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1.
Environ Monit Assess ; 193(1): 46, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33415474

RESUMO

The activities of the artisanals and small-scale miners in Nasarawa state, Nigeria, are increasing daily without considering the loss of biodiversity, which has continuously disrupted ecological functions and environmental balance. The study aimed at investigating the effect of tantalite mining activities on flora diversity. Three study sites were selected for floristic data collection, comprising tantalite mining site A situated in Azara, Awe LGA; tantalite mining site B situated in Tunga, Awe LGA; and referred site C situated along the Makurdi-Obi Road, Lafia LGA. Eight plots of 20 × 20 m were systematically placed along two transect lines of 1000 m with 500 m distance apart. The total numbers of 32 plant species, at the ratio of 11:20:21 individual species, were found in sites A, B, and referred site C, respectively. Tantalite mining site A showed 46% rare herbs dominating the site, with an introduction of new non-native species of Jateorhiza spp. and Hyptis suaveolens, presenting a significantly high number of individuals (p ˂ 0.0069). Tantalite site B, Tunga, had 50% reductions of several indigenous tree species such as Daniellia oliveri and Vitex doniana, while site A had 75% reduction of tree species. Therefore, the floristic diversity in site A endured a higher degradation than in site B. The indigenous species in site A were almost completely replaced with problematic weeds, invasive weed species, and non-native plant species. The tree diversities in sites A and B were seriously threatened, and H. suaveolens has been regarded as a potentially invasive plant species in Nasarawa state, Nigeria.


Assuntos
Monitoramento Ambiental , Mineração , Biodiversidade , Humanos , Nigéria , Óxidos , Tantálio
2.
Ecotoxicol Environ Saf ; 208: 111624, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396144

RESUMO

Phthalate esters (PAEs), such as dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), are used extensively as additives and plasticizers, and have become ubiquitous in the environment. PAEs in the soil could have adverse effects on crop plants as well as humans via accumulations in food chain. Thus, it is important to explore strategies to reduce the bioavailability of phthalate esters. We investigated the effects of Fe-Mn oxide-modified biochar composite (FMBC) applications on the quality of wheat grown in DBP- and DEHP-polluted brown soil. The application of FMBC and biochar (BC) increased the wheat grain biomass by 9.71-223.01% and 5.40-120.15% in the DBP-polluted soil, and 10.52-186.21% and 4.50-99.53% in the DEHP-spiked soil in comparison to the controls. All FMBC treatments were better than the BC treatments, in terms of decreasing DBP and DEHP bioavailability for the wheat grains. The activities of the glutamine synthetase and glutamic-pyruvic transaminase in the flag leaves at the filling stage and of granule-bound starch synthase, soluble starch synthase, and adenosine diphosphate-glucose pyrophosphorylase in the grains at maturity increased significantly with increases in either the BC or FMBC applications. This, in turn, increased the starch, protein, and amino acid content in the wheat grains. Compared with the BC treatment, the FMBC amendment induced only slight increases in the aforementioned factors. This study offers novel insights into potential strategies for decreasing PAEs bioavailability in soil, with potential positive implications for crop quality and environmental health improvements.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Ácidos Ftálicos/química , Poluentes do Solo/metabolismo , Triticum/fisiologia , Dibutilftalato/análise , Dibutilftalato/metabolismo , Dietilexilftalato/metabolismo , Grão Comestível/química , Poluição Ambiental , Ésteres/análise , Humanos , Ferro/análise , Óxidos/análise , Plastificantes/análise , Solo/química , Poluentes do Solo/análise , Triticum/metabolismo
3.
Ecotoxicol Environ Saf ; 208: 111626, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396146

