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1.
Chemosphere ; 243: 125438, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995886

RESUMO

The use of three-dimensional electrode is a new electrochemical oxidation technology for landfill leachate treatment. In this study, a particle electrode was developed using Fe/C granules, which were suspended between the cathode and the anode to create a three-dimensional electrode. The three-dimensional electrode activated sodium persulfate to treat landfill leachate. Fe/C granules were prepared by incorporating iron filings and hydrothermally carbonized biochar into alginate beads. The optimal parameters of the three-dimensional electrode for chemical oxygen demand (COD) removal from landfill leachate were determined based on a series of single factor experiments as an operating voltage of 5 V, a sodium persulfate concentration of 28 mM, and 1 g of Fe/C granules. Treatment with the three-dimensional electrode at optimized conditions achieved 72.9% removal of COD and 99.9% removal of ammonia nitrogen, resulting in landfill leachate being clear and transparent. The changes in total organic carbon, nitrite, and nitrate concentrations indicated that most organic pollution and ammonia nitrogen were converted into CO2 and N2. This study provides an alternative technology for the treatment of refractory organic pollutants.


Assuntos
Técnicas Eletroquímicas/instrumentação , Eletrodos/normas , Poluentes Químicos da Água/química , Purificação da Água/métodos , Amônia/isolamento & purificação , Análise da Demanda Biológica de Oxigênio , Carbono/química , Carbono/isolamento & purificação , Química Orgânica , Ferro/química , Nitrogênio/isolamento & purificação , Oxirredução , Compostos de Sódio/química , Sulfatos/química , Poluentes Químicos da Água/isolamento & purificação
2.
Ecotoxicol Environ Saf ; 188: 109891, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31740236

RESUMO

The study focuses on degradation efficiency of non-radical activation and radical activation systems of persulfate (PS) to degrade imidacloprid (IMI) by using sodium persulfate (SPS) as PS source. Copper oxide (CuO)-SPS and CuO/biochar (BC)-SPS were selected as PS non-radical activation systems, and pyrite (PyR)-SPS was selected as PS radical activation system. The degradation by CuO-SPS, CuO/BC-SPS and PyR-SPS systems was investigated from acidic to basic conditions (pH 3.0-11.0). Highest degradation by CuO-SPS and CuO/BC-SPS systems was achieved over pH 11.0. In contrast, highest degradation by PyR-SPS system was achieved over pH 3.0, however, PyR-SPS system was also found effective up to pH 9.0. It was found that degradation was more efficient in PS radical activation system, indicating that IMI could be oxidized by radicals rather than by activated PS. Electron paramagnetic resonance (EPR) analysis was carried out to investigate the generation of sulfate (SO4-) and hydroxyl (OH) radicals, which indicated the presence of SO4- and OH in CuO-SPS, CuO/BC and PyR-SPS systems. However, free radical quenching analysis indicated that radicals were main reactive oxygen species for degradation. The lower degradation in PS non-radical activation systems was probably resulted from radicals existed as minor reactive oxygen species. The findings indicated that non-radical oxidation systems showed low reality for degradation and good degradation could be achieved by radical oxidation system. The degradation was also carried out in real waters to investigate the potential applicability of applied systems, which supported PyR-SPS system for effective degradation.


Assuntos
Carvão Vegetal/química , Cobre/química , Radicais Livres/química , Neonicotinoides/análise , Nitrocompostos/análise , Compostos de Sódio/química , Sulfatos/química , Poluentes Químicos da Água/análise , Concentração de Íons de Hidrogênio , Radical Hidroxila/química , Ferro/química , Modelos Teóricos , Oxirredução , Sulfetos/química , Purificação da Água
3.
Ecotoxicol Environ Saf ; 187: 109779, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31639643

