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1.
Food Chem ; 322: 126757, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32283378

RESUMO

In the present work, for the first time, the filamentous fungus Fusarium sp. was utilized for devising a novel method for pre-concentration and determination of trace amounts of Pb(II), Cu(II), Cd(II), and Zn(II) ions, using a mini-column packed with Fusarium-coated multi-walled carbon nanotubes and inductively coupled plasma-optical emission spectrometry. Optimal analytical conditions including pH, ionic strength, elution solution, sample and eluent flow rates, and sample volume were determined. The detection limits were 0.39, 0.060, 0.021, and 0.025 ng mL-1 for Pb(II), Cu(II), Cd(II), and Zn(II) cations, respectively. This new method demonstrated a high performance for the analytes, and their adsorption was not affected by the different co-existing ions. The present procedure was validated by the analysis of standard reference materials, since the obtained data were in close agreement with reference values. Finally, this new procedure was successfully applied to analysis of heavy metal cations in natural food and water samples.


Assuntos
Fusarium/química , Metais Pesados/análise , Nanotubos de Carbono/química , Extração em Fase Sólida , Espectrofotometria/métodos , Adsorção , Cátions/química , Células Imobilizadas/química , Cobre/análise , Água Doce/análise , Concentração de Íons de Hidrogênio , Chumbo/análise , Chumbo/isolamento & purificação , Limite de Detecção , Metais Pesados/isolamento & purificação , Metais Pesados/normas , Concentração Osmolar , Padrões de Referência , Espectrofotometria/normas
2.
Chemosphere ; 254: 126745, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32315813

RESUMO

The capacity of biochars derived from agricultural wastes to remove Cd(II) and Cu(II) from aqueous solution and contaminated mine water was evaluated using laboratory-based batch sorption experiments. To examine immobilization of heavy metals, biochars produced in a commercial-scale mobile pyrolizer from feedstocks: poultry litter; lucerne shoot; vetch shoot; canola shoot; wheat straws; and sugar-gum wood, were tested in a liquid-based system. Biochars were characterized by FTIR, XPS and XRD before and after the mine water treatment. Lucerne biochar had the highest Langmuir sorption capacity of Cd(II) (6.28 mg g-1) and vetch-derived biochar had the highest Cu(II) sorption capacity (18.0 mg g-1) at pH 5.5. All the biochars exhibited higher sorption capacity for Cu(II) than for Cd(II). The smaller ionic radius and higher electronegativity of Cu(II), and the PO43-, CO32- and N-containing functional groups of biochars enhanced their binding affinity. The results demonstrated that poultry litter-derived biochar was effective at removal of the Cd(II) and Cu(II) from mine water up to the levels recommended by the World Health Organisation. The results revealed that precipitation with CO32- and PO43-, complexation with -OH and -COOH groups and electrostatic interaction with O-containing surface functional groups were the main mechanisms involved in the removal of multi-metals by biochars, and that selection of feedstock materials for biochar production is important to maximise remediation of multi-metals in contaminated water.


Assuntos
Cádmio/isolamento & purificação , Carvão Vegetal/química , Cobre/isolamento & purificação , Purificação da Água/métodos , Adsorção , Agricultura , Cádmio/análise , Cobre/química , Metais Pesados/química , Metais Pesados/isolamento & purificação , Mineração , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
3.
Artigo em Inglês | MEDLINE | ID: mdl-32168914

