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1.
Environ Pollut ; 265(Pt A): 115002, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32563950

RESUMO

Mercury (Hg) is commonly extracted from solid phase samples using aqua regia for total Hg (tHg) analysis. However, uncertainties exist regarding the complete extraction of Hg by aqua regia, especially from carbonaceous materials. To investigate whether aqua regia can completely extract Hg from biochars, batch-style experiments were carried out to evaluate extraction efficiency of aqua regia with respect to Hg-loaded biochar and to characterize the residual Hg speciation and spatial distribution. Different types of biochars (raw, FeCl3-modified, and FeSO4-modified, prepared at different temperatures) were reacted with Hg-spiked solution before the digestion experiments. Adsorption analyses indicate the biochars were successfully loaded with Hg and that the Hg content was higher in biochars pyrolyzed at higher temperature (900 versus 300 or 600 °C). The results of digestion experiments indicate Hg could not be completely extracted from the biochars tested, with a greater percentage of residual Hg in biochars pyrolyzed at 600 (60 ± 15%) and 900 (75 ± 22%) than 300 °C (7 ± 2%). Furthermore, the fraction of residual Hg in FeSO4-modified biochars after aqua regia digestion was significantly lower than in FeCl3-modified and unmodified biochars. Confocal micro-X-ray fluorescence imaging (CMXRFI) showed residual Hg in biochars is concentrated on surfaces prior to digestion, but more homogeneously distributed after digestion, which indicates Hg on biochar surface is more easily digested. Hg extended X-ray absorption fine structure (EXAFS) spectra modelling showed residual Hg in biochars mainly exists as Hg(II)-Cl. These results indicate extra caution should be paid for tHg determinations using aqua regia digestion method in soil (especially in forest), sediment, and peat samples containing black carbon, activated carbon, or biochar.


Assuntos
Carvão Vegetal , Mercúrio , Adsorção , Ácido Clorídrico , Ácido Nítrico , Extratos Vegetais , Síncrotrons
2.
3.
Ecotoxicol Environ Saf ; 200: 110759, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32470677

RESUMO

Feather analysis has been widely used as a biomonitoring tool to assess metal contamination in birds, as their sampling is a non-destructive and ethically preferable technique. However, for feathers to be useful as a biomonitor of heavy metals, exogenous contamination has to be efficiently removed. Although much effort has been put into this, no washing procedure has yet proven able to ensure the total removal of the surface-associated metals. The purpose of this study was to propose an efficient washing procedure of feather samples prior to metal analysis, on the basis of comparison of various washing schemes designed according to previous analytical trials, and of the verification of the efficacy of the optimal scheme in cleaning intentionally contaminated feathers. Our investigation showed that dilute nitric acid alone or in combination with a detergent (Extran) or acetone under mild agitation of the samples performed better that any other cleaning scheme applied. Thus, a multi-step procedure including the sequential use of all three reagents was tested against feather samples contaminated by adsorbed or particulate metal species. The procedure was able to completely eliminate the external metal loads in all cases except for the partial removal of severe contamination with adsorbed Cd.


Assuntos
Poluentes Ambientais/análise , Plumas/química , Metais Pesados/análise , Ácido Nítrico , Animais , Monitoramento Biológico/métodos , Aves
4.
Environ Pollut ; 261: 114231, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32113112

RESUMO

Chromium (Cr) poses serious consequences on human and animal health due to its potential carcinogenicity. The present study aims at preparing a novel biochar derived from Chenopodium quinoa crop residues (QBC), its activation with magnetite nanoparticles (QBC/MNPs) and strong acid HNO3 (QBC/Acid) to evaluate their batch and column scale potential to remove Cr (VI) from polluted water. The QBC, QBC/MNPs and QBC/Acid were characterized with SEM, FTIR, EDX, XRD as well as point of zero charge (PZC) to get an insight into their adsorption mechanism. The impact of different process parameters including dose of the adsorbent (1-4 g/L), contact time (0-180 min), initial concentration of Cr (25-200 mg/L) as well as solution pH (2-8) was evaluated on the Cr (VI) removal from contaminated water. The results revealed that QBC/MNPs proved more effective (73.35-93.62-%) for the Cr (VI) removal with 77.35 mg/g adsorption capacity as compared with QBC/Acid (55.85-79.8%) and QBC (48.85-75.28-%) when Cr concentration was changed from 200 to 25 mg/L. The isothermal experimental results follow the Freundlich adsorption model rather than Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherm models. While kinetic adsorption results were well demonstrated by pseudo second order kinetic model. Column scale experiments conducted at steady state exhibited excellent retention of Cr (VI) by QBC, QBC/MNPs and QBC/Acid at 50 and 100 mg Cr/L. The results showed that this novel biochar (QBC) and its modified forms (QBC/Acid and QBC/MNPs) are applicable with excellent reusability and stability under acidic conditions for the practical treatment of Cr (VI) contaminated water.


