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1.
Ecotoxicol Environ Saf ; 204: 111129, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32805505

RESUMO

Anaerobic digestate has been widely used for agricultural activities as an organic fertilizer product. Dissolved organic matter (DOM) derived from anaerobic digestate plays a key role in the speciation, bioavailability and ultimate fate of metals that is related to agriculture and food safety as well as the soil environment. Hence, the binding properties of Cu, Pb and Zn with digestate DOM are investigated using two-dimensional correlation spectroscopy (2D-COS) in combination with ultraviolet absorption, synchronous fluorescence spectra (SFS) and Fourier transform infrared (FTIR) spectroscopy. The 2D absorption COS shows that the DOM at 200 nm is most susceptive with the addition of Pb, followed by Zn and Cu. The log-transformed absorption spectra can also obtain more valuable signals than that from conventional absorption spectra. The 2D-SFS-COS indicates that protein-like peak is more sensitive to the variation of the concentration of metal ions, and fulvic-like substances can preferentially interact with the three heavy metals (HMs). The 2D-FTIR-COS reveals that Cu(II) and Zn(II) ions can be bonded preferentially to the N-H of secondary amide (II), and phenolic OH groups shows a favorable binding with Pb(II). Humic-like peaks with Cu(II) and Zn(II) obtains relatively higher log KM values than fulvic- and protein-like substances. However, the proportion of initial fluorescence (f) for DOM-Cu(II) and DOM-Zn(II) decreased with an increase in wavelength. Protein-like materials have more fluorescent substances that can combine with Cu(II) and Zn(II). This study provides a guide for understanding the geochemical behavior of metal ions in agricultural soils when anaerobic digestate is applied as an organic fertilizer product.


Assuntos
Substâncias Húmicas/análise , Esterco/microbiologia , Metais Pesados/química , Anaerobiose , Animais , Galinhas , Fertilizantes , Fluorescência , Solo/química , Espectrometria de Fluorescência/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
2.
Chemosphere ; 259: 127403, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32603963

RESUMO

The ability of thiol-modified humic acids (HAs) to release arsenic in tailings soil after being modified with different sulfur-containing reagents were significantly improved. The structure and physicochemical properties of humic acid (HA) before and after thiol-modification were characterized. The 3-MPTS-HA treated with 3-mercaptopropyltrimethoxysilane (3-MPTS) effectively improved the mobility of arsenic, and its reducing ability was increased from 2 mmol g-1 to 3.54 mmol g-1. The S content of humic acids were also significantly increased after treatment with sulfur-containing reagents, in which the oxygen-containing functional group (e.g., C = O, C-O) on the surface of HA may be the active sites for binding with sulfur-containing reagents. It was found in the XPS spectrum that because the thiol group is easily oxidized, there are many S forms in thiol-modified HA. The -SH content in Na2S·9H2O-HA, l (+)-Cysteine-HA (Cys-HA), thioglycolic acid (TGA-HA) and 3-MPTS-HA was determined by fluorescence method to be 13.9, 78.45, 90.34, and 192.29 µmol g-1, respectively. The study demonstrated that surface thiol modification can increase the abundance of thiol in HA and enhance reactivity, which will further promote the application of HA in the treatment of heavy metal contaminated tailing soil.


Assuntos
Arsênico/química , Poluentes do Solo/química , Substâncias Húmicas/análise , Metais Pesados/química , Solo/química , Poluentes do Solo/análise , Compostos de Sulfidrila
3.
Chemosphere ; 260: 127650, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32693263