RESUMO

Electrokinetic remediation is a useful technique for the removal of ionic contaminants in soils, sediments, sludges, and other solid porous matrixes. The efficiency of metal removal and the electricity consumption in the electrokinetic treatment of soils largely depend on electric and physicochemical conditions. This study analyzes the electrokinetic treatment of Mn contaminated kaolinite clay specimen and the influence of voltage, current intensity, moisture content, pH, and facilitating agents on metal removal and energy consumption. The objective of this study is to identify the influence of the typical variables used in electrokinetic remediation. The results showed that the operation at constant voltage or constant current intensity were equivalent in terms of metal removal and energy consumption, as long as the electric field intensity was kept low to minimize the consumption in parallel electrochemical reactions, especially the electrolysis of water. The moisture content had a significant influence on the Mn removal. Moisture content higher that 50 percent resulted in very effective Mn removal as compared with kaolinite specimens with lower moisture. The control of pH in the electrolyte solutions and the addition of facilitating agents (organic acids) enhanced the removal of Mn but increased the electric energy cost. Overall, the best conditions for Mn removal involved low to moderate electric potential difference (10 to 30 V), the use of citric acid as the facilitating agent, and the pH control in the cathode at a slightly acid pH. The electrokinetic treatment of a sludge from a water treatment plant contaminated with Mn was effective when pH control on the cathode was used. Mn and various metals (66% of Mn, 30% of Cu, 56% of Zn, 21% Sr, and 21% of Fe) were removed with moderate electricity and acid consumption.


Assuntos
Recuperação e Remediação Ambiental , Manganês/análise , Metais Pesados , Poluentes do Solo , Argila , Eletricidade , Eletrodos , Manganês/isolamento & purificação , Metais Pesados/análise , Metais Pesados/isolamento & purificação , Solo , Poluentes do Solo/análise , Poluentes do Solo/isolamento & purificação
4.
Environ Monit Assess ; 192(4): 240, 2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32185514

RESUMO

Metal ion contamination in wastewater is an issue of global concern. The conventional methods of heavy metal removal from wastewater have some drawbacks, ranging from generation of sludge to high cost of removal. Adsorption technique for copper(II), zinc(II), and chromium(VI) using activated carbon has been found efficient. However, it is not economical on a large scale. This, therefore, necessitates the search for economical and readily available plant biomass-based activated carbons for the sequestration of the metal ions. This review presents the state of the art on the adsorption of copper(II), zinc(II), and chromium(VI) from industrial wastewater. Based on the literature review presented, the groundnut husk and corncob based activated carbons were found to possess the maximum adsorption capacities for copper(II), zinc(II), and chromium(VI) removal, when compared with the other plant biomass-based activated carbons. The high values of the adsorption capacities obtained were as a result of the isotherms and pH of the adsorbent as well as the initial concentration of the metal solutions. From the review, the equilibrium data fitted better with Langmuir and Freundlich isotherms than with other isotherms. Research gaps were identified which include a need to investigate the kinetic and the thermodynamic behaviors of the metal ions onto the studied adsorbents. Furthermore, a comparative analysis of the three types of activation of the adsorbents should be investigated using single and multi-metals. The optimization of particle size, contact time, temperature, initial concentration, and adsorbent dosage for adsorption of copper(II), zinc(II), and chromium(VI) onto the studied adsorbents using response surface methodology is equally required.


Assuntos
Cromo , Metais Pesados , Águas Residuárias , Purificação da Água , Adsorção , Biomassa , Carvão Vegetal , Cromo/isolamento & purificação , Cobre/isolamento & purificação , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Cinética , Metais Pesados/isolamento & purificação , Zinco/isolamento & purificação
5.
Molecules ; 25(3)2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32041154

RESUMO

A composite membrane based on polycaprolactone (PCL) and cellulose nanofibers (CNF) with different compositions was prepared using the electro-spinning method, with the objective of developing organic membranes with good mechanical properties to remove contaminants from water. Water is a resource of primary importance for life and human activities. In this sense, cellulose obtained from agave bagasse and polycaprolactone nanofibers was used to prepare membranes that were tested by filtering tap water. The membranes obtained presented a porosity and structure on a nanometric scale. The water quality variables evaluated after filtration with the PCL/CNF membranes showed 100% turbidity removal, 100% conductivity, and heavy metal removal of the order of 75% to 99% for iron and chromium. CNF comprises biowaste derived from tequila production, and it has added value. Electro-spun CNF and PCL membranes can be applied as a "green" and eco-friendly filtration system for water purification.