Assuntos
Carvão Vegetal , Cromo , Nanopartículas de Magnetita , Ácido Nítrico , Purificação da Água , Adsorção , Animais , Carvão Vegetal/química , Cromo/isolamento & purificação , Concentração de Íons de Hidrogênio , Cinética , Nanopartículas de Magnetita/química , Ácido Nítrico/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
5.
Food Chem ; 319: 126435, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32155538

RESUMO

A microwave-assisted digestion method using diluted HNO3 was developed for further determination of Al, Ca, Cr, Cu, Fe, K, Mn, Mo and Ni in rice samples by ICP OES. The following optimized conditions were established after full factorial design: digestion time of 14 min, concentration of 1 mol L-1 HNO3 and 2.5 mL of H2O2. The efficiency in decomposing organic matter with diluted acid was higher than 89%. The methodology was validated using the SRM NIST 1568a Rice Flour and recovery tests, with agreement between the determined and certified/added concentration values, and RSD of up to 12%. The limits of detection of the method were in the range of 0.0087 mg kg-1 (Mn) to 1.6 mg kg-1 (Ca). In addition, a simple and inexpensive spectrophotometric method was proposed for the quantification of organic carbon in varied samples (carbohydrates, proteins, lipids) in the form of digested or solids.


Assuntos
Micro-Ondas , Ácido Nítrico/química , Oryza/química , Minerais/análise , Espectrofotometria
6.
Chemosphere ; 251: 126356, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32146186

RESUMO

EPA 3051A and Aqua Regia (AR) are widely adopted by global environmental agencies to assess soil quality in relation to potentially harmful elements (PHE). However, previous study has shown the formation of large amounts of short-range order materials (SRO) in the residues of these extractions. Residues obtained from the 3051A and AR were recovered from filter papers. To characterize the SRO in these residues, sequential extractions were performed with 0.2 mol L-1 ammonium oxalate (AO) and 0.5 mol L-1 NaOH. On average (n = 15), the 3051A and AR residues contained 37% and 60% of SRO, respectively. The largest amounts of SRO formed in the AR residue was in sample 5 (99% of SRO). The main component of the SRO was Al2O3-AO, Fe2O3-AO and SiO2-NaOH. The formation of SRO and PHE resorption levels were random and highly dependent on the mineralogy of the soil clay fraction. Soils rich in smectites, which are more common in temperate regions, formed larger amounts of SRO. The association of Pb with the SRO was more pronounced in the 3051A residue than in the AR residue. If SRO was not extracted after 3051A, in sample 7, for example, 595 mg kg-1 of Pb (10.2%) would have not been accounted. The maximum PHE resorptions in SRO were (%): Pb - 10; Cu - 470; Ba - 280; As - 21. The underestimation of PHE contents due to resorption mechanisms may lead an environmental agency to certify the use of an area contaminated with PHE.


Assuntos
Monitoramento Ambiental/métodos , Certificação , Ácido Clorídrico , Metais Pesados/análise , Ácido Nítrico , Dióxido de Silício , Solo/química , Poluentes do Solo/análise
7.
Bioresour Technol ; 304: 122992, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32086032

RESUMO

To meet the urgent demands for sustainable and efficient, environmental-friendly wastewater treatment, a Microbial fuel cell reactor system with MnO2/TiO2/g-C3N4 (manganese dioxide/ titanium dioxide/graphitic carbon nitride) @GAC (granular activated carbon) electrode was developed. It was both efficient and energy-saving in treating organic acid wastewater generated in Nylon production, with high-concentration COD and residual nitric acid. The MnO2/TiO2/g-C3N4 catalyst was deposited on GAC via in-situ growth and sol-gel method. The COD, NH4+-N and NO3--N was efficiently removed (respectively 98%, 99% and 99%). The COD removal capacity (17.77 kg COD m-3d-1) and the maximum power density (1176.47 mW m-3) was respectively 36.83% and 65.29% higher than the GAC cathode system. The anodic and cathodic microbial consortiums in MFC were analyzed and compared. The MnO2/TiO2/g-C3N4@GAC MFC system is technically feasible and cost-effective in treating industrial wastewater.