RESUMO

In recent years, the composite pollution of microplastics with organic pollutants and heavy metal ions in the water environment, including their combined toxicity, has received increasing attention. However, the mechanism underlying the joint effect of antibiotics and heavy metals on the surface behavior of microplastics has not been reported. The primary purpose of this article was to analyze the adsorption of levofloxacin (OFL) onto polyvinyl chloride (PVC) in an aqueous solution. The adsorption behavior was studied using kinetics, thermodynamics, and isotherm models, and the effects of several environmental factors, such as ionic strength, fulvic acid, and heavy metals, were determined. The adsorption kinetics and isotherms models indicated that the whole adsorption process was controlled by both intraparticle and outer diffusion, as well as chemical adsorption, which was the dominant mechanism. Based on the results of the thermodynamic experiment, the adsorption process was a nonspontaneous and exothermic reaction process. Furthermore, the presence of Cu2+, Zn2+, and Cr3+ ions significantly promoted the adsorption of OFL, but the presence of Cd2+ and Pb2+ ions inhibited its adsorption. At the same time, the presence of the ionic strength and fulvic acid remarkably restricted the adsorption process. These findings confirmed that electrostatic interactions, ion exchange, intermolecular hydrogen bonds, and halogen bond cooperation were the main adsorption mechanisms. This paper mainly discusses the interaction between combinations of pollutants with microplastics, which provides theoretical guidance for the interface behavior, migration and transformation of marine microplastics in the actual environment.


Assuntos
Levofloxacino/química , Metais Pesados/química , Microplásticos/química , Poluentes Químicos da Água/química , Adsorção , Antibacterianos , Difusão , Poluentes Ambientais , Íons , Cinética , Concentração Osmolar , Plásticos/química , Cloreto de Polivinila , Termodinâmica , Água/química
4.
Chemosphere ; 260: 127673, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32693264

RESUMO

Soils contaminated with Pb, Zn and Cd are hazardous. Persistent EDTA and biodegradable GLDA, EDDS and IDS have been used as chelators in the ReSoil soil washing technology, which recycles chelator and curbs toxic emissions. The washed soils supported similar growth of buckwheat (F. esculentum) and better growth of Chinese cabbage (B. rapa) compared with the original (not-remediated) soil. The growth of buckwheat on EDDS-washed soil was an exception and was 67% suppressed. The activities of enzymes of the plant antioxidant preventive system were assessed in roots and leaves of Chinese cabbage on all soils. Similar activities were measured, confirming that washed soils are not harmful to the plants. Plant uptake of potentially toxic elements was reduced from all washed soils, i.e. buckwheat grown on GLDA-washed soils accumulated up to 27 and 83 times less Pb and Cd than in the original soil. The initial Pb emissions in leachate from GLDA and IDS washed soils were up to 89 and 92% higher than those of the original soil, respectively. The latter emissions ceased to the levels measured in original, EDTA and EDDS washed soils. Soil physical properties (water holding capacity, aggregate stability) and soil functionality, assessed as soil respiration and activity of enzymes indicative for soil C, N and P cycle, were similar in all soils after 10 weeks of plant growth experiment. The overall results indicate a low impact of the remediation on soil quality. Soils washed with EDTA performed slightly better compared to GLDA-, EDDS- and IDS-washed soils.


Assuntos
Metais Pesados/química , Poluentes do Solo/química , Animais , Quelantes , Ácido Edético , Isópodes , Metais Pesados/análise , Desenvolvimento Vegetal , Reciclagem , Solo , Poluentes do Solo/análise
5.
J Environ Sci Health B ; 55(8): 704-711, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32500809

RESUMO

In order to solve the problem of heavy metal-organic compound soil pollution, in this paper, we developed a highly efficient electro kinetic-laccase combined remediation (EKLCR) system. The results showed that the EKLCR system had an obvious migration effect on heavy metals (copper and cadmium) and good migration-degradation effect on phenanthrene. The migration rates of copper and cadmium were 48.3% and 40.3%, respectively. Especially, with the presence of laccase, the removal rate of phenanthrene on Cu2+-contaminated soil was higher than that of Cd2+-contaminated soil due to the significant effect of heavy metals on the enzymatic activity of laccase. The average migration-degradation rate of phenanthrene by EKLCR system was 45.4%. Finally, gas chromatography-mass spectrometry (GC/MS) was used to analyze the degradation intermediates of phenanthrene in the soil, which included 9,10-Phenanthrenequinone, phthalic acid, and 2,2-Biphenyldicarboxylic Acid. In addition, we give the possible degradation pathways of phenanthrene, 2,2-Biphenyldicarboxylic Acid is further degraded to produce phthalic acid. The products of the phthalic acid metabolic pathway are protocatechuic acid, pyruvic acid or succinic acid, the final products of these organic acids are carbon dioxide and water.


