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1.
Chemosphere ; 287(Pt 2): 132156, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34826898

RESUMO

In the recent decades, due to rapid increase in industrialization, urbanization, anthropogenic activity in the catchments, removal of heavy metals contaminants in wastewater has become global challenges. Numerous advance technologies have been introduced to deal with these problems but failed in reducing adequate pollution load in the contaminated water and/or wastewater. In this study, sulfur-ferromagnetic nanoparticles (SFMNs) were synthesized by modification of nano-Fe3O4, which can be rapidly separated from the environment by an external magnetic field after in situ repair. Its structure and physical properties were characterized by conventional techniques included Transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The ability of the SFMNs to remove Pb2+ and Cd2+ was studied at different temperatures and initial metal ions concentrations. The adsorption kinetics showed that the adsorption equilibrium time of Pb2+ and Cd2+ was 300 min consequently adsorption process of SFMNs fit well (R2 > 0.99) with pseudo-second-order model. The adsorption thermodynamics showed that the adsorption of Pb2+ and Cd2+ on SFMNs is spontaneous (negative value of ΔG0) endothermic process (positive value of ΔH0) and fit well (R2 > 0.98) with the Langmuir isothermal model. Density functional theory (DFT) calculations show that SFMNs can transfer electrons to Pb2+ and Cd2+, and the metal ions form stable chelates on the ligand surface. This study implies that newly synthesized sulfur-ferromagnetic nanoparticles could play an instrumental role in metal ions removal from water and wastewater.


Assuntos
Nanopartículas , Poluentes Químicos da Água , Cádmio , Chumbo , Enxofre , Águas Residuárias , Poluentes Químicos da Água/análise
2.
Chemosphere ; 287(Pt 2): 132210, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34826912

RESUMO

Volatile sulfur compounds (VSCs) are important sources of unpleasant odours in biosolid emissions. However, the study of VSCs may be limited by complications in their gas phase measurements due to reactivity, transformations and varying reported odour detection thresholds. A range of methods were used to quantitatively analyse VSCs in wastewater biosolid emissions. VSCs were identified in aged biosolid emissions by gas chromatography (GC) with a sulfur chemiluminescence detector (SCD) and mass spectrometry coupled with olfactory detection port (MS/O). In total, 10 VSC's were identified with two volatile organic sulfur compounds (VOSCs), allyl methyl sulfide and methyl propyl sulfide being reported for the first time in biosolid emissions. The emission patterns of different VSCs varied as the biosolids aged. Initially, the median concentrations of H2S, dimethyl sulfide (DMS), dimethyl trisulfide (DMTS), methanethiol (MeSH) and ethanethiol (EtSH) were orders of magnitude greater than their reported odour detection threshold, suggesting they would contribute to the odorous impact of the biosolids. The maximum H2S value was equal to 59.9 × 103 µg/m3 and was at least one magnitude higher compared to VOSCs, such as dimethyl disulfide (DMDS) (3.8×103 µg/m3), DMS (4.53 × 103 µg/m3), EtSH (2.83 × 103 µg/m3) and MeSH (3.25 × 103 µg/m3). Among the identified VSCs, H2S was the prominent odorant in terms of the magnitude and the frequency of detection, both initially as well as throughout storage. However, DMTS should be considered as a high priority or key odorant due to its odour activity value (OAV) and frequency of detection (sensorially detected in more than 75% of samples, with an OAVs higher than 1).