Assuntos
Fontes de Energia Bioelétrica , Carvão Vegetal , Eletricidade , Eletrodos , Grafite , Compostos de Manganês , Ácido Nítrico , Compostos de Nitrogênio , Óxidos , Titânio , Águas Residuárias
8.
Sci Total Environ ; 714: 136788, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-31982766

RESUMO

Acid rain (AR) is a serious issue in China, particularly in the Yangtze River Delta region where the economy has undergone rapid development. Over the last few years, the composition of acid rain in the Yangtze River Delta region has gradually changed from sulfuric acid rain (SAR) to nitric acid rain (NAR) due to controls on SO2 emissions, but increased NOx emissions. These changes have made ecosystems more complex. For this study, we halted AR treatments in Quercus acutissima forest plots that had received simulated AR for one year and monitored them from the following February to November. We investigated their soil resident enzyme and microbial metabolic activities, as well as community functional diversity. The results revealed that AR treatments negatively affected both the soil microbial activity and soil microbial community functional diversity; however, both managed to recover over time, once the AR treatments were stopped. During the AR treatment and recovery periods, four main categories (carbohydrates, carboxylic acids, amino acids, and polymers) were dominantly utilized. The utilization of pyruvic acid, which was affected by the AR treatments, as well as d-mannitol and tween 80, accounted for changes in the peak values of the C substrate groups during the AR treatment recovery period. Finally, changes in the activities of soil enzymes recorded following AR recovery, were closely related to the utilization of six C substrate groups. Our results suggested that the recovery of soils following the cessation of NAR stress was more rapid than from SAR. Further, that short-term NAR could be easily treated during the transformation from SAR to NAR in the Yangtze River Delta region. These results might also enrich the basic data relating to post-AR treatments on the soil environment, while having significance toward guiding further studies on the recovery of ecosystems from AR.


Assuntos
Chuva Ácida , Microbiologia do Solo , China , Microbiota , Ácido Nítrico , Solo
9.
Chemosphere ; 239: 124788, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521935

RESUMO

Digestion of biomass derived carbonaceous materials such as biochar (BC) can be challenging due to their high chemical recalcitrance and vast variations in composition. Reports on the development of specific sample digestion methods for such materials remain inadequate and thus require considerable attention. Nine different carbonaceous materials; slow-pyrolyzed tea-waste and king coconut BC produced at 300 °C, 500 °C and 700 °C, sludge waste BC produced at 700 °C, wet fast-pyrolyzed Douglas-Fir BC and steam activated coconut shell BC have been tested to evaluate a relatively fast and convenient open-vessel digestion method using seven digestion reagents including nitric acid (NA), fuming nitric acid (FNA), sulfuric acid (SA), NA/SA, FNA/SA, NA/H2O2 and SA/H2O2 mixtures. From the tested digestion reagents, SA/H2O2 mixture dissolved low temperature produced BC (LTBC) within 2 h with occasional shaking and no external heating. Except peroxide mixtures, the other reagents were used to evaluate microwave digestion (MWD) efficiency. Nitric acid mixture was capable of only completely digesting LTBC in the MWD procedure whereas FNA, NA/SA and FNA/SA mixtures resulted in the successful dissolution of all tested carbonaceous materials. Amongst them, FNA provided the least matrix effect in the quantification of the four metals tested using flame atomic absorption spectrophotometry. Tested recoveries for FNA were satisfactory as well. It was concluded that FNA is a preferable reagent for microwave digestion of BC.


