Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 10.147
Filtrar
1.
Water Res ; 179: 115894, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32408185

RESUMO

In drinking water treatment, natural organic matter (NOM) is effectively removed from surface water using ion exchange (IEX). A main drawback of using IEX for NOM removal is the production of spent IEX regeneration brine, a polluting waste that is expensive to discharge. In this work, we studied ceramic nanofiltration as a treatment for the spent NOM-rich brine, with the aim to reduce the volume of this waste and to recycle salt. Compared to polymeric nanofiltration, the fouling was limited. When NOM is rejected and concentrated, a clean permeate with the regeneration salt (NaCl) could be produced and reused in the IEX regeneration process. Bench scale studies revealed that NOM could be effectively separated from the NaCl solution by steric effects. However, the separation of NaCl from other salts present in the brine, such as Na2SO4, was not sufficient for reuse purposes. The low sulphate rejection was mainly due to the low zeta potential of the membrane at the high ionic strength of the brine. The permeate of the ceramic nanofiltration should be treated further to obtain a sodium chloride quality that can be recycled as a regenerant solution for ion exchange. Further treatment steps will benefit from the removal of NOM from the brine.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Cerâmica , Troca Iônica , Sais
2.
Food Chem ; 321: 126674, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32244137

RESUMO

Lake deposits, plant-based ashes, filtrates and evaporites or alkaline salts are used traditionally in food preparations by local populations in Africa, Asia, South America, and Oceania. Depending on the context, traditional alkaline salts are used to reduce cooking times, improve rheological characteristics of starchy doughs, maintain the color of vegetables, improve the viscosity of sticky vegetables, and act as emulsifiers. This review highlights some of the relationships among chemical composition and physicochemical properties of traditional alkaline salts when used in solution as well as their functionalities. In addition, their potential toxicity and physiological effects are explored, which might lead to a better understanding of some previously unexplained functionalities and future trends in research, such as their impact on human health.


Assuntos
Lagos/química , Plantas/química , Sais/química , Animais , Culinária , Alimentos , Humanos , Viscosidade
3.
Nature ; 581(7807): 215-220, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32225176

RESUMO

A new and highly pathogenic coronavirus (severe acute respiratory syndrome coronavirus-2, SARS-CoV-2) caused an outbreak in Wuhan city, Hubei province, China, starting from December 2019 that quickly spread nationwide and to other countries around the world1-3. Here, to better understand the initial step of infection at an atomic level, we determined the crystal structure of the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 bound to the cell receptor ACE2. The overall ACE2-binding mode of the SARS-CoV-2 RBD is nearly identical to that of the SARS-CoV RBD, which also uses ACE2 as the cell receptor4. Structural analysis identified residues in the SARS-CoV-2 RBD that are essential for ACE2 binding, the majority of which either are highly conserved or share similar side chain properties with those in the SARS-CoV RBD. Such similarity in structure and sequence strongly indicate convergent evolution between the SARS-CoV-2 and SARS-CoV RBDs for improved binding to ACE2, although SARS-CoV-2 does not cluster within SARS and SARS-related coronaviruses1-3,5. The epitopes of two SARS-CoV antibodies that target the RBD are also analysed for binding to the SARS-CoV-2 RBD, providing insights into the future identification of cross-reactive antibodies.


Assuntos
Betacoronavirus/química , Peptidil Dipeptidase A/química , Peptidil Dipeptidase A/metabolismo , Receptores Virais/química , Receptores Virais/metabolismo , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/metabolismo , Sequência de Aminoácidos , Anticorpos Neutralizantes/imunologia , Betacoronavirus/metabolismo , Sítios de Ligação , Sequência Conservada , Cristalografia por Raios X , Epitopos/química , Epitopos/imunologia , Evolução Molecular , Humanos , Ligação de Hidrogênio , Modelos Moleculares , Ligação Proteica , Domínios Proteicos , Vírus da SARS/química , Sais/química , Alinhamento de Sequência , Água/análise , Água/química
5.
PLoS One ; 15(3): e0230431, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32191756