Assuntos
Odorantes , Compostos Orgânicos Voláteis , Biossólidos , Cromatografia Gasosa-Espectrometria de Massas , Odorantes/análise , Enxofre , Compostos de Enxofre/análise , Compostos Orgânicos Voláteis/análise , Águas Residuárias
3.
Chemosphere ; 287(Pt 1): 131998, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34450373

RESUMO

The sulfur-based autotrophic denitrification (SAD) and the solid organic carbon-based denitrification processes are both efficient techniques to remove nitrate from wastewater, and the hydrogen ions generated by the SAD process would be consumed in the heterotrophic denitrification process. Therefore, it is possible to improve the denitrification capacity when the solid organic carbon was added into a SAD reactor. In this study, corncob powder and sawdust powder were selected as solid organic carbon sources, and the sulfur-based autotrophic denitrification integrated biomass-based heterotrophic denitrification system was formed (SBD). The laboratory and field experiments showed that SBD could shorten the start-up period, decrease the sulfate productivity, and maintain a good denitrification performance when treated wastewater. According to the field experiment results, when the HRT was 1 h, the effluent total nitrogen (TN) concentration was always lower than 15 mg L-1. In addition, nitrite inhibition was observed when the concentration of nitrite in the reactors reached above 30 mg L-1. The mixture of elemental sulfur powder, shell powder, corncob powder, and sawdust powder with a mass ratio of 6:2:1:1 was the optimal filter for the SBD system, with an average nitrate reduction rate (NAR) of 420 mg NO3-N·L-1·d-1 obtained at the end of the study. During the whole operation, the major autotrophs in the SBD systems were Thermomonas, Ferritrophicum, and Thiobacillus, while the major heterotrophs were Saprospiraceae, Ferruginibacter, Dokdonella, and Simplicispira. Overall, the SBD system was a feasible and practically favorable way to remove nitrate from wastewater.


Assuntos
Desnitrificação , Águas Residuárias , Processos Autotróficos , Biomassa , Reatores Biológicos , Estudos de Viabilidade , Nitratos , Nitrogênio , Enxofre
4.
Chemosphere ; 287(Pt 1): 131975, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34454228

RESUMO

Autotrophic denitrification with biosulfur (ADBIOS) provides a sustainable technological solution for biological nitrogen removal from wastewater driven by biogenic S0, derived from biogas desulfurization. In this study, the effect of different biofilm carriers (conventional AnoxK™ 1 and Z-200 with a pre-defined maximum biofilm thickness) on ADBIOS performance and microbiomics was investigated in duplicate moving bed-biofilm reactors (MBBRs). The MBBRs were operated parallelly in continuous mode for 309 days, whilst gradually decreasing the hydraulic retention time (HRT) from 72 to 21 h, and biosulfur was either pumped in suspension (days 92-223) or supplied in powder form. Highest nitrate removal rates were approximately 225 (±11) mg/L·d and 180 (±7) mg NO3--N/L·d in the MBBRs operated with K1 and Z-200 carriers, respectively. Despite having the same protected surface area for biofilm development in each MBBR, the biomass attached onto the K1 carrier was 4.8-fold more than that on the Z-200 carrier, with part of the biogenic S0 kept in the biofilm. The microbial communities of K1 and Z-200 biofilms could also be considered similar at cDNA level in terms of abundance (R = 0.953 with p = 0.042). A relatively stable microbial community was formed on K1 carriers, while the active portion of the microbial community varied significantly over time in the MBBRs using Z-200 carriers.


Assuntos
Desnitrificação , Microbiota , Biofilmes , Reatores Biológicos , Nitrogênio , Enxofre , Eliminação de Resíduos Líquidos , Águas Residuárias/análise
5.
Chemosphere ; 287(Pt 1): 131982, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34461339

RESUMO

Advanced oxidation is a very efficient method in wastewater treatment, but it is a waste of resources to directly oxide the high concentration of valuable organics into carbon dioxide and water. In this paper, the combination of persulfate and wet air oxidation was developed to recover organics from high concentration of wastewater, along with high mineralization of the residual organics. Nitrogen and sulfur co-doped hollow spherical polymers with narrow size distribution was recovered from the simulated benzothialzole (BTH) wastewater in this facile way, along with chemical oxygen demand (COD) removal rate higher than 90%. The formation route of the polymers was intensively studied based on detailed analysis of different kinds of reaction intermediates. The polymers can be further carbonized into co-doped hollow carbon microsphere, which showed better performance in organic contaminants removal than a commercial activated carbon both in adsorption or catalytic persulfate oxidation. This proposed a new strategy to simultaneously combine oxidation and polymerization for resource recovery from wastewater with high concentration of heterocyclic compounds.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Benzotiazóis , Microesferas , Nitrogênio , Oxirredução , Polímeros , Enxofre , Eliminação de Resíduos Líquidos , Águas Residuárias
6.
Food Chem ; 372: 131142, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34600193