Assuntos
Celulose/química , Metais Pesados/isolamento & purificação , Poliésteres/química , Poluentes Químicos da Água/isolamento & purificação , Agave/química , Cromo/isolamento & purificação , Ferro/isolamento & purificação , Membranas Artificiais , Nanofibras/química , Porosidade , Purificação da Água/instrumentação
6.
Chemosphere ; 247: 125963, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32069729

RESUMO

Lead (Pb) pollution in the soil is becoming more and more serious, and lead poisoning incidents also constantly occur. Therefore, the remediation of lead pollution in the soil has attracted widespread attention. In this study, heavy metal lead in soil was remediated by mechanochemical methods. The effects of different ball milling conditions on the toxic leaching concentration and morphological distribution (BCR sequential extraction procedure) of lead in contaminated soil were analyzed, including the addition of calcium dihydrogen phosphate (Ca(H2PO4)2), ball milling time, and ball milling speed. The reaction mechanism was analyzed by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and a laser particle size analyzer. The results show that the optimal conditions for mechanochemical immobilization were 10% additive (Ca(H2PO4)2), milling speed of 550 rpm, and ball milling time for 2 h. Under this condition, the toxic leaching concentration of lead from contaminated soil was 4.36 mg L-1, and in the BCR sequential extraction procedure, Pb was mainly present in the residual fraction (54.96%). The mechanism of mechanochemical solidification of heavy metal lead in soil is that, during the ball milling process, the lead precipitates with Ca(H2PO4)2 to produce dense agglomerates (Pb3(PO4)2 and PbxCa10-x(PO4)6(OH)2), which fixes the lead in the soil and hampers its leaching.


Assuntos
Fosfatos de Cálcio/química , Recuperação e Remediação Ambiental/métodos , Chumbo/isolamento & purificação , Poluentes do Solo/química , Pirofosfato de Cálcio/química , Precipitação Química , Chumbo/química , Metais Pesados/química , Metais Pesados/isolamento & purificação , Microscopia Eletrônica de Varredura , Poluentes do Solo/análise , Poluentes do Solo/isolamento & purificação
7.
Environ Sci Pollut Res Int ; 27(7): 7657-7671, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31889268

RESUMO

The metal contents of the soil and plant tissues in a large chromium salt-producing factory wasteland were determined to assess the properties of soil contamination and to identify plant species accumulating a range of heavy metals. Total metal contents in the factory soils presented a high heterogeneity, and the principal contaminants were Cd and Cr. All plant species examined were metal-tolerant, but to different extents. Especially, the maximum accumulation of Cd (15.61 mg kg-1) and Cr (925.07 mg kg-1) was found in Melia azedarach L. Subsequently, the Cd and Cr bioaccumulation and diverse physiological properties of M. azedarach seedlings exposed to different concentrations of Cd(II), Cr(VI), or Cd(II) + Cr(VI) in nutrient solutions were further investigated. All treated seedlings were able to survive under heavy metal stress, and the accumulation of both metals in plant tissues increased with elevation of metal exposure strength. M. azedarach showed a BCF greater than 147.56 for Cd and 36.76 for Cr. Meanwhile, the TF was lower than 0.25 for Cd and 0.32 for Cr. The highest bioaccumulation in root tissues was 2708.03 mg kg-1 Cd and 824.65 mg kg-1 Cr for seedlings cultured with 20 mg L-1 Cd(II) or 20 mg L-1 Cr(VI). Cd and Cr increased each other's uptake in seedlings although a reduced accumulation in roots occurred when exposed to the highest concentration of Cd(II) + Cr(VI) treatment (20 mg L-1). At either level of concentration, the degree of plant growth inhibition and oxidative damage caused by heavy metals was Cd(II) + Cr(VI) > Cr(VI) > Cd(II). Superoxide dismutase and peroxidase exhibited positive and effective responses to low-Cd(II) or Cr(VI) concentration stress, but their activities decreased with increasing metal exposure strength. The behavior of the non-enzymatic antioxidants (GSH, soluble protein, and proline) in plant involved in the detoxification of ROS induced by metal exposure was correlated well with higher Cd and Cr accumulations. Here, the potentiality of M. azedarach with the capacity to accumulate and stabilize Cd/Cr in metal-contaminated soil by phytoremediation process has been explored.