RESUMO

Mollusk shell is composed of two CaCO3 polymorphs (calcite and aragonite) and an organic matrix that consists of acetic acid- or ethylenediaminetetraacetic acid (EDTA)-soluble and insoluble proteins and other biomolecules (polysaccharides, ß-chitin). However, the shell matrix proteins involved in nacre formation are not fully known. Thus, the aim of this study was to identify and characterize a novel protein from the acetic acid-insoluble fraction from the shell of Pteria sterna, named in this study as Ps19, to have a better understanding of the biomineralization process. Ps19 biochemical characterization showed that it is a glycoprotein that exhibits calcium- and chitin-binding capabilities. Additionally, it is capable of inducing aragonite plate crystallization in vitro. Ps19 partial peptide sequence showed similarity with other known shell matrix proteins, but it displayed similarity with proteins from Crassostrea gigas, Mizuhopecten yessoensis, Biomphalaria glabrata, Alpysia californica, Lottia gigantea and Elysia chlorotica. The results obtained indicated that Ps19 might play an important role in nacre growth of mollusk shells.


Assuntos
Calcificação Fisiológica , Carbonato de Cálcio/metabolismo , Proteínas de Transporte/metabolismo , Quitina/metabolismo , Pinctada/metabolismo , Sequência de Aminoácidos , Animais , Proteínas de Transporte/química , Proteínas de Transporte/isolamento & purificação , Cristalização , Peptídeos/química , Peptídeos/metabolismo , Sais , Solubilidade , Análise Espectral Raman
6.
Water Res ; 175: 115688, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32171095

RESUMO

Ion exchange is widely used to treat nitrate-contaminated groundwater, but high salt usage for resin regeneration and management of waste brine residuals increase treatment costs and add environmental burdens. Development of palladium-based catalytic nitrate treatment systems for brine treatment and reuse has showed promising activity for nitrate reduction and selectivity towards the N2 over the alternative product ammonia, but this strategy overlooks the potential value of nitrogen resources. Here, we evaluated a hybrid catalytic hydrogenation/membrane distillation process for nitrogen resource recovery during treatment and reuse of nitrate-contaminated waste ion exchange brines. In the first step of the hybrid process, a Ru/C catalyst with high selectivity towards ammonia was found to be effective for nitrate hydrogenation under conditions representative of waste brines, including expected salt buildup that would occur with repeated brine reuse cycles. The apparent rate constants normalized to metal mass (0.30 ± 0.03 mM min-1 gRu-1 under baseline condition) were comparable to the state-of-the-art bimetallic Pd catalyst. In the second stage of the hybrid process, membrane distillation was applied to recover the ammonia product from the brine matrix, capturing nitrogen as ammonium sulfate, a commercial fertilizer product. Solution pH significantly influenced the rate of ammonia mass transfer through the gas-permeable membrane by controlling the fraction of free ammonia species (NH3) present in the solution. The rate of ammonia recovery was not affected by increasing salt levels in the brine, indicating the feasibility of membrane distillation for recovering ammonia over repeated reuse cycles. Finally, high rates of nitrate hydrogenation (apparent rate constant 1.80 ± 0.04 mM min-1 gRu-1) and ammonia recovery (overall mass transfer coefficient 0.20 m h-1) with the hybrid treatment process were demonstrated when treating a real waste ion exchange brine obtained from a drinking water utility. These findings introduce an innovative strategy for recycling waste ion exchange brine while simultaneously recovering potentially valuable nitrogen resources when treating contaminated groundwater.


Assuntos
Destilação , Nitrogênio , Hidrogenação , Troca Iônica , Nitratos , Sais
7.
PLoS One ; 15(3): e0229794, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32134972