RESUMO

To determine the glutathione (GSH) content in vegetables, an "on-off-on" fluorescence probe was developed by a synthesis of nitrogen and sulfur co-doped carbon dots (N,S-CDs) using the microwave pyrolysis considering citric acid and L-cysteine as precursors. The fluorescence of N,S-CDs was quenched by adding Cu2+ at a concentration of 20-200 µmol/L due to the inner filter effect. The quenched fluorescence of N,S-CDs@Cu2+ system was recovered by adding the GSH at a concentration of 10-150 µmol/L due to the sulfhydryl-metal compound mechanism. By observing the GSH concentrations measured by our N,S-CDs@Cu2+ system vs. a traditional fluorescent chelating method, the two measurements provided the GSH data with a good consistence by showing the RSD range of 1.86%-2.27%. This indicates the validation and novelty of our N,S-CDs@Cu2+ system as being a powerful fluorescent probe for effectively and efficiently determining the GSH in vegetables.


Assuntos
Glutationa , Pontos Quânticos , Carbono , Corantes Fluorescentes , Nitrogênio , Espectrometria de Fluorescência , Enxofre , Verduras
7.
Bioresour Technol ; 343: 126107, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34637910

RESUMO

High light is beneficial for purple non-sulfur bacteria (PNSB) growth. However, excessive light causes photoinhibition. In this novel study, flashing light was used to alleviate photoinhibition and promote biomass growth in PNSB wastewater treatment. Results showed that flashing light effectively increased biomass production. The highest biomass concentration (2688.8 mg/L) and chemical oxygen demand removal (in 177 µmol/m2/s-0.75 duty cycle-1000 Hz group) were 41.5% and 28.4% higher than that in the constant stress light group (same incident light). This group also increased biomass concentration by 21.3% and reduced energy consumption by 26.2% compared with the constant normal light group (same energy input). The shortened single light provision time of flashing light increased the relative electron transportation rate by 116.6%, avoiding photoinhibition, promoting energy utilisation, and enhancing substance synthesis. Flashing light can be used as a light regulation strategy to enhance biomass accumulation and reduce energy consumption in PNSB-based industries.


Assuntos
Proteobactérias , Purificação da Água , Análise da Demanda Biológica de Oxigênio , Biomassa , Luz , Enxofre
8.
Bioresour Technol ; 343: 126108, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34637911

RESUMO

Types of microbial aggregates have essential effects on bacterial communities' characteristics, thus affecting the pollutants removal. An up-flow biofilm reactor was used to study the different performances of S2-/NO2- removal and functional genes in suspended sludge and biofilms. The metabolic pathways of sulfurous and nitrogenous pollutants in the desulfurization-denitrification process were proposed. The results showed that S0 formation dominated the reactor with a high S2- concentration. Autotrophic Sulfurovum responsible for S2-/S0 oxidation was the only dominant bacteria in suspended sludge. Heterotrophic Desulfocapsa responsible for SO42- reduction coexisted with Sulfurovum and dominated in biofilms. S2- oxidation to S0 was catalyzed via fccA/B and sqr genes in suspended sludge. S32-/S0 oxidation to SO42- was catalyzed via dsrA/B gene in biofilms. SO42- and NO2- were removed via the dissimilatory sulfate reduction and denitrification pathway, respectively. This work provides a fundamental and practical basis for optimizing suspended sludge/biofilm systems for S2-/NO2- removal.


