Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
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.
Sci Total Environ ; 764: 142813, 2021 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-33097246

RESUMEN

Exploiting the full potential of copper-based nanoparticles in the activation of peroxymonopersulfate (PMS) is a great challenge due to their insufficient dispersity and electronic properties. We report here a novel iron­nitrogen co-doped carbon nanotube (FNC) modified with a Cu2O nanocomposite (Cu2O/FNC) that exhibits ultrahigh catalytic performance in the activation of PMS to degrade fluconazole (~95%). Catalytic performance evaluation illustrated that Cu2O/FNC also has wide pH applicability (3.0-11.0), long-term stability and excellent adaptability. In addition, luminescent bacteria toxicity tests confirm that Cu2O/FNC/PMS significantly reduced the acute biotoxicity of various recalcitrant pollutants (reduced by 45-83%). By identifying the reactive oxygen species (ROS) and catalytic performance for various pollutants, we propose that pollutants that interact weekly with activators are mostly destroyed by sulfate radicals and hydroxyl radicals, whilst both radical and non-radical routes were involved in the degradation of pollutants that were easily adsorbed. By modifying Cu2O with FNC, several crucial properties such as the specific surface area, surface defects, active sites and the charge transfer rate were significantly improved, leading to excellent catalytic performance for pollutant removal. Finally, a reasonable reaction mechanism is advanced for the fluconazole degradation pathway. This study not only develops a novel PMS oxidation system for fluconazole degradation, but also provides a new strategy to improve the reactivity and applicability of PMS activators by combining radical and non-radical activation pathways.


Asunto(s)
Hierro , Nanotubos de Carbono , Electrónica , Nitrógeno , Peróxidos
4.
J Colloid Interface Sci ; 558: 163-172, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31586736

RESUMEN

This study examined the relationship between surface oxygen vacancies (OVs) and ceria-based heterogeneous Fenton catalytic activity. Compared with pure iron oxide and ceria, iron-doped ceria with abundant OVs (FeCeOx) exhibits higher rhodamine B (RhB) degradation efficiency (98%) and has a wider applicable pH range (3.0-9.0). The surface hydroxyl radicals are proved to be the predominant reactive species in the oxidation of RhB. Annealing the FeCeOx in an oxygen atmosphere appears to eliminate the OVs, significantly inhibiting the decomposition of H2O2 and the degradation of target pollutants. As multifunctional active sites, OVs are energetically more favorable for the adsorption of reactants than other sites, due to their high electron density. They not only accelerate the Fe(III)/Fe(II) cycle, they also immediately activate H2O2, dissolved oxygen or even water molecules to produce oxidative species, which accounts for the ideal degradation of RhB in the heterogeneous Fenton system. This study clarifies the mechanism of the ceria-based heterogeneous Fenton and provides a better understanding of the surface design of heterogeneous Fenton catalysts.

5.
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
6.
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
7.
Environ Sci Pollut Res Int ; 23(21): 22172-22182, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27544529

RESUMEN

Nano zero-valent iron (nZVI) and its modified nanomaterials are widely used in the degradation of some halogenated organic pollutants. In this study, we explored the effects of different proportions of tetrahydrofuran (THF) (50, 60, 70, 80, 90, and 100 %) on the degradation of decabromodiphenyl ether (BDE209) by Ni/Fe and nZVI nanoparticles with reference to the degradation kinetics, products, and pathway. The results illustrated that the effects of solvent on the degradation of BDE209 were similar when the two kinds of nanomaterials were used, although the Ni/Fe bimetallic nanoparticles exhibited a better catalytic activity compared with the pure nZVI during the degradation of BDE209. The apparent reaction rate constant (k obs) increased with the proportion of the water in the system, enhancing the degradation of BDE209. In terms of degradation products, a high proportion of THF led to an accumulation of higher-brominated BDEs, inhibiting the further debromination of BDE209. The inhibitory effect of the solvent (THF) can be explained that water played a role of hydrogen donor during the reductive degradation of BDE209 in the THF/water system. However, the proportion of THF in the degradation system posed no effect on the BDE209 debromination pathway and debromination location. The difficulty of para-debromination was observed in all of the solvent systems.


