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1.
Water Sci Technol ; 82(5): 940-953, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031072

RESUMO

Ag-Cu ions in cooling water may inhibit the activity of sulfate-reducing bacteria and therefore provide solutions to microbiologically induced corrosion (MIC) problems, mainly caused by Desulfovibrio sp. To investigate this, the MIC behavior of Desulfovibrio sp. on 316L stainless steel in terms of growth and extracellular polymeric substances (EPS) production was investigated in the presence of Ag-Cu ions. Laboratory-scale systems were set up with final concentrations of 0.13 ppm Ag and 0.3 ppm Cu ions, as they are the frequently used doses for cooling waters, and operated over 720 hours. The corrosion rate was evaluated by gravimetric assay, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. The growth of Desulfovibrio sp. was assessed by bacterial counting and EPS production. Ag-Cu ions in the biofilm were assessed by inductively coupled plasma - optical emission spectrometry (ICP-OES) and EDS-elemental mapping analyses. It was concluded that the ion concentrations used caused an increase in EPS production, especially of protein. The corrosion rate of the metal by Desulfovibrio sp. in the presence of ions was detected as being 29 times higher than that in the sterile medium with the ions after 720 hours. The results suggested that Desulfovibrio sp. exhibited more corrosive behavior in the presence of non-toxic concentrations of Ag-Cu ions.


Assuntos
Desulfovibrio , Aço Inoxidável , Corrosão , Íons , Prata
2.
Water Sci Technol ; 82(5): 984-997, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031075

RESUMO

The research aimed to develop a novel mesoporous aluminosilicate/zeolite composite by the template co-precipitation method. The effect of aluminosilicate (AlSi) and zeolite (NaY) on the basic properties and adsorption capacity of the resultant composite was conducted at different mass ratios of AlSi/NaY (i.e., 5/90, 10/80, 15/85, 20/80, and 50/50). The adsorption characteristics of such composite and its feedstock materials (i.e., aluminosilicates and zeolite) towards radioactive Sr2+ ions and toxic metals (Cu2+ and Pb2+ ions) in aqueous solutions were investigated. Results indicated that BET surface area (SBET), total pore volume (VTotal), and mesopore volume (VMeso) of prepared materials followed the decreasing order: aluminosilicate (890 m2/g, 0.680 cm3/g, and 0.644 cm3/g) > zeolite (623 m2/g, 0.352 cm3/g, and 0.111 cm3/g) > AlSi/NaY (20/80) composite (370 m2/g, 0.254 cm3/g, and 0.154 cm3/g, respectively). The Langmuir maximum adsorption capacity (Qm) of metal ions (Sr2+, Cu2+, and Pb2+) in single-component solution was 260 mg/g, 220 mg/g, and 161 mg/g (for zeolite), 153 mg/g, 37.9 mg/g, and 66.5 mg/g (for aluminosilicate), and 186 mg/g, 140 mg/g, and 77.8 mg/g for (AlSi/NaY (20/80) composite), respectively. Ion exchange was regarded as a domain adsorption mechanism of metal ions in solution by zeolite; meanwhile, inner-surface complexation was domain one for aluminosilicate. Ion exchange and inner-surface complexation might be mainly responsible for adsorbing metal ions onto the AlSi/NaY composite. Pore-filling mechanism was a less important contributor during the adsorption process. The results of competitive adsorption under binary-components (Cu2+ and Sr2+) and ternary-components (Cu2+, Pb2+, and Sr2) demonstrated that the removal efficacy of target metals by the aluminosilicate, zeolite, and their composite remarkably decreased. The synthesized AlSi/NaY composite might serve as a promising adsorbent for real water treatment.


Assuntos
Zeolitas , Silicatos de Alumínio , Íons , Chumbo
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3388-3392, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018731

RESUMO

This paper reports on the customized thinning of neural probes based on silicon (Si) using deep reactive ion etching (DRIE) as a post-processing step. The reduced probe dimensions are expected to minimize local tissue trauma, while guaranteeing probe integrity during implantation. For DRIE, the probes are partially masked by a micromachined Si cover chip comprising tailored cavities enabling any desired thinned length l and probe thickness t by a proper choice of cover chip design and DRIE parameters, respectively. A broad variety of probe designs were realized with shank tip thicknesses ranging from 35 µm down to 2 µm. All probes could successfully be implanted into a brain tissue phantom, demonstrating a pronounced reduction in insertion force from 0.55 mN for unprocessed probes to 0.08 mN for 2-µm-thin shanks. When the dura mater was mimicked by a polyethylene (PE) membrane, forces were reduced from 28.9 mN to 16.6 mN for 15-µm-thin shanks.