RESUMO

Soil application of biochars has been shown to effectively immobilize potentially toxic elements (PTEs). Soil water regime can also affect PTE availability. No previous studies have examined the interactive effect of biochars and soil water regime on Pb availability. Therefore, this study investigated the effect of high and low temperature (300 and 600°C) biochars derived from cow manure (CB), municipal compost (MB) and licorice root pulp (LB) applied at 3 wt%, under two soil moisture regimes (field capacity (FC) and saturation (ST)) on Pb release kinetics and chemical fractions in a Pb-contaminated calcareous soil. Results showed that CB and MB treatments significantly enhanced Pb stabilization compared to LB, attributed to their favorable chemical properties (high P, ash, carbonate, oxidizable C content and high pH) which could promote Pb conversion into stable chemical fractions. Immobilization of Pb was enhanced under saturated conditions compared to FC by the treatments, which is attributed to increased soil pH, reduction of metal oxides and possible formation of sulfides. The most significantly effective treatments were the CB300, CB600 and MB600 treatments under ST, as indicated by significant decrease in soil Pb mobility factor from 29.1% (CL+FC) to 21.2-22.9%, and 11.7-16.3% increase in non-EDTA-extractable Pb. Results of this study demonstrate that combined application of high ash biochars and soil water saturation significantly enhances Pb immobilization in calcareous soil.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Poluição Ambiental , Esterco , Óxidos , Solo/química , Poluentes do Solo/análise
4.
Nat Commun ; 12(1): 46, 2021 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-33397902

RESUMO

The exploration of highly efficient processes to convert renewable biomass to fuels and value-added chemicals is stimulated by the energy and environment problems. Herein, we describe an innovative route for the production of methylcyclopentadiene (MCPD) with cellulose, involving the transformation of cellulose into 3-methylcyclopent-2-enone (MCP) and subsequent selective hydrodeoxygenation to MCPD over a zinc-molybdenum oxide catalyst. The excellent performance of the zinc-molybdenum oxide catalyst is attributed to the formation of ZnMoO3 species during the reduction of ZnMoO4. Experiments reveal that preferential interaction of ZnMoO3 sites with the C=O bond instead of C=C bond in vapor-phase hydrodeoxygenation of MCP leads to highly selective formations of MCPD (with a carbon yield of 70%).


Assuntos
Celulose/química , Ciclopentanos/química , Óxidos/química , Oxigênio/química , Adsorção , Catálise , Relação Estrutura-Atividade , Difração de Raios X
5.
Ecotoxicol Environ Saf ; 208: 111752, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396077

RESUMO

Arsenic is a toxic heavy metal vastly dispersed all over the earth crust. It manifests several major adverse health issues to millions of arsenic exposed populations. Arsenic is associated with different types of cancer, cardiovascular disorders, diabetes, hypertension and many other diseases. On the contrary, arsenic (arsenic trioxide, As2O3) is used as a chemotherapeutic agent in the treatment of acute promyelocytic leukemia. Balance between arsenic induced cellular proliferations and apoptosis finally decide the outcome of its transformation rate. Arsenic propagates signals via cellular and nuclear pathways depending upon the chemical nature, and metabolic-fates of the arsenical compounds. Arsenic toxicity is propagated via ROS induced stress to DNA-repair mechanism and mitochondrial stability in the cell. ROS induced alteration in p53 regulation and some mitogen/ oncogenic functions determine the transformation outcome influencing cyclin-cdk complexes. Growth factor regulator proteins such as c-Jun, c-fos and c-myc are influenced by chronic arsenic exposure. In this review we have delineated arsenic induced ROS regulations of epidermal growth factor receptor (EGFR), NF-ĸß, MAP kinase, matrix-metalloproteinases (MMPs). The role of these signaling molecules has been discussed in relation to cellular apoptosis, cellular proliferation and neoplastic transformation. The arsenic stimulated pathways which help in proliferation and neoplastic transformation ultimately resulted in cancer manifestation whereas apoptotic pathways inhibited carcinogenesis. Therapeutic strategies against arsenic should be designed taking into account all these factors.