Assuntos
Biodegradação Ambiental , Cádmio/isolamento & purificação , Cromo/isolamento & purificação , Melia/metabolismo , Poluentes do Solo/isolamento & purificação , China , Metais Pesados/isolamento & purificação , Raízes de Plantas/metabolismo
8.
Chemosphere ; 243: 125439, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995887

RESUMO

This paper introduces a novel method for ethylenediaminetetraacetic acid (EDTA)-enhanced electrokinetic (EK) remediation by combining dual cation-exchange membranes and circulation methods for an aged electroplating soil contaminated by chrome (Cr), copper (Cu), and nickel (Ni). Three laboratory-scale EK experiments were carried out, including T1, the traditional EK process; T2, the traditional EDTA-enhanced EK process; and T3, the assisted EDTA-enhanced EK process. The results obtained show that removal of Cu and Ni in T3 was 3-10 times higher than after T1 and T2. However, the removal of Cr (total) was small in all experiments because of the high content of Cr(III). T3 eliminated the metal accumulation problem that existed for T1 and T2. Simultaneously, the highly acidified area (pH < 4) was reduced from 80% in T1 and T2 to only 20% in T3. The results obtained in T3 indicate that the chelating effect of EDTA has a greater ability to dissolve oxidizable Cu and Ni in the soil than the acidification effect. Toxicity evaluation confirmed that the soil treated by T3 presented a lower effect on a luminescent bacterium (Photobacterium phosphoreum T3) because soil pH tended to be more neutral after this treatment. This research provides a novel method for removing heavy metals from soil in a more environmentally friendly way and clarifies the cause of the existing problems of low removal efficiency and high accumulation in the traditional EK process.


Assuntos
Técnicas Eletroquímicas/métodos , Recuperação e Remediação Ambiental/métodos , Resinas de Troca de Cátion , Compostos de Cromo/isolamento & purificação , Cobre/química , Cobre/isolamento & purificação , Ácido Edético/química , Galvanoplastia , Metais Pesados/isolamento & purificação , Níquel/isolamento & purificação , Solo/química , Poluentes do Solo/isolamento & purificação
9.
PLoS One ; 15(1): e0227883, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31999756

RESUMO

Health implications to the population due to the consumption of contaminated vegetables has been a great concern all over the world. In this study, the levels of heavy metals (Cr, Cd, Zn, Fe, Pb, As, Mn, Cu, Hg, Ni and Co) in soil and commonly consumed vegetables from Mojo area in central Ethiopia have been determined using Inductively Coupled Plasma Optical Emission Spectrophotometer (ICP-OES) and possible health risks due to the consumptions of the vegetables have also been estimated. The levels of As, Pb, Cd, Zn, Cu, Hg and Co were exceeded the reference level in agricultural soil. Likewise, As, Pb, Cd, Cr and Hg levels exceeded the recommended values in vegetable samples with concentrations ranging from 1.93-5.73, 3.63-7.56, 0.56-1.56, 1.49-4.63 and 3.43-4.23 mg/kg, respectively. It was observed that leafy vegetable (cabbage) has accumulated heavy metals to greater extent compared with tomato. The estimated daily intake (EDI) of toxic metals due to the consumption of the vegetables were below the maximum tolerable daily intake (MTDI). However, the total health quotient (THQ), calculated based on EDI of the heavy metals were found > 1 for As and Hg due to tomato consumption and for As, Hg and Co due to cabbage consumption, suggesting significant health risk. The health index (HI) due to the intake of toxic metals from the consumption of both vegetables were much > 1, with HI values of 7.205 and 15.078 due to tomato and cabbage consumption, respectively. This clearly suggests the possible adverse health effect to adult population from the consumption of tomato and cabbage from the study area. The total cancer risk (TCR) analysis have also revealed the potential adverse cancer risk induced by As, Cd, Hg, and Ni from the consumption of both tomato and cabbage as their TCR values were above the threshold level. Based on the results of this study, there would be a significant health risk (both non-carcinogenic and carcinogenic) to the consumer associated with the consumption of cabbage and tomato being cultivated in Mojo area. Consequently, we recommend a strict regulatory control on the safety of vegetables originated from the study area.


