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1.
Environ Toxicol ; 39(4): 2350-2362, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38156432

RESUMO

The widespread presence of microplastics (MPs) in the environment poses a significant threat to biological survival and human health. However, our understanding of the toxic effects of MPs on the kidneys remains limited. This study aimed to investigate the underlying mechanism of the toxic effects of MPs on the kidneys using an ischemia-reperfusion (IR) mouse model. Four-week-old ICR mice were exposed to 0.5 µm MPs for 12 weeks prior to IR injury. The results showed that MPs exposure could aggravate the IR-induced damage to renal tubules and glomeruli. Although there were no significant changes in blood urea nitrogen and serum creatinine levels 7 days after IR, MPs treatment resulted in a slight increase in both parameters. In addition, the expression levels of inflammatory factors (MCP-1 and IL-6) at the mRNA level, as well as macrophage markers (CD68 and F4/80), were significantly higher in the MPs + IR group than in the Sham group after IR. Furthermore, MPs exposure exacerbated IR-induced renal fibrosis. Importantly, the expression of pyroptosis-related genes, including NLRP3, ASC, GSDMD, cleaved caspase-1, and IL-18, was significantly upregulated by MPs, indicating that MPs exacerbate pyroptosis in the context of renal IR. In conclusion, our findings suggest that MPs exposure can aggravate renal IR-induced pyroptosis by activating NLRP3-GSDMD signaling.


Assuntos
Proteína 3 que Contém Domínio de Pirina da Família NLR , Traumatismo por Reperfusão , Humanos , Camundongos , Animais , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Microplásticos , Plásticos/metabolismo , Camundongos Endogâmicos ICR , Rim/metabolismo , Traumatismo por Reperfusão/genética
2.
Environ Toxicol ; 39(2): 1018-1030, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38064261

RESUMO

In recent years, microplastics (MPs) have gained significant attention as a persistent environmental pollutant resulting from the decomposition of plastics, leading to their accumulation in the human body. The liver, particularly of individuals with type 2 diabetes mellitus (T2DM), is known to be more susceptible to the adverse effects of environmental pollutants. Therefore, to investigate the potential impact of MPs on the liver of diabetic mice and elucidate the underlying toxicological mechanisms, we exposed db/db mice to 0.5 µm MPs for 3 months. Our results revealed that MPs exposure resulted in several harmful effects, including decreased body weight, disruption of liver structure and function, elevated blood glucose levels, impaired glucose tolerance, and increased glycogen accumulation in the hepatic tissue of the mice. Furthermore, MPs exposure was found to promote hepatic gluconeogenesis by perturbing the PP2A/AMPK/HNF4A signaling pathway. In addition, MPs disrupt redox balance, leading to oxidative damage in the liver. This exposure also disrupted hepatic lipid metabolism, stimulating lipid synthesis while inhibiting catabolism, ultimately resulting in the development of fatty liver. Moreover, MPs were found to induce liver fibrosis by activating the Wnt/ß-catenin signaling pathway. Furthermore, MPs influenced adaptive thermogenesis in brown fat by modulating the expression of uncoupling protein 1 (UCP1) and genes associated with mitochondrial oxidative respiration thermogenesis in brown fat. In conclusion, our study demonstrates that MPs induce oxidative damage in the liver, disturb glucose and lipid metabolism, promote hepatic fibrosis, and influence adaptive thermogenesis in brown fat in diabetic mice. These findings underscore the potential adverse effects of MPs on liver health in individuals with T2DM and highlight the importance of further research in this area.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Camundongos , Humanos , Animais , Diabetes Mellitus Tipo 2/metabolismo , Microplásticos , Plásticos/metabolismo , Plásticos/farmacologia , Proteínas Quinases Ativadas por AMP/metabolismo , Via de Sinalização Wnt , Diabetes Mellitus Experimental/metabolismo , beta Catenina/genética , beta Catenina/metabolismo , Fibrose , Fígado , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Fator 4 Nuclear de Hepatócito/metabolismo
3.
Ecotoxicol Environ Saf ; 267: 115618, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37939553