Asunto(s)
Bromo/química , Contaminantes Ambientales/química , Éteres Difenilos Halogenados/química , Hierro/química , Solventes/química , Halogenación , Nanopartículas del Metal/química , Níquel/química
8.
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.

9.
Environ Sci Pollut Res Int ; 23(19): 19164-72, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27351875

RESUMEN

The potential for nanoscale phosphate amendments to remediate heavy metal contamination has been widely investigated, but the strong tendency of nanoparticles to form aggregates limits the application of this technique in soil. This study synthesized a composite of biochar-supported iron phosphate nanoparticle (BC@Fe3(PO4)2) stabilized by a sodium carboxymethyl cellulose to improve the stability and mobility of the amendment in soil. The sedimentation test and column test demonstrated that BC@Fe3(PO4)2 exhibited better stability and mobility than iron phosphate nanoparticles. After 28 days of simulated in situ remediation, the immobilization efficiency of Cd was 60.2 %, and the physiological-based extraction test bioaccessibility was reduced by 53.9 %. The results of sequential extraction procedures indicated that the transformation from exchangeable (EX) Cd to organic matter (OM) and residue (RS) was responsible for the decrease in Cd leachability in soil. Accordingly, the pot test indicated that Cd uptake by cabbage mustard was suppressed by 86.8 %. Compared to tests using iron phosphate nanoparticles, the addition of BC@Fe3(PO4)2 to soil could reduce the Fe uptake of cabbage mustard. Overall, this study revealed that BC@Fe3(PO4)2 could provide effective in situ remediation of Cd in soil.


Asunto(s)
Cadmio/química , Carbón Orgánico/química , Restauración y Remediación Ambiental/métodos , Nanopartículas/química , Contaminantes del Suelo/química , Carboximetilcelulosa de Sodio , Hierro/química , Metales Pesados/química , Planta de la Mostaza , Fosfatos/química , Suelo/química , Contaminantes del Suelo/análisis
10.
J Colloid Interface Sci ; 436: 258-66, 2014 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-25280370

RESUMEN

In this study, Fe3O4 NPs (named as Fe3O4 NPs-PO) were prepared by steel pickling waste liquor to reduce the cost of preparation, and were compared with those obtained by the common co-precipitation method (named as Fe3O4 NPs-CP) which prepared from chemical reagent using BET, XRD, XPS, TEM and SEM techniques. The results indicated that Fe3O4 NPs-PO nanoparticles mainly existed in the form of Fe3O4 and appeared to be roughly spherical in shape with a size range of 20-50 nm. The heterogeneous Fenton-like catalytic capacity of Fe3O4 NPs-PO in US+Fe3O4+H2O2 system was comprehensively investigated. BPA could be degraded within a wide pH range of 7-10. The removal efficiencies of BPA were close to 100% and about 45% total organic carbon (TOC) in solution was eliminated at the optimized conditions. It was found that ·OH radicals which mainly caused the degradation of BPA were promptly generated due to the catalysis of the Fe3O4 NPs-PO. Furthermore, the comparative study of catalytic activity, stability and reusability between Fe3O4 NPs-PO and Fe3O4 NPs-CP showed that the two catalysts both remained good activity after several reaction cycles and no significant change in composition and structure was observed, the loss of catalyst was negligible, which demonstrated that Fe3O4 NPs-PO were promising in ultrasonic Fenton-like process to treat refractory organics.