Assuntos
Desnitrificação , Esgotos , Bactérias/genética , Biofilmes , Reatores Biológicos , Nitrogênio , Enxofre
9.
Bioresour Technol ; 343: 125896, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34649059

RESUMO

This study for the first time bioreduced Te(IV) using elemental sulfur (S0) as electron donor, achieving 91.17%±0.8% conversion with reaction rate of 0.77 ± 0.01 mg/L/h in a 60-day cultivation. Characterization using X-ray photoelectron spectroscopy and X-ray power diffraction analyses confirmed that most removed Te(IV) was reduced to elemental Te(0) deposits, while ion chromatogram analysis showed that most S(0) was oxidized to sulfite and sulfate. High-throughput 16S rRNA gene sequencing indicated that the Te(IV) reduction coupled to S(0) oxidation was mediated synergistically by a microbial consortia with S(0)-oxidizing bacteria (Thiobacillus) to generate volatile fatty acids as metabolites and Te(IV)-reducing bacteria (Rhodobacter) to consume formed volatile fatty acids to yield Te(0). The synergy between these two strains presents a novel bioremediation consortium to efficiently treat Te(IV) wastewaters.


Assuntos
Elétrons , Enxofre , Oxirredução , RNA Ribossômico 16S/genética , Sulfatos
10.
Environ Pollut ; 292(Pt B): 118378, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34656685

RESUMO

The deposition of reactive nitrogen and sulphur has profound effects on ecosystem functioning. In the last decades, monitoring networks providing high resolution spatio-temporal deposition estimates have been set up, but equivalent information on historic deposition is mostly missing. However, understanding vegetation change and mitigate future loss of biodiversity and ecosystem functioning is only possible evaluating the effects of its strongest drivers, which includes deposition in many ecosystems. Here, we combine different data sources to provide estimates of historic deposition in forested ecosystems on a high spatio-temporal scale for a federal state in Central Germany from 1880 to present. We make use of data from field measurement stations together with elevation and precipitation data from the last three decades to build a simple deposition model, validate this model with a model publicly available covering the time range from 2000 to present, and extrapolate deposition from this joint model to the past using European deposition trends from the last 150 years. Our approach can easily be adapted to other data and spatial areas shows how to use raw deposition data together with publicly available data on elevation and precipitation to construct simple deposition models covering recent and historic times in areas and for times for which no data are available.


Assuntos
Ecossistema , Nitrogênio , Biodiversidade , Monitoramento Ambiental , Florestas , Nitrogênio/análise , Enxofre/análise
11.
Environ Pollut ; 292(Pt B): 118399, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34695515

RESUMO

Evidence suggests that the invasion of Spartina alterniflora (S. alterniflora) poses potentially serious risks to the stability of coastal wetlands, an ecosystem that is extremely vulnerable to both biological and non-biological threats. However, the effects and mechanisms of sulfur (S) in mediating the growth and expansion of S. alterniflora are poorly understood, particularly when sediments are contaminated with cadmium (Cd). A 6-month greenhouse study was conducted to evaluate the mediating effect of S on Cd tolerance and growth of S. alterniflora. Treatments consisted of a factorial combination of three S rates (applied as Na2SO4; 0, 500, 1000 mg kg-1 dry weight (DW), as S0, S500, and S1000) and four Cd rates (applied as CdCl2; 0, 1, 2, 4 mg kg-1 DW, as Cd0, Cd1, Cd2, and Cd4). Results showed that although the exogenous S supply obviously increased Cd accumulation in roots (up to 71.22 ± 6.43 mg kg-1 DW) due to the decrease of Fe concentration in iron plaque (down to 4.02 ± 1.18 mg g-1 DW), biomass reduction and oxidative stress in plant tissues were significantly alleviated. The addition of S significantly up-regulated the concentration of compounds related to Cd tolerance, including proline and glutathione. Therefore, the translocation of Cd was restricted, and plant growth was not impacted. The present study demonstrated that the exogenous sulfur supply could promote the growth of S. alterniflora and enhance its tolerance to Cd. Therefore, under the effects of S. alterniflora, the increased fluctuations of S pool caused by the release and deposition of S might further exacerbate S. alterniflora expansion in Cd contaminated coastal wetlands.