RESUMO

Nanoplastics (NPs) and Microplastics (MPs) pollution has become a severe threat to the planet and is a growing concern. However, their effects on male reproductive toxicity remain poorly understood. In this study, a series of morphological analyses were completed to explore the influence of NPs and MPs exposure on the testis in mice. After 12-weeks exposure, although both NPs and MPs exposure can lead to reproductive toxicity, compared with NPs exposure, exposure to MPs leads to a more significant increase in reproductive toxicity dependent on some particle size. Moreover, increased reproductive toxicities, including increased spermatogenesis disorders, and sperm physiological abnormality, oxidative stress, testis inflammation was more associated with MPs group than NPs group. Ultra-pathological structure observed by transmission electron microscopy indicated that both NPs and MPs have different effects on spermatogonia, spermatocytes and Sertoli cells. Exposure to MPs resulted in decreased Sertoli cell numbers and reduced Leydig cell area, and showed no effects on differentiation of Leydig cells by the expression level of the Insulin-Like factor 3 (INSL3) in Leydig cells. Transcriptomic sequencing analysis provided valuable insights into the differential effects of NPs and MPs on cellular processes. Specifically, our findings demonstrated that NPs were predominantly involved in the regulation of steroid biosynthesis, whereas MPs primarily influenced amino acid metabolism. This study demonstrates the effect of adult-stage reproductive toxicity in mice after exposure to NPs and MPs, which will deep the understanding of the NPs and MPs induced toxicity.


Assuntos
Microplásticos , Testículo , Masculino , Animais , Camundongos , Microplásticos/toxicidade , Plásticos , Sêmen , Espermatozoides
4.
BMC Plant Biol ; 19(1): 272, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31226952

RESUMO

BACKGROUND: Cyclophilins (CYPs), belonging to the peptidyl prolyl cis/trans isomerase (PPIase) superfamily, play important roles during plant responses to biotic and abiotic stresses. RESULTS: Here, a total of 79 CYPs were identified in the genome of Gossypium hirsutum. Of which, 65 GhCYPs only contained one cyclophilin type PPIase domain, others 14 GhCYPs contain additional domains. A number of cis-acting elements related to phytohormone signaling were predicated in the upstream of GhCYPs ORF. The expression analysis revealed that GhCYPs were induced in response to cold, hot, salt, PEG and Verticillium dahliae infection. In addition, the functional importance of GhCYP-3 in Verticillium wilt resistance was also presented in this study. GhCYP-3 showed both cytoplasmic and nuclear localization. Overexpression of GhCYP-3 in Arabidopsis significantly improved Verticillium wilt resistance of the plants. Recombinant GhCYP-3 displayed PPIase activity and evident inhibitory effects on V. dahliae in vitro. Moreover, the extracts from GhCYP-3 transgenic Arabidopsis displayed significantly inhibit activity to conidia germinating and hyphal growth of V. dahliae. CONCLUSIONS: Our study identified the family members of cotton CYP genes using bioinformatics tools. Differential expression patterns of GhCYPs under various abiotic stress and V. dahliae infection conditions provide a comprehensive understanding of the biological functions of candidate genes. Moreover, GhCYP-3 involved in the resistance of cotton to V. dahliae infection presumably through antifungal activity.