RESUMO

UV-activated persulfate (UV/PS) and peroxymonosulfate (UV/PMS) processes as alternative methods for removal of imidacloprid (IMP) were conducted for the first time. The reaction rate constants between IMP and the sulfate or hydroxyl radical were calculated as 2.33×109  or 2.42×1010 M-1 s-1, respectively. The degradation of IMP was greatly improved by UV/PS and UV/PMS compared with only UV or oxidant. At any given dosage, UV/PS achieved higher IMP removal rate than UV/PMS. The pH range affecting the degradation in the UV/PS and UV/PMS systems were different in the ranges of 6-8 and 9 to 10. SO42-, F- and NO3- had no obvious effect on the degradation in the UV/PS and UV/PMS systems. CO32- and PO43- inhibited the degradation of IMP in the UV/PS system, while they enhanced the degradation in the UV/PMS system. Algae organic matters (AOM) were used to consider the impact of the degradation of IMP for the first time. The removal of IMP were restrained by both AOM and natural organic matters. The higher removal rate of IMP demonstrated that both UV/PS and UV/PMS were suitable for treating the water containing IMP, while UV/PS was cost-effective than UV/PMS based on the total cost calculation. Finally, the degradation pathways of IMP were proposed.


Assuntos
Neonicotinoides/análise , Nitrocompostos/análise , Peróxidos/química , Compostos de Sódio/química , Sulfatos/química , Raios Ultravioleta , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Cinética , Modelos Teóricos , Oxirredução , Peróxidos/efeitos da radiação , Compostos de Sódio/efeitos da radiação , Sulfatos/efeitos da radiação
4.
Ecotoxicol Environ Saf ; 183: 109548, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31404726

RESUMO

Chemical oxidation has been applied to remove soil contaminants and thereby reduce human and ecological risks from contaminated sites. However, few studies have been conducted on the natural infiltration of oxidant solutions into unsaturated soil. Moreover, the infiltration capacity of oxidant solutions at various concentrations in unsaturated soil has not yet been studied. This study investigated the natural infiltration tendency of oxidant solutions like hydrogen peroxide (H2O2), potassium permanganate (KMnO4), and sodium persulfate (Na2S2O8), in sand and sandy loam. Cumulative infiltration was recorded from a soil column equipped with a Mariotte reservoir. The infiltration rate, sorptivity, and unsaturated hydraulic conductivity were obtained from the cumulative infiltration results. Na2S2O8 showed the highest infiltration rate in both sand and sandy loam, and the infiltration of Na2S2O8 increased as the concentration was increased from 0.05 to 1%. However, the infiltration of KMnO4 and H2O2 solutions was governed more by chemical reaction behavior than by liquid physical properties or soil hydraulic properties. The production of oxides and gas due to reaction induced clogging in flow paths, resulting in less infiltration. Infiltration of H2O2 at concentrations greater than 0.5% was not observed in sand or sandy loam due to gas formation and swelling.


Assuntos
Peróxido de Hidrogênio/química , Oxidantes/química , Permanganato de Potássio/química , Compostos de Sódio/química , Poluentes do Solo/análise , Solo/química , Sulfatos/química , Oxirredução , Óxidos/análise , Medição de Risco
5.
Environ Sci Process Impacts ; 21(9): 1560-1569, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31364657

RESUMO

In this study, the effects of key parameters on the degradation kinetics of sulfamethoxazole (SMX) in an Fe(ii)-activated persulfate (PS) process were elucidated. SMX could be completely degraded within 240 min at an initial pH of 3.3. It was found that 1 : 10 is the optimum molar ratio of Fe(ii) : PS. Typical water quality parameters, including solution pH, SMX concentration, inorganic ions and humic acid, are discussed for the degradation process. Although the SMX degradation kinetics varied for different water quality parameters, relatively high SMX removal could always be achieved. The Fe(ii)-activated persulfate process could maintain excellent SMX degradation under optimum reaction conditions. In addition, the reaction sites and intermediates of SMX were predicted by density functional theory (DFT) calculations and wave function analysis. The results of different calculations consistently indicate that N7 is the site with the highest electrophilic reactivity of SMX. The main intermediates formed were characterized through accurate mass measurement using UHPLC-HRMS/MS. Combined with the theoretical computations, the SMX degradation pathways in the Fe(ii)-activated persulfate process are proposed. This research could provide theoretical guidance for the degradation mechanism of sulfonamides and provide technical support for the design of efficient degradation reactions in the future.