RESUMO

In soil metal ecotoxicology research, dosing is usually performed with metal salts, followed by leaching to remove excess salinity. This process also removes some metals, affecting metal mixture ratios as different metals are removed by leaching at different rates. Consequently, alternative dosing methods must be considered for fixed ratio metal mixture research. In this study three different metal mixture dosing methods (nitrate, oxide and annealed metal dosing) were examined for metal concentrations and toxicity. In the nitrate metal dosing method leaching reduced total metal retention and was affected by soil pH and cation exchange capacity (CEC). Acidic soils 3.22 (pH 3.4, CEC 8 meq/100g) and WTRS (pH 4.6, CEC 16 meq/100g) lost more than 75 and 64% of their total metals to leaching respectively while Elora (6.7 pH, CEC 21 meq/100g) and KUBC (pH 5.6, CEC 28 meq/100g) with higher pH and CEC only lost 13.6% and 12.2% total metals respectively. Metal losses were highest for Ni, Zn and Co (46.0%, 63.7% and 48.4% metal loss respectively) whereas Pb and Cu (5.6% and 20.0% metal loss respectively) were mostly retained, affecting mixture ratios. Comparatively, oxide and annealed metal dosing which do not require leaching had higher total metal concentrations, closer to nominal doses and maintained better mixture ratios (percent of nominal concentrations for the oxide metal dosing were Pb = 109.9%, Cu = 84.6%, Ni = 101.9%, Zn = 82.3% and Co = 97.8% and for the annealed metal dosing were Pb = 81.7%, Cu = 80.3%, Ni = 100.5%, Zn = 89.2% and Co = 101.3%). Relative to their total metal concentrations, nitrate metal dosing (lowest metal concentrations) was the most toxic followed by metal oxides dosing while the annealed dosing method was generally non-toxic. Due to the lack of toxicity of the annealed metals and their higher dosing effort, metal oxides, are the most appropriate of the tested dosing methods, for fixed-ratio metal mixtures studies with soil invertebrates.


Assuntos
Metais Pesados/toxicidade , Óxidos/toxicidade , Poluentes do Solo/toxicidade , Solo/química , Animais , Concentração de Íons de Hidrogênio , Invertebrados , Metais Pesados/análise , Nitratos/análise , Nitratos/toxicidade , Óxidos/análise , Reprodução/efeitos dos fármacos , Sais/análise , Sais/toxicidade , Poluentes do Solo/análise , Testes de Toxicidade/métodos
8.
Pharm Res ; 37(4): 70, 2020 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-32185516

RESUMO

PURPOSE: While including amorphous solid dispersion (ASD) in tablet formulations is increasingly common, tablets containing high ASD loading are associated with slow disintegration, which presents a challenge to control pill burden for less potent compounds. METHODS: We use a model ASD, composed of a hydrophobic drug with copovidone and a non-ionic surfactant, to explore formulation options that can prevent slow disintegration. RESULTS: In addition to the ASD loading, the pH of the disintegration medium and the inclusion of inorganic salts in the tablet also have an impact on the tablet disintegration time. Certain kosmotropic salts, when added in the formulation, can significantly accelerate tablet disintegration, though the rank order in their effectiveness does not exactly follow the Hofmeister series at pH 1.8. The particle size and dissolution rate of the salt can contribute to its overall effectiveness. CONCLUSION: We provided a mechanistic explanation of the disintegration process: fast-dissolving kosmotropic salt results in a concentrated salt solution inside the restrained tablet matrix, thus inhibiting the dissolution of copovidone and preventing polymer gelling which is the main cause leading the slow disintegration. The outcome of this study has enabled the design of a higher ASD loading platform formulation for copovidone based ASD. Graphical Abstract MicroCT aids the mechanistic understanding of the role of inorganic salt in the tablet disintegration of amorphous solid dispersion based formulation.


Assuntos
Pirrolidinas/química , Sais/química , Comprimidos/química , Compostos de Vinila/química , Química Farmacêutica , Excipientes/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Concentração Osmolar , Tamanho da Partícula , Solubilidade
9.
DNA Cell Biol ; 39(5): 816-827, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32175765

RESUMO

Carrot is an annual or biennial herbaceous plant of the Apiaceae family. Carrot is an important vegetable, and its fresh taproot, which contains rich nutrients, is the main edible part. In the life cycle of carrot, NAC family transcription factors (TFs) are involved in almost all physiological processes. The function of NAC TFs in carrot remains unclear. In this study, 73 NAC family TF members in carrot were identified and characterized using transcriptome and genome databases. These members were divided into 14 subfamilies. Multiple sequence alignment was performed, and the conserved domains, common motifs, phylogenetic tree, and interaction network of DcNAC proteins were predicted and analyzed. Results showed that the same group of NAC proteins of carrot had high similarity. Eight DcNAC genes were selected to detect their expression profiles under abiotic stress treatments. The expression levels of the selected DcNAC genes significantly increased under treatments with low temperature, high temperature, drought, and salt stress. Results provide potentially useful information for further analysis of the roles of DcNAC transcription factors in carrot.


