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Fenton oxidation is a widely used method for the fast and efficient treatment of contaminated sediment, but few studies have investigated the management of Fenton-treated sediment for resource utilization. In this study, the evolutionary characteristics of bacterial community composition in Fenton-treated riverine sediment were investigated using 16S rRNA gene sequencing after the incorporation of rice straw biochar and sheep manure compost. The Fenton treatment caused a decline in the relative abundance of Bacteroidetes from 39% to 8% on the 7th day, and using biochar and compost rapidly increased the relative abundance of Firmicutes from 13% to 61% and 57%, respectively. Applying 1.25 wt% biochar after the Fenton treatment contributed to high Shannon diversity indices of 4.80, 4.69, and 4.76 on the 7th, 28th, and 56th day, respectively. The reduced differences of Shannon indexes on the 56th day indicated that the bacterial diversity among different treatments tended to be similar over time. The genera Flavisolibacter and Bacillus were representatively detected on the 7th day in the untreated sediment and Fenton/biochar-treated sediment, respectively. The number of feature bacteria decreased significantly from 88 on the 7th day to 29 on the 56th day. The community functions for the carbon, nitrogen, and sulfur cycles were sensitive to the Fenton-treatment and the subsequent treatment with biochar and compost. This study may provide a useful reference for follow-up work on the remediation of contaminated sediment using advanced oxidation processes, and promote the development of resource utilization of amended sediment.
Assuntos
Compostagem , Animais , Bactérias/genética , Carvão Vegetal , Esterco/microbiologia , RNA Ribossômico 16S/genética , Ovinos/genética , SoloRESUMO
Nanoparticles (NPs) are widely used for their special physical properties and released into the natural environment. When two types of NPs exist in the same environment, the presence of one type of NP may affect the properties of the other type of NP. This study investigated the toxic effects of multi-walled carbon nanotubes (MWCNTs) and copper oxide nanoparticles (CuO NPs) on Tetradesmus obliquus. Both NPs had toxic effects on algae, and the toxic effects of MWCNTs were significantly stronger than CuO NPs which the 96-hr median effective concentration to algae were 33.8 and 169.2 mg/L, respectively. Oxidative stress and cell membrane damage were the main reasons for the toxicity of NPs to algae, and they were concentration-dependent, and the existence of CuO NPs in some groups reduced cell membrane damage caused by MWCNTs which may because that CuO NPs formed heteroaggregation with MWCNTs, reducing the contact of nanoparticles with cell membranes, then reducing physical damage. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) results indicated cell damage, the heteroaggregation of MWCNTs-CuO NPs and obvious nanoparticles internalization. In some groups, the presence of CuO NPs significantly reduced reactive oxygen species (ROS) level induced by MWCNTs. However, for the highest concentration group, the ROS level was much higher than that of the two NPs alone treatment groups, which might be related to the high concentration of MWCNTs promoting the internalization of CuO NPs. MWCNTs and CuO NPs affected and interacted with each other, causing more complex toxic effects on aquatic organisms.
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Clorófitas/efeitos dos fármacos , Cobre , Nanopartículas Metálicas , Nanotubos de Carbono , Cobre/toxicidade , Água Doce , Nanopartículas Metálicas/toxicidade , Nanotubos de Carbono/toxicidade , Óxidos , Espécies Reativas de Oxigênio , Poluentes Químicos da Água/toxicidadeRESUMO
Recently, a large quantity of carbon nanotubes (CNTs) enters the environment due to the increasing production and applications. More and more researches are focused on the fate and possible ecological risks of CNTs. Some literatures summarized the effects of CNTs on the chemical behavior and fate of pollutants. However, little reviewed the effects of CNTs on the biodegradation of pollutants. In general, the effects of CNTs on the biodegradation of pollutants and the related mechanisms were summarized in this review. CNTs have positive or negative effects on the biodegradation of contaminants by affecting the functional microorganisms, enzymes and the bioavailability of pollutants. CNTs may affect the microbial growth, activity, biomass, community composition, diversity and the activity of enzymes. The decrease of the bioavailability of pollutants due to the sorption on CNTs also causes the reduction of the biodegradation of contaminants. In addition, the roles of CNTs are controlled by multiple mechanisms, which are divided into three aspects i.e., properties of CNTs, environment condition, and microorganisms themself. The better understanding of the fate of CNTs and their impacts on the biochemical process in the environment is conducive to determine the release of CNTs into the environment.