Assuntos
Compostos Ferrosos/química , Compostos de Sódio/química , Sulfametoxazol/análise , Sulfatos/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Substâncias Húmicas/análise , Cinética , Modelos Teóricos , Oxirredução , Sulfametoxazol/química , Poluentes Químicos da Água/química
6.
Chemosphere ; 232: 462-470, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158641

RESUMO

The activation of peroxydisulfate (PDS) by gas/liquid dielectric barrier discharge (DBD) plasma in a flat plate configuration was assessed through phenol removal. The results indicated that PDS addition exhibited a significantly promoting effect on phenol removal and mineralization. In the reaction lacking PDS, phenol in aqueous solution was removed from the initial 10 mg L-1 to 4.75 mg L-1 (by 52.5%), whereas the addition of 1770 mg L-1 PDS increased the overall removal to 78.7%, as indicated by a one-fold increase in the pseudo-first-order kinetic constant. In addition, the corresponding total organic carbon (TOC) removal was increased from 27.5% to 48.4%. Furthermore, an increased input voltage was favourable for increases in phenol removal, the kinetic constant and PDS utilization, which were also influenced by the PDS dose, initial solution pH and water matrix. In addition, through the analysis of radical quenching experiments, the enhancement could be mainly attributed to the production of SO4•- and •OH by PDS activation by discharge plasma. The DBD system coupled with PDS exhibited a high removal efficiency for phenol, and thus, the overall findings could provide new insight into wastewater treatment.


Assuntos
Fenol/análise , Gases em Plasma/química , Compostos de Sódio/química , Sulfatos/química , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Cinética
7.
Anal Sci ; 35(9): 967-972, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31080198

RESUMO

Nucleic acid aptamers have been widely used as synthetic probes for bioanalytical applications. Herein, we carried out a detailed study on the immobilization of a series of aptamers ranging from 37 to 88 bases, which are specific to either Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus), on a planar gold substrate via a polyadenine-mediated immobilization method. The resultant surfaces were characterized by both surface plasmon resonance spectroscopy (SPR) and X-ray photoelectron spectroscopy. The results clearly show that the aptamer solution at a lower ionic strength gives rise to a higher lateral density of the aptamer when compared to that at a higher ionic strength. The SPR aptasensors are then employed for detecting their corresponding bacteria (i.e., E. coli and S. aureus, respectively). The data indicate that the SPR aptasensor with a higher density of aptamer exhibits a better capture of target bacteria.


Assuntos
Aptâmeros de Nucleotídeos/química , Escherichia coli/isolamento & purificação , Ouro/química , Poli A/química , Staphylococcus aureus/isolamento & purificação , Ressonância de Plasmônio de Superfície/métodos , Aptâmeros de Nucleotídeos/genética , Aptâmeros de Nucleotídeos/metabolismo , Sequência de Bases , Brometos/química , Escherichia coli/metabolismo , Concentração Osmolar , Compostos de Sódio/química , Staphylococcus aureus/metabolismo
8.
Sci Total Environ ; 660: 923-930, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30743977

RESUMO

The removal of 17 pesticides (pymetrozine, flonicamid, imidacloprid, acetamiprid, cymoxanil, thiachloprid, spinosad, chlorantraniliprole, triadimenol, tebuconazole, fluopyram, difenoconazole, cyflufenamid, hexythiazox, spiromesifen, folpet and acrinathrin) found in agro-wastewater from washing of containers and phytosanitary treatments equipment, has been carried out using sodium persulfate (Na2S2O8) at pilot plant scale under natural sunlight. Persulfate is a strong oxidant, inexpensive and environmentally appropriate. However, this oxidant is slow in kinetics under ordinary conditions. Na2S2O8 can be activated by ultraviolet light, generating SO4- radicals, which are also a very strong oxidizing species (E0 = 2.6 V). Previously, preliminary experiments were carried out at laboratory scale using a photoreactor to optimize the Na2S2O8 (300 mg L-1) concentration on the rate constants of the found pesticides. The residual levels of the studied pesticides in agro-wastewater (900 L) were in the range 0.02-1.17 mg L-1 for acrinathrin and fluopyram, respectively. After treatment, nearly complete degradation (>97%) of the parent molecules was achieved although 13% of initial DOC was measured. No significant differences (p < 0.05) were found when comparing grown broccoli using reclaimed and unreclaimed water.