Assuntos
Recuperação e Remediação Ambiental/métodos , Metais Pesados/análise , Fenantrenos/análise , Poluentes do Solo/análise , Biodegradação Ambiental , Desenho de Equipamento , Cromatografia Gasosa-Espectrometria de Massas , Cinética , Lacase/metabolismo , Metais Pesados/química , Fenantrenos/química , Fenantrenos/metabolismo , Solo/química , Poluentes do Solo/química
6.
Chemosphere ; 257: 127140, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526467

RESUMO

The recent increase in municipal sludge worldwide has led to a great deal of interest in developing an efficient and environmentally friendly sludge treatment method. In the paper, the treatment of municipal sludge by hydrothermal oxidation (HTO) process with H2O2 as the oxidant was proposed. The impacts of HTO temperature and H2O2 mass fraction on the distribution of products, the moisture content, the migration behaviors of the heavy metals (HMs) of the resulted solid products, the concentration of volatile fatty acids (VFAs) and NH3-N contained in the resulted aqueous phase products and the pH value were investigated. The results indicated that the sludge reduction was achieved by HTO treatment, the increasing H2O2 mass fraction and HTO temperature can significantly improve the dewatering performance of the sludge. The potential toxicity fraction of Pb and Cd contained in the resulted solid residual increased with the increasing HTO severity and the potential toxicity fraction of solid residues was still lower than that of raw material. Acetic acid was the main VFAs produced from HTO treated sludge, and its concentration reached to the maximum value of 2923.41 mg/L at 230 °C under H2O2 mass fraction of 15%. The change in the pH of the resulted aqueous phase products was caused by the competition between the acidic (VFAs or CO2) or alkaline (NH3-N) substances derived from the sludge during HTO process. The HTO process was expected to be an efficient method for municipal sludge treatment due to its mild conditions and high heavy metal safety.


Assuntos
Eliminação de Resíduos Líquidos , Ácidos , Peróxido de Hidrogênio , Governo Local , Metais Pesados/química , Oxidantes , Oxirredução , Esgotos/química , Temperatura
7.
Chemosphere ; 259: 127369, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593814

RESUMO

Rapidly increasing water contamination has turned into a major threat globally. The pollutants such as organic and inorganic compounds, heavy metals, and biological organisms are among the major contributor to water pollution. Therefore, the removal of these contaminants has attracted the researchers a lot. Various methodologies are being carried out for the purpose. Among them, the metal-organic frameworks (MOFs) with several active sites and tailorable porous architectures as adsorbents or photocatalytic removal agents is a fast-growing class of coordination chemistry to remove these agents from water. To date, numerous approaches dealing with water treatment including conservative and advanced technologies have been presented. This article thoroughly reviews the application of MOFs toward how to remove the toxic agents from water. The leading objective is to present up-to-date information and references regarding MOFs based materials toward wastewater treatment applications.


Assuntos
Estruturas Metalorgânicas , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Poluentes Ambientais/química , Metais Pesados/química , Porosidade , Águas Residuárias , Poluentes Químicos da Água/análise , Poluição da Água , Purificação da Água/métodos
8.
Chemosphere ; 258: 127289, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535447