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Biodegradação Ambiental , Poluentes Ambientais , Nanotubos de Carbono , BiomassaRESUMO
Five biochars derived from lotus seedpod (LSP) were applied to examine and compare the adsorption capacity of 17ß-estradiol (E2) from aqueous solution. The effect of KOH activation and the order of activation steps on material properties were discussed. The effect of contact time, initial concentration, pH, ionic strength and humic acid on E2 adsorption were investigated in a batch adsorption process. Experimental results demonstrated that the pseudo second-order model fitted the experimental data best and that adsorption equilibrium was reached within 20â¯hr. The efficiency of E2 removal increased with increasing E2 concentration and decreased with the increase of ionic strength. E2 adsorption on LSP-derived biochar (BCs) was influenced little by humic acid, and slightly affected by the solution pH when its value ranged from 4.0 to 9.0, but considerably affected at pHâ¯10.0. Low environmental temperature is favorable for E2 adsorption. Chemisorption, π-π interactions, monolayer adsorption and electrostatic interaction are the possible adsorption mechanisms. Comparative studies indicated that KOH activation and the order of activation steps had significant impacts on the material. Post-treated biochar exhibited better adsorption capacity for E2 than direct treated, pre-treated, and raw LSP biochar. Pyrolyzed biochar at higher temperature improved E2 removal. The excellent performance of BCs in removing E2 suggested that BCs have potential in E2 treatment and that the biochar directly treated by KOH would be a good choice for the treatment of E2 in aqueous solution, with its advantages of good efficiency and simple technology.
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Estradiol/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Carvão Vegetal , Temperatura Alta , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Hidróxidos , Cinética , Lotus , Concentração Osmolar , Compostos de Potássio , Sementes , TemperaturaRESUMO
An easily separated photocatalyst, magnetic multi-walled carbon nanotubes/cerium dioxide (MMWCNTs-CeO2) nanocomposite, has been successfully prepared by hydrothermal synthesis and subsequent loading of magnetic nanoparticles. The synthesized nanocomposite was characterized by scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, and vibrating sample magnetometer. The characterization results indicated the successful synthesis of MMWCNTs-CeO2 nanocomposite. Photocatalytic degradation experiments were conducted to evaluate photocatalytic properties of MMWCNTs-CeO2 by using methylene blue (MB) as a model pollutant. After a light irradiation of two hours, relatively high degradation efficiency (97.5%) of MB was achieved by using MMWCNTs-CeO2 nanocomposite as photocatalyst in the presence of H2O2. The incorporation of magnetic nanoparticles could not only facilitate the separation of photocatalyst from the solution after treatment, but also enhance the photocatalytic degradation efficiency. The results of this study suggested that the synthesized MMWCNTs-CeO2 nanocomposite showed an attractive prospect for application in the treatment of organic wastewater.
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Cério/química , Magnetismo , Nanocompostos/química , Nanotubos de Carbono/química , Peróxido de Hidrogênio/química , Azul de Metileno/química , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Difração de Raios XRESUMO
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.