Assuntos
Carvão Vegetal/química , Resíduos , Cocos , Indústria de Laticínios , Peróxido de Hidrogênio , Metais/análise , Micro-Ondas , Ácido Nítrico/química , Pirólise , Esgotos , Espectrofotometria Atômica/métodos , Ácidos Sulfúricos/química
10.
Environ Technol ; 41(1): 86-99, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29927352

RESUMO

Optimizing supports for microorganisms is required for bioreactors. Carbon fibres (CF) were employed as supports for microorganisms. To optimize CF supports for immobilizing bacterial cells, we used methods of nitric acid oxidation and calcium ion coverage. We evaluated the capacity of these CF supports (untreated CF, nitric acid oxidation CF and Ca2+-covered CF) via bacterial cell adhesion tests, based on extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. The results implied that because of the high hamaker constants, oxidized CF supports had higher capacity in this regard than untreated CF supports. However, the growing oxygen groups increased the negative zeta potential of CF supports, thus likely to reduce their capacity, in accordance with XDLVO theory. Since the Ca2+ coverage could decrease the negative zeta potentials of CF without reducing the hamaker constants, it could enhance the capacity of oxidized CF supports. We concluded that a combination of nitric acid oxidation and Ca2+ coverage could increase the capacity of CF supports to immobilize bacterial cells.


Assuntos
Fibra de Carbono , Ácido Nítrico , Aderência Bacteriana , Reatores Biológicos , Cálcio
11.
Huan Jing Ke Xue ; 40(6): 2607-2614, 2019 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854651

RESUMO

Nitrogen dioxide (NO2) and nitric acid (HNO3) are nitrogen-containing acidic gases in the atmosphere, and they are important precursors of nitrate in aerosol and rainwater. The emission intensity of atmospheric nitrogen oxides is high in the subtropical region of China, but the concentrations and deposition rates of atmospheric nitrogen dioxide, nitric acid, particulate nitrate-nitrogen (NO3--Np), and rainwater nitrate-nitrogen (NO3--Nr) in a double rice region in subtropical China are still unclear,. In this study, the atmosphere concentrations of NO2-N, HNO3-N, NO3--Np in PM10, and NO3--Nr and related meteorological parameters were simultaneously monitored in a typical double rice region within a subtropical hilly region of China, with the aim of determining the characteristics and influencing factors of NO2-N, HNO3-N, NO3--Np, and NO3--Nr concentrations and quantifying the wet and dry deposition rates. The results showed that the annual mean concentrations of NO2-N, HNO3-N, NO3--Np, and NO3--Nr were 4.2 µg·m-3, 0.7 µg·m-3, 4.0 µg·m-3, and 1.0 mg·L-1, respectively, and the deposition rates were 1.5, 3.2, 2.3, and 6.1 kg·hm-2, respectively. The NO2-N concentrations were negatively correlated with air temperatures, and the HNO3-N concentrations were negatively correlated with wind speeds. TheNO3--Np concentrations were negatively correlated with air temperatures, positively correlated with NO2-N concentrations, but not significantly correlated with HNO3-N concentrations, thus indicating that NO2-N concentrations were an important limiting factor forNO3--Np pollution in this study area. The NO3--Nr concentrations were negatively correlated with rainfall, as well as the concentrations of HNO3-N and NO3--Np. The annual total dry and wet depositions of the atmospheric NO2-N, HNO3-N, NO3--Np, and NO3--Nr were 13.0 kg·hm-2, which indicates that these compounds are important sources of nitrogen in paddy fields and may have significant impacts on paddy fields and surrounding ecosystems.


Assuntos
Monitoramento Ambiental , Ácido Nítrico/análise , Dióxido de Nitrogênio/análise , Oryza , Solo/química , China , Ecossistema , Nitrogênio , Chuva/química , Temperatura
12.
Anal Chim Acta ; 1091: 95-102, 2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31679579