RESUMO

Anammox-based processes and microbial consortia have drawn extensive attention for their use in high-efficiency wastewater treatment technologies. Metals substantially affect the activity of anammox consortia and the quality of wastewater treatment plant effluent. Here, we explored the role of anammox consortia in terms of metals complexation in both single and multi-metal systems. Adsorption edges of single metal cations indicate that the adsorption preference was in the order: Pb(II) > Cd(II) > Cr(VI). A competitive effect was observed in multi-metal cations systems, with Pb(II) being preferably adsorbed and the degree of adsorption somewhat reduced in the presence of either Cd(II) or Cr(VI), while Cd(II) and Cr(VI) were easily exchanged and substituted by other metals. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) further suggest that the adsorption of Pb(II) and Cd(II) are as inner-sphere ion-exchange mechanisms, while Cr(VI) adsorption is mainly by outer-sphere complexation. Density functional theory (DFT) calculations highlight that Cd(II) and Pb(II) have different binding sites compared to Cr(VI), and the order of binding energy (Ebd) of three metal cations were Pb(II) > Cd(II) > Cr(VI). These calculations support the adsorption data in that Pb forms more stable complexes with anammox bacterial surface ligands. Surface complexation modelling (SCM) further predicted both the sorption of single metal cations and competitive adsorption of the three metals to anammox consortia, the exception being Cd at higher loadings. The results of this study highlight the potential role of anammox consortia in removing metal cations from wastewater in treatment systems.


Assuntos
Amônia/metabolismo , Reatores Biológicos/microbiologia , Metais Pesados/química , Consórcios Microbianos/fisiologia , Adsorção , Anaerobiose , Cátions , Teoria da Densidade Funcional , Metais Pesados/metabolismo , Oxirredução , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo
9.
Chemosphere ; 258: 127324, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32544812

RESUMO

Water is an extremely essential compound for human life and, hence, accessing drinking water is very important all over the world. Nowadays, due to the urbanization and industrialization, several noxious pollutants are discharged into water. Water pollution by various cytotoxic contaminants, e.g. heavy metal ions, drugs, pesticides, dyes, residues a drastic public health issue for human beings; hence, this topic has been receiving much attention for the specific approaches and technologies to remove hazardous contaminants from water and wastewater. In the current review, the cytotoxicity of different sorts of aquatic pollutants for mammalian is presented. In addition, we will overview the recent advances in various nanocomposite-based adsorbents and different approaches of pollutants removal from water/wastewater with several examples to provide a backdrop for future research.


Assuntos
Nanocompostos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Poluentes Ambientais , Humanos , Metais Pesados/química , Praguicidas/análise , Águas Residuárias/química , Água
10.
Chemosphere ; 255: 126965, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32417513

RESUMO

Adsorption rate is a critical parameter in the design of effective biosorbent treatment systems for heavy metals removal. Though numerous studies have identified the physico-chemical properties of biosorbents that exert influence on the adsorption rate, such influence has not been mathematically defined, limiting the effective design of adsorption systems. This study quantifies the influence of biosorbent physico-chemical properties including, specific surface area, surface functional groups, pore size, pore volume and zeta potential on the adsorption rate in relation to three divalent metal cations. Mathematical equations were developed to predict the influence of physico-chemical properties on pseudo second order kinetic constant and thereby predict the adsorption rate. Tea factory waste and coconut shell biochar were mixed in different weight percentages to vary the physico-chemical properties under consideration. Four different initial metal ion concentrations were used. Relationship between pseudo second order kinetic constant at each concentration with physico-chemical properties was quantified using regression analysis. The experimental analysis revealed that among the physico-chemical properties, acidic surface functional groups had the most profound influence on sorption mechanisms. Reliability and accuracy of the predictive models were significantly improved when separate models were developed for two ranges of initial metal ion concentrations. The outcomes of this study will contribute to the effective design and optimization of biosorbent mixtures with the capacity to remove Pb2+, Cu2+ and Cd2+ in wastewater.