11.
J Hazard Mater ; 275: 230-7, 2014 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-24880637

RESUMEN

The toxic effect of Cr(VI)-contaminated soil remediated by sodium carboxymethyl cellulose stabilized nanoscale zero-valent iron (CMC-stabilized nZVI) was assessed through in vitro toxicity and phytotoxicity tests. In vitro tests showed that 0.09 g L(-1) of Fe(0) nanoparticles (soil-to-solution ratio was 1 g:5 mL) significantly reduced the toxicity characteristic leaching procedure (TCLP) leachability and physiological based extraction test (PBET) bioaccessibility of Cr by 82% and 58%, respectively. Sequential extraction procedures (SEP) revealed that exchangeable (EX) Cr was completely converted to Fe-Mn oxides (OX) and organic matter (OM). Accordingly, phytotoxicity tests indicated that after 72-h remediation, Cr uptakes by edible rape and Chinese cabbage were suppressed by 61% and 36%, respectively. Moreover, no significant increase in Cr uptake was observed for either species after a 1-month static period for the amended soil. Regarding Fe absorption, germination and seedling growth, both plant species were significantly affected by CMC-nZVI-exposed soils. However, similar phytotoxicity tests conducted after 1 month showed an improvement in cultivation for both plants. Overall, this study demonstrated that CMC-nZVI could significantly enhance Cr immobilization, which reduced its leachability, bioavailability and bioaccumulation by plants. From a detoxification perspective, such remediation is technologically feasible and shows great potential in field applications.


Asunto(s)
Carboximetilcelulosa de Sodio/química , Cromo/química , Hierro/química , Nanopartículas del Metal/química , Contaminantes del Suelo/química , Brassica/efectos de los fármacos , Brassica/crecimiento & desarrollo , Brassica/metabolismo , Cromo/farmacocinética , Cromo/toxicidad , Restauración y Remediación Ambiental , Germinación/efectos de los fármacos , Hierro/farmacocinética , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Tallos de la Planta/efectos de los fármacos , Tallos de la Planta/crecimiento & desarrollo , Tallos de la Planta/metabolismo , Plantones/efectos de los fármacos , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Contaminantes del Suelo/farmacocinética , Contaminantes del Suelo/toxicidad
12.
Chemosphere ; 108: 433-6, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-24582360

RESUMEN

Our previous reports showed that nano zero-valent iron (nZVI), steel pickle liquor for the synthesis of nZVI (S-nZVI), nZVI immobilised in mesoporous silica microspheres (SiO2@FeOOH@Fe) and nano Ni/Fe bimetallic particles (Ni/Fe) have been proved to show good property for elimination of polybrominated diphenyl ethers (PBDEs). However, it is necessary to compare their reactivity, reusability and stability when applied to in situ remediation. In this study, the performances of different iron-based nanoparticles were compared through reusability, sedimentation and iron dissolution experiments. The SiO2@FeOOH@Fe and Ni/Fe nanoparticles were shown to have higher reusability and stability, as they could be reused more than seven times, and that the SiO2@FeOOH@Fe can effectively avoid leaching iron ions into the solution and causing secondary pollution in the reaction. This study may serve as a reference for PBDE remediation in the future.


Asunto(s)
Contaminantes Ambientales/aislamiento & purificación , Éteres Difenilos Halogenados/aislamiento & purificación , Hierro/química , Nanopartículas/química , Restauración y Remediación Ambiental , Níquel/química , Dióxido de Silicio/química , Solubilidad
13.
Sheng Wu Gong Cheng Xue Bao ; 26(3): 378-85, 2010 Mar.
Artículo en Chino | MEDLINE | ID: mdl-20518352