Assuntos
Daucus carota/genética , Daucus carota/fisiologia , Perfilação da Expressão Gênica , Genômica , Proteínas de Plantas/genética , Estresse Fisiológico/genética , Fatores de Transcrição/genética , Motivos de Aminoácidos , Sequência de Aminoácidos , Temperatura Baixa/efeitos adversos , Sequência Conservada , Daucus carota/efeitos dos fármacos , Daucus carota/crescimento & desenvolvimento , Evolução Molecular , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Sais/farmacologia , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo
10.
Macromol Rapid Commun ; 41(6): e1900644, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32022349

RESUMO

In a significant breakthrough from classical molecular (i.e., nonpolymeric) iodonium salts in light-induced photochemistry, the synthesis and use of new safer polymeric iodonium salts are reported here. They are shown to be involved in charge transfer complexes (CTCs) while in interaction with a safe amino acid derivative (N-phenylglycine). Also, this study demonstrates i) the formation of CTCs between the iodonium (acceptor) and an aryl/alkyl amine (donor) through UV-vis measurements of the monomer, ii) the formation of radicals in electron spin resonance spin trapping experiments when the CTCs are irradiated by visible light (405 nm), and iii) their efficiency as a photoinitiator to polymerize three different acrylic monomers under LED irradiation at 405 nm under air and their application to 3D resolved laser writing of thick samples (3 mm). High reactivity for polymeric iodonium salts comparable with molecular ones is exhibited with the advantage of potential lower migration. To the best of the authors' knowledge, this is the first reported instance of polymeric iodonium salts acting as polymerization initiators.


Assuntos
Radicais Livres/química , Compostos de Iodo/química , Polimerização/efeitos da radiação , Polímeros/química , Sais/química , Glicina/análogos & derivados , Glicina/química , Luz , Processos Fotoquímicos , Polietilenoglicóis/química , Polímeros/síntese química , Ácidos Polimetacrílicos/química , Poliestirenos/química
11.
Artigo em Inglês | MEDLINE | ID: mdl-32014662

RESUMO

A hybrid mode of hydrophobic interaction chromatography (HHIC) is an emerging analytical technique for the separation of biomolecules under non-denaturing conditions that combines elements of conventional hydrophobic interaction and reversed-phase chromatography. This article explores the impact of mobile phase composition such as salt concentration and organic modifier on the separation of therapeutic monoclonal antibodies and related large biomolecules using poly (alkyl aspartamide) silica HIC columns. The initial mobile phase salt concentration had a significant impact on the separation of a mixture of large biomolecules demonstrating that the relationship of elution and salt concentration was more complex than in conventional HIC. In general, the earlier eluting components exhibited greater retention at higher salt concentration as is typical of HIC separations. Conversely, the later eluting components showed greater retention at lower initial salt concentration. This differential is useful for improving the overall separation by widening the elution window for components of a mixture. In addition, no significant unfolding of the proteins was detected by intrinsic fluorescence or electrospray mass spectrometry. The impact of linear velocity and gradient steepness was also evaluated.


Assuntos
Anticorpos Monoclonais/química , Dióxido de Silício/química , Cromatografia Líquida de Alta Pressão , Interações Hidrofóbicas e Hidrofílicas , Sais/química , Solventes/química
12.
Food Chem ; 317: 126424, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32088405

RESUMO

In this study, a simple, efficient, and green effervescence tablet-assisted microextraction method based on the solidification of deep eutectic solvent (ETA-ME-SDES) was developed to determine picoxystrobin, pyraclostrobin, and trifloxystrobin in water, juice, wine, and vinegar samples by HPLC. An eco-friendly, hydrophobic, deep eutectic solvent (DES, acting as the extraction solvent) was synthesized by thymol and octanoic acid in the molar ratio of 1:5. The extraction solvent dispersed in sample solutions with the assistance of pH adjustment and effervescence reaction, and was collected after solidification in an ice bath. Several essential conditions, including the type and the volume of DESs, the amount of ammonia hydroxide, and the components of effervescence tablets were optimized. The limits of detection ranged from 0.15 to 0.38 µg L-1. Extraction recovery ranged from 77.4 to 106.9%. The proposed method was successful in determining the amount of strobilurin fungicides in water, juice, wine, and vinegar samples.