Assuntos
Cádmio , Áreas Alagadas , Cádmio/toxicidade , China , Ecossistema , Espécies Introduzidas , Poaceae , Enxofre
12.
Environ Pollut ; 292(Pt B): 118478, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34752789

RESUMO

Laboratory experiments and point observations, for instance in wetlands, have shown evidence that microbial sulfate reduction (MSR) can lower sulfate and toxic metal concentrations in acid mine drainage (AMD). We here hypothesize that MSR can impact the fate of AMD in entire catchments. To test this, we developed a sulfur isotope fractionation and mass-balance method, and applied it at multiple locations in the catchment of an abandoned copper mine (Nautanen, northern Sweden). Results showed that MSR caused considerable, catchment-scale immobilization of sulfur corresponding to a retention of 27 ± 15% under unfrozen conditions in the summer season, with local values ranging between 13 ± 10% and 53 ± 18%. Present evidence of extensive MSR in Nautanen, together with previous evidence of local MSR occurring under many different conditions, suggest that field-scale MSR is most likely important also at other AMD sites, where retention of AMD may be enhanced through nature-based solutions. More generally, the developed isotope fractionation analysis scheme provides a relatively simple tool for quantification of spatio-temporal trends in MSR, answering to the emerging need of pollution control from cumulative anthropogenic pressures in the landscape, where strategies taking advantage of MSR can provide viable options.


Assuntos
Mineração , Sulfatos , Ácidos , Enxofre , Isótopos de Enxofre/análise
13.
Food Chem ; 371: 131123, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34555706

RESUMO

The anabolism of aroma volatiles in response to non-biological factors during the drying process of shiitake mushrooms was analyzed. Temperatures (40 °C, 50 °C, and 60 °C) had secondary activation effects on the synthetase activity. The enzymatic reaction time could last 4-5 h under medium-temperature drying process (40 °C and 50 °C), and 1.5-2 h under a high-temperature drying process (60 °C and 70 °C). The aroma synthesis dominated by non-enzymatic reactions were chemical reactions between amino acids and reducing sugars. The hot-air drying process of shiitake mushroom was consistent with the cubic model and the key control points influencing the enzymatic reaction parameters were in the order of moisture rate > temperature > drying time > drying rate. The non-enzymatic reaction parameters were in the order of temperature > drying time > drying rate > moisture rate. The total sulfur volatiles produced in the optimized process were significantly higher, and the drying time of the process could be completed within 6 h.


Assuntos
Cogumelos Shiitake , Dessecação , Conservação de Alimentos , Odorantes/análise , Enxofre
14.
Chemosphere ; 287(Pt 2): 132149, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34496337

RESUMO

Electrotrophic denitrification is a promising novel nitrogen removal technique. In this study, the performance and the mechanism of electrotrophic denitrification coupled with sulfate-sulfide cycle were investigated under different anodic influent COD/SO42- ratios. The results showed that electrotrophic denitrification contributed to more than 22% total nitrogen removal in cathode chamber. Higher COD/SO42- ratios would deteriorate the sulfate reduction but enhance methane production. Further mass balance indicated that the electron flow utilized by methanogenic archaea (MA) increased while that utilized by sulfate-reducing bacteria (SRB) decreased as the COD/SO42- ratio increased from 0.44 to 1.11. However, higher COD/SO42- ratios would produce more electrons to strengthen electrotrophic denitrification. Microbial community analysis showed that the biocathode was predominantly covered by Thiobacillus that encoded with narG gene. These findings collectively suggest that electrotrophic denitrification could be a sustainable approach to simultaneously remove COD and nitrogen under suitable COD/SO42- ratio based on sulfur cycle in wastewater.