Assuntos
Resíduos de Praguicidas/análise , Compostos de Sódio/química , Sulfatos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Agricultura , Resíduos de Praguicidas/química , Luz Solar , Águas Residuárias/química , Poluentes Químicos da Água/química
9.
Biomed Mater Eng ; 30(2): 207-218, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30741668

RESUMO

BACKGROUND: Surface modification of metallic implants is critical for improving the clinical performance of the dental and orthopedic devices. Bioactive glasses exhibit different levels of cellular function and physicochemical behavior; however, there have been few previous studies on the effect of constituents of the bioactive glasses on the in vitro osteogenic activity and corrosion resistance of apatite-based coatings. OBJECTIVE: The objective of this work was to investigate the effect of SiO2, CaO, Na2O, and P2O5 on plasma-sprayed apatite coatings on Ti alloy substrates for tailoring the properties of implants making them suitable for clinical applications. METHODS: The corrosion potential and corrosion current of various coatings in simulated body fluid (SBF) were examined. MG63 cell proliferation, differentiation, and mineralization of plasma-sprayed apatite-matrix coatings were evaluated. RESULTS: The SiO2 and CaO-containing HA (HSC) coating had a higher corrosion potential than the other three coatings, while SiO2-containing HA (HS) coating displayed the highest corrosion current among all coatings. The effect of the oxides on cell functions followed the order SiO2 > CaO > P2O5 > Na2O in terms of cell attachment, proliferation, differentiation, and mineralization. CONCLUSIONS: The flexibility in oxide doping may allow for the tunable biological properties and corrosion-resistant ability of the apatite coatings.


Assuntos
Apatitas/química , Compostos de Cálcio/química , Materiais Revestidos Biocompatíveis/química , Óxidos/química , Compostos de Fósforo/química , Dióxido de Silício/química , Compostos de Sódio/química , Titânio/química , Ligas/química , Animais , Linhagem Celular , Proliferação de Células , Corrosão , Fibroblastos/citologia , Humanos , Teste de Materiais , Camundongos , Osteoblastos/citologia , Gases em Plasma/química
10.
Sci Total Environ ; 653: 1293-1300, 2019 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-30759569

RESUMO

Chemical oxidation and microbial degradation are promising treatments to remediate soils contaminated with persistent organic pollutants. Moderate pre-oxidation is able to enhance the subsequent bioremediation of organic pollutants in soil. In this study, the effects of pre-oxidation on the subsequent biodegradation of benzo[a]pyrene (BaP) were evaluated. The tested oxidants included potassium permanganate (PP) and iron-activated sodium persulfate (PS) at the concentration of 1-40 mmol L-1. The results showed that 20 mmol L-1 PS and 10 mmol L-1 PP treatments had the highest degradation efficiency of BaP in soil, up to 98.7% and 84.2%, without inhibiting subsequent microbial degradation. 10-20 mmol L-1 of the two oxidants significantly promoted viability of microbial community. Especially, PS facilitated the occurrence of more PAHs-degrading microorganisms. The expression of PAH-degradation gene in PS treatment was significantly higher than that in PP treatment (P < 0.05), leading to 12.0-18.4% higher degradation efficiencies of BaP. In general, proper oxidants of moderate dosages were able to promote microbial bioremediation of persistent organic pollutants in soil.


Assuntos
Benzo(a)pireno/metabolismo , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/metabolismo , Oxirredução , Permanganato de Potássio/química , Compostos de Sódio/química , Microbiologia do Solo , Sulfatos/química
11.
Ecotoxicol Environ Saf ; 172: 334-340, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30721877