Assuntos
Fenômenos Mecânicos , Silício , Encéfalo , Dura-Máter , Íons
4.
Water Sci Technol ; 82(7): 1430-1444, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079721

RESUMO

Cadmium contamination in industrial wastewater is an environmental issue posing a great threat to human and animal life. However, the available methods for the removal of cadmium at lower concentrations are limited. Such processes are often accompanied by sludge formation and lead to heavy metal wastage. This paper focuses on the application of an electrosorption process using modified activated carbon felt (MACF) electrodes for the removal and recovery of lower concentration of cadmium from a simulated wastewater sample without sludge formation. Activated carbon felt (ACF) electrodes were treated with 20% HNO3 for removing surface impurities and improving the surface area. The effect of the electrode modification was analyzed by performing various characterizations including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and cyclic voltammetry. The adsorption isotherm and kinetic models have also been studied. The effect of operating parameters including pH, voltage, initial concentration and time were analyzed and optimized using Box-Behnken design and were obtained as 6.42, 1.44 V, 0.50 mg/L and 131.51 min respectively. During the regeneration of electrodes, a concentrated cadmium solution of 18.55 mg/L was obtained, which showed the possibility of cadmium recovery. The maximum cadmium removal was 60.60% at the optimized conditions, revealing the significance of electrosorption for heavy metal treatment.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Animais , Cádmio , Carvão Vegetal , Eletrodos , Íons , Águas Residuárias
5.
Environ Monit Assess ; 192(10): 622, 2020 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-32894359

RESUMO

Soils are facing new environmental contaminants, such as nanomaterials. While these emerging contaminants are increasingly being released into soil, their potential impact on this medium and their effect on soil's major chemical components (e.g., sulfate, nitrate, ammonia, and phosphate) have yet to be examined, as well as their relation with microbial toxicity. Herein, column experiments were conducted to investigate the behavior of major ions under 10 and 200 mg/L multiple contaminations of graphene nanomaterials in agricultural and undisturbed soils, as well as the retention of the graphene nanomaterials in the soil and their effect on soil zeta potentials throughout the column. Moreover, to evaluate the impact of the risks of graphene nanomaterial contamination on soil major ions, the present study also examines the bacterial toxicity. The results showed that graphene retention was influenced the soil zeta potentials. Graphene also influenced the concentrations of the major ions in soil and the order of the influence degree was sulfate > phosphate > ammonia > nitrate. The changes of the major ions in soil by the exposure of graphene nanomaterials have also affected the response of selected bacteria.


Assuntos
Grafite , Nanoestruturas , Poluentes do Solo/análise , Monitoramento Ambiental , Íons , Solo , Microbiologia do Solo
6.
Water Sci Technol ; 82(1): 170-184, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910801

RESUMO

In this study, manganese dioxide was evenly distributed on the surface of activated carbon (AC), and the porous structure of AC and the surface functional groups of manganese dioxide were used to adsorb the heavy metal ion Pb(II). The advantages of microwave heating are fast heating and high selectivity. The mole ratio control of the AC and MnO2 in 1:0.1, microwave heating to 800 °C, heat preservation for 30 min. The maximum adsorption capacity of the MnO2-AC prepared by this method on Pb(II) can reach 664 mg/L at pH = 6. It can be observed by scanning electron microscope (SEM) that manganese dioxide particles are dispersed evenly on the surface and pore diameter of AC, and there is almost no agglomeration. The specific surface area was 752.8 m2/g, and the micropore area was 483.9 m2/g. The adsorption mechanism was explored through adsorption isotherm, adsorption kinetics, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). It is speculated that the adsorption mechanism includes electrostatic interaction and specific adsorption, indicating that lead ions enter into the void of manganese dioxide and form spherical complexes. The results showed that the adsorption behavior of Pb(II) by MnO2-AC was consistent with the Langmuir adsorption model, the quasi-second-order kinetic model, and the particle internal diffusion model.