Assuntos
Arsênico/fisiologia , Proliferação de Células/fisiologia , Plásticos/metabolismo , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Arsênico/metabolismo , Trióxido de Arsênio/metabolismo , Trióxido de Arsênio/farmacologia , Arsenicais/metabolismo , Proliferação de Células/efeitos dos fármacos , Humanos , Mitocôndrias/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neoplasias , Óxidos/toxicidade , Transdução de Sinais/efeitos dos fármacos
6.
Chemosphere ; 262: 127828, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32763579

RESUMO

Cadmium (Cd) pollution is a widespread environmental problem that decreases crop production, destroys the microbial ecology of soil, and poses a severe risk to human health. Organo-chemical amendment is a cost-effective, eco-friendly, and community-acceptable widely applied an in situ technique for metal-contaminated farmland. In this study, we mixed lime, zeolite, calcium magnesium phosphate fertilizer, and biochar in a mixture ratio of 71:23:5:1 to form a mixed amendment. Field and laboratory experiments were conducted to study the effects of the mixed amendment on soil exchangeable Cd content, plant Cd accumulation, and soil microbial community. It was found that the application of 0.5% mixed amendment decreased exchangeable soil Cd by more than 85% and 64% in wheat and rice season, respectively, compared with control (CK), without increasing pH. Moreover, the application of 0.5% mixed amendment decreased Cd accumulation in grains by 22.9% and 41.2% in wheat and rice season, respectively, compared to CK. The result of phospholipid fatty acids (PLFAs) shows that the level of soil microbial diversity and species richness under mixed amendment treatments were higher than in lime treatment, indicating more copiotrophic conditions and faster rate of nutrient turnover in mixed amendment than pure lime treatment. Hence, it concluded that the mixed amendment has a strong effect on fixing exchangeable soil Cd and reducing the accumulation of Cd in crops. Finally, it was observed that the mixed amendment improved the soil microbial community structure and accelerate the rate of nutrient turnover by microbes under this favorable condition comparative to individual treatments.


Assuntos
Cádmio/química , Microbiota/efeitos dos fármacos , Microbiologia do Solo , Poluentes do Solo/química , Agricultura/métodos , Cádmio/análise , Cádmio/toxicidade , Compostos de Cálcio , Carvão Vegetal , Produtos Agrícolas , Poluição Ambiental , Recuperação e Remediação Ambiental/métodos , Fertilizantes , Humanos , Microbiota/fisiologia , Oryza/efeitos dos fármacos , Óxidos , Fosfatos , Rotação , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Triticum
7.
Chemosphere ; 262: 127837, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32768755

RESUMO

The effect of oxidation degree of graphene oxides (GO) on their removal from wastewater via froth flotation was studied in this work. Four types of GO samples with different oxidation degrees were synthesized and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force spectroscopy (AFM) et al. The effects of cetyl trimethyl ammonium bromide (CTAB) concentration, pH, stirring time on the removal of GO by froth flotation had been discussed. It was found that the addition of CTAB could improve surface hydrophobicity of GO, endowing GO to be easily separated by froth flotation. The removal was dependent on CTAB dosage, pH and stirring time. Moreover, the removal first increased and then decreased with the increasing oxidation degree of GO, and less kinetic energy input was needed to overcome the energy barrier between GO flocs with the increase of oxidation degree. The removal mechanism was proven to be electrostatic attraction, and the different contents of oxgenous-containing functional groups in GOs with various oxidation degrees played a vital role in their removal via froth flotation.


Assuntos
Grafite/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Interações Hidrofóbicas e Hidrofílicas , Oxirredução , Óxidos/química , Espectroscopia Fotoeletrônica , Águas Residuárias
8.
Chemosphere ; 262: 127853, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32777616