RESUMO

Poly(ADP-ribose) polymerase-1 (PARP-1) activity is closely related to tumor, which is a promising biomarker for cancer diagnosis. So far, only a few methods have been developed for PARP-1 activity assay because both PARP-1 and its catalytic products lack valuable optical or electrochemical property. Herein, we propose a more specific method to label probes on great deal of phosphate groups of PAR. Firstly, versatile peptides were used to prepare CuNPs. This peptide not only worked as reducing agent to prepare CuNPs but also had guanidine groups to label PAR autonomously and specifically. Unlike most previously reported methods based on unspecific electrostatic interactions, CuNPs probes covered by guanidine groups labelled PAR with phosphate groups via intense covalent-like interactions. On the other hand, PARP-1 catalyzed the formation of PAR in each isolated reaction container of the detection array, realizing the high-throughput detection and enhancing the detection efficiency. Ultimately, CuNPs were oxidized into Cu2+ and precisely detected by stripping voltammetry. Hence, selectivity and efficiency of PARP-1 detection were both improved. Meanwhile, this approach was successfully used to detect the efficiency of PARP-1 inhibitor and the PARP-1 contents in real cells, indicating its great potential for clinical diagnosis and high-throughput PARP-1 inhibitor screen.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Ensaios Enzimáticos/métodos , Nanopartículas Metálicas/química , Poli(ADP-Ribose) Polimerase-1/sangue , Linhagem Celular Tumoral , Cobre/química , DNA/química , Humanos , Limite de Detecção , NAD/química , Ácido Nítrico/química , Peptídeos/química , Poli(ADP-Ribose) Polimerase-1/química
13.
Int J Biol Macromol ; 141: 150-160, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31487514

RESUMO

Three polysaccharides (WZP1, WZP2, WZP3) and their Se-enriched products (SeWZP1, SeWZP2 and SeWZP3) were obtained from Pleurotus ostreatus using a simple, rapid method and HNO3-Na2SeO3 method, respectively. The molecular weight distribution profiles of all samples except SeWZP2 showed double peaks. The average molecular weights (Mw) of WZP1-3 were 48.6 kDa, 20.2 kDa and 11.8 kDa, respectively, and of SeWZP1-3 were 19.6 kDa, 37.7 kDa, 14.5 kDa, respectively. The complexity of monosaccharide composition of WZP1-3 was inversely proportional to the ethanol concentration used in the ethanol precipitation process. Additionally, the results of biological activity tests indicated that α-glucosidase inhibitory activity of WZP1-3 was related to the molecular weight and the monosaccharide composition complexity. The selenized modification can improve the α-glucosidase-inhibiting, hydroxyl radical-scavenging activity of P. ostreatus polysaccharides. Therefore, by improving their bioactivities by selenization, the polysaccharides of P. ostreatus could be utilized as a natural health food supplement.


Assuntos
Depuradores de Radicais Livres/química , Polissacarídeos Fúngicos/química , Inibidores de Glicosídeo Hidrolases/química , Pleurotus/química , Peso Molecular , Ácido Nítrico/química , Selenito de Sódio/química
14.
Anal Sci ; 35(12): 1375-1379, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31474661

RESUMO

We developed a reference material (RM) for the determination of hexavalent chromium (Cr(VI)) in tap water. The tap water RM was prepared by adding a Cr(VI) standard solution to the raw material without acidification, i.e., under the original pH conditions of 7.6, because the decrease in the concentration of Cr(VI) was observed when the tap water had been adjusted to pH 1 with HNO3. The prepared tap-water RM (2 L) was packed in 10 fluororesin (PFA) bottles with an inside plug (200 mL each). Each PFA bottle (Cr(VI)-containing tap water) was sealed in a reclosable poly bag and then stored at 5°C in a refrigerator. The tap water RM had a Cr(VI) concentration of 51 µg L-1. The concentration of Cr(VI) was determined by diphenylcarbazide absorptiometry using a 100-mm quartz cell. The detection limit of Cr(VI) in the sample solution corresponding to three-times the standard deviation (n = 5) of blank values was 0.51 µg L-1. The homogeneity of Cr(VI) in the tap water RM was evaluated by an analysis of the variance after the Cochran test. There was no significant difference between the within-bottle and between-bottle variances of the analytical results, indicating that the tap water RM was sufficiently homogeneous. The stability of Cr(VI) in the tap water RM was investigated by monitoring the Cr(VI) concentration over a period of 6 months. The slope of the regression line of the Cr(VI) concentration versus the storage time did not significantly differ from zero, indicating that the tap water RM was stable for 6 months. The concentrations (50 - 51 µg L-1) of Cr(VI) in the tap water RM were in good agreement with the total chromium concentrations (50 - 51 µg L-1) obtained by atomic absorption spectrometry.