Assuntos
Metais Pesados/química , Modelos Químicos , Poluentes Químicos da Água/química , Adsorção , Carvão Vegetal , Cocos , Concentração de Íons de Hidrogênio , Cinética , Metais Pesados/análise , Reprodutibilidade dos Testes , Águas Residuárias/química , Poluentes Químicos da Água/análise
11.
Chemosphere ; 252: 126578, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32443268

RESUMO

In the past few years, two-dimensional (2D) nanomaterials have emerged great potential for the removal of valuable metals and the capture of polluted-heavy metals. Herein, hierarchically flower-like microcrystals with 2D WS2 nanosheets (F-WS2 MCs) were prepared by one-pot hydrothermal synthesis strategy and its adsorption performances for precious metals were systematically assessed. The excellent adsorption efficiencies of ∼86.8%, ∼27.6%, and ∼94.1% towards Ag (I), Pd (II), and Au (III) respectively were achieved within 120 min, and the adsorption curves were in good agreement with a pseudo-second-order kinetic model showing a fast uptake rate at the optimum pH values (1.30 for Au (III), 1.43 for Ag (I), and 3.20 for Pd (II)). The adsorption isotherm followed well in the Langmuir model with the maximum removal capacities (qmax) of 186.2 mg g-1 for Ag (I), 67.29 mg g-1 for Pd (II), and 1340.6 mg g-1 for Au (III), respectively. Furthermore, for recycling purposes, the relevant desorption solution was investigated with different ratios of monobasic acid and thiourea, suggesting the best desorption efficiency of 93.03%, 88.08%, and 85.34% for Ag (I), Pd (II), and Au (III), respectively. By characterizing the crystalline phase, and micromorphology element mapping of F-WS2 MCs before and after adsorption, the strong affinity and significant adsorption-reduction were indicated to dominate the adsorption process. Therefore, this work broadens the application range of WS2 microcrystals, providing an alternative material for capturing precious metals and wastewater treatment applications.


Assuntos
Metais Pesados/química , Modelos Químicos , Adsorção , Ouro/química , Cinética , Reciclagem , Prata
12.
SAR QSAR Environ Res ; 31(5): 347-371, 2020 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-32460542

RESUMO

Two simple and reliable correlations are introduced for the prediction of emission and absorption of porphyrins and their derivatives, i.e. metalloporphyrins and ligand coordinated metalloporphyrins. They can be used to sense the extracted precious metals. The proposed models require only simple structural parameters such as the number of carbon, metal and metal-free molecular fragments of desirable porphyrins or their derivatives. Since the proposed models depend on molecular structures of the desired compounds, they can be easily applied for complex molecular structures. Experimental data of 272 porphyrin derivatives were used to derive and test the novel models for the assessment of their emission (Em.) and absorption (Abs.) values in three solvents namely dichloromethane, toluene and chloroform. The values of the coefficients of determination (r 2) for the training set (183 compounds) in dichloromethane and three different test sets, corresponding to the three mentioned solvents, for the emission and absorption correlations were greater than 0.70. The calculated values of the root-mean-square error (RMSE) for the training sets of Em. and Abs. correlations were equal to 7.56 and 4.86 nm, respectively. Further statistical parameters also confirm the high reliability of the new models.


Assuntos
Quelantes/química , Porfirinas/química , Relação Quantitativa Estrutura-Atividade , Solventes/química , Clorofórmio/química , Hidroquinonas/química , Ligantes , Substâncias Macromoleculares/química , Metais Pesados/química , Cloreto de Metileno/química
13.
Chemosphere ; 256: 127110, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32464361

RESUMO

Organic matter plays many roles in the soil ecosystem. One property of the substance concerns the metal complexation and interaction with organic contaminants. In this sense, the humic substances (HS), a heterogeneous mixture of compounds, naturally derived from degradation of biomass, have been widely studied in environmental sciences. Recent advances showed a new way to produce humic-like substances (HLS) through hydrothermal carbonization of biomass. Thus, this study aimed to evaluate the HLS of hydrochars, produced by using a mixture of sugarcane bagasse and vinasse with sulfuric acid added (1 and 4% v/v), and to assess their interactions with metal ions, (Fe(III), Al(III), Cu(II) and Co(II)) using EEM-PARAFAC and a two-dimensional FTIR correlation analysis. The results were compared to the humic substances extracted from the Amazonian Anthrosol, as a model of anthropogenic organic matter. NMR analysis showed that humic-like extracts from hydrochar are mainly hydrophobic, while the soil has a greater contribution of polar moieties. The HLS and HS showed similar complexation capacities for Fe(III), Al(III) and Cu(II) assays. For Co(II) HLS exhibited larger affinities than HS. Two-dimensional correlation analysis FTIR showed that chemical groups may undergo conformational alteration with metal additions to achieve more stable arrangements (higher stability constant). Therefore, these results contribute more knowledge about the mechanism of HS and metal ion interaction, as well as showing that HTC can be an interesting option for HLS production, to be used as humic based materials.