Assuntos
Intoxicação por Metais Pesados/epidemiologia , Metais Pesados/isolamento & purificação , Poluentes do Solo/isolamento & purificação , Verduras/efeitos dos fármacos , Etiópia/epidemiologia , Contaminação de Alimentos/prevenção & controle , Humanos , Lycopersicon esculentum/química , Lycopersicon esculentum/efeitos dos fármacos , Mercúrio/isolamento & purificação , Mercúrio/toxicidade , Metais Pesados/toxicidade , Medição de Risco , Poluentes do Solo/toxicidade , Verduras/química
10.
J Chromatogr A ; 1620: 460833, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31959460

RESUMO

Distribution coefficient (Kd) data provides the analyst with a powerful set of tools for designing elemental chemical separations. While considerable Kd data exists in the literature for traditional anion and cation exchange resins, a comprehensive Kd study for the majority of the periodic table has not been published to date for several newer Eichrom extraction chromatographic resins. Kd values for the sorption of 41 different of elements on TEVA, TRU, UTEVA, and Diphonix resin were determined in this work. The power of Kd data in designing chemical separations is then demonstrated through development of separation methods for several challenging chemical separations including U/Mo/Te, Zr/Nb/Mo, and Cd isolation. Separation methodologies are finally applied to soil samples, where the ability for each separation to perform under complex matrix conditions is evaluated.


Assuntos
Cromatografia/métodos , Metais Pesados/isolamento & purificação , Solo
11.
Molecules ; 25(3)2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31991663

RESUMO

The determination of organic and inorganic pollutants in fish samples is a complex and demanding process, due to their high protein and fat content. Various novel sorbents including graphene, graphene oxide, molecular imprinted polymers, carbon nanotubes and metal-organic frameworks (MOFs) have been reported for the extraction and preconcentration of a wide range of contaminants from fish tissue. MOFs are crystalline porous materials that are composed of metal ions or clusters coordinated with organic linkers. Those materials exhibit extraordinary properties including high surface area, tunable pore size as well as good thermal and chemical stability. Therefore, metal-organic frameworks have been recently used in many fields of analytical chemistry including sample pretreatment, fabrication of stationary phases and chiral separations. Various MOFs, and especially their composites or hybrids, have been successfully utilized for the sample preparation of fish samples for the determination of organic (i.e., antibiotics, antimicrobial compounds, polycyclic aromatic hydrocarbons, etc.) and inorganic pollutants (i.e., mercury, palladium, cadmium, lead, etc.) as such or after functionalization with organic compounds.


Assuntos
Peixes , Análise de Alimentos , Grafite/química , Estruturas Metalorgânicas/química , Metais Pesados , Nanotubos de Carbono/química , Alimentos Marinhos , Animais , Metais Pesados/análise , Metais Pesados/isolamento & purificação
12.
Micron ; 130: 102817, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31924593

RESUMO

Presence of heavy metal in industrial wastewater is hazardous to the surrounding environment. Biosorption of heavy metal is an effective technology for the treatment of industrial wastewater. This research work has been carried out on removal of chromium (III) metal ions by employing waste fish scales as bioadsorbent. A batch adsorption process was carried out with different adsorbent dosage, solution pH and contact time. The results show the highest 99.7518 % chromium (III) metal ions at bioadsorbent dosage 0.8 g, pH of the solution 5 and contact time 90 min, initial concentration 150 mg/l chromium ion. The adsorption isotherms data fitted well with the Langmuir isotherm model with R2 = 0.9998, qmax = 18.3486 mg/g, and RL = 0.00007325. As well as pseudo-first and second kinetics model was also analyzed for the description of adsorption and found to be well fitted (R2 = 1) for adsorption kinetics. The surface properties activated fish scales and chromium loaded fish scale were investigated by scanning electron microscopy, X-ray spectroscopy, Fourier-transform infrared spectroscopy, and thermal analysis and agree with outcomes.