Assuntos
Cromo/análise , Água Potável/química , Poluentes Químicos da Água/análise , Cromo/química , Limite de Detecção , Ácido Nítrico/química , Padrões de Referência , Poluentes Químicos da Água/química
15.
Plant Physiol Biochem ; 144: 118-126, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31563092

RESUMO

As nitrogen deposition increases, acid rain is gradually shifting from sulfuric acid rain (SAR) to nitric acid rain (NAR). Acid rain can severely affect plant growth, damage ecosystems, and reduce biodiversity. Thus, a shift in acid rain type presents another challenge to the conservation of endangered plant species. We investigated the effect of three acid rain types (SAR, mixed acid rain [MAR], and NAR) and pH on the growth of an endangered Chinese endemic tree, Horsfieldia hainanensis Merr., using simulated rain in a greenhouse environment. Over nine months, growth indices, chlorophyll content, antioxidant enzyme activity, malondialdehyde content, and chlorophyll fluorescence parameters were investigated for treated and control saplings. The results indicated that at a pH of 5.6, H. hainanensis could adapt to SAR and MAR, but NAR inhibited below-ground growth. At a pH of 2.5 and 4.0, SAR inhibited stem and leaf biomass accumulation, whereas NAR inhibited root biomass accumulation and altered root morphology. MAR had intermediary effects between those of SAR and NAR. Adverse effects on leaf physiology were reduced as the rain type shifted from SAR to NAR; however, roots were increasingly adversely affected. Our results suggest that conservation efforts for H. hainanensis should shift from an above-ground to a below-ground focus as acid rain transitions toward NAR.


Assuntos
Chuva Ácida/toxicidade , Myristicaceae/fisiologia , Ácido Nítrico/toxicidade , Ácidos Sulfúricos/toxicidade , Árvores/fisiologia , China , Ecossistema , Concentração de Íons de Hidrogênio , Myristicaceae/efeitos dos fármacos , Árvores/efeitos dos fármacos
16.
Water Sci Technol ; 80(1): 86-97, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31461425

RESUMO

The present study investigated the preparation of nitric acid modified powder activated carbon (MPAC) and its adsorption of trace amounts of Ni(II) from aqueous solution. Results showed that raw powder activated carbon modified with 15% nitric acid (MPAC-15%) had the most developed pore structure and the highest adsorption efficiency for Ni(II) in aqueous solution. For MPAC-15%, the pore width was dominated by micropores with pore width about 1 nm and the total amount of chemical functional groups of MPAC-15% was 0.6630 mmol/g. Ni(II) adsorption tests indicated that the highest adsorption efficiency of MPAC-15% was 98%. The adsorption saturation time of MPAC-15% was about 120 min and the pH-dependent adsorption test showed that neutral conditions (6.5 < pH < 7.5) were suitable for Ni(II) adsorption. The adsorption kinetic analysis revealed that the pseudo-second order adsorption model fitted the adsorption process significantly. Thus, Ni(II) adsorption by MPAC-15% was dominated not only by physical adsorption via highly developed micropores but also by chemical adsorption between Ni(II) and surface functional groups. Adsorption isotherm analysis illustrated the Langmuir model was favorable for the adsorption of Ni(II), with R2 = 0.9874.


Assuntos
Níquel/química , Ácido Nítrico/química , Poluentes Químicos da Água/química , Adsorção , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Purificação da Água
17.
Talanta ; 204: 592-601, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357339

RESUMO

Development of conjugated polymers with fluorescence sensing characteristics has received close attention from researchers in fields of environmental protection, biosensing and toxins detection on food. In this paper, novel polyaniline derivatives of poly(9-methyl-9H-carbazol-3-amine) and poly(9,9-dihexyl-9H-fluoren-2-amine) are prepared by facile chemical polymerization. Then they are characterized with NMR (Nuclear Magnetic Resonance), GPC (Gel Permeation Chromatography), XRD (X-Ray Diffraction), FT-IR (Fourier Transform Infrared spectroscopy), FL (Fluorescence spectrometry) and UV-vis (Ultraviolet-visible spectroscopy) characterizations and further applied to the fluorescence detection of different acids and amines. Moreover, the obtained poly(9-methyl-9H-carbazol-3-amine) displays excellent fluorescence properties in the detection for both acids and amines. Besides, this poly(9-methyl-9H-carbazol-3-amine) can not only be used for fluorescence detection in solution, but also can be prepared into solid state and applied in the gas phase fluorescence detection. This work has greatly expanded the scope of application to these polyaniline derivatives materials, opening a new path for the researches on multi-functional chemosensor.