RESUMO

Green rusts (GRs) are redox active towards contaminants but they are not stable for long distance transport during the soil and groundwater remediation. In this study, green rust chloride (GR) was stabilized by selected regents, including silicate (Si), phosphate (P), fulvic acid (FA), carboxymethyl cellulose (CMC) and bone char (BC), then these stabilized GR, collectively named GR-X, would be further applied for Cr(VI) removal from aqueous solution. The stabilization experiment demonstrated that the release of Fe(II) from GR was effectively suppressed by above reagents, enabling at least 50% lower Fe(II) leaching from the stabilized GR-X than that from the pristine GR. The intact hexagonal GR plates and crystallinity were also confirmed by the SEM images and XRD patterns after storage for 7 days, indicating the stable structure of GR-X was remained. In the Cr(VI) removal tests, Cr(VI) was eliminated by GR-X in seconds with a Fe(II) utilization efficiency over 90%. The Cr species examination demonstrated that the GR-X was able to transfer Cr(VI) into stable Cr(III)-Fe(III) precipitates (Fe-Mn oxides fraction). After Cr(VI) removal tests, all reactors were exposed to the air for 1 week to monitor pH fluctuation and evaluated the risk of acidification. The results indicate that, except for GR-Si system, the other post-remediation systems are stable and the pH buffering ability of GR-X could avoid acidification and lower the Cr leaching risk.


Assuntos
Cromo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Carboximetilcelulose Sódica , Cromo/análise , Água Subterrânea , Ferro/química , Cinética , Oxirredução , Óxidos , Solo/química , Água/química , Poluentes Químicos da Água/análise
9.
Chemosphere ; 262: 127904, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32799153

RESUMO

Manganese accumulated in corrosion scales on drinking water distribution systems (DWDSs) can be released into bulk water, causing discolouration and thereby leading to customer concerns about drinking water quality. A static release experiment was conducted on iron pipe scales under three different temperatures, pH values, alkalinity values, sulfate (SO42-) concentrations, and disinfectants to study the separate effect of these factors on Mn release from pipe scales under stagnant conditions. Results showed that more Mn was released from corrosion scales under the conditions of lower pH, lower alkalinity, higher temperature, and higher SO42- concentrations. Three commonly used disinfectants, sodium hypochlorite (NaClO), chlorine dioxide (ClO2), and monochloramine (NH2Cl) were found to inhibit the release of Mn from iron corrosion scales, with the ranked order of inhibitory effect of ClO2≈NaClO > NH2Cl under the same CT (product of disinfectant concentration and contact time) value. The orthogonal experimental results indicated that SO42- and alkalinity had extremely significant effects on the release of Mn from pipe scales, while pH and disinfectant type had a significant impact on the release of Mn from pipe scales. Thus, the SO42- concentration and alkalinity of the bulk water should be determined to avoid excessive release of Mn into drinking water. However, further investigation of the effect of disinfectants on Mn release in DWDSs is necessary. This research helps establish a systematic understanding of the influential factors in Mn release from pipe scales into bulk water, as well as their significant relationships.


Assuntos
Água Potável/química , Manganês/análise , Poluentes Químicos da Água/análise , Compostos Clorados , Corrosão , Desinfetantes/análise , Concentração de Íons de Hidrogênio , Ferro , Óxidos , Sulfatos/análise , Temperatura , Qualidade da Água , Abastecimento de Água
10.
Chemosphere ; 262: 127845, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32799147

RESUMO

A Fe-Cu bimetal catalyst (FCHS) was synthesized by depositing Fe3O4 on the shell of CuOx hollow spheres, which were prepared via a soft template method. Several characterization methods, including XRD, SEM-EDS&mapping, TEM, FTIR, and XPS, were used to reveal the morphology and surface properties of FCHS. The characterization results demonstrated that the double-shell hollow structure is formed with a dense coating of Fe3O4 nanoparticles on the surface of CuOx hollow spheres. FCHS can exhibit excellent catalytic activity to degrade sulfadiazine (SDZ) with the oxidant of persulfate (PS). The optimal SDZ removal performance was explored by adjusting reaction parameters, including catalyst dosage, oxidant dosage, and solution pH. The SDZ removal efficiency in the FCHS + PS system could reach 95% at the optimal reaction condition ([catalyst]0 = 0.2 g/L, [PS]0 = 2 mM, pH = 7.0) with 5 mg/L of SDZ. Meanwhile, the degradation efficiency decreased with the coexistence of phosphate or carbonate anions. According to the results of radicals scavenging experiments and the electron paramagnetic resonance analysis, the radicals of SO4·-, O2·- and ·OH generated in the FCHS + PS system contribute to the degradation of SDZ. Moreover, the results of XPS revealed that the solid-state charge-transfer redox couple of Fe(III)/Fe(II) and Cu(I)/Cu(II) can promote the activation of PS. It means that the cooperation effect between Cu oxides and Fe oxides in the double-shell structure is beneficial to the catalytic degradation of SDZ. Furthermore, four possible pathways for SDZ degradation were proposed according to the analysis of intermediate products detected by the LCMS-IT-TOF.