Assuntos
Ciclofilinas/genética , Resistência à Doença/genética , Gossypium/genética , Doenças das Plantas/microbiologia , Verticillium , Sequência de Aminoácidos , Arabidopsis/genética , Clonagem Molecular , Sequência Conservada , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Humanos , Doenças das Plantas/genética , Reguladores de Crescimento de Plantas/metabolismo , Alinhamento de Sequência , Estresse Fisiológico , Transcriptoma
5.
Environ Sci Technol ; 52(14): 7876-7883, 2018 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-29905472

RESUMO

Layered FeII-FeIII hydroxide chloride (chloride green rust, GRCl) has high reactivity toward reducible pollutants such as chlorinated solvents. However, this reactive solid is prone to dissolution, and hence loss of reactivity, during storage and handling. In this study, adsorption of silicate (Si) to GRCl was tested for its ability to minimize GRCl dissolution and to inhibit reduction of carbon tetrachloride (CT). Silicate adsorbed with high affinity to GRCl yielding a sorption maximum of 0.026 g of Si/g of GRCl. In the absence of Si, the pseudo-first-order rate constant for CT dehalogenation by GRCl was 2.1 h-1, demonstrating very high reactivity of GRCl but with substantial FeII dissolution up to 2.5 mM. When Si was adsorbed to GRCl, CT dehalogenation was blocked and FeII dissolution extent was reduced by a factor of 28. The addition of glycine (Gly) was tested for reactivation of the Si-blocked GRCl for CT dehalogenation. At 30 mM Gly, partial reactivation of the GRCl was observed with pseudo-first-order rate constant for CT reduction of 0.075 h-1. This blockage and reactivation of GRCl reactivity demonstrates that it is possible to design a switch for GRCl to control its stability and reactivity under anoxic conditions.


Assuntos
Tetracloreto de Carbono , Ferro , Compostos Ferrosos , Glicina , Hidróxidos , Oxirredução , Silicatos
6.
Bioresour Technol ; 406: 130979, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38879054

RESUMO

Addressing the drawbacks of traditional flocculants on microalgae biomass harvesting is crucial for large-scale industrial applications of microalgae production. In this study, cationic bioflocculant was successfully prepared by introducing cationic groups into the side chain of guar gum, achieving in-situ algae flocculation efficiency of 83.5 % with the dosage of 18.0 mg/L under pH = 10.0. Through a harmonious integration of predictive modelling and practical experimentation, a superior cell flocculation capacity of 23.5 g/g was achieved. In addition, the environmental safety and biocompatibility of cationic guar gum was assessed, using the typical suspension quantitative bacteriostatic method and the fluorescent double-staining technique. The results showed that the inhibition efficiency of Staphylococcus aureus in the system containing 60.0 mg/L cationic guar gum was only 12.0 % and there was no inhibition against Escherichia coli colonies. These findings provide a safe and green flocculant for efficient microalgae harvesting and spent medium treatment.


Assuntos
Cátions , Floculação , Galactanos , Mananas , Microalgas , Gomas Vegetais , Galactanos/farmacologia , Galactanos/química , Gomas Vegetais/química , Gomas Vegetais/farmacologia , Floculação/efeitos dos fármacos , Mananas/farmacologia , Mananas/química , Microalgas/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Concentração de Íons de Hidrogênio
7.
Water Res ; 256: 121589, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38608620

RESUMO

Fe2+ is usually adsorbed to the surface of iron-bearing clay, and iron (hydr)oxide in groundwater. However, the reductive activity of Fe(OH)2, a prevalent intermediate during the transformation of Fe2+, remains unclear. In this study, high-purity Fe(OH)2 was synthesized and tested for its activity in the degradation of carbon tetrachloride (CT). XRD data confirm that the synthesized material is a pure Fe(OH)2 crystal, exhibiting sharp peaks of (001) and (100) facets. Zeta potential analysis confirms that the off-white Fe(OH)2 is a colloidal suspension with a positive charge of ∼+35-50 mV. FTIR spectra reveal the formation of a coordination compound Fe2+ with OH-/OD-, derived from NaOH/OD. SEM and HRTEM results demonstrate that the Fe(OH)2 crystal has a regular octahedral structure with a size of ∼30-70 nm and average lattice spacings of 2.58 Å. Mössbauer spectrum verifies that the Fe2+ in Fe(OH)2/Fe(OD)2 is hexacoordinated with six Fe-O bonds. XAFS data demonstrate that the Fe-O bonds become shorter as the OH-:Fe(II) ratios increase. DFT results indicate that the (100) crystal face of Fe(OH)2 more readily transfers electrons to CT. In addition to being adsorbed to iron compounds, structural Fe2+ compounds such as Fe(OH)2 could also accelerate the electron transfer from Fe2+ to CT through shortened Fe-O bonds. The rate constant of CT reduction by Fe(OH)2 is as high as 0.794 min-1 when the OH-:Fe(II) ratio is 2.5 in water. This study aims to enhance our understanding of the structure-reactivity relationship of Fe2+ compounds in groundwater, particularly in relation to electron transfer mechanisms.