Assuntos
Escamas de Animais/química , Cromo/isolamento & purificação , Peixes , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Animais , Concentração de Íons de Hidrogênio , Cinética , Metais Pesados/isolamento & purificação , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície
13.
Sensors (Basel) ; 20(1)2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31948064

RESUMO

A new methodology involving the use of Bovine Serum Albumin (BSA) as a probe and liquid crystal (LC) as a signal reporter for the detection of heavy metal ions in water at neutral pH was developed. BSA acted as a multi-dentate ligand for the detection of multiple metal ions. The LC sensor was fabricated by immobilizing 3 µg mL-1 BSA solution on dimethyloctadecyl-[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP)-coated glass slides. In the absence of heavy metal ions, a dark optical image was observed, while in their presence, a dark optical image turned to bright. The optical response was characterized by using a polarized optical microscope (POM). The BSA based LC sensor selectively detected toxic metal ions as compared to s block metal ions and ammonium ions in water. Moreover, the limit of detection was found to be very low (i.e., 1 nM) for the developed new biosensor in comparison to reported biosensors.


Assuntos
Técnicas Biossensoriais , Metais Pesados/isolamento & purificação , Soroalbumina Bovina/química , Água/análise , Animais , Bovinos , Humanos , Cristais Líquidos/química , Metais Pesados/toxicidade , Água/química
14.
Environ Sci Pollut Res Int ; 27(2): 1625-1639, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31755054

RESUMO

A novel and efficient bio-adsorbent based on magnetic activated carbon nanocomposites (MAC NCs)-modified by sulfamic acid (H3NSO3) has been developed from pistachio shell precursor as agricultural by-products and then was applied for heavy metal removal. Design an experimental model (Central Composite Design (CCD)) for adopting surface response could efficiently be used for adsorption process, and it is an economical way of obtaining the optimal adsorption conditions based on the limited number of experiments. The variants of adsorbent dosage, metal ion concentration, and contact time were optimized for Cu(II) metal by CCD. In addition, adsorption capacity and isoelectric point (pHzpc) of adsorbent were studied at different pH values. Kinetic and isotherm of adsorption were investigated via the Langmuir and the pseudo-second-order model. The maximum adsorption capacity using the Langmuir model was 277.77 mg g-1 for Cu(II) ions on H2NSO3-MAC NCs. Then adsorption process was investigated for ions of Fe(II), Zn(II), and Ni(II) under optimized condition. Also, the competitive adsorption of Fe(II), Zn(II), and Ni(II) ions mixed solution onto H2NSO3-MAC NCs was conducted. Adsorption-desorption results exhibited that the H2NSO3-MAC NCs can be used up to seven cycles while they have excellent performance. Finally, to evaluate the efficiency of this bio-adsorbent, the removal of heavy metals from wastewater of the Sarcheshmeh copper mine as a real sample was studied. Graphical abstract.


Assuntos
Carvão Vegetal , Metais Pesados/isolamento & purificação , Mineração , Pistacia/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cobre , Concentração de Íons de Hidrogênio , Resíduos Industriais , Cinética , Águas Residuárias
15.
Chemosphere ; 241: 125097, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31629235

RESUMO

Microbial fuel cells (MFCs) can remove and recover metals in wastewater; however, there are relatively few studies of metal removal from soil by MFCs. In this study, we developed a three-chamber soil MFC consisting of an anode, contaminated soil, and cathode chamber to remove heavy metals from soil. The performance of the soil MFC was investigated by assessing the relationships among current, voltage, and Cu migration, and reduction. The developed soil MFC successfully reduced and removed Cu, and the Cu removal efficiency in the cathode surpassed 90% after only 7 days of operation. External resistance had a remarkable effect on the performance of the soil MFC which was depended on cathodic polarization. The pH in the cathode also depended on the external resistance. Lower external resistance were associated with lower pH values, higher Cu removal efficiencies, and greater amounts removed in the cathode. Based on sequential fractionation, the acid-extractable and reducible fractions were the main fractions that migrated within the three-chamber soil MFC. Enhancing the voltage output in the three-chamber soil MFC by increasing the external resistance promoted Cu migration, enriched Cu near the cathode, and facilitated Cu removal. Therefore, the developed three-chamber soil MFC not only supports heavy metal migration from soil towards the cathode, but can also realize reduction of heavy metals in the cathode by adjusting the current or voltage generated by the soil MFC.