Assuntos
Reatores Biológicos , Desnitrificação , Nitrogênio , Sulfatos , Enxofre , Águas Residuárias
15.
Spectrochim Acta A Mol Biomol Spectrosc ; 265: 120365, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34509893

RESUMO

Sulfur quantum dots (S-dots) show great potential for applications in various field, due to their favorable biocompatibility, high stability, and antibacterial properties. However, the use of S-dots in chemical sensing is limited by the lack of functional groups on the surface. In this work, a fluorescence glutathione (GSH) assay is developed based on the GSH modulated quenching effect of Cu2O nanoparticles (NP) on S-dots. The fluorescence of S-dots is effectively quenched after forming complex with Cu2O NP through a static quenching effect (SQE). Introducing of GSH can trigger the decomposition of Cu2O NP into GSH-Cu(I) complex, which leads to the weaken of SQE and the partial recover of the fluorescence. The intensity of recovered fluorescence shows a positive correlation with the concentration of GSH in the concentration range of 20 to 500 µM. The fluorescence GSH assay shows excellent selectivity and robustness towards various interferences and high concentration salt, which endow the successful detection of GSH in human blood sample. The presented results provide a new door for the design of fluorescence assays, which also provides a platform for the applications in nanomedicine and environmental science.


Assuntos
Cobre , Nanopartículas , Pontos Quânticos , Corantes Fluorescentes , Glutationa , Humanos , Limite de Detecção , Enxofre
16.
Sci Total Environ ; 802: 149780, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34461478

RESUMO

In order to evaluate the potential risk of surface water acidification in regions with historically-elevated acid deposition and to measure the recovery of such ecosystems after policy changes, critical loads and their exceedances were estimated for 349 headwater streams across China using a modified SSWC model. Such a model considered the acid-neutralizing capacity derived from high base cation deposition and the robust retention of sulfate and nitrate. Results indicated that China's streams had higher critical loads (averaged at 4.7 keq·ha-1·yr-1) and were less sensitive to acid deposition as compared to Europe and North America. The proportion of surveyed streams with acid deposition exceeded critical load decreased from 40.4% in 2005 to 29.5% in 2018, indicating a significant decrease in risk of surface water acidification, and thus a benefit from the emission abatement in recent years. Nonetheless, a relatively high risk of acidification still existed in southeast China with lower critical loads and most critical load exceedances. More efforts should be put into implementing emission control policies in the future.


Assuntos
Ecossistema , Rios , China , Monitoramento Ambiental , Água Doce , Sulfatos , Enxofre/análise
17.
J Colloid Interface Sci ; 605: 129-137, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34311307

RESUMO

Lithium-sulfur (Li-S) batteries are greatly expected to be the favored alternatives in the next-generation energy-storage technologies due to their exceptional advantages. However, the shuttle effect and sluggish reaction kinetics of polysulfides largely hamper the practical success of Li-S batteries. Herein, a unique iron carbide (Fe3C) nanoparticles-embedded porous biomass-derived carbon (Fe3C-PBC) is reported as the excellent immobilizer and promoter for polysulfides regulation. Such a distinctive composite strongly couples the vast active sites of Fe3C nanoparticles and the conductive network of porous biomass-derived carbon. Therefore, Fe3C-PBC is endowed with outstanding adsorptivity and catalytic effect toward inhibiting the shuttle effect and facilitating the redox kinetics of polysulfides, demonstrated by the detailed experimental demonstrations and theoretical calculation. With these synergistic effects, the Fe3C-PBC/S electrode embraces a superb capacity retention of 82.7% at 2C over 500 cycles and an excellent areal capacity of 4.81 mAh cm-2 under the high-sulfur loading of 5.2 mg cm-2. This work will inspire the design of advanced hosts based on biomass materials for polysulfides regulation in pursuing the superior Li-S batteries.