Assuntos
Compostos de Manganês , Poluentes Químicos da Água/análise , Adsorção , Carvão Vegetal , Íons , Chumbo , Micro-Ondas , Óxidos
7.
Chemosphere ; 254: 126903, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957296

RESUMO

We used discarded oyster shells to prepare vaterite calcium carbonate microparticles and explored the removal effects and the underlying mechanism toward several heavy metal ions. The removal efficiency for each ion type was: Pb2+ (99.9%), Cr3+ (99.5%), Fe3+ (99.3%), and Cu2+ (57.1%). With the exception of Cu2+, vaterite calcium carbonate particles exhibited excellent removal performance on all tested heavy metal ions, with exceptional results for Pb2+. The factor affecting the removal efficiency of heavy metal ions is shown to involve an ion exchange reaction between calcium and the heavy metal ions resulting in recrystallization. Vaterite calcium carbonate particles prepared by this method have the advantage of low price, easy synthesis, and reduction of environmental waste. Thus, this procedure for synthesizing vaterite CaCO3 provides an environmentally responsible method for preparing materials that can be economically incorporated into common consumer products such as household drinking water filtration systems.


Assuntos
Exoesqueleto/química , Carbonato de Cálcio/química , Metais Pesados/análise , Ostreidae , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Animais , Concentração de Íons de Hidrogênio , Troca Iônica , Íons , Microesferas , Propriedades de Superfície
8.
Waste Manag ; 118: 331-340, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32920496

RESUMO

Pneumatic separation was used to separate the valuable current collectors and harmful separators in spent lithium-ion batteries (LIBs) to avoid the plastic pollution caused by the separators in this study. Theoretical calculations for suspension velocities of the current collectors and separators indicate that they could be separated under special conditions. Furthermore, a special Z-shaped pneumatic separator was used to separate the current collectors and separators for the first time. Experiments for manually cut samples indicate that the efficiency of pneumatic separation is approximately 100% with the sizes and airflow velocities in the range of 3-4 cm and 6.96-7.8 m/s, respectively. Furthermore, industrial experiments of pneumatic separation indicate that the recoveries of the current collectors and separators are approximately 99.23% and 98.64%, respectively. Computer simulations of the separation process indicate that the turbulence and the changes in high-speed zones in the pneumatic separator benefit the separation of current collectors and separators. In conclusion, pneumatic separation is a promising technology to separate crushed current collectors and separators.


Assuntos
Lítio , Reciclagem , Fontes de Energia Elétrica , Eletrodos , Íons
9.
Bull Environ Contam Toxicol ; 105(4): 530-537, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32940716

RESUMO

An increase in the production and usage of gold nanoparticles (AuNPs) triggers the necessity to focus on their impact on ecosystems. Therefore, the purpose of this study was to investigate the acute toxicity of AuNPs and ionic gold (Au (III)) to organisms representing all trophic levels of the aquatic ecosystem, namely producers (duckweed Lemna minor), consumers (crustacean Daphnia magna, embryos of Danio rerio) and decomposers (bacteria Vibrio fischeri). The organisms were exposed according to a standardized protocol for each species and endpoints. The AuNPs (1.16 and 11.6 d.nm) were synthesized using citrate (CIT) and polyvinylpyrrolidone (PVP) as capping agents, respectively. It was found, that Au (III) was significantly more toxic than AuNPs PVP and AuNPs CIT. AuNPs showed significant toxicity only at high concentrations (mg/L), which are not environmentally relevant in the present time, but a cautious approach is advised, due to the possibility of interactions with other contaminants.


Assuntos
Aliivibrio fischeri/efeitos dos fármacos , Araceae/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Ouro/toxicidade , Íons/toxicidade , Nanopartículas Metálicas/toxicidade , Peixe-Zebra , Animais , Organismos Aquáticos , Daphnia/embriologia , Relação Dose-Resposta a Droga , Embrião não Mamífero/efeitos dos fármacos , Testes de Toxicidade Aguda
10.
Chemosphere ; 254: 126876, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957286