Assuntos
Fontes de Energia Bioelétrica , Cobre/química , Eletricidade , Metais Pesados/isolamento & purificação , Poluentes do Solo/isolamento & purificação , Impedância Elétrica , Eletrodos , Solo , Águas Residuárias
16.
Chemosphere ; 241: 125004, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31590025

RESUMO

A simple foaming method was applied to fabricate urea formaldehyde (UF) microspheres with cross-linked porous structures for environmental remediation of heavy metals. The specific surface area and average pore radius of the resultant foamed UF microspheres were 11-29 m2/g and 11-25 nm, respectively, which increased with the increasing molar ratio of formaldehyde to urea. All the foamed UF microspheres showed good removal of heavy metals ions (Pb(II), Cu(II), and Cd(II)) in both single- and mixed-metal solutions. Further investigations of Pb(II) adsorption on a selected UF microspheres showed fast kinetics and relatively high adsorption capacity (21.5 mg/g), which can be attributed to the mesoporous structure and abundance of oxygen surface functional groups of the microspheres. Both experimental and model results showed that chelation or complexation interactions between Pb(II) and the surface functional groups were responsible to the strong adsorption of the heavy metal ions on the microspheres. Hydrochloric acid (0.05 M) successfully desorbed Pb(II) from the post-adsorption microspheres for multiple times and the regenerated microspheres showed high Pb(II) removal rates (>96%) in five adsorption-desorption cycles. With many promising advantages, foamed UF microspheres show great potential as a wastewater treatment agent for heavy metal removal.


Assuntos
Recuperação e Remediação Ambiental/métodos , Formaldeído/química , Metais Pesados/isolamento & purificação , Microesferas , Ureia/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Íons , Metais Pesados/química , Águas Residuárias/química , Poluentes Químicos da Água/química
17.
Chemosphere ; 242: 125182, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31678853

RESUMO

To effectively improve the heavy metal removal efficiency and stability of biomass adsorbents, a novel biochar colloids-mycelial pellets (BC-MP) composite was prepared via a biological assembly method. BC-MP was successfully produced with increased surface area and multisorption sites by physical adsorption, electrostatic interaction and hydrogen-bond formation between BC and extracellular polymers on MP. To investigate the performance and mechanisms of heavy metal adsorption by BC-MP, batch experiments were conducted with cadmium (Cd (II)) as the model pollutant. Results showed that BC-MP had higher removal efficiency (57.66%) compared to BC (5.45%) and MP (38.45%), respectively, due to the synergistic effect. The maximum adsorption capacity of Cd (II) on BC-MP was 102.04 mg/g based on Langmuir isotherm model. Adsorption kinetics analysis indicated that chemical sorption was the key factor controlling the adsorption of Cd (II) onto BC-MP. Multiple characterization tests revealed that the main mechanisms of the adsorption process were surface complexation, cation exchange and precipitation. The BC-MP composite showed excellent heavy metal removal efficiency with long-term adsorption stability, suggesting its potential as a promising biosorbent for heavy metal removal from industrial wastewater.


Assuntos
Carvão Vegetal/química , Coloides/química , Metais Pesados/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Biomassa , Cádmio/análise , Cádmio/isolamento & purificação , Cinética , Metais Pesados/análise , Águas Residuárias/análise , Poluentes Químicos da Água/análise
18.
Chemosphere ; 241: 125043, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683417

RESUMO

Over the past few decades, cyclodextrin-based adsorbents have drawn worldwide attention as new-generation adsorbents for wastewater treatment due to its extraordinary physicochemical properties. This review outlined the recent development in the synthesis of cyclodextrin-based adsorbents as well as highlighted their applications in the removal of heavy metals, dyes, endocrine disrupting chemicals (EDCs), and mixed pollutants from water. The cross-linked and immobilized cyclodextrin-based adsorbents exhibited excellent adsorption performances. The removal of dyes and heavy metals were effectively controlled by ion exchanging, mainly depending upon the pH; while the adsorptions of EDCs always occurred in cyclodextrin cavities and pH-independent. An easier separation process between aqueous and adsorbents could be achieved compared to native cyclodextrin, which promoted the application of cyclodextrin-based adsorbents in practical industry. This review could provide an inspiration for the advanced study in the development of cyclodextrin-based adsorbents for high efficiency wastewater treatment.