Assuntos
Antibacterianos/química , Grafite/química , Nanopartículas Metálicas/química , Óxidos/química , Prata/química , Purificação da Água/métodos , Catalase/metabolismo , Desinfecção , Escherichia coli/enzimologia , Concentração de Íons de Hidrogênio , Íons , Peroxidação de Lipídeos , Nanocompostos/química , Estresse Oxidativo , Espectroscopia Fotoeletrônica , Staphylococcus aureus/enzimologia , Superóxido Dismutase/metabolismo , Tioglicolatos/metabolismo , Águas Residuárias , Água/química , Microbiologia da ÁguaRESUMO
In mineral-rich areas, eutrophic lakes are at risk of HMs pollution. However, few papers focused on the repair of HMs in eutrophic environment. Our study analyzed multiple forms of HMs, pore structure and microbial responses in the water-sediment system of eutrophic lake treated with biochar, Effective Microorganisms (EMs) or/and microplastics (MPs). As biochar provided an ideal carrier for EMs, the remediation of biochar-supported EMs (BE) achieved the greatest repairment that improved the bacterial indexes and greatly decreased the most HMs in various forms across the water-sediment system, and it also reduced metal mobility, bioavailability and ecological risk. The addition of aged MPs (MP) stimulated the microbial activity and significantly reduced the HMs levels in different forms due to the adsorption of biofilms/EPS adhered on MPs, but it increased metals mobility and ecological risks. The strong adsorption and high mobility of aged MPs would increase enrichment of HMs and cause serious ecological hazards. The incorporation of BE and MP (MBE) also greatly reduced the HMs in full forms, which was primarily ascribed to the adsorption of superfluous biofilms/EPS, but it distinctly depressed the microbial activity. The single addition of biochar and EMs resulted in the inability of HMs to be adsorbed due to the preferentially adsorption of dissolved nutrients and the absence of effective carrier, respectively. In the remediation cases, the remarkable removal of HMs was principally accomplished by the adsorption of HMs with molecular weight below 100 kDa, especially 3 kDa â¼100 kDa, which had higher specific surfaces and abundant active matters, resulting in higher adsorption onto biofilms/EPS.
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Carvão Vegetal , Metais Pesados , Microplásticos , Plásticos , Lagos , Metais Pesados/análise , ÁguaRESUMO
DOM (dissolved organic matter) play a crucial role in lakes' geochemical and carbon cycles. Eutrophication evolution would influence nutrient status of waters and investigating the DOM variation helps a better understanding of bioremediation on environmental behavior of DOM in eutrophic lakes. In our study, the contents, compositions and characteristics of systematic DOM&SOM (sediment organic matter) were greatly influenced by seasonal changes. But the effective bioremediations obviously reduced the DOM concentration and thus mitigated the eutrophication outbreak risks in water bodies due to the increased MBC (microbial biomass carbon), microbial activity and metabolism. In early summer, the overall DOM in each treatment were readily low levels and derived from both autochthonous and exogenous origins, dominated by fulvic acid-like. In midsummer, the DOM contents and characteristics in each treatment increased significantly as phytoplankton activity improved, and the majority of DOM were humic acid-like and mainly of biological origin. The greatest differences of enzymes, MBC, microbial metabolism and DOM&SOM removal among different treatments were observed in summer months. In autumn, the systematic DOM&SOM slightly reduced due to the deceased microbial activity, in which the microbial humic acids were main component and derived from endogenous sources. Additionally, the gradually decreased SOM with cultivated time in each treatment was a result of microbiological conversion of SOM into DOM. For various treatments, BE, BE.A, BE.C and BE.E increased the MBC, enzymatic and microbial activities due to the application of biochar-supported EMs. Among these, BE and BE.A, especially BE.A with oxygen supplement, achieved the most desirable effect on reducing systematic DOM&SOM levels and increasing enzymatic and microbial activities. The group of EM also reduced the levels of DOM&SOM as improved degradation of EMs for DOM. However, BC, BE.C and BE.E finally did not achieved the desirable effect on reducing DOM&SOM due to the suppression of microbial activities, respectively, from high dose of biochar, weakening of dominant species and additional introduction of EMs in low liveness.
