 in China. We measure the population quality index (PQI) using the Projection Pursuit method from four aspects and regional metabolic efficiency (RME) using emergy analysis and Index-DEA. Then, the Tobit model is used to explore the impact of population quality change on regional metabolism from a multi-scale perspective. The results show that the influence has some variability at different scales. From the total sample, the response of regional metabolism to population quality is significantly positive. For different PQI regions, the RME has a positive response to PQI in both, but this response is more obvious in advanced PQI regions. For regions in different locations, RME has positive response to PQI in both East and West, but there is no obvious response in the Central. These findings are closely related to global sustainable development.
Increasing heavy metal pollution problems have raised word-wide concerns. Cadmium (Cd), being a highly toxic metal, poses potential risks both to ecosystems and human health. Compared with ...conventional technologies, phytoremediation, being cost-efficient, highly stable and environment-friendly, is believed to be a promising green technology for Cd decontamination. However, Cd can be easily taken up by plants and may cause severe phytotoxicity to plants, thus limiting the efficiency of phytoremediation. Various researches are being done to investigate the effects of exogenous substances on the mitigation of Cd toxicity to plants. Calcium (Ca) is an essential plant macronutrient that involved in various plant physiological processes, such as plant growth and development, cell division, cytoplasmic streaming, photosynthesis and intracellular signaling transduction. Due to the chemical similarity between Ca and Cd, Ca may mediate Cd-induced physiological or metabolic changes in plants. Recent studies have shown that Ca could be used as an exogenous substance to protect plants against Cd stress by the alleviation of growth inhibition, regulation of metal uptake and translocation, improvement of photosynthesis, mitigation of oxidative damages and the control of signal transduction in the plants. The effects of Ca on toxic concentrations of Cd in plants are reviewed. This review also provides new insight that plants with enhanced Ca level have improved resistance to Cd stress.
Soil degradation, characterized by declines in nutrient status and simultaneous accumulation of pesticide residues, is a major problem affecting agricultural ecosystems. Previous studies indicate ...that biochar application to soil has promise as a practical method to alleviate these pressures: increasing crop yield and enhancing pesticide degradation. Here, we review the roles of biochar in both chemical and biological promotion of pesticide degradation and the potential benefits of biochar relating to the efficiency of fertilizer use, availability of nutrients, and nutrient exchange. Biochar typically has a high surface area featuring many functional groups, a high cation exchange capacity, and high stability. Major factors that impact on the nutrient retention characteristics of biochar (e.g., feedstock, pyrolysis temperature, and application rate) are also discussed herein. Nonetheless, more studies of the long-term impacts on soil properties from biochar addition are still required before it can be possible to accurately quantify the sustainability of this approach to sequester carbon and restore soil function.
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