Assuntos
Ciclodextrinas/química , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Corantes/isolamento & purificação , Metais Pesados/isolamento & purificação
19.
Chemosphere ; 241: 125121, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683424

RESUMO

The present study firstly reports spent Ganoderma lucidum substrate derived biochars (SLBCS) for the effective removal of Pb2+/Cd2+ from water. The effects of pyrolysis temperature on the SLBCS characteristics and Pb2+/Cd2+ adsorption mechanism was studied systematically. The surface physicochemical properties of SLBCS were significantly affected by the pyrolysis temperature. The increase in pyrolysis temperature from 250 to 650 °C resulted in a drastic increase in the biochar surface area and the well development of mesoporous structure, which could provide more effective adsorption sites for Pb2+ and Cd2+ onto SLBCS. According to the Langmuir model, the obtained maximum adsorption capacity of Pb2+ onto SL650 reached 262.76 mg g-1, while that of Cd2+ reached 75.82 mg g-1. The adsorption capacities of SL650 for Pb2+ and Cd2+ were even higher than that of other modified biochars. The high adsorption capacity of SL650 for Pb2+, attributed to the precipitation supported by high temperature, benefitted the formation of carbonate minerals. Two possible mechanisms involved in Cd2+ sorption: carbonate precipitation and coordination with π electrons. Desorption of SL650 showed high efficiency for Pb2+, but slightly low efficiency for Cd2+. These results indicate that SL650 can be applied for removing heavy metals, especially Pb2+, from polluted water.


Assuntos
Cádmio/isolamento & purificação , Carvão Vegetal/química , Chumbo/isolamento & purificação , Reishi/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Cádmio/análise , Temperatura Alta , Metais Pesados/isolamento & purificação , Água , Poluentes Químicos da Água/análise
20.
Chemosphere ; 241: 125039, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31606568

RESUMO

Heavy metal removal from contaminated soils is a long-term challenging problem important for global economics, environment, and human health. Marine and freshwater-originated Mn(II)-oxidizing bacteria are considered as the promising bioremediation agents for environmental applications. However, practical application of soil-originated Mn(II)-oxidizing bacteria remains to be developed for contaminated soil remediation. In this work, the Mn(II) biosorption/oxidation mechanism of a new soil-originated bacterium and its bioleaching efficiency of heavy metals from soils was studied in detail. First, we found, isolated and identified a new highly Mn(II)-tolerant bacterial strain Providencia sp. LLDRA6 from heavy metal-contaminated soils. Next, strain LLDRA6 demonstrated its high Mn(II) biosorption capacity in aqueous solution. Then, Mn(II) adsorption by LLDRA6 was largely proven to be a synergistic effect of (i) Mn(II) precipitation on the cell surface, (ii) oxidation of Mn(II) into BioMnOx on the cell surface, and (iii) intracellular accumulation of insoluble MnCO3. Finally, combination bioleaching by the bacterium of Providencia sp. LLDRA6 and its formed BioMnOx was proposed to develop a potential environment-friendly and cost-effective technique to remediate severely heavy metal-contaminated soils. The bioleaching tests demonstrated that the combination of Providencia sp. LLDRA6 and BioMnOx exhibited an excellent removal efficiency for heavy metals of Pb (81.72%), Cr (88.29%), Cd (90.34%), Cu (91.25%), Mn (56.13%), and Zn (59.83%) from contaminated soils, resulting in an increase of removal efficiency in the range of 1.68-26.4% compared to Providencia sp. LLDRA6 alone. Moreover, the bacterial leachate facilitated the residual fraction of metals to transform into the easily migratory fractions in soils. These findings have demonstrated that strain LLDRA6 has high adsorption ability to remove heavy metals from contaminated soils, thus providing a promising bio-adsorbent for environmental bioremediation.


Assuntos
Biodegradação Ambiental , Manganês/química , Metais Pesados/isolamento & purificação , Providencia/metabolismo , Poluentes do Solo/isolamento & purificação , Adsorção , Bactérias/metabolismo , Humanos , Metais Pesados/análise , Oxirredução , Poluentes do Solo/análise
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