Assuntos
Sulfadiazina/química , Poluentes Químicos da Água/química , Catálise , Cobre , Compostos Férricos/química , Oxidantes , Oxirredução , Óxidos , Poluentes Químicos da Água/análise
11.
Chemosphere ; 262: 127885, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32805658

RESUMO

In recent years, research on graphene oxide (GO) has developed rapidly in both academic and industrial applications such as electronic, biosensor, drug delivery, water treatment and so forth. Based on the large amount of applications, it is anticipated that GO will inevitably find its own way to the environment, if used are not restricted to prevent their release. Environmental transformation is an important transformation process in the natural environment. In this review, we will summarize the recent developments on environmental transformation of GO in the aquatic environment. Although papers on environmental transformation of graphene-based nanomaterials can be found, a systematic picture describing photo-transformation of GO (dividing into different irradiation sources), environmental transformation of GO in the dark environmental, the environmental toxicity of GO are still lacking. Thus, it is essential to summarize how different light sources will affect the GO structure and reactive oxygen species generation in the photo-transformation process, how GO will react with various natural constituents in the aquatic environment, whether GO will toxic to different aquatic organisms and what will be the interactions between GO and the intracellular receptors in the intracellular level once GO released into the aquatic environment. This review will arouse the realization of potential risk that GO can bring to the aquatic environment and enlighten us to pay attention to behaviors of other two-dimensional GO-like nanomaterials, which have been intensively applied and studied in recent years.


Assuntos
Grafite/química , Poluentes Químicos da Água/química , Organismos Aquáticos , Nanoestruturas/química , Óxidos/química , Poluentes Químicos da Água/toxicidade
12.
J Environ Sci (China) ; 99: 249-259, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183702

RESUMO

A series of Sr-doped BiFeO3 perovskites (Bi1-xSrxFeO3, BSFO) fabricated via sol-gel method was applied as peroxydisulfate (PDS) activator for ciprofloxacin (CIP) degradation. Various technologies were used to characterize the morphology and physicochemical features of prepared BSFO samples and the results indicated that Sr was successfully inserted into the perovskites lattice. The catalytic performance of BiFeO3 was significantly boosted by strontium doping. Specifically, Bi0.9Sr0.1FeO3 (0.1BSFO) exhibited the highest catalytic performance for PDS activation to remove CIP, where 95% of CIP (10 mg/L) could be degraded with the addition of 1 g/L 0.1BSFO and 1 mmol/L PDS within 60 min. Moreover, 0.1BSFO displayed high reusability and stability with lower metal leaching. Weak acidic condition was preferred to neutral and alkaline conditions in 0.1BSFO/PDS system. The boosted catalytic performance can be interpreted as the lower oxidation state of Fe and the existence of affluent oxygen vacancies generated by Sr doping, that induced the formation of singlet oxygen (1O2) which was confirmed as the dominant reactive species by radical scavenging studies and electron spin resonance (ESR) tests. The catalytic oxidation mechanism related to major 1O2 and minor free radicals was proposed. Current study opens a new avenue to develop effective A-site modified perovskite and expands their application for PDS activation in wastewater remediation.