Assuntos
Carvão Vegetal/química , Substâncias Húmicas/análise , Metais Pesados/química , Solo/química , Sítios de Ligação , Brasil , Ecossistema , Interações Hidrofóbicas e Hidrofílicas , Íons , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Chemosphere ; 253: 126647, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32276119

RESUMO

There is a knowledge gap for the application of one-dimensional graphene in the adsorption process. Our hypothesis was based on the fact that graphene oxide nanoribbons (GONRs) as one-dimensional graphene with more desired edges and specific surface area than other carbonaceous nanomaterials have more oxygen containing functional groups (active sites) on their edges and basal planes and therefore are more capable in adsorption of pollutants. In this regard, we synthesized GONRs by unzipping of multi-walled carbon nanotubes (MWCNTs) and investigated the adsorption behavior of GONRs by ultrasonic-assisted adsorptive removal of As(V) and Hg(II) ions from aqueous solution. The obtained results showed that As(V) ions are more favorably adsorbed onto the GONRs than Hg(II) ions and with increasing initial As(V) and Hg(II) ions concentration to 300 ppm, the equilibrium adsorption uptake of the synthesized GONRs increases to 155.61 and 33.02 mg/g for As(V) and Hg(II) ions, respectively through a rapid separation process in just 12 min. Also, three kinetic models and Freundlich and Langmuir adsorption isotherms were applied to evaluate the obtained experimental results. Our findings highlight the potential application of GONRs as one-dimensional graphene adsorbent with more desired edges than MWCNTs and graphene oxide (GO) and high adsorption capacity for selective removal of heavy metals.


Assuntos
Grafite/química , Metais Pesados/química , Nanoestruturas/química , Poluentes Químicos da Água/química , Adsorção , Arsênico , Concentração de Íons de Hidrogênio , Íons , Cinética , Mercúrio/análise , Nanotubos de Carbono , Água , Poluentes Químicos da Água/análise
15.
Chemosphere ; 253: 126627, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32278907

RESUMO

Manganese (Mn) contamination is a common environmental problem in the world and manganese oxidizing bacteria (MOB) play important roles in bioremediation of heavy metal and organic pollution. In this study, a novel MOB consortium AS containing core microbes of Sphingobacterium and Bacillus was acclimated from Mn-contaminated rivulet sediments. The MOB consortium AS presented good Mn(II) removal performance under 500-10,000 mg/L Mn(II), with Mn(II) removal capacities ranging from 481 to 3478 mg/L. In coexistence systems of Mn(II) and Fe(II), Ni(II), Cu(II), and Zn(II), the MOB consortium AS removed 98%, 91%, 99%, and 76% of Mn(II), respectively. Additionally, the MOB consortium AS could utilize multiple carbon sources (e.g., Chitosan, ß-Cyclodextrin, and Phenanthrene) to remove Mn(II), with Mn(II) removal efficiencies ranging from 11% to 97%. Meanwhile, XRD, XPS, FTIR, SEM, and EDS analyses reflected that biogenic Mn oxides (bio-MnOx-C) contained C, O, Mn (Mn(II) and Mn(IV)) and embodied in rhodochrosite and birnessite. The bio-MnOx-C exhibited second-order kinetic reaction for removal of dye, with corresponding decolorization capacities of 22.0 mg/g for methylene blue and 23.8 mg/g for crystal violet. In addition, bio-MnOx-C showed adsorption capacities of 159.0 mg/g for Cu(II), 130.7 mg/g for Zn(II), and 123.3 mg/g for Pb(II). Overall, this study illustrates consortium AS and bio-MnOx-C have great potentials in remediation of pollution caused by heavy metals and organic pollutants.