RESUMO

Chromium is a controversial element, since it has been classified as essential trace element, to chemically and biologically inert compound, to potent intoxicator. Concerns have been risen for chromium effects on human and aquatic life because chromium has been accused for genotoxicity and carcinogenesis. Metals and their ions or complexes (and thus chromium substances) are included in the indicative list of main pollutants (Annex VIII of the Water Framework Directive (2000/60/EC)). Biological effects of chromium are strongly depended on chromium speciation. No universal CrIII or CrVI discharge limits to the aquatic environment have been suggested by the EU. International bodies within the EU, such as the Helsinki Commission and the Oslo-Paris Convention, have issued recommendations on chromium discharge levels. National CrVI and CrIII discharge limits vary in each EU Member State with respect to the receiving water body (marine water, lake, river, sewer system). The maximum discharge limit to the aquatic environment in EU is 1 and 5 mg L-1 for CrVI and Crtotal, respectively. The present work summarizes EU legislation, with respect to the discharge limits to the aquatic environment for CrVI and CrIII. EU national limits that are currently effective are presented and compared to the limits in other parts of the world, such as Australia, Asia, USA, Latin America and South Africa. It is wise that future perspective of chromium policy should differentiate between CrIII and CrVI discharge limits to the aquatic environment, as analytical techniques become more sensitive and chromium speciation specific, and environmental awareness rises.


Assuntos
Cromo/análise , Monitoramento Ambiental , Poluentes Químicos da Água/análise , Ásia , Austrália , Europa (Continente) , Íons , Rios , África do Sul , Oligoelementos
11.
Nat Commun ; 11(1): 4530, 2020 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-32913195

RESUMO

Various cancer cells have been demonstrated to have the capacity to form plasmonic gold nanoparticles when chloroauric acid is introduced to their cellular microenvironment. But their biomedical applications are limited, particularly considering the millimolar concentrations and longer incubation period of ionic gold. Here, we describe a simplistic method of intracellular biomineralization to produce plasmonic gold nanoparticles at micromolar concentrations within 30 min of application utilizing polyethylene glycol as delivery vector for ionic gold. We have characterized this process for intracellular gold nanoparticle formation, which progressively accumulates proteins as the ionic gold clusters migrate to the nucleus. This nano-vectorized application of ionic gold emphasizes its potential biomedical opportunities while reducing the quantity of ionic gold and required incubation time. To demonstrate its biomedical potential, we further induce in-situ biosynthesis of gold nanoparticles within MCF7 tumor mouse xenografts which is followed by its photothermal remediation.


Assuntos
Cloretos/administração & dosagem , Portadores de Fármacos/química , Compostos de Ouro/administração & dosagem , Ouro/química , Nanopartículas Metálicas/química , Neoplasias/tratamento farmacológico , Nanomedicina Teranóstica/métodos , Animais , Biomineralização/efeitos da radiação , Feminino , Ouro/efeitos da radiação , Humanos , Hipertermia Induzida/métodos , Íons , Células MCF-7 , Nanopartículas Metálicas/efeitos da radiação , Camundongos , Fotoquimioterapia/métodos , Polietilenoglicóis/química , Ensaios Antitumorais Modelo de Xenoenxerto
12.
Nat Commun ; 11(1): 4557, 2020 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-32917908

RESUMO

Why metalloenzymes often show dramatic changes in their catalytic activity when subjected to chemically similar but non-native metal substitutions is a long-standing puzzle. Here, we report on the catalytic roles of metal ions in a model metalloenzyme system, human carbonic anhydrase II (CA II). Through a comparative study on the intermediate states of the zinc-bound native CA II and non-native metal-substituted CA IIs, we demonstrate that the characteristic metal ion coordination geometries (tetrahedral for Zn2+, tetrahedral to octahedral conversion for Co2+, octahedral for Ni2+, and trigonal bipyramidal for Cu2+) directly modulate the catalytic efficacy. In addition, we reveal that the metal ions have a long-range (~10 Å) electrostatic effect on restructuring water network in the active site. Our study provides evidence that the metal ions in metalloenzymes have a crucial impact on the catalytic mechanism beyond their primary chemical properties.


Assuntos
Anidrases Carbônicas/química , Íons/química , Metaloproteínas/química , Metais/química , Sítios de Ligação , Anidrase Carbônica II/química , Anidrase Carbônica II/metabolismo , Anidrases Carbônicas/metabolismo , Catálise , Domínio Catalítico , Cobalto/química , Cobre/química , Cristalografia por Raios X , Humanos , Íons/metabolismo , Cinética , Metaloproteínas/metabolismo , Metais/metabolismo , Modelos Moleculares , Níquel/química , Conformação Proteica , Relação Estrutura-Atividade , Especificidade por Substrato , Zinco/química
13.
Nat Commun ; 11(1): 3818, 2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32732937

RESUMO

The formation of peptide bonds by energetic processing of amino acids is an important step towards the formation of biologically relevant molecules. As amino acids are present in space, scenarios have been developed to identify the roots of life on Earth, either by processes occurring in outer space or on Earth itself. We study the formation of peptide bonds in single collisions of low-energy He2+ ions (α-particles) with loosely bound clusters of ß-alanine molecules at impact energies typical for solar wind. Experimental fragmentation mass spectra produced by collisions are compared with results of molecular dynamics simulations and an exhaustive exploration of potential energy surfaces. We show that peptide bonds are efficiently formed by water molecule emission, leading to the formation of up to tetrapeptide. The present results show that a plausible route to polypeptides formation in space is the collision of energetic ions with small clusters of amino acids.