Assuntos
Ciprofloxacino , Estrôncio , Compostos de Cálcio , Óxidos , Titânio
13.
Chemosphere ; 262: 127567, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32755692

RESUMO

Acid mine drainage (AMD) is recognized as a challenge encountered by mining industries globally. Cyclic mineralization method, namely Fe2+ oxidation/mineralization-residual Fe3+ reduction-resultant Fe2+ oxidation/mineralization, could precipitate Fe and SO42- present in AMD into iron hydroxysulfate minerals and greatly improve the efficiency of subsequent lime neutralization, but the current Fe0-mediated reduction approach increased the mineralization cycles. This study constructed a bacteria-driven biomineralization system based on the reactions of Acidithiobacillus ferrooxidans-mediated Fe2+ oxidation and Acidiphilium multivorum-controlled Fe3+ reduction, and utilized water-dropping aeration and biofilm technology to satisfy the requirement of practical application. The resultant biofilms showed stable activity for Fe conversion: the efficiency of Fe2+-oxidation, Fe-precipitation, and Fe3+-reduction maintained at 98%, 32%, and 87%, respectively. Dissolved oxygen for Fe-oxidizing bacteria growth was continuously replenished by water-dropping aeration (4.2-7.2 mg/L), and the added organic carbon was mainly metabolized by Fe-reducing bacteria. About 89% Fe and 60% SO42- were precipitated into jarosite mineral after five biomineralization cycles. Fe was removed via forming secondary mineral precipitates, while SO42- was coprecipitated into mineral within the initial three biomineralization cycles, and then mainly precipitated with Ca2+ afterwards. Fe concentration in AMD was proven to directly correlate with subsequent lime neutralization efficiency. Biomineralization for five cycles drastically reduced the amount of required lime and neutralized sludge by 75% and 77%, respectively. The results in this study provided theoretical guidance for practical AMD treatment based on biomineralization technology.


Assuntos
Ferro/análise , Poluentes Químicos da Água/análise , Acidiphilium , Acidithiobacillus , Ácidos , Bactérias/metabolismo , Biodegradação Ambiental , Biomineralização , Compostos de Cálcio , Compostos Férricos , Ferro/metabolismo , Minerais , Mineração , Óxidos , Sulfatos , Poluentes Químicos da Água/metabolismo
14.
Chemosphere ; 262: 127803, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32755694

RESUMO

Mine tailings pose a huge hazard for environmental and human health, and the establishment of vegetation cover is crucial to reduce pollutant dispersion for the surroundings. However, their hostile physicochemical conditions hamper plant growth, compromising phytoremediation strategies. This study aims to investigate the role of organo-mineral amendments and plant growth-promoting rhizobacteria (PGPR) on the improvement of mine tailings properties and Lolium perenne L. (ryegrass) growth. Plants were grown in mine tailings mixed with an agricultural soil (1:1), 10% compost, and supplied with two different inorganic amendments - rock phosphate (6%) or lime (3%), and inoculated with the rhizobacterial strains Advenellakashmirensis BKM20 (B1) and Mesorhizobium tamadayense BKM04 (B2). The application of organo-mineral amendments ameliorated tailings characteristics, which fostered plant growth and further enhanced soil fertility and microbial activity. These findings were consistent with the increase of total organic carbon levels, with the higher numbers of heterotrophic and phosphate solubilizing bacteria, and higher dehydrogenase and urease activities, found in these substrates after plant establishment. Plant growth was further boosted by PGPR inoculation, most noticeable by co-inoculation of both strains. Moreover, inoculated plants showed increased activities for several antioxidant enzymes (catalase, peroxidase, polyphenoloxidase, and glutathione reductase) which indicate a reinforced antioxidant system. The application of agricultural soil, compost and lime associated with the inoculation of a mixture of PGPR proved to enhance the establishment of vegetation cover, thus promoting the stabilization of Kettara mine tailings. Nonetheless, further studies are needed in order to confirm its effectiveness under field conditions.