RESUMEN

To study the possibilities for improvement of the ornamental character and production of secondary metabolites by using Wedelia trilobata hairy roots, we investigated the induction of W. trilobata L. hairy roots and its consumption changes of carbon resource, nitrogen resource, phosphate and calcium in the medium during liquid culture. The results showed that hairy roots could be incited from the cut edges of leaf explants 7 days after inoculation with Agrobacterium rhizogenes ATCC15834 and could have an autonomous growth on the medium without phytohormones. The PCR amplification showed that rol genes of Ri plasmid of A. rhizogenes was integrated and expressed into the genome of transformed hairy roots. The hairy root line grew very slowly in 0-7 days, very fast from 7 to 21 days. During the liquid culture of hairy roots, sucrose, NO3(-)-N, PO4(3-) and Ca2+ in the medium could be gradually absorbed and utilized with time. The content of NO3(-)-N in the medium was 5.8% of the initial amount at day 7, while sucrose content was about 50% of the initial amount. At day 35, the NO3(-)-N and sucrose content in the medium was 1.82% and 3.39% of the initial amount, respectively. In combination with Ca2+ consumption, PO4(3-) of the medium was rapidly absorbed and utilized. At day 7, the content of PO4(3-) in the spent medium was only 1.76% of the initial amount; but even at day 35, the content of Ca2+ in the spent medium was still 61.3% of the initial amount. The results presented here had provided the possibilities on improvement the ornamental character and how to prepare optimum medium for large scale cultivation and production of secondary metabolites from W. trilobata L. hairy roots.


Asunto(s)
Técnicas de Cultivo/métodos , Raíces de Plantas/crecimiento & desarrollo , Transformación Genética , Wedelia/crecimiento & desarrollo , Wedelia/genética , Raíces de Plantas/citología , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Plantas Modificadas Genéticamente/metabolismo , Rhizobium/genética , Rhizobium/fisiología , Wedelia/microbiología
14.
Sheng Wu Gong Cheng Xue Bao ; 26(2): 147-58, 2010 Feb.
Artículo en Chino | MEDLINE | ID: mdl-20432931

RESUMEN

To study if Solanum nigrum hairy roots can be used for phytoremediation of Cd contamination, we investigated the effects of cadmium (Cd) alone, and in combination with different concentrations of CaCl2, on growth, activities of superoxide dismutase (SOD) and peroxidase (POD) and Cd absorption by hairy roots of S. nigrum L. var pauciflorum. The results showed that Cd concentrations of lower than 50 micromol/L enhanced the growth of hairy roots, while higher than 100 micromol/L inhibited growth and decreased the number of branched roots, also causing the root tips to become brown and shorter in length. In comparison with a control, the soluble protein content, the activities of SOD and POD in hairy roots cultures showed a trend of first increased and then gradually decreased, while the malondialdehyde (MDA) content significantly increased, when increasing the Cd concentrations. Cd concentration of 100 micromol/L or 300 micromol/L in combination with 10-30 mmol/L CaCl2 resulted in a decreased content of soluble protein and MDA in the hairy roots, but an enhanced SOD activity. The increased POD activities were observed when cultured in 100 micromol/L Cd and 10-30 mmol/L CaCl2 but decreased when cultured in 300 micromol/L Cd and 10-30 mmol/L CaCl2. Atomic Absorption Spectrometry determination showed that the Cd absorbed and adsorbed by the hairy roots increased along with the increase of Cd concentration. The exogenous addition of 10-30 mmol/L CaCl2 could reduce the toxicity of Cd. This was achieved on one hand by reducing the absorption of Cd, on the other hand by decreasing the lipid peroxidation through regulating the activities of antioxidant enzymes SOD and POD in the hairy roots.


Asunto(s)
Cadmio/aislamiento & purificación , Raíces de Plantas/crecimiento & desarrollo , Contaminantes del Suelo/aislamiento & purificación , Solanum nigrum/fisiología , Superóxido Dismutasa/metabolismo , Absorción , Biodegradación Ambiental , Cadmio/metabolismo , Cloruro de Calcio/metabolismo , Peroxidasa/metabolismo , Raíces de Plantas/fisiología , Contaminantes del Suelo/metabolismo , Solanum nigrum/enzimología , Solanum nigrum/crecimiento & desarrollo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...