Assuntos
Aminoácidos/química , Simulação de Dinâmica Molecular , Peptídeos/química , Termodinâmica , beta-Alanina/química , Dipeptídeos/síntese química , Dipeptídeos/química , Íons/química , Oligopeptídeos/síntese química , Oligopeptídeos/química , Peptídeos/síntese química , Espectrometria de Massas por Ionização por Electrospray/métodos , Água/química
14.
Water Sci Technol ; 81(11): 2410-2421, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32784284

RESUMO

The objective of this study is to model the breakthrough adsorption curves of Co (II) ions using spent tealeaves in fixed-bed column experiments. Spent leaves of green tea (GT), peppermint tea (PM) and chamomile (CM) were packed in glass columns with a diameter of 2 cm and height of 15 cm, and used as filters for the removal of the pollutant. Aqueous solutions of cobalt (II) ions (100 mg/L) at pH 6 were prepared and pumped against gravity through the columns at a uniform flow rate of 5 mL/min. Breakthrough curves were fitted for the residual concentration data using the Thomas, Yoon-Nelson, and Clark models, with added empirical terms to delineate the lower tail of the breakthrough curve. These mathematical models were successfully linearized using the natural logarithm for parameter estimation. The results reveal that the Co (II) adsorption fits all three models for all the adsorbents. The Thomas model indicated that the calculated adsorption capacities followed the trend: PM > GT > CM with values of 59.7, 25.2, and 24.9 mg/g respectively. Moreover, CM showed the highest adsorption rates with all the mathematical models, whereas Yoon-Nelson theory provided evidence that PM has the longest 50% adsorption breakthrough among the adsorbents. Lastly, morphological and textural studies indicate that all spent leaves are good candidates as adsorbents due to their high surface heterogeneity. This study proposes the use of spent tealeaves as Co (II) adsorbents because they are inexpensive and environmentally beneficial.


Assuntos
Poluentes Químicos da Água/análise , Purificação da Água , Adsorção , Cobalto , Íons
15.
J Environ Sci (China) ; 96: 127-137, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32819687

RESUMO

Herein, we developed the invasive plant-derived biochar (IPB) functionalized with CaAl-LDH at five mass ratios using a physical mixture method, assessed their adsorption perform for Eu(III), and explored the relative mechanisms. Results show that the IPB successfully loaded CaAl-LDH in five composites and their Eu(III) sorption affinities were strongly affected by solution pH, contact time, temperature, and the mass ratio of LDH and IPB. All the sorpiton process for Eu(III) occurred on the heterogeneous surface of five composites and the boundary layer diffusion limited the chemical sorption rate. Interestingly, the CaAl-LDH/IPB composite with high ratio of IPB had higher sorption capacity than the one with high ratio of LDH due to larger porosity of the former. Three mechanisms containing ion exchange between Al and Eu ions, surface complexation with carboxyl- and oxygen-containing functional groups, and precipitation were involved in the Eu(III) sorption, but the dominant sorption mechanism for each CaAl-LDH/IPB composite differed with different mass ratio of CaAl-LDH and IPB. In composite with more IPB (e.g., CaAl-LDH/IPB-13), both ion exchange and surface complexes dominated the sorption process and the intensity of Eu3+ was identified with the one of Eu2O3. Whereas in composites with high LDH, ion exchange dominated the sorption and the intensity of Eu3+ was obviously higher than the one of Eu2O3. This research will provide a new perspective for the application of the LDH/biochar materials.