RESUMO

Excess sulfonamides are discharged into the environmental system due to the abuse of antibiotics, which threatens the ecological environment and human health. In this study, the ferric and ferrous as well as calcium peroxide (CP), sodium percarbonate (SPC) and sodium persulfate (SPS) have been used to build Fenton-like system for the sulfanilamide (SA) removal. Compared with other Fenton-like system, the Fe3+/CP system exhibited better degradation capacity and 94.65% SA was removed with 3.0 mM CP and 3.0 mM Fe3+. A response surface and corresponding quadratic regression equation were obtained by using a three-level Box-Behnken factorial design with the initial pH value and the dosage of Fe3+ and CP as the model parameters. Depended on the result of the response surface, the optimum conditions of the removal of SA in Fe3+/CP system could be obtained: [Fe3+] = 2.96 mM, [CaO2] = 2.33 mM and [pH] = 6.45. Besides that, the influences of Na+, Mg2+, Cl-, HCO3-, NO3- and HA on SA removal were also investigated under the optimum condition. The results revealed that the high concentration of HCO3- was able to inhibit degradation of SA while other ions and HA have little effect on SA degradation. These results provided a novel strategy to evaluate the catalyst/oxidant system by combining experiment and computer simulation in wastewater treatment.


Assuntos
Peróxido de Hidrogênio/química , Sulfanilamida/química , Carbonatos/química , Catálise , Simulação por Computador , Compostos Férricos/química , Compostos Ferrosos/química , Concentração de Íons de Hidrogênio , Ferro/química , Oxidantes/química , Peróxidos/química , Compostos de Sódio/química , Sulfatos/química , Águas Residuárias/química
12.
Int J Biol Macromol ; 124: 582-590, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30502427

RESUMO

In this work, a multielement compound fertilizer (MCF) was fabricated using ammonium zinc phosphate (AZP) as kernel nutrient element, and polydopamine (Pdop) film as inner coating. Besides, sodium carboxymethyl starch (SCS) was proposed as a constituent in AZP@Pdop mixture due to its adhesion, gelling and swelling abilities, to prepare well dispersed suspensions and consolidate the single-coated fertilizer. What's more, iron (Fe), the vital microelement for the growth of crops and alleviating the leaf chlorosis, was chelated by the carboxylate groups of SCS, contributing to make the outer coating compact. The release behavior showed that zinc (Zn), phosphorus (P) and Fe reached 60% cumulative release in 30 days, and the use efficiency of nutrients for corn was about 60%. In summary, this work provides a novel approach to improve the utilization efficiency and prolong duration of the MCF, which might have a potential application in agronomics.


Assuntos
Fertilizantes , Indóis , Polímeros , Compostos de Sódio , Amido/análogos & derivados , Compostos de Amônio/química , Produtos Agrícolas , Fertilizantes/análise , Indóis/química , Fosfatos/química , Fósforo , Polímeros/química , Compostos de Sódio/química , Solo/química , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/química , Termogravimetria , Zea mays , Zinco , Compostos de Zinco/química
13.
Environ Sci Process Impacts ; 21(1): 63-73, 2019 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-30534711

RESUMO

The reaction of ozone with bromide is an initiation process in bromine activation resulting in the formation of reactive bromine species with impacts on the fate of compounds in the lower atmosphere. Environmental halide sources often contain organics, which are known to influence aqueous bulk reactivity. Here, we present a study investigating the temperature dependence of bromide oxidation by ozone using a coated wall flow tube reactor coated with an aqueous mixture of citric acid, as a proxy for oxidized secondary organic matter, and sodium bromide. Using the resistor model formulation, we quantify changes in the properties of the aqueous bulk relevant for the observed reactivity. The reactive uptake coefficient decreased from 2 × 10-6 at 289 K to 0.5 × 10-6 at 245 K. Our analysis indicates that the humidity-driven increase in concentration with a corresponding increase in the pseudo-first order reaction rate was countered by the colligative change in ozone solubility and the effect of the organic fraction via increased viscosity and decreased diffusivity of ozone as the temperature decreased. From our parameterization, we provide an extension of the temperature dependence of the reaction rate coefficients driving the oxidation of bromide, and assess the temperature-dependent salting effects of citric acid on ozone solubility. This study shows the effects of the organic species at relatively mild temperatures, between the freezing point and eutectic temperature of sea as is typical for the Earth's cryosphere. Thus, this study may be relevant for atmospheric models at different scales describing halogen activation in the marine boundary layer or free troposphere including matrices such as sea-spray aerosol and brine in sea ice, snow, and around mid-latitude salt lakes.