Assuntos
Ácido Acético/análise , Cromatografia Líquida de Alta Pressão , Sucos de Frutas e Vegetais/análise , Fungicidas Industriais/análise , Estrobilurinas/análise , Poluentes Químicos da Água/análise , Vinho/análise , Acetatos/análise , Fungicidas Industriais/química , Concentração de Íons de Hidrogênio , Iminas/análise , Limite de Detecção , Microextração em Fase Líquida/métodos , Sais/química , Estrobilurinas/química , Poluentes Químicos da Água/química
13.
Int J Food Microbiol ; 321: 108541, 2020 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-32044583

RESUMO

Butter is a complex matrix characterized by a high fat content. Existing publications on the behavior of Listeria monocytogenes in this type of food reported contrasted results. This study was performed to provide further information and data about raw milk butter's ability to support survival or growth of L. monocytogenes. Durability tests were performed on naturally contaminated samples of raw milk butter with various physico-chemical characteristics. At the end of shelf life, no growth of L. monocytogenes was observed in the studied butters, regardless of their physico-chemical characteristics (pH, aw, water dispersion index and salt concentration) and the initial level of contamination. The number of positive samples and the colony counts of L. monocytogenes were even decreased at the end of the storage period.


Assuntos
Manteiga/microbiologia , Microbiologia de Alimentos , Listeria monocytogenes/isolamento & purificação , Leite/microbiologia , Animais , Contagem de Colônia Microbiana , Concentração de Íons de Hidrogênio , Listeria monocytogenes/crescimento & desenvolvimento , Listeria monocytogenes/fisiologia , Viabilidade Microbiana , Leite/química , Sais/análise , Água/análise
14.
J Photochem Photobiol B ; 204: 111800, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32028188

RESUMO

Herein, we have reported the synthesis, characterization and catalytic activity of highly stable gold nanoparticles (Au NPs) using red cabbage extract (RCE) under UV irradiation. The anthocyanin groups predominantly existing in RCE play an essential role for biosynthesis of stable Au NPs. The reasons for using anthocyanins: 1) they act as chelating agents for preferentially reacting with gold ions (Au3+) to form Au3+- anthocyanin complexes, 2) as light-active reductants for reduction of Au3+ to zero valent Au0 under UV irradiation and 3) as stabilizing agent for preventing Au NPs from aggregation in high salt concentration owing to their unique salt tolerance property. We also demonstrate that how reaction time, concentration of RCE, pH value of reaction solutions and using one more reducing agent affected formation of the Au NPs. The stability of RCE Au NPs was comparatively studied with commercial (citrate stabilized) Au NPs against 100 mM salt (NaCl) solution. The RCE-Au NP showed reduction ability for conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). UV-vis spectrometry, transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential (ZT) methods were utilized to characterize the Au NPs. We demonstrated that how whole RCE (anthocyanins molecules are major component) can be used as photo-active reducing and stabilizing agents to form Au NPs in a short time under UV irradiation and strong reducing agent without additional agents.


Assuntos
Brassica/química , Ouro/química , Nanopartículas Metálicas/química , Raios Ultravioleta , Antocianinas/química , Brassica/metabolismo , Catálise , Química Verde , Nitrofenóis/química , Oxirredução , Extratos Vegetais/química , Sais/química
15.
Chemosphere ; 249: 126115, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32045756