Assuntos
Matéria Orgânica Dissolvida , Lagos , Lagos/química , Estações do Ano , Carvão Vegetal , Substâncias Húmicas/análiseRESUMO
Heavy metals are still the critical pollutants in industrial wastewater and there is an urgent need for efficient and environmentally friendly treatment technologies. Reduced graphene oxide (rGO) is widely used for preparations of nanofiltration (NF) membranes but suffers from poor hydrophilicity and electronegativity. In this work, a double-charged rGO/g-C3N4-P membrane was prepared for removal of heavy metals at low pressure. Graphitic carbon nitride (g-C3N4) assisted reduction of GO membranes under ultraviolet (UV) irradiation, and the modification of functional groups with high polarity improved the hydrophilicity of membrane surface. The filtration performance for heavy metals of rGO/g-C3N4-P membrane was evaluated under low pressure (1-2 bar). The rejection rates of Cu2+, Cr3+, Mn2+, Cd2+, and Pb2+ by membranes reduced by UV for 18 h (rGO/g-C3N4-18-P membrane) reached 94.72 %, 98.05 %, 82.32 %, 88.2 % and 77.15 %, respectively. In the experiment of mixed simulated wastewater, the rejection rates of NO3- and SO42- both reached >95 %. Outstanding rejection rates were attributed to the interaction and the synergy effect of double-charged layers as well as steric effects. Meanwhile, the water flux of rGO/g-C3N4-18-P membrane was as high as 37.14-50.16 L m-2h-1bar-1 (1-2 bar). The high flux was due to the reduced degree of oxidation so that water molecules transported between GO nanochannels more smoothly and the transport path was shortened through the nanopores of g-C3N4. Obviously, flux and heavy metal rejection of rGO/g-C3N4-18-P membrane were simultaneously improved, breaking "trade-off" effect. Furthermore, rGO/g-C3N4-18-P membrane showed excellent antifouling ability and the potential for heavy metal wastewater filtration in comparison with other NF membranes reported in literature.
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Graphene oxide (GO) membranes have suffered from the instability of water permeability and low rejection of pollutant separation. In this paper, a reasonable modification protocol for GO nanosheets at the molecular level was proposed. A molecular cross-linking strategy was adopted to regulate the interlayer spacing of GO nanosheets, and nanofiltration membranes with high water stability and excellent antifouling capacity were prepared, which could effectively reject antibiotics and salts. The GO1-MPD0.5 (the mass ratio of GO nanosheets to MPD is 1:0.5) and GO/GO1-MPD0.5-0.25 (the doping ratio of GO1-MPD0.5 is 25%) membranes had stable water permeability of 4.22 ± 0.06 and 3.65 ± 0.11 L m-2 h-1 bar-1, and the rejection rates for ciprofloxacin (CIP) and ofloxacin (OFX) were 93.35 ± 3.62 and 95.48 ± 2.97 and 85.89 ± 6.52 and 88.21 ± 3.67%, respectively. Molecular dynamics simulations well explained the high water stability of membranes, and the cross-linked hydrophobic benzene ring played a role in the rejection of pollutant molecules. Moreover, the GO1-MPD0.5 membrane showed excellent antifouling capacity and the flux recovery ratio (FRR) was more than 98%. This paper provides a new idea for the design of nanofiltration membranes with high stability and good rejection permeability at the molecular level and provides a prospect for the application of nanofiltration membranes in practical water treatment and water purification.
