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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.
The microplastic pollution and related ecological impacts in the aquatic environment have attracted global attention over the past decade. Microplastics can be ingested by aquatic organisms from ...different trophic levels either directly or indirectly, and transferred along aquatic food chains, causing different impacts on life activities of aquatic organisms. In addition, microplastics can adsorb various environmental chemical contaminants and release toxic plastic additives, thereby serving as a sink and source of these associated chemical contaminants and potentially changing their toxicity, bioavailability, and fate. However, knowledge regarding the potential risks of microplastics and associated chemical contaminants (e.g., hydrophobic organic contaminants, heavy metals, plastic additives) on diverse organisms, especially top predators, remains to be explored. Herein, this review describes the effects of microplastics on typical aquatic organisms from different trophic levels, and systematically summarizes the combined effects of microplastics and associated contaminants on aquatic biota. Furthermore, we highlight the research progress on trophic transfer of microplastics and associated contaminants along aquatic food chain. Finally, potential human health concerns about microplastics via the food chain and dietary exposure are discussed. This work is expected to provide a meaningful perspective for better understanding the potential impacts of microplastics and associated contaminants on aquatic ecology and human health.
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•Combined effects of microplastics and associated chemicals on aquatic biota are reviewed.•Trophic transfer of microplastics and associated chemicals is highlighted.•Microplastic properties and environmental factors affect microplastic ingestion.•Potential human health concerns via food chain and dietary exposure are discussed.•Perspectives for current challenges and future researches are prospected.
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•Aging degree of microplastics was evaluated by physical methods and chemical index.•Environmentally-relevant TWP showed the greatest adsorption capacity to Pb(II).•Adsorption ...mechanism involved complexation, electrostatic and cation-π interaction.•Fragmentation and desorption risk of biodegradable microplastics required attention.•Humic acid and suspended sediment played multiple roles in the adsorption process.
In this study, the adsorption behavior of lead (Pb(II)) onto environmentally-relevant tire wear particles (TWP) gained by natural weathering and mechanical abrasion, ultraviolet-aged polylactic acid microplastics (UV-PLA), and ultraviolet-aged polystyrene microplastics (UV-PS) was compared to investigate the difference of representative microplastics between the adsorption capacity and mechanism. Our results indicated that the aging processes significantly improved the adsorption capacity to Pb(II), and TWP had the highest adsorption amount, followed the order by UV-PLA, UV-PS, PLA and PS. Electrostatic interaction and complexation of oxygen-containing functional groups played crucial roles in the adsorption of Pb(II) onto UV-PLA, the adsorption mechanisms of UV-PS involved electrostatic interaction, complexation and cation-π interaction, while adsorption of TWP was might dominated by the complexation of surface functional groups and properties of the complex rubber co-polymer. Interestingly, the low concentration of humic acid (HA) most significantly improved adsorption capacity of aged microplastics to Pb(II), otherwise it was severely suppressed at higher concentration of HA. Besides, the adsorption behavior of different binary systems between aged microplastics and suspended sediment to Pb(II) had complicated synergistic or suppressive effects with a concentration-dependent and polymer-dependent trend. Furthermore, UV-PLA had the far stronger desorption ability of Pb(II) than that of TWP and UV-PS, suggesting that metal-contaminated biodegradable microplastics posed the higher ecological risks to aquatic organisms. Desorption quantity and rates of Pb(II) from aged microplastics in the simulated sediment system were generally higher than those in turbulent water column. Collectively, these findings provide a wide insight into adsorption capacity and mechanisms of metal ions on the representative aged microplastics and the desorption behavior in complex aquatic environments.
Plastic debris exists worldwide and research on microplastic pollution has gradually spread from the oceans to freshwater and terrestrial systems. Coral reefs not only serve as one of the most ...charismatic and biodiverse ecosystems on our planet, but also maintain the human harvesting of natural resources and livelihoods of hundreds of millions of people. However, the abundance and distribution characteristics of microplastics in coral reef systems receive little scientific attention. Meanwhile, the impacts of microplastics and nanoplastics on coral health and its potential mechanisms remain further studied. Herein, this review first summarized the current status of microplastics pollution in global coral reefs, especially included (i) abundance and distribution characteristics of microplastics in different media (e.g., seawater, sediment, corals), and (ii) possible sources of microplastics in reef regions. Furthermore, the main interaction mechanisms between microplastics and corals are highlighted. Following this, the direct or indirect impacts of microplastics on coral species are discussed. With the rapid increase of plastic consumption and background of pervasive global coral bleaching, research on marine microplastics must focus on the critical coral reef regions and include a comprehensive knowledge about the distribution, fate, and potential risks from an ecosystem perspective.