Assuntos
Corantes/química , Metais Pesados/química , Adsorção , Bactérias , Biodegradação Ambiental , Manganês/química , Compostos de Manganês , Azul de Metileno , Modelos Químicos , Oxirredução , Óxidos/química
16.
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
17.
Ecotoxicol Environ Saf ; 197: 110587, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32325327

RESUMO

The persistence and bioaccumulation of environmental pollutants in water bodies, soils and living tissues remain alarmingly related to environmental protection and ecosystem restoration. Adsorption-based techniques appear highly competent in sequestering several environmental pollutants. In this review, the recent research findings reported on the assessments of composts and compost-amended soils as adsorbents of heavy metal ions, dye molecules and xenobiotics have been appraised. This review demonstrates clearly the high adsorption capacities of composts for umpteen environmental pollutants at the lab-scale. The main inferences from this review are that utilization of composts for the removal of heavy metal ions, dye molecules and xenobiotics from aqueous environments and soils is particularly worthwhile and efficient at the laboratory scale, and the adsorption behaviors and effectiveness of compost-type adsorbents for agrochemicals (e.g. herbicides and insecticides) vary considerably because of variabilities in structure, topology, bond connectivity, distribution of functional groups and interactions of xenobiotics with the active humic substances in composts. Compost-based field-scale remediation of environmental pollutants is still sparse and arguably much challenging to implement if, furthermore, real-world soil and water contamination issues are to be addressed effectively. Hence, significant research and process development efforts should be promptly geared and intensified in this direction by extrapolating the lab-scale findings in a cost-effective manner.


Assuntos
Corantes/química , Compostagem , Poluentes Ambientais/química , Metais Pesados/química , Xenobióticos/química , Adsorção , Agroquímicos/química , Recuperação e Remediação Ambiental , Substâncias Húmicas
18.
Artigo em Inglês | MEDLINE | ID: mdl-32260493

RESUMO

The effects of engineered nanoparticles (ENPs) on heavy metal fate and biotoxicity in farmland soil are mostly unknown. A flooding-drying simulation experiment was conducted to study the effects of three typical metal oxide nanoparticles (TiO2-NPs, ZnO-NPs and CuO-NPs) on the chemical speciation of heavy metals and micronutrient bioavailability in paddy soil. The results showed that the addition of ZnO-NPs and CuO-NPs caused significant increases in soil pH, Eh and EC after a 90-d flooding-drying process. ZnO-NPs and CuO-NPs addition caused clearly increase in the Zn and Cu concentrations in the acid-soluble fraction, Fe/Mn oxides-bound fraction and organic-bound fraction, leading to higher bioavailability in the soil. DTPA-extractable Zn and Cu increased to 184.6 mg kg-1 and 145.3 mg kg-1 in the maximum ZnO-NPs and CuO-NPs concentration treatments (500 mg kg-1). TiO2-NPs promoted the transformation of Mn from a Fe/Mn oxides-bound fraction to an acid-soluble fraction. Soil Cd bioavailability obviously decreased in the TiO2-NPs treatment but increased in the ZnO-NPs and CuO-NPs treatments.


Assuntos
Nanopartículas Metálicas , Metais Pesados , Poluentes do Solo , Disponibilidade Biológica , Nanopartículas Metálicas/química , Metais Pesados/química , Micronutrientes , Óxidos , Solo , Poluentes do Solo/química
19.
Chemosphere ; 249: 126341, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32213393