Assuntos
Incrustação Biológica , Sais , Antibacterianos/farmacologia , Incrustação Biológica/prevenção & controle , PermeabilidadeRESUMO
For better sustainable resource recovery and elevating the separation efficiency of dye/salt mixture, it is essential to develop an appropriate nanofiltration membrane for the treatment of textile dyeing wastewater containing relatively smaller molecule dyes. In this work, a novel composite polyamide-polyester nanofiltration membrane was fabricated by tailoring amino functionalized quantum dots (NGQDs) and ß-cyclodextrin (CD). An in-situ interfacial polymerization occurred between the synthesized NGQDs-CD and trimesoyl chloride (TMC) on the modified multi-carbon nanotubes (MWCNTs) substrate. The incorporation of NGQDs significantly elevated the rejection (increased by â¼ 45.08%) of the resultant membrane for small molecular dye (Methyl orange, MO) compared to the pristine CD membrane at low pressure (1.5 bar). The newly developed NGQDs-CD-MWCNTs membrane exhibited enhanced water permeability without compromising the dye rejection compared to the pure NGQDs membrane. The improved performance of the membrane was primarily attributed to the synergistic effect of functionalized NGQDs and the special hollow-bowl structure of CD. The optimal NGQDs-CD-MWCNTs-5 membrane expressed pure water permeability of 12.35 L m-2h-1 bar-1 at the pressure of 1.5 bar. Noteworthily, the NGQDs-CD-MWCNTs-5 membrane not only showed high rejection for the larger molecular dye of Congo Red (CR, 99.50%) but also for the smaller molecular dye of MO (96.01%) and Brilliant Green (BG, 95.60%) with the permeability of 8.81, 11.40, and 6.37 L m-2h-1 bar-1, respectively at low pressure (1.5 bar). The rejection of inorganic salts by the NGQDs-CD-MWCNTs-5 membrane was 17.20% for sodium chloride (NaCl), 14.30% for magnesium chloride (MgCl2), 24.63% for magnesium sulfate (MgSO4), and 54.58% for sodium sulfate (Na2SO4), respectively. The great rejection of dyes remained in the dye/salt binary mixed system (higher than 99% for BG and CR, <21% for NaCl). Importantly, the NGQDs-CD-MWCNTs-5 membrane exhibited favorable antifouling performance and potential good operation stability performance. Consequently, the fabricated NGQDs-CD-MWCNTs-5 membrane suggested a prospective application for the reuse of salts and water in textile wastewater treatment owing to the effective selective separation performance.
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Dye/salt separation in textile wastewater is of great importance. Membrane filtration technology is an environmentally friendly and effective approach to solve this issue. In this study, a thin-film composite membrane with a tannic acid (TA)-modified carboxylic multiwalled carbon nanotube (MWCNT) interlayer (M-TA) was prepared by interfacial polymerization with amino-functionalized graphene quantum dots (NGQDs) acting as aqueous monomers. The addition of the M-TA interlayer favored the formation of a thinner, more hydrophilic, and smoother selective skin layer for the composite membrane. The pure water permeability of the M-TA-NGQDs membrane was â¼9.32 L m-2 h-1 bar-1, which was higher than that of the NGQDs membrane without the interlayer. Meanwhile, the M-TA-NGQDs membrane presented better methyl orange (MO) rejection (97.79%) than the NGQDs membrane (87.51%). The optimal M-TA-NGQDs membrane exhibited excellent dye rejection (Congo red (CR): 99.61%; brilliant green (BG): 96.04%) and low salt rejection (NaCl < 15%). Noticeably, the M-TA-NGQDs membrane displayed effective selective separation performance (CR and BG > 99%) for dye/NaCl mixed solutions even at a high NaCl concentration of 50,000 mg/L. Furthermore, the M-TA-NGQDs membrane presented high water permeability recovery ratio values (91.02-98.20%). Importantly, the M-TA-NGQDs membrane showed excellent chemical stability (acid/alkali resistance). Generally, the fabricated M-TA-NGQDs membrane exhibited a great prospect for applications in dye wastewater treatment and water recycling, especially for the effective selective separation of dye/salt mixtures for high-salinity textile dyeing wastewater.
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A nanofiltration membrane functionalized with metal-organic frameworks (MOFs) is promising to enhance micropollutant removal and realize wastewater reclamation. However, the current MOF-based nanofiltration membranes still suffer from severe fouling problems with an indefinable mechanism when used for antibiotic wastewater treatment. Hence, we report a nature-inspired MOF-based thin-film nanocomposite (TFN-CU) membrane to explore its rejection and antifouling behavior. Compared with unmodified membranes, the optimal TFN-CU5 membrane (with 5 mg·mL-1 C-UiO-66-NH2) had high water permeance (17.66 ± 1.19 L·m-2·h-1·bar-1), exceptional rejection for norfloxacin (97.92 ± 2.28%) and ofloxacin (95.36 ± 1.03%), and excellent long-term stability for treating synthetic secondary effluent with antibiotic rejection over 90%. Furthermore, it also showed superior antifouling capability (flux recovery up to 95.86 ± 1.28%) in bovine serum albumin (BSA) filtration after fouling cycles. Deriving from the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach, the antifouling mechanism between BSA and the TFN-CU5 membrane was mainly attributed to the inhibited adhesion forces because the growing short-ranged acid-base interaction caused repulsive interfacial interactions. It is further revealed that BSA fouling behavior is slightly retarded under an alkaline environment, while strengthened in the presence of calcium ions and humic acid, as well as high ionic strength. In short, the nature-inspired MOF-based TFN membranes possess exceptional rejection and organic fouling resistance, giving insights into the design of antifouling membranes during antibiotic wastewater reclamation.