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•Abundance and distribution of microplastics in coral reefs are firstly reviewed.•Source and characteristics of microplastics vary from different coral reef regions.•Microplastic prevalence is attributed to human activities and natural factors.•Microplastics interact with corals by active ingestion and passive surface adhesion.•Microplastic exposure influence coral physiology, energetics, growth and health.
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In this work, a novel engineered biochar prepared through modification with chitosan and pyromellitic dianhydride (PMDA) was investigated as an adsorbent for the removal of heavy ...metal ions from single metal and mixed-metal solutions (Cd, Cu and Pb). Characterization experiments with FTIR and XPS suggested that the novel modified biochar had more surface functional groups compare to the pristine biochar. Adsorption experiments indicated that the initial pH of the solution influenced the ability of biochars to adsorb heavy metals in single- and multi-metal systems. Moreover, the chitosan-PMDA modified biochar had strong selective adsorption of Cu(II). Mechanism studies showed that chemisorption was the major mechanism for heavy metal removal by the chitosan-PMDA modified biochar. Furthermore, the types of effective functional group for these heavy metal removal were different. The NCO group played a dominant role in the process of Pb(II) removal, while several N-containing functional groups and CC groups participated in the adsorption of Cd(II). The novel engineered biochar had selective adsorption capacity for copper due to the N-containing functional groups, meanwhile abundant carbonyl groups also participated in the removal of copper, and may reduce Cu(II) to Cu(I).
•NMSH had different adsorption behaviors and mechanisms for Cr(VI) and Sb(V).•Different concentrations of Cr(VI) and Sb(V) exhibited different coadsorption behaviors.•NMSH could reduce Cr(VI) to ...Cr(III), but not Sb(V).•NMSH had great anti-interference ability to coexisting inorganic ions and organic matter.
A novel amino-functionalized hydrothermal biochar modified with nitric acid and nicotinamide (NMSH) was prepared and applied to remove heavy metal in different systems. The study of batch adsorption found that NMSH had different adsorption behaviors for Cr(VI) and Sb(V), and different concentrations of heavy metal ions exhibited different coadsorption behaviors in mixed system. NMSH had great anti-interference ability to coexisting inorganic ion and humic substance. The maximum adsorption capacity of NMSH was 132.74 mg/g for Cr(VI), and 241.92 mg/g for Sb(V). Moreover, different interfering ions and matter had different effects on adsorption. The mechanism study found that the adsorption mechanism of NMSH involved multiple interactions, and the mechanisms were different. Some O-containing functional groups of NMSH could reduce Cr(VI) to Cr(III), but not Sb(V). NMSH had great removal efficiency and reusability performance, which suggested that NMSH had prospects for practical wastewater treatment.
In this work, a novel sludge biochar/Zn–Al layered double hydroxide composite (SL) was synthesized in a facile co-precipitation method, and it was used to simultaneously remove benzotriazole (BTA) ...and lead ion (Pb(II)). Batch adsorption experiments demonstrated that composites with sludge content of 1.0 g (SL-1.0) had a great adsorption performance for BTA and Pb(II). The maximum adsorption capacities of SL-1.0 for BTA and Pb(II) were 239.6 and 226.1 mg g−1, respectively. There was preferential adsorption of BTA in BTA and Pb(II) binary system. The adsorption mechanism analysis indicated that the BTA and Pb(II) adsorption involved electrostatic attraction and chemical bonding with surface functional groups on SL-1.0. Specifically, hydrogen bonding and π-π interaction were mainly ascribed to BTA adsorption, while complexation with surface function groups dominated Pb(II) adsorption. With the advantages of facile synthesis and excellent adsorption capacity, SL-1.0 possesses great potential for simultaneously removing of BTA and Pb(II) from wastewaters.
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•A novel adsorbent (SL-1.0) was successfully prepared by loading LDH onto SBC.•The existence of benzotriazole had little effect on Pb(II) adsorption onto SL-1.0.•There was preferential adsorption of benzotriazole in the binary system of benzotriazole and Pb(II).•Hydrogen bonding and π-π interaction were mainly ascribed to benzotriazole adsorption.•The complexation with surface function groups dominated Pb(II) adsorption.