Assuntos
Atmosfera/química , Brometos/química , Bromo/química , Ozônio/química , Ácido Cítrico/química , Compostos Orgânicos , Oxirredução , Ozônio/análise , Sais , Compostos de Sódio/química , Solubilidade , Temperatura , Viscosidade
14.
Chemosphere ; 215: 333-341, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30326439

RESUMO

The effects of wheat straw powder (WSP) used as physical conditioner on sludge dewatering was investigated under sodium persulfate (SPS)/Fe(II) oxidation. Sludge dewatering performance in terms of capillary suction time (CST), specific resistance to filtration (SRF) and moisture content (MC) was enhanced with increasing WSP and SPS dosages. The results showed presence of synergistic effect in WSP and SPS conditioning system, with sludge CST and SRF reduced by 43.9% and 65.6%, respectively, after dosing 0.75 g/g DS (dry solid) WSP, 120 mg/g DS SPS and 33 mg/g DS Fe(II), indicating that sludge dewatering became more easily. Correspondingly, bound water was released and decreased from 5.75 g/g DS to 1.5 g/g DS and deep dewatered sludge MC reached to 58.2% under 2 MPa pressure. Mechanically, tightly bound extracellular polymeric substances (TB-EPS) with larger molecular weights were oxidized and degraded into loosely bound-EPS (LB-EPS) and soluble organic matter with smaller molecular weights by SPS/Fe(II). Additionally, the organic matters released from or still in WSP was also oxidized resulting in more channels and less fine particles.


Assuntos
Compostos Ferrosos/química , Esgotos/química , Compostos de Sódio/química , Sulfatos/química , Triticum/química , Molhabilidade/efeitos dos fármacos , Compostos Ferrosos/farmacologia , Oxirredução , Polímeros , Pós/farmacologia
15.
J Chromatogr A ; 1583: 28-38, 2019 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-30448052

RESUMO

Effects of two salt additives, NaCl and NaClO4, at the fixed concentrations of 0.215 M on the properties of aqueous two-phase systems (ATPSs) formed by dextran (Dex) and polyethylene glycol (PEG), and the effects of NaClO4 at the same concentration on the properties of ATPS formed by PEG and Na2SO4 were examined. The effects of these salt additives on partitioning of 12 small organic compounds and five proteins in the above ATPSs were studied. In each system with a given salt additive, 0.5 M sorbitol, 0.5 M sucrose, and 0.5 M and 1.5 M trimethylamine N-oxide (TMAO) were also used as additives. The results obtained were compared with those reported previously for the Dex-PEG ATPS without salt additives and PEG-Na2SO4 ATPS without salt additives and in the presence of 0.215 M NaCl. It is shown that the differences between the solvent properties of the phases in the systems formed by polymer and salt exceed those observed in the systems formed by two polymers. The three most significant solvent features of the systems are hydrophobic and electrostatic properties and hydrogen bonding donor acidity of the solvent media. Osmolyte additives were found to have a significant effect on the differences between the electrostatic properties of the phases. Analysis of the partition coefficients of 12 organic compounds and five proteins showed that the osmolyte additives may affect the partition behavior of compounds in a compound-specific manner. The relative contributions of different types of interactions of a given compound with aqueous media change in the presence of salt and osmolyte additives. Analysis of the variability ranges of partition coefficient, K, in the systems studied showed that for small organic compounds, the ranges of K-values observed in the PEG-Na2SO4 ATPSs exceed those determined in the Dex-PEG ATPSs quite significantly, whereas for proteins, the range of K-values in Dex-PEG ATPSs exceeded those in PEG-Na2SO4 ATPSs for three proteins, and were very similar for two proteins. This observation supported the notion that the ATPSs formed by two polymers are more suitable for protein analysis than those formed by a single polymer and a salt. The single polymer-salt ATPSs have an advantage for protein isolation/separation.