Assuntos
Coloides , Coloides/química , Ferro/química , Oxirredução , Compostos Férricos/química , Halogenação , Água Subterrânea/química
8.
Water Res ; 254: 121342, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38428238

RESUMO

The coordination environment of Fe(II) significantly affect the reductive reactivity of Fe(II). Lactate is a common substrate for enhancing microbial dechlorination, but its effect on abiotic Fe(II)-driven reductive dechlorination is largely ignored. In this study, the structure-reactivity relationship of Fe(II) is investigated by regulating the ratio of lactate:Fe(II). This work shows that lactate-Fe(II) complexing enhances the abiotic Fe(II)-driven reductive dechlorination with the optimum lactate:Fe(II) ratio of 10:20. The formed hydrogen bond (Fe-OH∙∙∙∙∙∙O = C-) and Fe-O-C metal-ligand bond result in a reduced Fe(II) coordination number from six to four, which lead to the transition of Fe(II) coordination geometry from octahedron to tetrahedron/square planar. Coordinatively unsaturated Fe(II) results in the highest reductive dechlorination reactivity towards carbon tetrachloride (k1 = 0.26254 min-1). Excessive lactate concentration (> 10 mM) leads to an increased Fe(II) coordination number from four to six with a decreased reductive reactivity. Electrochemical characterization and XPS results show that lactate-Fe(II)-I (C3H5O3-:Fe(II) = 10:20) has the highest electron-donating capacity. This study reveals the abiotic effect of lactate on reductive dechlorination in a subsurface-reducing environment where Fe(II) is usually abundant.


Assuntos
Ácido Láctico , Metais , Tetracloreto de Carbono/química , Compostos Ferrosos
9.
Bioresour Technol ; 393: 130135, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38043688

RESUMO

Alterations in microbial community succession patterns and enzyme activities by petroleum pollutants during co-composting of straw and swine manure with the supplementary nitrogen source are unclear. In this study, urea was added into co-composting systems, and the removal performance of petroleum, microbial enzyme activity and community changes were investigated. Results showed that the polyphenol oxidase and catalase activities which were both related to the degradation of petroleum contaminants were accordingly increased from 20.65 to 30.31 U/g and from 171.87 to 231.86 U/g due to urea addition. The removal efficiency of petroleum contaminants in composting with urea increased from 45.06% to 82.29%. The addition of urea increased the diversity and abundance of petroleum-degrading microorganisms, and enhanced microbial linkages. This study provides a novel strategy for the degradation of petroleum hydrocarbon as well as a new insight into the effect of urea on both microbial processes and composting phases.


Assuntos
Compostagem , Microbiota , Petróleo , Suínos , Animais , Esterco , Solo
10.
Sci Total Environ ; 931: 172825, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38692311