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•A novel biochar-copolymer composite (CPBC) was synthesized for water treatment.•The maximum removal capacity of Cr by CPBC was 491.3 mg/g.•The process of Cr(VI) removal involved the ...synergy of adsorption and reduction.•CPBC had considerable removal efficiency in various real water samples.
In this work, a novel biochar-copolymer composite (CPBC) that can efficiently remove Cr(VI) from water was successfully synthesized. The physicochemical properties of CPBC were fully characterized by various characterization techniques. The removal performance and mechanisms of Cr(VI) by CPBC were systematically studied. The results of characterization showed that CPBC possessed a considerable pore structure and abundant oxygen-containing and nitrogen-containing functional groups. The results of experiments demonstrated that CPBC had excellent performance for Cr(VI) removal. CPBC could remove 99.7% of Cr(VI) in half an hour, with the maximum removal capacity of 491.3 mg/g, and it could effectively resist the interference of various coexisting ions and organics. Through the analysis of the removal mechanism, it was found that the process of Cr(VI) removal by CPBC involved the synergy of adsorption and reduction. Different functional groups in CPBC played different roles. Among them, hydroxyl groups could reduce Cr(VI) to Cr(III) with the participation of hydrogen ions, protonated N combined with negatively charged Cr(VI) through electrostatic interaction, and other oxygen-containing nitrogen-containing groups remove Cr(VI) and Cr(III) through complexation. Furthermore, the practical application potential of CPBC was evaluated from generality, reusability, and actual water treatment capacity. It was found that the removal efficiency of CPBC for various pollutants exceeded 97.2%, it could be recycled for more than three times, and the removal efficiency of Cr(VI) in several actual water samples exceeded 91.7%, demonstrating that the good practical application potential of CPBC.
•Z-scheme γ-Fe2O3/g-C3N4 achieved high degradation efficiency in the photo-Fenton system.•γ-Fe2O3/g-C3N4 has excellent anti-interference capability and sustainability.•Z-scheme γ-Fe2O3/g-C3N4 had ...good recyclability.•·OH was the dominant active substance for OTC degradation.•Photo-Fenton degradation mechanism of oxytetracycline by γ-Fe2O3/g-C3N4 was analyzed.
With the urbanization and industrialization of the world, the pollution of water due to the misuse of antibiotics is increasing. In this study, a Z-scheme γ-Fe2O3/g-C3N4 composite photocatalyst was prepared, and the removal efficiency of oxytetracycline (OTC) reached 85.7% within 60 min under the Photo-Fenton reaction system higher than that of g-C3N4 and γ-Fe2O3. The composite has great anti-interference capability and sustainability, and the recyclability was demonstrated using hysteresis return lines data. The photoelectrochemical characterization was analyzed to investigate the effect of the building of Z-scheme heterojunction on the photogenerated carrier separation efficiency. The charge behavior of heterojunction interfaces was probed in conjunction with DFT calculations, and differential charge maps were used to visualize charge distributions to analyze possible charge transfer pathways. In addition, the active substances in the system were identified by ESR data and capture experiments. The results showed that ·OH was the dominant active substance for OTC degradation. Meanwhile, LC-MS data combined with Fukui function calculations led to the derivation of a possible degradation pathway dominated by ·OH. This research provides a reference for subsequent studies of non-homogeneous Photo-Fenton systems and offers a viable option for mitigating OTC pollution in water bodies.
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•A novel modified biochar for environmental remediation was synthesized.•Sulfamic acid significantly improved the adsorption performance of biochar.•Pore filling played an important ...role in adsorption.•The maximum adsorption capacity of SABC exceeded 412.95 mg/g.
In this work, a novel modified biochar was prepared by pretreatment of Camellia oleifera shell with sulfamic acid. The effects of sulfamic acid on the properties of feedstock and biochar, and the influence of pyrolysis temperature on the modification was investigated. Furthermore, the adsorption mechanism of modified biochar for tetracycline (TC) was explore. The results showed that the specific surface area (170.97 m2/g) of the modified biochar was 2.6 times larger than that of the original biochar (65.31 m2/g). In addition, sulfamic acid treatment introduced more functional groups for biochar. These modification effects significantly improved the adsorption performance of biochar. The maximum adsorption capacity of sulfamic acid modified biochar for TC was 412.95 mg/g. The adsorption mechanism studies demonstrated that there were many interactions in the adsorption process, including electrostatic interaction, H bonding, π-π interaction, pore filling. In general, sulfamic acid was a potential green modification reagent, which could be used to improve the adsorption performance of biochar.