RESUMO

The BCR sequential extraction scheme (SES), initially developed for soils and sediments, is frequently adopted to evaluate the environmental risks of municipal solid waste incineration (MSWI) fly ash. Within the procedure, metals are liberated from the matrix hosting them relying on the selectivity of the chosen chemical reagents or operation conditions. However, the effect of the high content of alkaline substances in MSWI fly ash on the selectivity of acetic acid to acid-soluble fraction metals was ignored. In this study, the feasibility of the BCR SES for evaluating MSWI fly ash was assessed by adjusting the acetic acid washing times in the acid-soluble extraction step. The metal fractionation, as well as mineralogy, morphology, and surface chemistry of the residues after three successive acid washing processes, were analyzed. The results reveal that only easily soluble salts, but not hydroxides, are entirely extracted after the first acid washing (pH∼12.0). Importantly, carbonates (generally reported as an indicator of the complete release of acid-soluble metals) are mostly decomposed only after the third acid washing (pH∼3.8). The incomplete dissolution of calcium carbonates in a single-step acid washing may convey misleading results of metal fractionation and underestimates the environmental risk of potentially toxic elements. Therefore, complete removal of carbonates should be employed as the endpoint of the acid-soluble fraction extraction step in the evaluation of MSWI fly ash. This work can help in selecting proper strategies for fly ash management and developing proper sequential extraction schemes for similar high-alkalinity hazardous waste risk assessment.


Assuntos
Incineração/métodos , Metais Pesados/análise , Carbono/química , Carbonatos/química , Fracionamento Químico , Cinza de Carvão/química , Material Particulado/química , Eliminação de Resíduos , Sais , Resíduos Sólidos/análise , Oligoelementos/análise
16.
Chem Commun (Camb) ; 56(20): 3081-3084, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32051996

RESUMO

Surface CIEE based on Zn-HDS as host material and GSH-CuNCs as guest molecules was developed to produce fluorescence composite GSH-CuNCs/Zn-HDS for the first time. It displays high quantum yield, long fluorescence lifetime and good stability, and was applied to sensitive bioenzyme sensing and fabrication of a high performance light-emitting diode.


Assuntos
Cobre/química , Enzimas/análise , Corantes Fluorescentes/química , Luz , Nanopartículas Metálicas/química , Zinco/química , Enzimas/metabolismo , Glutationa/química , Tamanho da Partícula , Sais/química , Propriedades de Superfície
17.
Water Res ; 173: 115571, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32035280

RESUMO

This study demonstrated the presence of a critical equivalent ratio of the competing anion (i.e., sulfate and bicarbonate) to chloride ion in recycled brine to achieve highly-selective nitrate removal from nitrate-rich groundwater in the standard-anion exchange resin (AER) (i.e., with trimethylamine functional groups) column process. With increasing bicarbonate (or sulfate):chloride equivalent ratio in brine used to circularly activate/regenerate the standard-AER column, considerable bicarbonate (sulfate) removal and dumping were observed. The critical bicarbonate (sulfate):chloride equivalent ratio of 2:5 (8:1) in brine effectively achieved zero net bicarbonate (sulfate) removal (<5%) from feedwater during long-term exhaustion-regeneration cyclic operation. The feed rate (6-18 BV/h) played a key role in determining the critical sulfate:chloride equivalent ratio in brine, while the feed sulfate concentration (145-345 mg/L) slightly changed the critical sulfate:chloride equivalent ratio. The use of optimized ternary brine (with a sulfate:chloride:bicarbonate equivalent ratio of 42:5:2) stably achieved long-term highly-selective nitrate removal from groundwater in the standard-AER column process with brine electrochemical treatment. The possible mechanism for nitrate selectivity included the modification of the sulfate: and bicarbonate:chloride equivalent ratios in the standard-AER column by the optimized brine in circular activation/regeneration mode; this changed the column elution and breakthrough curves, inhibited the competition of sulfate and bicarbonate for ion exchange sites during exhaustion according to the separation factor, and finally achieved selective nitrate removal from feedwater.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Resinas de Troca de Ânions , Troca Iônica , Nitratos , Sais
18.
Water Res ; 173: 115555, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32058149

RESUMO

We use numerical simulations to study the possible spatiotemporal effects of brine release from five desalination plants, located along the Israeli Mediterranean coastline. It is commonly believed that salinity anomalies, associated with brine discharge from desalination plants, causes effects which are confined to an area of several hundreds of meters from the discharge outfall. We show that discharging brine using diffusers produces small but robust salinity anomalies that propagate tens of kilometers as density currents (DCs). In contrast, premixing the brine with power plant cooling water compensates the negative buoyancy and prevents their generation. The propagating DCs can impact coastal water dynamics by increasing the velocities and transports in alongshore and downslope directions. The spreading and trajectories of the DCs was strongly influenced by seasonal stratification. In winter, due to a mixed water column, the DCs were relatively focused and propagate downslope. While in the summer they are confined to a narrow band along the coastline. Our model results highlight the possibility that brine discharge might have a large scale, non-negligible effect on shelf circulation than previously considered. Further studies are needed to assess the environmental, dynamical and ecological effects of desalination brine propagation, especially in the far field.