Assuntos
Lítio , Nanopartículas , Biomassa , Carbono , Compostos Inorgânicos de Carbono , Compostos de Ferro , Porosidade , Sulfetos , Enxofre
18.
Food Chem ; 366: 130613, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34304136

RESUMO

A colorimetric and fluorescence dual-signal method based on sulfur quantum dots (SQDs) was established for determination of iron (II) (Fe2+) and H2O2 in foods. Due to the complexation of Fe2+ with SQD, Fe2+ can cause fluorescence quenching of SQDs, and the color of the mixed solution changed from light yellow to deep green. By use of Fenton reaction, H2O2 can restore the quenched fluorescence of SQDs, and the color of the mixture changed from green to colorless. The concentration of Fe2+ and H2O2 has a good linear relationship with the fluorescence intensity and absorbance in the range of 2.5-55 µM and 1.25-500 µM, and the detection limits were 1.41 µM and 0.54 µM, respectively. For determination of H2O2, the linear ranges were 1.17-1.97 mM and 0.867-1.50 mM, and the detection limits were 0.03 µM and 0.06 µM, respectively.


Assuntos
Pontos Quânticos , Colorimetria , Peróxido de Hidrogênio , Ferro , Enxofre
19.
Food Chem ; 367: 130741, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34399272

RESUMO

Volatile sulfur-containing compounds (VSCs) provide an important contribution to foods due to their special odors. In this study, VSCs in 21 cold-pressed rapeseed oils (CROs) from 9 regions in China were extracted and separated by headspace solid-phase microextraction combined with gas chromatography coupled with sulfur chemiluminescence detection. 19 VSCs were identified by authentic standards, and the total concentration of VSCs in all CROs ranged from 49.0 to 18129 µg/kg. Dimethyl sulfide (DMS), with its high odor activity value (7-14574), was the most significant aroma contributor to the CROs. Furthermore, S-methylmethionine (SMM) in rapeseed was first affirmed by ultra-performance liquid chromatography-tandem mass spectrometry and isotope quantitation. The positive correlation coefficient between DMS and SMM was 0.793 (p < 0.05), which confirmed SMM as a crucial precursor of DMS in CROs. This study provided a theoretical basis for selecting rapeseed materials by the distribution of essential VSCs and the source of DMS.


Assuntos
Compostos de Enxofre , Compostos Orgânicos Voláteis , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Cromatografia Gasosa-Espectrometria de Massas , Odorantes/análise , Óleo de Brassica napus , Sulfetos , Enxofre , Compostos de Enxofre/análise , Espectrometria de Massas em Tandem , Compostos Orgânicos Voláteis/análise
20.
Chemosphere ; 286(Pt 1): 131599, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34315084

RESUMO

In this study, 11 low/uncontaminated (including Lufa 2.2) and 9 contaminated field soils with varying geophysical and physicochemical characteristics were evaluated for toxicities based on oxygen consumption of sulfur-oxidizing bacteria (SOB). Oxygen consumption of the low/uncontaminated soils ranged between 7.9 mL and 9.5 mL, while contaminated soils ranged between 0.4 mL and 5.4 mL. Inherent test variability (CVi), variation due to soil natural properties (CVns) and minimal detectable difference (MDD) values ranged 1.2%-3.9%, 3.5%-16.9%, and 2.1%-4.3%, respectively. The toxicity threshold of 20% was established for soil toxicity based maximal tolerable inhibition (MTI). All the contaminated soils were found to be toxic and showed inhibition between 42% and 100% above the 20% threshold value. Increased proportions of clay and slit enhanced the of inhibitory effect of contaminants on SOB by reducing the oxygen consumption. Current study provides a suitable method for the rapid toxicity assessment of contaminated field soils with the advantages of ease of handling and rapidity without employing elutriates and sophisticated equipments and tools.


Assuntos
Poluentes do Solo , Solo , Bactérias , Bioensaio , Oxirredução , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Enxofre/toxicidade
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