RESUMO

Carbonaceous materials catalyze reductive dechlorination of chlorinated ethylenes (CEs) by iron(II) materials providing a new approach for the remediation of CE polluted groundwater. While most CEs are reduced via ß-elimination, vinyl chloride (VC), the most toxic and recalcitrant CE, degrades by hydrogenolysis. The significance of carbon catalysts for reduction of VC is well documented for iron(0) systems, but hardly investigated with iron(II) materials as reductants. In this study, a layered iron(II)­iron(III) hydroxide sulfate (green rust) was used as reductant for VC, with an N-doped graphene (NG), prepared by co-pyrolysis of graphene and urea, as catalyst. VC (80 µM) was completely reduced to ethylene within 336 h in the presence of 5 g Fe/L GR and 5 g/L NG pyrolyzed at 950 °C, following pseudo-first-order kinetics with a rate constant of 0.017 h-1. Dosing experiments demonstrated that dechlorination of VC takes place on the NG phase. Monitoring of hydrogen formation, cyclic voltammetry, and quenching experiments demonstrated that atomic hydrogen contributes significantly to the dehalogenation reaction, where NG is critical for formation of atomic hydrogen. CE competition experiments demonstrated the presence of specific VC reduction sites with hydrogenolysis being unaffected by concurrent ß-elimination reactions. The system exhibited excellent performance in natural groundwaters and in comparison with iron(0) systems. This study demonstrates that GR + NG is a promising system for remediation of VC contaminated groundwater, and the mechanistic part of the study can be used as a reference for subsequent studies.

11.
Chemosphere ; 361: 142563, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38851498

RESUMO

In this study, the growth characteristics of microalgae cultured with different carbon sources were analyzed, and the flocculation characteristics under the influence of carbon sources were evaluated using three typical flocculants. The results showed that the organic carbon sources could significantly increase the content of extracellular proteins in microalgae. Specifically, the extracellular protein concentrations of microalgae cultured with pure BG-11, ethanol, sodium acetate and glucose were 18.2 29.2, 97.3, and 34.7 mg/g, respectively. During the flocculation process, microalgae cultured with sodium acetate exhibited a weak response to the flocculant because of excessive extracellular proteins inhibited flocculation. In addition, the flocculation efficiency was also less than 50.0% cultured with sodium acetate in all pH test ranges when alum and chitosan were used as flocculants. It could be inferred that the flocculant initially happened to charge neutralization with the negatively charged proteins in the solution and then bridged the charges with the microalgae. These findings provide insights into the effects of different carbon sources on microalgal flocculation, promising organic integration of microalgae wastewater treatment and harvesting.


Assuntos
Carbono , Chlorella , Floculação , Microalgas , Chlorella/crescimento & desenvolvimento , Carbono/química , Microalgas/crescimento & desenvolvimento , Quitosana/química , Acetato de Sódio/química , Águas Residuárias/química , Glucose , Concentração de Íons de Hidrogênio , Etanol/química , Eliminação de Resíduos Líquidos/métodos
12.
Water Res ; 245: 120636, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37748348

RESUMO

Labile Fe(III) phase (includes Fe(III)aq, Fe(III)ads, or Fe(III)s species) is an important intermediate during the interaction between Fe(II) and Fe(III) (oxyhydr)oxides, but how does labile Fe(III) influence the electron transfer from Fe(II) to oxidant environmental pollutant during this Fe(II)-Fe(III) interaction is unclear. In this work, the dynamic change of Fe(II,III) (oxyhydr)oxides at the same time scale is simulated by synthesizing Fe(III)-Fe(II)-I (Fe(III)+NaOH+Fe(II)+NaOH) with different Fe(II)/Fe(III) ratios. CCl4 is used as a convenient probe to test the reduction kinetics of mixed valence Fe(II,III)(oxyhydr)oxides with different Fe(II):Fe(III) ratios. The Mössbauer spectra results reveal the Fe(III)labile in the solid phase is in octahedral coordination. The electron-donating capability of Fe(II) was improved with increasing Fe(III) content, but suppressed when [Fe(III)] ≥ 30 mM. The reductive dechlorination of CT by Fe(III)-Fe(II)-I decreased gradually with the increase of Fe(III) content, because more amount Fe(III)labile in solid phase is accumulated. This shows that the electron transfer from Fe(II) to Fe(III)labile rather than to CT is enhanced with increasing Fe(III) content. FTIR data shows that the hydroxylation of Fe(II) with Fe(OH)3 occurs preferentially in the non-hydrogen bonded hydroxyl group, causing the decrease of its reductive reactivity. The presence of [Fe(III)-O-Fe(II)]+ in Fe(III)-Fe(II)-I can stabilize the dichlorocarbene anion (:CCl2-), favouring the conversion of CT to CH4 (13.1%). The aging experiment shows that Fe(III)labile surface may maintain the reductive reactivity of Fe(II) during aging when [Fe(III)] = 5-20 mM. This study deepens our understanding of the mass transfer pathway of iron oxyhydroxides induced by Fe(II) and its impact on the reductive dechlorination of CT.