Assuntos
Compostos de Anilina/química , Carbazóis/química , Fluorenos/química , Corantes Fluorescentes/química , Compostos de Anilina/síntese química , Carbazóis/síntese química , Etilenodiaminas/análise , Etilenodiaminas/química , Fluorenos/síntese química , Fluorescência , Corantes Fluorescentes/síntese química , Ácido Clorídrico/análise , Ácido Clorídrico/química , Ligação de Hidrogênio , Limite de Detecção , Metilaminas/análise , Metilaminas/química , Ácido Nítrico/análise , Ácido Nítrico/química , Reprodutibilidade dos Testes , Espectrometria de Fluorescência/métodos
18.
Talanta ; 204: 663-669, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357350

RESUMO

A high-throughput, sensitive and rapid method was developed for the determination of Zn, Cu and Fe in small volumes (30 µL) of human serum using inductively coupled plasma mass spectrometry (ICP-MS). The sample preparation procedure employed simple 100-fold dilution of the serum samples with 1.0% butanol, 0.5% v/v ammonia, 0.02% v/v Triton X-100 and 0.01% v/v HNO3. The reliability of the method was evaluated using serum UTAK certified reference material, and the results matched well with the certified values. The method was applied to determine Zn, Cu and Fe in 81 human serum samples from participants in Alzheimer disease (AD) and age-related macular degeneration (AMD) studies. No significant differences were found in Zn and Cu levels between age matched controls, AD and AMD patients. Whilst iron levels appeared marginally higher in the AMD group, compared with the AD group, iron showed larger overall variability than the other two elements.


Assuntos
Cobre/sangue , Ferro/sangue , Espectrometria de Massas/métodos , Zinco/sangue , Doença de Alzheimer/sangue , Amônia/química , Humanos , Degeneração Macular/sangue , Ácido Nítrico/química , Octoxinol/química
19.
Mater Sci Eng C Mater Biol Appl ; 103: 109795, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31349459

RESUMO

Porous gold nanoparticles (GNPs) attracted considerable attention due to their remarkable properties. The porous GNPs due to the high surface area-to-volume ratio have potential applications in areas such as drug delivery, biosensors, and fuel cells. The most frequently used method for synthesis of porous GNPs is the de-alloying approach. Despite the benefits of this approach, the nanoparticles synthesized by this method were not very stable. Nevertheless, we report herein a novel, facile and simple method for synthesis of stable porous GNPs based on Tween 20-capped GNPs (Tween GNPs) and nitric acid. On the other hand, when DNA is loaded to GNPs surface, the resulted conjugates have the potential to be used in different fields such as biomedicine, materials science and especially in nano-biotechnology. Generally, the DNA loading on GNPs is performed using a salt-aging method and its incubating time takes about 24 h. Here, GNPs was replaced by porous GNPs and the incubation time for loading was reduced to 2 h without the needs for tedious salt addition process.


Assuntos
DNA/química , Ouro/química , Nanopartículas Metálicas/química , DNA/metabolismo , Ácido Nítrico/química , Polissorbatos/química , Porosidade , Eletricidade Estática
20.
Food Chem ; 299: 125172, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31325716

RESUMO

The composition of inorganic elements is a key factor in determining the quality of fruit wines. However, the use of direct sample injection is challenging for multi-elemental analysis of fruit wine samples. In this paper, an analytical method using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was established for determining multiple elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Hg, and Pb) in fruit wine. The fruit wine was diluted using ultrapure water and acidified with nitric acid before injecting into the ICP-MS/MS. Spectral interferences in the complex matrix composition of different fruit wine samples, in the MS/MS mode, were eliminated using mixed reaction gases of O2/H2 and NH3/He/H2 through the mass shift and on-mass methods. The limits of detection ranged from 0.41 to 58.1 ng L-1. This study demonstrates a new approach for multi-elemental analysis in fruit wine with great convenience and high accuracy.


Assuntos
Análise de Alimentos/métodos , Espectrometria de Massas em Tandem/métodos , Oligoelementos/análise , Vinho/análise , Amônia/química , Frutas , Gases/química , Hidrogênio/química , Ácido Nítrico/química , Oxigênio/química
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