Assuntos
Dextranos/química , Percloratos/química , Polietilenoglicóis/química , Cloreto de Sódio/química , Compostos de Sódio/química , Sulfatos/química , Água/química , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Proteínas/química , Solventes/química , Eletricidade Estática
16.
Environ Sci Pollut Res Int ; 26(5): 4367-4380, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29855874

RESUMO

This study evaluates the technical, economical, and environmental impact of sodium persulfate (Na2S2O8) as an enhancing agent in a photo-Fenton process within a solar-pond type reactor (SPR). Photo-Fenton (PF) and photo-Fenton intensified with the addition of persulfate (PFPS) processes decolorize 97% the azo dye direct blue 71 (DB71) and allow producing a highly biodegradable effluent. Intensification with persulfate allowed reducing treatment time in 33% (from 120 to 80 min) and the consumption of chemical auxiliaries needed for pH adjustment. Energy, reagents, and chemical auxiliaries are still and environmental hotspot for PF and PFPS; however, it is worth mentioning that their environmental footprint is lower than that observed for compound parabolic concentrator (CPC)-type reactors. A life-cycle assessment (LCA) confirms that H2O2, NaOH, and energy consumption are the variables with the highest impact from an environmental standpoint. The use of persulfate reduced the relative impact in 1.2 to 12% in 12 of the 18 environmental categories studied using the ReCiPe method. The PFPS process emits 1.23 kg CO2 (CO2-Eqv/m3 treated water). On the other hand, the PF process emits 1.28 kg CO2 (CO2-Eqv/m3 treated water). Process intensification, chemometric techniques, and the use of SPRs minimize the impact of some barriers (reagent and energy consumption, technical complexity of reactors, pressure drops, dirt on the reflecting surfaces, fragility of reactor materials), limiting the application of advanced oxidation systems at an industrial level, and decrease treatment cost as well as potential environmental impacts associated with energy and reagents consumption. Treatment costs for PF processes (US$0.78/m3) and PFPS processes (US$0.63/m3) were 20 times lower than those reported for photo-Fenton processes in CPC-type reactors.


Assuntos
Compostos Azo/química , Compostos de Sódio/química , Sulfatos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Dióxido de Carbono , Pegada de Carbono , Meio Ambiente , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Ferro/química , Modelos Teóricos , Oxirredução , Tanques , Luz Solar
17.
Food Chem Toxicol ; 123: 28-41, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30342114

RESUMO

Arsenic is a ubiquitous contaminant, with typical human dietary intake below 1 µg/kg bw/d and extreme drinking water exposures up to ∼50 µg/kg bw/d. The formation and binding of trivalent metabolites are central to arsenic toxicity and strong human evidence suggests special concern for early life exposures in the etiology of adult diseases, especially cancer. This study measured the metabolism and disposition of arsenite in neonatal mice to understand the role of maturation in metabolic activation and detoxification of arsenic. Many age-related differences were observed after gavage administration of arsenite, with consistent evidence in blood and tissues for higher exposures to trivalent arsenic species in neonatal mice related to the immaturity of metabolic and/or excretory functions. The evidence for greater tissue binding of arsenic species in young mice is consistent with enhanced susceptibility to toxicity based on metabolic and toxicokinetic differences alone. Lactational transfer from arsenite-dosed dams to suckling mice was minimal, based on no dosing-related changes in the levels of arsenic species in pup blood or milk collected from the dams. Animal models evaluating whole-life exposure to inorganic arsenic must use direct dosing in early neonatal life to predict accurately potential toxicity from early life exposures in children.


Assuntos
Intoxicação por Arsênico/metabolismo , Arsenicais/metabolismo , Arsenitos/metabolismo , Leite/química , Compostos de Sódio/metabolismo , Animais , Intoxicação por Arsênico/fisiopatologia , Arsenicais/química , Arsenitos/química , Feminino , Contaminação de Alimentos , Humanos , Lactação , Masculino , Camundongos , Leite/metabolismo , Compostos de Sódio/química , Distribuição Tecidual , Toxicocinética
18.
Int J Mol Sci ; 19(11)2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30380703