Assuntos
Estruturas Metalorgânicas , Nanocompostos , Águas Residuárias , Fluoroquinolonas , Antibacterianos/farmacologia , Membranas ArtificiaisRESUMO
This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups, on the surface of iron oxide magnetic nanoparticles. Transmission Electron Microscopy (TEM) imaging showed shellac-coated magnetic nanoparticle (SCMN) adsorbents had a core-shell structure with a core of 20 nm and shell of 5 nm. Fourier Transform Infrared Spectroscopic analysis suggested the occurrence of reaction between carboxyl groups on the SCMN adsorbent surface and cadmium ions in aqueous solution. Kinetic data were well described by pseudo second-order model and adsorption isotherms were fitted with both Langmuir and Freundlich models with maximum adsorption capacity of 18.80 mg/g. SCMN adsorbents provided a favorable adsorption capacity under high salinity conditions, and cadmium could easily be desorbed using mild organic acid solutions at low concentration.
Assuntos
Cádmio/isolamento & purificação , Compostos Férricos/química , Nanopartículas/química , Resinas Vegetais/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Cloreto de Sódio/química , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Purificação da ÁguaRESUMO
The ability of microplastics (MPs) to interact with environmental pollutants is of great concern. Riverine sediments, as sinks for multi-pollutants, have been rarely studied for MPs risk evaluation. Meanwhile, MPs generated from biodegradable plastics are questioning the safety of the promising materials. In this study, we investigated the effects of typical non-degradable polyethylene (PE) and biodegradable polylactic acid (PLA) MPs on sediment enzymes, arsenic (As) fractionation, and microbial community structures in As-contaminated riverine sediments. The results indicated that the presence of MPs (1% and 3%, w/w) led As transformed into more labile and bioavailable fractions in riverine sediments, especially under higher As and MPs levels. Analysis on microbial activities and community structures confirmed the strong potential of MPs in inhibiting microbial activities and shifting bacterial community succession patterns through enrichment of certain microbiota. Moreover, biodegradable PLA MPs presented stronger alterations in arsenic fractionation and microbial community structures than PE MPs did, which might be jointly attributed to adsorption behaviors, microbial alterations, and potential PLA degradation behaviors. The study indicated that MPs contamination increased As mobility and bioavailability, and shifted microbial communities in riverine sediments. Moreover, biodegradable MPs might lead to stronger microbial alterations and increases in As bioavailability, acting as a threat to ecological safety, which needed further exploration.
Assuntos
Arsênio , Microbiota , Poluentes Químicos da Água , Arsênio/análise , Arsênio/toxicidade , Microplásticos/toxicidade , Plásticos , Poliésteres , Polietileno , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidadeRESUMO
Proper treatment of wastewater is one of the key issues to the sustainable development of human society, and people have been searching for high-efficiency and low-cost methods for wastewater treatment. This article reviews recent studies about pyrite-mediated advanced oxidation processes (AOPs) in removing refractory organics from wastewater. The basic information of pyrite and its characteristics for AOPs are first introduced. Then, the performance and mechanisms of pyrite-mediated Fenton oxidation, electro-Fenton oxidation, and persulfate oxidation processes are carefully reviewed and presented. Natural pyrite is an abundant low-cost heterogeneous catalyst for AOPs, and the slow release of Fe2+ and the self-regulation of solution pH are highlighted characteristics of pyrite-mediated AOPs. In AOPs, the interaction between Fe3+ and pyrite facilitates the Fe2+ regeneration and the Fe2+/Fe3+ cycle. Making pyrite into nanoparticles, assisting by ultrasound and light irradiation, and adding exogenous Fe3+, organic chelating agents, or biochar is effective to enhance the performance of pyrite-mediated AOPs. Based on the analyses of those pyrite-mediated AOPs and their enhancing strategies, the future development directions are proposed in the aspects of toxicity research, mechanism research, and technological coupling.