Assuntos
Biodegradação Ambiental , Recuperação e Remediação Ambiental/métodos , Mesorhizobium/fisiologia , Desenvolvimento Vegetal , Poluentes do Solo/análise , Bactérias , Compostos de Cálcio , Lolium/crescimento & desenvolvimento , Minerais , Mineração , Óxidos , Solo/química
15.
Sci Total Environ ; 753: 141835, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32898807

RESUMO

Mn(III) has been regarded as the origin of oxidative reactivity of MnO2 recently, however this remains controvertible. Herein, carbamazepine (CBZ), a typical refractory pharmaceutical, was treated by δ-, α-, ß-, and γ-MnO2 and the role of Mn(III) was investigated. After the removal of Mn(III) by pyrophosphate washing, the δ-MnO2 exhibited a higher kinetics rate (0.180 min-1) than the sample before washing (0.075 min-1). Dissolved Mn(III) in the forms of acetate-complex Mn(III), newly acid-dissolved Mn(III) from MnO2 solid, and in-situ generated Mn(III) showed negligible oxidative reactivity towards the oxidation of CBZ. These evidenced that Mn(III) did not play a critical role in the oxidation of CBZ. The oxidative reactivity of MnO2 with different structures for the oxidation of CBZ followed the order: δ-MnO2 >> > α-MnO2 ≈ Î³-MnO2 > ß-MnO2. Density functional theory calculations suggested that the crystalline plane of δ-MnO2 significantly contributed to the oxidation of CBZ, thus leading to the superior performance of δ-MnO2. A new surface reaction dominated mechanism was proposed, which implies that the oxidative reactivity of MnO2 may not result from Mn(III) as previously believed. These findings could shed light on the understanding of MnO2-involved oxidation in water treatment and natural processes.


Assuntos
Compostos de Manganês , Preparações Farmacêuticas , Carbamazepina , Oxirredução , Óxidos
16.
Chemosphere ; 262: 127791, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32799141

RESUMO

Mercury (Hg) that leaches from municipal sewage sludge (MSS) landfill under natural rain is of increasing concern. The column leaching experiments were conducted to investigate the leaching characteristics of total mercury (THg) and methylmercury (MeHg) as well as pH, total organic carbon (TOC), and total suspended solids (TSS) in the raw sludge (RS) and lime-conditioned sludge (LCS) under simulated rain with different acidities (pH 6.5 and 2.9). Results showed the release of MeHg in the leachates presented different patterns from THg. And the final amounts of MeHg in the MSS columns were 1.49 (RS at pH = 6.5), 1.88 (RS at 2.9), 1.97 (LCS at pH = 6.5), and 2.06 times (LCS at pH = 2.9) higher than the initial amounts, suggesting methylation of inorganic Hg (IHg) occurred in the leaching process. The leaching efficiencies of THg and MeHg in RS was lower than that in LCS, indicating lime was more favorable for the release of THg and MeHg. And lower values of pH of the simulated rain promoted the release of THg and MeHg from RS while the opposite was true for LCS. This study provides a better understanding of the release and biogeochemical transformations of Hg in MSS.


Assuntos
Monitoramento Ambiental/métodos , Mercúrio/análise , Compostos de Metilmercúrio/análise , Chuva/química , Esgotos/química , Poluentes Químicos da Água/análise , Compostos de Cálcio/química , China , Modelos Teóricos , Óxidos/química
17.
Chemosphere ; 262: 127738, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32763575

RESUMO

A Pt-Co3O4 catalyst named Pt-Co(OH)2-O was prepared by metal-organic templates (MOTs) conversion and used for catalytic oxidation of toluene. Through the conversion, the morphology of catalysts transformed from rhombic dodecahedron to nanosheet and the coated Pt nanoparticles (NPs) were more exposed. The Binding energy shift in XPS test indicates that the strong metal-support strong interaction (SMSI) has enhanced, and the physicochemical changes caused by it are characterized by other techniques. At the same time, Pt-Co(OH)2-O showed the best catalytic performance (T50 = 157 °C, T90 = 167 °C, Ea = 40.85 kJ mol-1, TOFPt = 2.68 × 10-3 s-1) and good stability. In addition, the in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) studies have shown that because SMSI weakened the Co-O bond, the introduction of Pt NPs can make the migration of oxygen in the catalyst easier. The change of binding energy change and the content of various species in the quasi in situ XPS experiment further confirmed that the Pt-Co(OH)2-O catalyst has stronger SMSI, resulting in its stronger electron transfer ability and oxygen migration ability, which is conducive to catalytic reactions. This work provides new ideas for the development of supported catalysts and provides a theoretical reference for the relevant verification of SMSI.