13.
Water Res ; 228(Pt A): 119386, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36427462

RESUMO

Fe(II) and silicate can form Si-Fe(II) co-precipitates in anoxic groundwater and sediments, but their phase composition and reactivity towards subsurface pollutants are largely unknown. Three types of Si-Fe(II) co-precipitations with the same chemical composition, namely Si-Fe(II)-I, Si-Fe(II)-II, and Si-Fe(II)-III, have been synthesized by different hydroxylation sequences in this work. It was found that Si-Fe(II)-III reduce carbon tetrachloride (CT) much faster (k1=0.04419 min-1) than Si-Fe(II)-I (0 min-1) and Si-Fe(II)-II (7.860 × 10-4 min-1). XRD results show that the main component of Si-Fe(II)-III is ferrous silicate (FeSiO3), which is quite different from that of Si-Fe(II)-I and Si-Fe(II)-II. The unique arrangement of hydroxyl coordination, the less distorted octahedral structure, the polyhedral morphology and the absence of Si-A center vacancies in Si-Fe(II)-III are responsible for its high reductive dehalogenation reactivity. The highest redox activity of Si-Fe(II)-III was shown by electrochemical characterization. The [FeII-O-Si]+ in Si-Fe(II)-III may stabilize the dichlorocarbene anion (˸CCl2-), which favors the transformation of CT to methane (9.2%). The Si-Fe(II) co-precipitates consist of countless internal electric fields, and the transformation of hydroxyl and CT both consumed electrons. The coexistence of hydroxyl and CT increases the electron density in the electron-rich region due to their electronegativity, enhancing their electron-accepting capabilities. This study deepens our understanding of the phase composition and electronic structure of Si-Fe(II) co-precipitates, which fills the gap in the reductive dehalogenation of halides by Si-Fe(II) co-precipitates.


Assuntos
Eletricidade , Água Subterrânea , Tetracloreto de Carbono , Elétrons , Radical Hidroxila , Compostos Ferrosos
14.
J Hazard Mater ; 458: 131872, 2023 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-37379598

RESUMO

Humic acid (HA) and ferrous minerals (e.g. green rust, GR) are abundant in groundwater. HA acts as a geobattery that take up and release electrons in redox-alternating groundwater environments. However, the impact of this process on the fate and transformation of groundwater pollutants is not fully understood. In this work, we found that the adsorption of HA on GR inhibited the adsorption of tribromophenol (TBP) under anoxic conditions. Meanwhile, GR could donate electrons to HA, causing the electron donating capacity of HA rapidly increase from 12.7% to 27.4% in 5 min. The electron transfer process from GR to HA significantly increased the yield of hydroxyl radicals (•OH) and the degradation efficiency of TBP during GR-involved dioxygen activation process. Compared to the limited electronic selectivity (ES) of GR for •OH production (ES = 0.83%), GR-reduced HA improves the ES by an order of magnitude (ES = 8.4%). HA-involved dioxygen activation process expands the •OH generation interface from solid phase to aqueous phase, which is conducive to the degradation of TBP. This study not only deepens our understanding on the role of HA in •OH production during GR oxygenation, but also provides a promising approach for groundwater remediation under redox-fluctuating conditions.