Assuntos
Poluentes Químicos da Água , Purificação da Água , Humanos , Peróxido de Hidrogênio , Ferro , Oxirredução , Sulfetos , Poluentes Químicos da Água/análiseRESUMO
Thin-film nanocomposite (TFN) membranes with efficient molecular separation and organic solvent resistance are active in demand in wastewater treatment and resource reclamation, meeting the goal of emission peaks and carbon neutrality. In this work, a simple and rational design strategy has been employed to construct a sandwich-structured membrane for removing fluoroquinolone antibiotics and recycling organic solvents. The sandwich-structured membrane is composed of a porous substrate, a hydrophilic tannic acid-polyethyleneimine (TA-PEI) interlayer, and a polyamide (PA) selective layer decorated with metal-organic framework (PA-MOF). Results manifest that the hydrophilic TA-PEI interlayer played a bridging and gutter effect to achieve effective control in amide storage, amine diffusion, and nanomaterial downward leakage at the immiscible interface. The PA-MOF selective layer has been changed to a loosely crumpled surface, endowing functionalities on the sandwich-structured membrane that included limited pores, strengthened electronegativity, and stronger hydrophilicity. Thus, an enhanced water flux of 87.23 ± 7.43 LMH was achieved by the TFN-2 membrane (0.04 mg·mL-1 UiO-66-NH2), which is more than five times that of the thin-film composite membrane (17.46 ± 3.88 LMH). The rejection against norfloxacin, ciprofloxacin, and levofloxacin is 92.94 ± 1.60%, 94.62 ± 1.29%, and 96.92 ± 1.05%, respectively, effectively breaking through the "trade-off" effect between membrane permeability and rejection efficiency. Further antifouling results showed that the sandwich-structured membrane had lower flux decay ratios (3.36â¼7.07%) and higher flux recovery ratios (93.40â¼98.40%), as well as superior long-term stability after 30 days of filtration. Moreover, organic solvent resistance testing confirms that the sandwich-structured membrane maintained stable solvent flux and better recovery rates in ethanol, acetone, isopropanol, and N,N-dimethylformamide. Detailed nanofiltration mechanism studies revealed that these outstanding performances are based on the joint effect of the TA-PEI interlayer and PA-MOF selective layer, proposing a new perspective to break through the bottleneck of nanofiltration application in a complex environment.
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Antibacterianos , Membranas Artificiais , Filtração/métodos , Estruturas Metalorgânicas , Nylons/química , Ácidos Ftálicos , SolventesRESUMO
Pyrite and engineering carbon materials have received increasing attention for their catalytic potential in Fenton reactions due to their extensive sources and low cost. However, effects of carbon materials on the degradation of pollutants by pyrite-catalyzed heterogeneous Fenton oxidation have not been fully understood. In this study, the performance of pyrite-catalyzed heterogeneous Fenton system on the degradation of ciprofloxacin (CIP) was investigated in the presence of activated carbon (AC), biochar (BC), and carbon nanotubes (CNTs). Synchronous and asynchronous experiments (adsorption and catalysis) were conducted to elucidate the roles of the carbon materials in pyrite-catalyzed Fenton reactions. The results demonstrated that all the three carbon materials accelerated the pyrite-catalyzed Fenton oxidation of CIP. Under the experimental conditions, the reaction rates, which were obtained by fitting the synchronous experimental results with the pseudo-first-order kinetic model, of pyrite/AC, pyrite/BC and pyrite/CNTs with H2O2 for the removal of CIP were 8.28, 3.40 and 3.37 times faster than that of pyrite alone. Adsorption experiments and characterization analysis showed that AC had a higher adsorption capacity than BC and CNTs for CIP, which enabled it to distinguish itself in assisting the pyrite-catalyzed Fenton oxidation. In the presence of the carbon materials, the adsorption effect should not be neglected when studying the catalytic performance of pyrite. Free radical quenching experiments and electron spin-resonance spectroscopy (ESR) were used to detect and identify free radical species in the reactions. The results showed that hydroxyl radicals (â¢OH) contributed significantly to the degradation of CIP. The addition of carbon materials promoted the production of â¢OH, which favored the degradation of CIP. The results of this study suggested that the synergistic effect of oxidation and adsorption promoted the removal of CIP in pyrite/carbon materials/H2O2 systems, and coupling pyrite and carbon materials shows great potential in treating antibiotic wastewater.