Assuntos
Nanopartículas Metálicas/química , Tolueno/química , Catálise , Cobalto/química , Poluentes Ambientais/química , Oxirredução , Óxidos/química , Oxigênio/química , Espectroscopia Fotoeletrônica , Platina/química , Espectroscopia de Infravermelho com Transformada de Fourier
18.
Chemosphere ; 264(Pt 1): 128428, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33022504

RESUMO

The toxic effect of eight metal oxide nanoparticles (MONPs) on Escherichia coli was experimentally evaluated following standard bioassay protocols. The obtained cytotoxicity ranking of these studied MONPs is Er2O3, Gd2O3, CeO2, Co2O3, Mn2O3, Co3O4, Fe3O4/WO3 (in descending order). The computed EC50 values from experimental data suggested that Er2O3 and Gd2O3 were the most acutely toxic MONPs to E. coli. To identify the mechanism of toxicity of these 8 MONPs along with 17 other MONPs from our previous study, we employed seven classifications and machine learning (ML) algorithms including linear discriminant analysis (LDA), naïve bayes (NB), multinomial logistic regression (MLogitR), sequential minimal optimization (SMO), AdaBoost, J48, and random forest (RF). We also employed 1st and 2nd generation periodic table descriptors developed by us (without any sophisticated computing facilities) along with experimentally analyzed Zeta-potential, to model the cytotoxicity of these MONPs. Based on qualitative validation metrics, the LDA model appeared to be the best among the 7 tested models. The core environment of metal defined by the ratio of the number of core electrons to the number of valence electrons and the electronegativity count of oxygen showed a positive impact on toxicity. The identified properties were important for understanding the mechanisms of nanotoxicity and for predicting the potential environmental risk associated with MONPs exposure. The developed models can be utilized for environmental risk assessment of any untested MONP to E. coli, thereby providing a scientific basis for the design and preparation of safe nanomaterials.


Assuntos
Nanopartículas Metálicas , Óxidos , Teorema de Bayes , Simulação por Computador , Escherichia coli , Nanopartículas Metálicas/toxicidade , Óxidos/toxicidade
19.
J Endod ; 47(1): 146-155, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33065177

RESUMO

The aim of this case report was to present a reparative treatment approach of an extensive internal inflammatory resorption with a lateral perforation and apical and lateral inflammatory lesions. Only the necrotic coronal part of the pulp was removed, and the vital pulp tissue within the resorption cavity and the apical part of the root canal was left uninstrumented. Bleeding was induced, and the blood clot was covered with mineral trioxide aggregate. Hard tissue repair and healing of the apical lesion could be observed in the 3-year recall.


Assuntos
Materiais Restauradores do Canal Radicular , Reabsorção da Raiz , Compostos de Alumínio/uso terapêutico , Compostos de Cálcio/uso terapêutico , Combinação de Medicamentos , Humanos , Óxidos/uso terapêutico , Tratamento do Canal Radicular , Reabsorção da Raiz/diagnóstico por imagem , Reabsorção da Raiz/terapia , Silicatos/uso terapêutico
20.
Chemosphere ; 263: 127870, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32835967

RESUMO

Polyhedral CoOx was synthesized by calcination of Co-based metal-organic framework ZIF-67 and highly dispersed Pt nanoparticles were successfully loaded on CoOx. The catalytic results showed that Ptnano/CoOx had the best activity and stability. As compared with conventional Co3O4, polyhedral CoOx showed more excellent catalytic oxidation performance of toluene, which was related to enhanced oxygen mobility, defective structure and rich active oxygen species provided by Polyhedral CoOx. Moreover, Pt-CoOx metal-support interaction enhanced the dispersion of Pt species and showed more Pt0 ratio. It was reasonable that the gaseous O2 can be activated directly or moved into the catalyst's surface to form oxygen cycle.


Assuntos
Cobalto , Nanopartículas , Óxidos , Tolueno
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