Assuntos
Carvão Vegetal , Água , Adsorção , Íons
16.
J Environ Sci (China) ; 96: 93-98, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32819703

RESUMO

A signal-amplified mercury sensing biosensor with desired sensitivity was developed through firstly using the GFP mutant with fluorescence increasing response towards Hg2+ as the reporter module. The developed biosensor showed response for Hg2+ in a relatively wide range of 1-10,000 nmol/L, and the detection limit was improved one or two orders of magnitude in comparison with most metal-sensing biosensors in similar constructs. In addition, the biosensor could distinguish Hg2+ easily from multiple metal ions and displayed strong adaptability to extensive pH conditions (pH 4.0-10.0). More importantly, the developed biosensor was able to provide an initial assessment of Hg2+ spiked in the environmental water with the recoveries between 85.70% and 112.50%. The signal-amplified strategy performed by the modified reporter module will be widely applicable to many other whole-cell biosensors, meeting the practical requirements with sufficient sensing performance.


Assuntos
Técnicas Biossensoriais , Mercúrio , Íons , Limite de Detecção
17.
Environ Pollut ; 266(Pt 2): 115277, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32777697

RESUMO

Three types of diatomite-based adsorbents-diatomaceous earth (DE), purified diatomite (PD), and diatomite@MgO/CaO (D@MgO) were used for adsorption decontamination of ammonium from Lake Qarun water (28.7 mg/L). The adsorption properties of the three diatomite-based adsorbents were evaluated by both batch and fixed-bed column adsorption studies. The kinetic results demonstrated removal percentages of 97.2%, 69.5%, and 100% using DE, PD, and D@MgO, respectively, at a 1 g/L adsorbent dosage. The adsorption results using DE and D@MgO showed the best fitness with pseudo-first-order kinetic and Langmuir isotherm models, while the obtained results using PD demonstrate better fitness with the Freunlidich model. The recognised fitting results with the pseudo-first-order model and estimated adsorption energies demonstrated physical uptake of ammonium by DE (5.93 kJ/mol), PD (4.05 kJ/mol), and D@MgO (7.81 kJ/mol). The theoretical maximum ammonium uptake capacity of DE, PD, and D@MgO were 63.16 mg/g, 59.5 mg/g, and 78.3 mg/g, respectively. Using synthetic adsorbents in a fixed-bed column system for treating ammonium ions in Lake Qarun water resulted in removal percentages of 57.4%, 53.3%, and 62.6% using a DE bed, PD bed, and D@MgO bed, respectively, after treating approximately 7.2 L of Lake Qarun water using a bed thickness of 3 cm, a flow rate of 5 mL/min, pH 8, and the determined ammonium concentration in Lake Qarun water (28.7 mg/L). The curves demonstrated breakthrough times of 900 min, 900 min, and 960 min for the DE bed, PD bed, and D@MgO bed, respectively, with 1440 min as the saturation time. The columns' performances also were studied based on the Thomas model, the Adams-Bohart model, and the Yoon-Nelson model.


Assuntos
Compostos de Amônio , Poluentes Químicos da Água/análise , Purificação da Água , Adsorção , Terra de Diatomáceas , Egito , Eutrofização , Íons , Cinética , Lagos
18.
Aquat Toxicol ; 227: 105582, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32823071

RESUMO

While it is likely that ENPs may occur together with other contaminants in nature, the combined effects of exposure to both ENPs and environmental contaminants are not studied sufficiently. In this study, we investigated the acute and sublethal toxicity of PVP coated silver nanoparticles (AgNP) and ionic silver (Ag+; administered as AgNO3) to the marine copepod Calanus finmarchicus. We further studied effects of single exposures to AgNPs (nominal concentrations: low 15 µg L-1 NPL, high 150 µg L-1 NPH) or Ag+ (60 µg L-1), and effects of co-exposure to AgNPs, Ag+ and the water-soluble fraction (WSF; 100 µg L-1) of a crude oil (AgNP + WSF; Ag++WSF). The gene expression and the activity of antioxidant defense enzymes SOD, CAT and GST, as well as the gene expression of HSP90 and CYP330A1 were determined as sublethal endpoints. Results show that Ag+ was more acutely toxic compared to AgNPs, with 96 h LC50 concentrations of 403 µg L-1 for AgNPs, and 147 µg L-1 for Ag+. Organismal uptake of Ag following exposure was similar for AgNP and Ag+, and was not significantly different when co-exposed to WSF. Exposure to AgNPs alone caused increases in gene expressions of GST and SOD, whereas WSF exposure caused an induction in SOD. Responses in enzyme activities were generally low, with significant effects observed only on SOD activity in NPL and WSF exposures and on GST activity in NPL and NPH exposures. Combined AgNP and WSF exposures caused slightly altered responses in expression of SOD, GST and CYP330A1 genes compared to the single exposures of either AgNPs or WSF. However, there was no clear pattern of cumulative effects caused by co-exposures of AgNPs and WSF. The present study indicates that the exposure to AgNPs, Ag+, and to a lesser degree WSF cause an oxidative stress response in C. finmarchicus, which was slightly, but mostly not significantly altered in combined exposures. This indicated that the combined effects between Ag and WSF are relatively limited, at least with regard to oxidative stress.