RESUMO

Microencapsulation of lipase from Yarrowia lipolytica IMUFRJ 50682 was performed by ionotropic gelation with sodium alginate. Sodium alginate, calcium chloride and chitosan concentrations as well as complexation time were evaluated through experimental designs to increase immobilization yield (IY) and immobilized lipase activity (ImLipA) using p-nitrophenyl laurate as substrate. To adjust both parameters (IY and ImLipA), the desirability function showed that microcapsule formation with 3.1%(w/v) sodium alginate, 0.19%(w/v) chitosan, 0.14 M calcium chloride, and 1 min complexation time are ideal for maximal immobilization yield and immobilized lipase activity. A nearly twofold enhancement in Immobilization yield and an increase up to 280 U/g of the lipase activity of the microcapsules were achieved using the experimental design optimization tool. Chitosan was vital for the high activity of this new biocatalyst, which could be reused a second time with about 50% of initial activity and for four more times with about 20% of activity.


Assuntos
Enzimas Imobilizadas/química , Proteínas Fúngicas/química , Lipase/química , Yarrowia/enzimologia , Compostos de Alumínio/química , Cloreto de Cálcio/química , Cápsulas , Quitosana/química , Compostos de Sódio/química
19.
ACS Comb Sci ; 20(11): 595-601, 2018 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-30277748

RESUMO

Understanding the behavior of combinatorially developed luminescent materials requires detailed characterization methods that have been lacking thus far. We developed a device for directly surveying the luminescent properties of thin-film libraries created through combinatorial gradient sputter deposition. Step-scan recorded excitation-, emission- and luminescence decay spectra of a thin-film library were resolved and combined with EDX measurements on the same film, relating composition to luminescent properties. This technique was applied to a single-substrate gradient thin-film library of NaBr0.73I0.27 to NaBr0.09I0.91, doped with 6.5% to 16.5% Eu2+. This gradient film closely followed Vegard's law, with emission fluently shifting from 428 to 439 nm. In comparison, pure NaBr:Eu2+ showed emission at 428 nm and NaI:Eu2+ at 441 nm. Luminescence decay measurements demonstrated a great degree of concentration quenching in the gradient film. From these measurements we could conclude that an optimized phosphor would most efficiently luminesce when close to NaI:Eu2+. This gradient film confirmed that the method presented in this work allows to both study and optimize luminescent behavior in a broad range of host- and dopant systems.


Assuntos
Európio/química , Substâncias Luminescentes/química , Bibliotecas de Moléculas Pequenas/química , Brometos/química , Técnicas de Química Combinatória , Luminescência , Medições Luminescentes , Compostos de Sódio/química , Iodeto de Sódio/química
20.
Food Chem Toxicol ; 121: 676-686, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30278242

RESUMO

Arsenic is a ubiquitous contaminant, with typical dietary intake below 1 µg/kg bw/d and drinking water exposures up to 50 µg/kg bw/d. Arsenic exposures are associated with human diseases and doses of toxicological concern are similar to typical dietary intake. Metabolism of arsenite to dimethylarsinate (DMAV) by arsenite-3-methyltransferase (As3MT) promotes clearance, but also generates reactive trivalent intermediates that bind extensively to cellular thiols. This study measured pentavalent and trivalent arsenic species in blood and tissues after oral and intravenous administration of arsenite (50 µg/kg bw). After oral administration, the intestine and liver contained elevated levels of AsIII and MMAIII, relative to erythrocytes, lung, and kidney, suggesting incomplete conversion to DMA during first-pass metabolism. However, blood concentrations of the predominant species, DMA, were similar for oral and intravenous dosing. While all tissues examined contained DMAIII, muscle, brain, and plasma had undetectable levels of MMAIII. Tissue levels of arsenic species were similar following intravenous vs. oral administration, except lower in the intestine. The results confirm the role of metabolism in producing fluxes of putatively toxic trivalent arsenic intermediates. Tissue dosimetry suggests that the intestine, liver, lung, and kidney could be more susceptible to effects of bound arsenic, relative to muscle and brain.


Assuntos
Arsênico/classificação , Arsenitos/farmacocinética , Compostos de Sódio/farmacocinética , Administração Oral , Animais , Área Sob a Curva , Arsênico/química , Arsenitos/química , Eritrócitos , Feminino , Meia-Vida , Injeções Intravenosas , Camundongos , Reprodutibilidade dos Testes , Compostos de Sódio/química
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