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Nanotubos de Carbono , Poluentes Químicos da Água , Antibacterianos , Catálise , Carvão Vegetal/química , Ciprofloxacina/química , Peróxido de Hidrogênio/química , Ferro , Oxirredução , Sulfetos , Águas Residuárias , Poluentes Químicos da Água/químicaRESUMO
The natural environment is a complex system, and there is never only one kind of nanomaterial entering the environment. However, many studies only considered the plant toxicity of one kind of nanomaterial and do not consider the influence of two or more kinds of nanomaterials on plant toxicity. Multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanoparticles (ZnO NPs) are two common and widely used nanomaterials in water environment, so these two kinds of nanomaterials were chosen to explore the effects of their combined toxicity on cabbage. This study investigated the toxicity of MWCNTs combined with ZnO NPs on cabbage by measuring the length of roots and stems, chlorophyll content, oxidative stress, antioxidant enzyme activity, metal element content, and root scanning electron microscopy. The toxicity of single MWCNTs toward cabbage was attributed to direct oxidative damage, while the toxicity of single ZnO NPs toward cabbage was due to the high level of zinc concentration. Moreover, ZnO NPs (10 mg/L) ameliorated MWCNTs toxicity toward cabbage by improving the activity of antioxidant enzymes. ZnO NPs (50 and 100 mg/L) because of the high content of zinc disrupted the balance of other metals in the plant and increased the toxicity of MWCNTs. In conclusion, the combined toxicity of different concentrations and types of nanomaterials should be considered for a more accurate assessment of environmental risks.
Assuntos
Brassica , Nanopartículas , Nanotubos de Carbono , Óxido de Zinco , Antioxidantes/metabolismo , Brassica/metabolismo , Nanotubos de Carbono/toxicidade , Estresse Oxidativo , Óxido de Zinco/toxicidadeRESUMO
Plastic discharged into the environment would break down into microplastics (MPs). However, the possible impact of MPs on heavy metals in the aquatic sediment remains unknown. In order to evaluate the potential role of MPs as carriers of coexisting pollutants, the adsorption capacity of lead ions from sediment onto aged degradable and conventional MPs were investigated as a function of lead ions concentration, contact time, temperature, MPs dosage, aging time, and fulvic acid concentration. MPs were exposed to UV to obtain aged polyethylene (A-PE) and aged polylactic acid (A-PLA). The aging treatment increased the oxygen content, specific surface area and hydrophilicity of MPs. The adsorption capacity of A-PE for Pb(II) in sediment increased from 10.1525 to 10.4642 mg g-1 with the increasing aging time. However, the adsorption capacity of A-PLA for Pb(II) in sediment decreased from 9.3199 to 8.7231 mg g-1 with the increasing aging time. The adsorption capacity of MPs in sediment for Pb(II) was in the following order: A-PE > PLA > PE > A-PLA. Fulvic acid could promote the adsorption of Pb(II) by MPs in sediment. These results indicated that the aging process of the plastics in the environment would affect its role as a carrier of coexisting pollutants.