Assuntos
Copépodes/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Petróleo/toxicidade , Prata/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Copépodes/genética , Copépodes/metabolismo , Interações Medicamentosas , Expressão Gênica/efeitos dos fármacos , Íons , Nanopartículas Metálicas/química , Estresse Oxidativo/genética , Água do Mar/química , Prata/química , Solubilidade , Testes de Toxicidade Aguda , Testes de Toxicidade Subaguda , Poluentes Químicos da Água/química
19.
J Chromatogr A ; 1627: 461393, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823098

RESUMO

The selective extraction and column separation rear earth elements (REEs) were investigated in the present work. Herein, the functional ligand of N, N-dioctyldiglycolic acid (DODGA) was synthesized and chemically grafted on the silica gel (SG) particles to give the novel material SG@DODGA. The obtained SG@DODGA was fully characterized by NMR, BET (Brunauer-Emmett-Teller) N2 physisorption analysis, atom force microscopy (AFM), scanning electronic microscopy (SEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). After investigating the adsorption capability of the SG@DODGA towards 16 kinds of REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc), the results showed that the adsorption kinetic data was better fitted with pseudo-second-order model and Elovich model, the adsorption isotherms data was suitable for Freundlich model. The above result also indicated that the adsorption mechanism between the SG@DODGA and REEs was chemical ion exchange. Moreover, choose SG@DODGA as the column chromatography stationary phase and packed in a glass column for the column studies to obtain breakthroughs profile of each REEs. Furthermore, the column was used to try to separate the mixed 16 kinds of REEs. The first attempt to preliminary separate REEs result showed that this column could be applied for simply separating REEs. The light REEs La, Ce, Pr, Nd exhibited better separation effect than the other REEs.


Assuntos
Glicolatos/química , Metais Terras Raras/isolamento & purificação , Sílica Gel/química , Adsorção , Concentração de Íons de Hidrogênio , Íons , Cinética , Ligantes , Nitrogênio/química , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termogravimetria
20.
Yakugaku Zasshi ; 140(8): 955-960, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32741867

RESUMO

A nickel-aluminium-zirconium complex-layered hydroxide (NAZ), which was synthesized using each inorganic sulfate mixing ratio of 0.9 : 1.0 : 0.1, was prepared and calcined at different temperatures. The physicochemical properties of the NAZ were analyzed by scanning electron microscopy, specific surface area, number of hydroxyl groups, and pore volume. The specific surface area, number of hydroxyl groups, and pore volume of NAZ was 51.9 m2/g, 1.08 mmol/g, and 0.27 µL/g, respectively. The amount of phosphate ion adsorbed onto NAZ was higher than that onto calcined NAZ at different temperatures. Therefore, the interaction between phosphate ions and NAZ was assessed using the elemental distribution analysis and the binding energy. After adsorption, the intensity of phosphorus atoms increased, indicating that the phosphate ions were adsorbed onto the NAZ surface. Additionally, phosphorus peaks (189 eV for 2s and 130 eV for 2p), which were not detected before adsorption, were clearly detected after adsorption. On the other hand, the intensity of the sulfur peak (165 eV for 2p) decreased after adsorption. Thus, we evaluated the ion exchange between phosphate ion and sulfate ion in the interlayer space of the NAZ. As a result, the correlation coefficient between the amount of phosphate ion adsorbed and the amount of sulfate ion released was positively correlated (r=0.960). Therefore, it can be clearly stated that one of the adsorption mechanisms of phosphate ions was related to ion exchange in the interlayer space of the NAZ. These findings are useful for preventing the eutrophication and recovery of phosphate ion in water environments.


Assuntos
Complexos de Coordenação/química , Complexos de Coordenação/síntese química , Hidróxidos/química , Hidróxidos/síntese química , Fosfatos/química , Adsorção , Alumínio , Fenômenos Químicos , Eutrofização , Troca Iônica , Íons , Microscopia Eletroquímica de Varredura , Níquel , Zircônio
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