RESUMO

Current mechanism studies in plant heavy metal tolerance do not consider the effects of different phenolic acids on the bioavailability of heavy metals and the comparison with antioxidant enzyme system in the hydroxyl radical scavenging capacity. In present study, by a set of pot culture experiments with adding cadmium (Cd) and zinc (Zn) to the sediments, the effects of different phenolic acids on the toxicity of Cd and Zn in Kandelia obovata and the dominant role in scavenging hydroxyl radicals were evaluated. The results showed that 100 mg kg-1 Zn treatment promoted the growth of plant under high concentrations of Cd and Zn stress. Under the stress of Cd and Zn, the phenolic acids were mainly metabolized by phenylpropanoid and flavonoid pathways, supplemented by shikimate and monolignol pathways in K. obovata. Eleven phenolic acids with different abilities of scavenging free radicals were detected in the plant, including pyrogallic acid (Gal), coumaric acid (Cou), protocatechuic acid (Pro), chlorogenic acid (Chl), 4-hydroxy benzoic acid (Hyd), caffeic acid (Caf), vanillic acid (Van), ferulic acid (Fer), benzoic acid (Ben), and salicylic acid (Sal). By adding phenolic acids to the sediments, chlorogenic acid (Chl), pyrogallic acid (Gal), cinnamic acid (Cin), and coumaric acid (Cou) behave as more reactive in changing Cd or Zn into residual fractions than the others, and chlorogenic acid (Chl), pyrogallic acid (Gal), ferulic acid (Fer) and caffeic acid (Caf) have higher ability of scavenging hydroxyl radicals than the others. In summary, K. obovata tends to synthesize phenolic acids with strong scavenging ability of free radicals and changing the bioavailability of Cd and Zn under high concentration of Cd and Zn stress. Phenolic acids played a crucial role in the mitigative effect of heavy metal stress via scavenging free radicals and involving in the process of Cd and Zn uptake and tolerance. The results will provide important theoretical basis and method guidance for mangrove wetland conservation.


Assuntos
Hidroxibenzoatos/química , Metais Pesados/química , Rhizophoraceae/fisiologia , Antioxidantes/metabolismo , Disponibilidade Biológica , Cádmio/química , Cádmio/metabolismo , Ácidos Cafeicos , Ácidos Cumáricos , Metais Pesados/metabolismo , Rhizophoraceae/efeitos dos fármacos , Áreas Alagadas , Zinco/química , Zinco/metabolismo
20.
Chemosphere ; 250: 126290, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32120149

RESUMO

Arsenic- and trace metals-bearing gypsum (As-gypsum) is one of the major hazardous solid wastes produced from metallurgical industry that poses a serious threat to the environment. However, the method for effective extraction of As and trace metals from As-gypsum is still lacking. In this study, simultaneous extraction of As and trace metals from a hydrometallurgical As-gypsum via hydrothermal recrystallization in acid solution was investigated. The effects of the type (H2SO4 vs HCl) and concentration of acid, and temperature on extraction efficiency were assessed. The results showed that 99% As, >92% Cu and >96% Zn could be extracted from the As-gypsum during hydrothermal treatment in 6 mol L-1 H2SO4 at 90 and 120 °C, but Pb and Cd could not be extracted efficiently. The results of hydrothermal treatment in HCl solutions demonstrated that higher HCl concentration and temperature significantly enhanced the extraction efficiency and 100% As, Cu2+, Zn2+, Pb2+ and >90% Cd were removed from the As-gypsum after treatment in 6 mol L-1 HCl, at 120 °C, for 12 h. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy results revealed that dissolution-recrystallization of gypsum is the key process for the removal of the incorporated As and trace metals. Thermodynamic modelling indicated that the released HAsO42-/Me2+ transformed into H3AsO4/MeCln(2-n) (1 ≤ n ≤ 4) species in HCl solution, hence inhibiting their reincorporation into the recrystallization products via isomorphic substitution for SO42-/Ca2+. This work provides a simple and effective method for detoxification and reclamation of As-gypsum.


Assuntos
Arsênico/química , Arsênico/toxicidade , Sulfato de Cálcio/química , Resíduos Perigosos , Inativação Metabólica , Metalurgia , Metais , Metais Pesados/química , Oligoelementos/química , Difração de Raios X
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