15.
Bioresour Technol ; 384: 129352, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37336459

RESUMO

Microalgae cultivation for biodiesel production is promising, but the high demand for nutrients, such as nitrogen and phosphorus, remains a limiting factor. This study investigated effects of struvite, a low-cost nutrient source, on microalgae production under different physiological phases. Changes in element concentrations were determined to characterize the controllable nutrient release properties of struvite. Results showed that nutrient elements could be effectively supplemented by struvite. However, responses of microalgae under different growth stages to struvite varied obviously, achieving the highest biomass (0.53 g/L) and the lowest (0.32 g/L). Moreover, the microalgal lipid production was obviously increased by adding struvite during the growth phase, providing the first evidence that struvite could serve as an alternative buffering nutrient source to culture microalgae. The integration of microalgae cultivation with struvite as a buffering nutrient source provides a novel strategy for high ammonia nitrogen wastewater treatment with microalgae for biodiesel production.


Assuntos
Microalgas , Águas Residuárias , Estruvita , Biomassa , Biocombustíveis , Fósforo , Nutrientes , Lipídeos , Nitrogênio/análise
16.
Sci Total Environ ; 824: 153825, 2022 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35157856

RESUMO

Carbonous materials were found to catalyze the dechlorination of trichloroethylene (TCE) by green rust (GR), but the catalytic mechanism was not fully understood. We have developed a facile ball milling method to synthesize N-doped graphene (NG) with various N species, catalyzing fast dechlorination of TCE to acetylene by GR with the highest acetylene production rate of ~0.1 d-1. The adsorption of TCE onto NG is mainly derived from the graphene region of NG, and high pyridinic N is essential for the enhanced TCE reduction by GR. Oxygen species did not enhance the TCE reduction in GR/NG system. High dechlorination rates are correlated to a high amount of defect in NG and a high electron conductivity of NG. Pyridinic N has the highest adsorption energy for TCE among all the N species, which leads to the highest catalytic performance. High electrochemically active surface area resulted from the high content of pyridinic N facilitate the NG-catalyzed dechlorination. The acetylene production rate in real groundwater is still around one-third of that in ultrapure water. This work not only reveals the catalytic mechanism of NG-catalyzed dechlorination by GR, but also provide a feasible approach for practical remediations of TCE-contaminated groundwater using GR-NG mixture.


Assuntos
Grafite , Água Subterrânea , Tricloroetileno , Acetileno , Água Subterrânea/química , Ferro/química , Nitrogênio , Tricloroetileno/química
17.
Water Res ; 217: 118398, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35413564

RESUMO

As a reductive Fe(II)-bearing mineral, green rust (GR) is able to reduce halogenated compounds in anoxic subsurface environments. The redox condition of subsurface environment often changes from anoxic to oxic due to natural and anthropogenic disturbances, but the interaction of GR with halogenated compounds in oxic, and anoxic-to-oxic transition conditions has not been studied. This study reveals that GR can sequester TBP for a short time (4 to 10 h) under anoxic conditions. Later, GR undergoes structural transformation to ferrihydrite and magnetite with the desorption of TBP. GR-derived iron (hydr)oxides can generate 33.8 µM of •OH upon 50 h exposure to dioxygen, which leads to 67% of oxidative degradation of TBP. The anoxic-to-oxic transition during the TBP adsorption process initiates the TBP desorption immediately, and also results in the oxidative degradation of TBP via the production of •OH. The oxygenation of GR immediately forms magnetite which activate dioxygen to produce •OH. Also, the GR-derived magnetite acts as a Fe(II) source, and free Fe(II) in solution and Fe(II) adsorbed on magnetite surface both contribute to dioxygen activation. This work provides vital evidence on the role of GR in the fate and transformation of TBP in redox alternating subsurface environments.


Assuntos
Compostos Férricos , Óxido Ferroso-Férrico , Adsorção , Compostos Férricos/química , Oxirredução , Estresse Oxidativo , Oxigênio
18.
Water Res ; 222: 118959, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35964514

RESUMO

The groundwater environment often undergoes the transition from anoxic to oxic due to natural processes or human activities, but the influence of this transition on the fate of groundwater contaminates are not entirely understood. In this work, the degradation of tribromophenol (TBP) in the presence of environmentally relevant iron (oxyhydr)oxides (green rust, GR) and trace metal ions Cu(II) under anoxic/oxic-alternating conditions was investigated. Under anoxic conditions, GR-Cu(II) reduced TBP to 4-BP completely within 7 h while GR only had an adsorption effect on TBP. Under oxic conditions, GR-Cu(II) could generate •OH via dioxygen activation, which resulted in the oxidative transformation of TBP. Sixty-five percentage of TBP mineralization was achieved via a sequential reduction-oxidation process, which was not achieved through single reduction or oxidation process. The produced Cu(I) in GR-Cu(II) enhanced not only the reductive dehalogenation under anoxic conditions, but also the O2 activation under oxic conditions. Thus, the fate of TBP in anoxic/oxic-alternating groundwater environment is greatly influenced by the presence of GR-Cu(II). The sequential reduction-oxidation degradation of TBP by GR-Cu(II) is promising for future remediation of TBP-contaminated groundwater.


Assuntos
Cobre , Ferro , Adsorção , Humanos , Oxirredução , Óxidos
19.
Water Res ; 221: 118791, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35777317

RESUMO

Reductive dechlorination of chlorinated organic pollutants (COPs) by Fe(II) occurs in natural environments and engineered systems. Fe(II) ions undergo hydroxylation in aqueous solutions to form Ferrous Hydroxyl Complex (FHC), which plays an essential role in Fe(II)-mediated reductive dechlorination. However, how hydroxyl groups of FHC bridge the electron transfer from Fe(II) to COPs is still not fully understood. This work shows that the rate of reductive dechlorination of carbon tetrachloride (CT) by FHC increased with increasing OH- dosage. XRD data shows the increase of OH- dosage transform FHC from Fe2(OH)3Cl to Fe(OH)2, which leads to increased reductive strength of FHC. More non-hydrogen bonded hydroxyl groups coordinate with Fe(II) in FHC with increasing the OH- dosage, which stabilizes the octahedral structure of Fe(II) as shown by Mössbauer data. Electrochemical analysis reveals that the increase of OH- dosage enhances the reductive activity of FHC, which is also confirmed by the decreased HOMO-LUMO gap. It was found that FHC dechlorinated CT to methane, which was attributed to the stabilization of trichlorocarbene anion(˸CCl3-) by [surface-O-Fe(II)-OH]+. This work deepens our understanding on the bridge effect of hydroxyl groups on the electron transfer from Fe(II) to COPs, and provides a theoretical foundation for the reductive dechlorination of COPs in both natural environments and engineered systems.


Assuntos
Tetracloreto de Carbono , Elétrons , Tetracloreto de Carbono/química , Transporte de Elétrons , Compostos Ferrosos/química , Radical Hidroxila , Oxirredução
20.
Sci Total Environ ; 805: 150288, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-34536868

RESUMO

Recovery of the nitrogen (N) and phosphorus (P) in wastewater would help to minimize eutrophication and their reuse would lead to a more sustainable society. Sewage sludge and fly ash were used to fabricate ceramsite in the laboratory. After modified with alkali or lanthanum it was shown in benchtop experiments to effectively recover N and P from real wastewater treatment plant effluent. The N&P-adsorbed ceramsite was then applied as an eco-friendly, slow-release fertilizer to promote the germination, growth and blooming of Impatiens commelinoides, realizing the recycling of N and P from wastewater. Emergy analysis shows that such recycling is more sustainable than the current two approaches (i.e., landfill and incineration) for sludge disposal. This work thus demonstrates a sustainable solution combining the reuse of solid waste, effective wastewater purification and recovery of N and P nutrients. Applying the technologies demonstrated would help to minimize the environmental impact of wastewater and solid waste.


Assuntos
Fósforo , Águas Residuárias , Adsorção , Misturas Complexas , Nitrogênio , Esgotos , Eliminação de Resíduos Líquidos
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