Assuntos
Sais , Água do Mar , Israel , Salinidade
19.
PLoS One ; 15(1): e0227589, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31935245

RESUMO

Desalination plants along the Mediterranean Israeli coastline currently provide ~587 million m3 drinking water/year, and their production is planned to increase gradually. Production of drinking water is accompanied by a nearly equivalent volume of brine discharge with a salinity of ~80 that is twice the normal, which can potentially impact marine ecosystems. The goal of this study was to examine whether benthic foraminifera, a known sensitive marine bio-indicator, are affected by this brine-discharge. For that, we investigated the seasonal and cumulative effect of brine discharges of three operating desalination facilities along the Israeli coast. Those facilities are located in Ashkelon, Hadera, and Sorek. The brine-discharge in the first two desalination plants is associated with thermal pollution, while the Sorek facility entails increased salinity but no thermal pollution. In four seasonal cruises during one year, we collected surface sediment samples in triplicates by grabs from the outfall (near the discharge site), and from a non-impacted control station adjacent to each study site. Our results highlight that the most robust responses were observed at two out of three desalination shallow sites (Ashkelon and Hadera), where the brine was discharged directly from a coastal outfall and was accompanied with thermal pollution from the nearby power plants. The total foraminiferal abundance and diversity were, generally, lower near the outfalls, and increased towards the control stations. Moreover, changes in the relative abundances of selected species indicate their sensitivity to the brine discharge. The most noticeable response to exclusively elevated salinity was detected at Sorek discharge site, where we observed a sharp decline in organic-cemented agglutinated benthic foraminifera, suggesting that these are particularly sensitive to elevated salinity. The herein study contribute new insights into the effect of brine discharge from desalination plants, on benthic foraminifera, and propose a scientifically-based ecological monitoring tool that can help stakeholders.


Assuntos
Monitoramento Ambiental/métodos , Foraminíferos/metabolismo , Sais/efeitos adversos , Ecossistema , Sedimentos Geológicos , Israel , Mar Mediterrâneo , Centrais Elétricas , Salinidade , Água do Mar , Espécies Sentinelas/metabolismo
20.
Waste Manag ; 103: 334-341, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31923840

RESUMO

Thermal treatment could effectively realize the detoxification of heavy metals in municipal solid waste incineration (MSWI) fly ash through the approach of removal or stabilization process. To lower the operating temperature and suppress the evaporation of heavy metals, a molten salts (NaCl-CaCl2) thermal treatment method was proposed for the detoxification of heavy metals from MSWI fly ash at a relatively mild condition (600/800 °C). The fate of heavy metals during the heating process and their stabilization properties in the remained ash slag after molten salts thermal treatment were investigated. The results showed that, compared with the traditional thermal treatment, heavy metals were more easily chlorinated by the means of molten salts thermal treatment. The well distributed chloride in molten salts facilitated the direct chlorination of PbO/CdO. Furthermore, Al2O3 in ash enhanced the indirect chlorination of CuO/PbO/CdO, except for ZnO. In contrast, SiO2 showed better performance in promoting the indirect chlorination of heavy metal oxides. Meanwhile, some Zn2+ was precipitated from molten salts as Si/Al-Zn composite oxides through the interactions with ash containing Si/Al oxides. On the other hand, the dissolved heavy metals in molten salts showed a good thermal stability during the thermal treatment. The volatilization fractions of all detected heavy metals were less than 5%. After the molten salts thermal treatment, heavy metals in the ash slag were well stabilized and the amount of heavy metals leached was significantly lower than that from the raw fly ash.


Assuntos
Metais Pesados , Eliminação de Resíduos , Carbono , Cinza de Carvão , Incineração , Material Particulado , Sais , Dióxido de Silício , Resíduos Sólidos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA