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1.
J Hazard Mater ; 421: 126709, 2022 01 05.
Artículo en Inglés | MEDLINE | ID: mdl-34315021

RESUMEN

Nanoscale zero-valent iron nanoparticles (nZVI) have been used for groundwater remediation and wastewater treatment due to their high reactivity, high adsorption capacity and nontoxicity. However, side reactions generally occur in tandem with the target contaminants removal process, resulting in poor electron selectivity (ES) of nZVI, and subsequently restricting its commercial application. Major efforts to increase ES of nZVI have been made in recent years. This review's objective is to provide a progress report on the significant developments in nZVI's ES during the past decade. Firstly, the definition of ES and its quantification approaches were documented, and the intrinsic (i.e. particle size, crystallinity, and surface area) and extrinsic factors (i.e. solutions pH, target contaminant concentration, and presence of co-contaminants) affecting the ES of nZVI were reported. The latest techniques for increasing ES were summarized in detail, with reference made to sulfidation, magnetization, carbon loading and other features. Then the mechanisms of those strategies for ES enhancement were described. Finally, some constructive suggestions on future research directions concerning nZVI's ES in the future were proposed.


Asunto(s)
Restauración y Remediación Ambiental , Agua Subterránea , Contaminantes Químicos del Agua , Purificación del Agua , Electrones , Hierro , Contaminantes Químicos del Agua/análisis
2.
Bioresour Technol ; 341: 125743, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34438283

RESUMEN

Reducing the preparation cost of magnetic biochar is necessary for its large-scale application as an adsorbent. In this study, stainless steel pickling waste liquor and rice straw were successfully applied to synthesize of magnetic biochar (SPWL-MBC). Several iron oxides adhered on the biochar matrix, mainly Fe3O4, Fe2O3 and FeO. SPWL-MBC exhibited superparamagnetism, and its specific surface area was 274.29 m2/g. The material was able to adsorb a model contaminant, crystal violet (CV), with a maximum adsorption capacity of approximately 111.48 mg/g. Adsorption mechanism analysis showed that iron oxides, π-π interaction, hydrogen bonding and electrostatic interaction were responsible for the adsorption of CV. The CV adsorption efficiency of SPWL-MBC remained 71.91% after three adsorption-regeneration cycles. These outcomes illustrate that the magnetic biochar prepared from stainless steel pickling waste liquor can effectively remove CV from wastewater.


Asunto(s)
Oryza , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Violeta de Genciana , Cinética , Fenómenos Magnéticos , Acero Inoxidable
3.
J Environ Manage ; 299: 113595, 2021 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-34450304

RESUMEN

Mechanochemistry has been proved to be an effective method to remediation of organic-contaminated sites. However, the high ball-to-powder mass ratio (CR) limits the large-scale application of mechanochemistry. In this study, co-milling additives were introduced to enhance the mechanochemical degradation of decabromodiphenyl ether (BDE209)-contaminated soil under the condition of low CR. Based on additive screening experiments, sodium borohydride was selected as the ideal additive to assist the mechanochemical degradation of BDE209, and the resulting removal efficiency was approximately 100% with 2 h of ball milling at a rotational speed of 550 rpm. The main degradation intermediates and degradation pathway of BDE209 were identified using gas chromatography-tandem mass spectrometry. It was proposed that the degradation of BDE209 by sodium borohydride-assisted mechanochemistry was a concurrent process of stepwise and multistage debromination. Meanwhile, the meta-bromine atom in BDE209 was more susceptible to debromination than those at the para and ortho positions. The evolution of the concentration of Br- was monitored by ion chromatography, which revealed that reduction and oxidation both occurred in the removal of BDE209. This paper provides a new perspective for reducing the CR in the mechanochemical remediation of BDE209-contaminated soil.


Asunto(s)
Éteres Difenilos Halogenados , Contaminantes del Suelo , Contaminación Ambiental , Oxidación-Reducción , Suelo , Contaminantes del Suelo/análisis
4.
J Stroke Cerebrovasc Dis ; 29(12): 105374, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33254366

RESUMEN

INTRODUCTION: The aim of this systematic review and meta-analysis was to compare the performance of first-line contact aspiration (ASP) and stent retriever (SR) in acute ischemic stroke caused by proximal large vessel occlusion. METHODS: Cochrane databases, MEDLINE and EMBASE were systematically searched for literatures reporting outcomes on thrombectomy with both first-line aspiration and first-line stent retriever in proximal occlusion. RESULTS: Thirteen studies with a total of 1614 patients were included. No differences were identified between the SR and ASP groups in terms of final reperfusion rate (modified thrombolysis in cerebral infarction 2b/3) (OR: 1.54, 95% CI: 0.88-2.70), complete recanalization rate (modified thrombolysis in cerebral infarction 3) (OR: 1.78, 95% CI: 0.58-5.44), and favorable outcomes (modified Rankin scale ≤2) (OR: 1.02, 95% CI: 0.79-1.32). With regard to adverse events, emboli to new territories (OR: 0.81, 95% CI: 0.31-2.14), intracranial hemorrhage (OR: 0.71, 95% CI: 0.40-1.28), 90-days mortality (OR: 1.02, 95% CI: 0.71-1.47) were similar between groups, while symptomatic intracerebral hemorrhage (OR: 0.43 95% CI: 0.21-0.86) was less seen in ASP. Subgroup analysis indicated that ASP was comparable to stent retriever with local aspiration (SRLA) (OR: 1.25 95% CI: 0.25-6.22) and superior to stent retriever alone (OR: 1.85 95% CI: 1.22-2.81). Moreover, in posterior circulation, contact aspiration achieved a significantly higher reperfusion (OR: 1.97 95% CI: 1.03-3.76) compared to stent retriever, and needed relatively less rescue therapies (21.5% vs 29.6%, p < 0.05). CONCLUSION: Our study suggested that contact aspiration might be advantageous over stent retriever alone and more suitable in posterior circulation. While ASP and SRLA thrombectomy were equally effective in achieving good clinical outcomes. However, further studies are needed to confirm these results.


Asunto(s)
Isquemia Encefálica/terapia , Procedimientos Endovasculares/instrumentación , Stents , Accidente Cerebrovascular/terapia , Trombectomía , Anciano , Anciano de 80 o más Años , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/fisiopatología , Circulación Cerebrovascular , Procedimientos Endovasculares/efectos adversos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Recuperación de la Función , Factores de Riesgo , Accidente Cerebrovascular/diagnóstico , Accidente Cerebrovascular/fisiopatología , Succión , Trombectomía/efectos adversos , Resultado del Tratamiento
5.
Water Sci Technol ; 81(7): 1452-1460, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32616697

RESUMEN

In the process of preparing magnetic palygorskite from waste pickling liquor of the steel industry, the dosage of NaOH will affect the properties of the magnetic palygorskite. The experimental results showed that magnetic palygorskite can be effectively prepared when NaOH dosage is between 255 and 330 g/L. Vibration sample magnetometry proved that different NaOH dosages can affect the saturation magnetization of magnetic palygorskite. The catalytic performance of five catalysts synthesized with different NaOH dosages hardly changed after five cycles of Fenton-like catalytic degradation of tetracycline (TC). The magnetic palygorskite prepared by this method had good catalytic performance even when the catalyst preparation conditions were magnified ten times, which can provide a reference for large-scale preparation of magnetic palygorskite.


Asunto(s)
Contaminantes Químicos del Agua/análisis , Compuestos de Magnesio , Fenómenos Magnéticos , Compuestos de Silicona , Hidróxido de Sodio
6.
Bioresour Technol ; 298: 122468, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31839494

RESUMEN

The difficulty of separating the powdered biochar from the environmental medium may lead to secondary pollution and hinder the large-scale application of biochar as an adsorbent. An effective strategy to solve this bottleneck is to introduce transition metals and their oxides into the biochar matrix, creating easily separable magnetic biochar. Magnetic biochar is also effective for the removal of pollutants from aqueous solution. This review comprises a systematic analysis of 109 papers published in recent years (From 2011 to June 2019), and summarises the synthetic methods and raw materials required for magnetic biochar preparation. The basic physicochemical properties of magnetic biochar are expounded, together with findings from relevant studies, and the application of magnetic biochar as an adsorbent or catalyst in environmental remediation are summarised. Other applications of magnetic biochar are also discussed. Finally, some constructive suggestions are given for the future direction of magnetic biochar research.


Asunto(s)
Restauración y Remediación Ambiental , Contaminantes del Suelo , Adsorción , Carbón Orgánico , Contaminación Ambiental , Fenómenos Magnéticos , Suelo
7.
Environ Sci Pollut Res Int ; 26(27): 28361-28371, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31372953

RESUMEN

Aging effects play a crucial role in determining applications of green-synthesised iron-based nanoparticles in wastewater treatment from laboratory scale to practical applications. In this study, iron-based nanoparticles (Ec-Fe-NPs) were synthesised using the extract of Eichhornia crassipes and ferric chloride. Scanning electron microscopy (SEM) revealed that the fresh Ec-Fe-NPs were spherical and had a narrow particle size range (50 to 80 nm). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that the Ec-Fe-NPs were mainly amorphous in nature and consisted of Fe0, FeO, Fe2O3 and Fe3O4. As they aged, the particle size of the liquid Ec-Fe-NPs gradually increased and then tended to stabilise. Ec-Fe-NPs that were aged for 28 days were only 19% less efficient than fresh material at removing Cr(VI). Extracts aged up to 28 days were also tested, and their antioxidant capacity was found to be 15.4% lower than that of the fresh extracts. Furthermore, the removal efficiency of Cr(VI) using iron-based nanoparticles synthesised with the aged extracts was 67.2%. Finally, the active components of the extracts, which were responsible for the reactivity and stability of the iron-based nanoparticles, were identified by liquid chromatography-mass spectrometry. Overall, green-synthesised iron-based nanoparticles show promise for Cr(VI) removal from wastewater in practical applications.


Asunto(s)
Cloruros/química , Eichhornia/química , Compuestos Férricos/química , Compuestos de Hierro/síntesis química , Nanopartículas del Metal/química , Extractos Vegetales/química , Aguas Residuales/análisis , Compuestos de Hierro/química , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Espectroscopía de Fotoelectrones , Difracción de Rayos X
8.
Bioresour Technol ; 289: 121613, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31202177

RESUMEN

In this study, Fenton-like catalysts (magnetic biochar) were synthesised by pyrolysis the different biomass pre-impregnated with steel pickling waste liquor. The results of degradation of metronidazole illustrated that the catalytic performance of magnetic biochar was significantly affected by biomass feedstocks. Electron spin resonance (ESR) and radical quenching experiments showed that the hydroxide radicals (OH) were the key reactive oxygen species responsible for the metronidazole removal. Levels of OH varied among different systems consistent with the removal of metronidazole. The activation of H2O2 by carbon-containing components and Fe species (Fe2O3 and Fe3O4) in magnetic biochar were confirmed to be less crucial to the degradation of metronidazole. Moreover, the Fe(II) (FeO) in magnetic biochar played the dominating role in degradation of metronidazole, and the Fe(II) content difference caused by biomass feedstocks was responsible for differences in the catalytic performance of different types of magnetic biochar.


Asunto(s)
Metronidazol , Acero , Biomasa , Carbón Orgánico , Peróxido de Hidrógeno , Pirólisis
9.
Environ Sci Pollut Res Int ; 26(10): 10136-10147, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30747323

RESUMEN

The removal of contaminants by iron-based nanomaterials was inevitably affected by the natural organic matter (NOM), which is one of the most abundant material on earth and exists in natural waters. This study was performed to investigate the main influence of humic acid (HA, representing NOM) on the behavior and reactivity of Ni/Fe nanoparticles in the removal of deca-brominated diphenyl ether (BDE209). Generally, the inhibitory effect of HA on the removal of BDE209 by Ni/Fe showed greater significance with an increase of HA concentration. The zeta potential and sedimentation experiments showed that the HA enhanced the dispersion and stabilization of Ni/Fe particles; however, the removal of BDE209 was found to be inhibited. Moreover, the corrosion capacity of the Ni/Fe nanoparticles showed a positive correlation with the effect of HA on the reactivity of Ni/Fe nanoparticles. Meanwhile, typical quinone compounds in HA had an adverse effect on the removal of BDE209. Additionally, the competitive adsorption experiments and characterization illustrated that the adsorption of HA by Ni/Fe nanoparticles was superior to BDE209. Overall, it was proposed that the corrosion of Ni/Fe was reduced as the contact between the nanoparticles and H2O was hindered due to the surface of Ni/Fe was occupied by the adsorbed HA, and thus inhibited the reactivity of Ni/Fe nanoparticles in the removal of BDE209.


Asunto(s)
Éteres Difenilos Halogenados/química , Sustancias Húmicas , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , Éter , Éteres Difenilos Halogenados/análisis , Hierro/química , Nanopartículas , Níquel/química , Bifenilos Polibrominados , Agua , Contaminantes Químicos del Agua/análisis
10.
Environ Sci Pollut Res Int ; 25(3): 2570-2579, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29128943

RESUMEN

In this study, soil culture experiments were conducted to explore the effects of biochar-supported Ni/Fe nanoparticles on the accumulation and translocation of polybrominated diphenyl ethers (PBDEs) in soil-plant system and its phytotoxicity to Brassica chinensis. Compared with those in BDE209 contaminated soils (S 1) and Ni/Fe nanoparticle-treated soil (S 3), the plant biomass, root, and shoot lengths in biochar-supported Ni/Fe nanoparticle-treated soil (S 4) were increased by 23 mg, 1.35 cm, and 2.08 cm and 27.2 mg, 1.75 cm, and 2.52 cm, respectively, suggesting that the phytotoxicity in S 4 treatment was significantly decreased. Moreover, in all treatments, the contents of BDE209, the total PBDEs, Ni, and Fe in sample plant tissues of S 4 were the lowest. In addition, the superoxide dismutase, peroxidase, and catalase activities in S 4 treatment were found to decrease by 33.8, 47.2, and 24.1%, respectively, compared to those in S 3. Results also showed that biochar addition not only reduced the uptake of PBDEs and heavy metals but also effectively improve soil fertility and reduce the leachability of Ni and Fe caused by Ni/Fe. Finally, the translocation factors (TFs) of PBDEs in four treatments followed the orders as S 1 > S 3 > S 4 > S 2, indicating that biochar has an inhibition effects on PBDE translocation in the plants. In summary, all of the results suggested that the phytotoxicity, translocation of PBDEs, and the negative effects caused by neat Ni/Fe nanoparticles in B. chinensis were decreased as a result of the effects of the biochar.


Asunto(s)
Brassica/efectos de los fármacos , Carbón Orgánico/química , Éteres Difenilos Halogenados/análisis , Hierro/química , Nanopartículas del Metal/química , Níquel/química , Contaminantes del Suelo/análisis , Biomasa , Éteres Difenilos Halogenados/toxicidad , Suelo/química , Contaminantes del Suelo/toxicidad
11.
J Hazard Mater ; 320: 341-349, 2016 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-27566927

RESUMEN

Ni/Fe bimetallic nanoparticles were synthesized using biochar as a support (BC@Ni/Fe) and their effectiveness in removing BDE209 from soil was investigated. BET, SEM, TEM, XPS and FTIR were used to characterize the catalyst, and the efficiencies of biochar, Ni/Fe nanoparticles and BC@Ni/Fe for removing BDE209 from soil were compared. The results showed that Ni/Fe bimetallic nanoparticles highly dispersed in the biochar, reducing its agglomeration. Thus, the reaction activity of BC@Ni/Fe was increased. The removal efficiency of BDE209 by BC@Ni/Fe was 30.2% and 69% higher than that by neat Ni/Fe and biochar, respectively. Meanwhile, an enhanced degradation efficiency of PBDEs in soil was realized by monitoring the formation of Br- ions with time in the system. In addition, the degradation products identified by GC-MS showed that the reductive degradation of BDE209 proceeded through stepwise or multistage debromination, for which the degradation pathways and removal mechanisms were speculated. Furthermore, BC@Ni/Fe reduced the bioavailability of metals in soil and adsorbed the degradation products of BDE209, representing an improvement over neat Ni/Fe nanoparticles for the remediation of PBDEs-contaminated soil.

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