Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.518
Filtrar
1.
Food Chem ; 336: 127709, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32763738

RESUMO

The microbiological, microstructural, and physicochemical impact of aqueous ozone mixing (AOM) on semi-dried buckwheat noodles (SBWN) was elucidated in this study. Microbiological measurements declared that AOM reduced the initial total plate count (TPC) of SBWN significantly (P < 0.05) with a prolonged shelf-life of 2 ~ 5 days. Meanwhile, AOM reduced the cooking loss and water absorption along with the enhancement of hardness and tension force. Scanning electron microscopy (SEM) showed that the protein network of surface and cross section became continuous and compact, and wrapped starch granules more effectively. Moreover, an obvious increase in the intensity of the high molecular protein bands was observed in the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) patterns. Furthermore, the sodium dodecyl sulfate extractable protein (SDSEP) under non-reducing condition obviously decreased, and then the SDSEP under reducing condition changed insignificantly (P > 0.05). These results indicated that AOM mainly promoted the protein cross-linking of SBWN by disulfide bond (SS) cross-links.


Assuntos
Fagopyrum/química , Indústria de Processamento de Alimentos/métodos , Ozônio/química , Culinária , Dissulfetos/química , Eletroforese em Gel de Poliacrilamida , Farinha/análise , Qualidade dos Alimentos , Armazenamento de Alimentos , Dureza , Microscopia Eletrônica de Varredura , Proteínas de Plantas/química , Água/química
2.
Food Chem ; 337: 127755, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777567

RESUMO

Since the beginning of the widespread use of pesticides, their removal from food has become a serious concern. In this study, the removal of residual pesticides (malathion and carbosulfan) from pak choi via treatment with ozonated water was investigated. Under the optimal treatment conditions, i.e., 2.0 mg/L ozonated water and a treatment duration of 15 min, malathion and carbosulfan were degraded by 53.0 and 33.0%, respectively, without any significant changes in color. Even though there was a slight decrease in vitamin C content (~7.9 mg/100 g) following the treatments, a significant decrease in the microbial colonies on the vegetables was observed. Additionally, the pesticide degradation mechanism showed good fitting with a "first + first"-order kinetic model (R2 > 0.9), and the slope (k) indicated that ozone had a more prominent degradation effect on malathion than on carbosulfan. Therefore, this study provides a theoretical basis for controlling agricultural pesticide residues in household applications.


Assuntos
Brassica rapa/química , Carbamatos/química , Carbamatos/isolamento & purificação , Malation/química , Malation/isolamento & purificação , Ozônio/química , Contaminação de Alimentos , Resíduos de Praguicidas/química , Resíduos de Praguicidas/isolamento & purificação , Verduras/química
3.
Chemosphere ; 262: 127969, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182096

RESUMO

Micropollutants like pharmaceuticals, hormones and pesticides are still found in treated municipal wastewater. An effective way to degrade micropollutants is to use oxidants such as ozone or hydroxyl radicals. We designed an innovative experimental protocol combining batch experiments and a study of a full-scale WWTP to understand and predict the removal via ozonation of typical micropollutants present in secondary treated effluents. First, the direct and indirect ozonation of 47 organic micropollutants was scrutinized, then a model was developed and calibrated to simulate the ozone transfers and the oxidation of the selected micropollutants. The kinetic rate constants between micropollutants and ozone or hydroxyl radicals (OH●) were determined for 47 micropollutants found in secondary treated effluent. We classified the micropollutants into low- (kO3 between 1.50 and 4.47 × 102 L mol-1. s-1), medium- (kO3 between 1.31 × 103 and 4.92 × 103 L mol-1. s-1) and high-oxidizable groups (kO3 between 9.44 × 104 and 8.18 × 106 L mol-1. s-1) according to their reactivity with ozone, and identified the major degradation pathways for all 47 micropollutants. Micropolluants of the low- and medium-oxidizable groups were largely eliminated by the indirect pathway, at 96% and 84% on average, respectively. In contrast, micropollutants of high-oxidizable group were largely eliminated by the direct pathway, at 98% on average. The model successfully simulated the direct and indirect ozonation of the 47 micropollutants in batch experiments and confirmed the predominant pathways for each group. Finally, the model was applied to the full-scale ozonation process operated at an ozone dose ranging from 0.5 to 1.6 gO3. gDOC-1. The model was found to reliably simulate the ozonation-process removal efficiencies for 4 micropollutants (imidacloprid, fenofibric acid, metronidazole and ketoprofen).


Assuntos
Oxidantes/química , Ozônio/química , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Radical Hidroxila/química , Cinética , Modelos Teóricos , Oxirredução
4.
Chemosphere ; 262: 127968, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182104

RESUMO

Electrocoagulation (EC) coupled with E-peroxone process (ECP) was a promising and cost-effective integrated technology for shale gas fracturing flowback water (SGFFW) treatment. In this study, the ECP process was comprehensively compared with two sequential processes (EC followed by E-peroxone (EC-E-peroxone) and E-peroxone followed by EC (E-peroxone-EC)) to elucidate the synergistic effect of this coupled process. In EC-E-peroxone process, COD decreased by 89.2%, while COD decreased by 82.5% for 180 min in E-peroxone-EC process. However, COD removal efficiency was 82.4% in ECP for only 90 min. Average current efficiency of the ECP process was 29.9%, which was twice than that of the sequential processes. The enhancement factor was calculated to be 1.63, demonstrating the substantial significant synergistic effects for ECP. Only low MW components could be observed for the EC-E-peroxone (average MW = 533 Da with PD ≈ 1) and ECP process (MW = 538 Da with PD ≈ 1). These results suggested that EC-E-peroxone and ECP process had much stronger oxidation ability, demonstrating the enhancement of OH production induced by the Al-based coagulants might be responsible for the significant enhancement of COD removal. These results indicated there could be a synergistic effect between EC and ozone in addition to EC and E-peroxone reactions. Compared to the two sequential processes, ECP was a high efficiency and space-saving electrochemical system with simultaneous coagulation and enhanced OH generation by the products of anode and the cathode.


Assuntos
Técnicas Eletroquímicas/métodos , Peróxido de Hidrogênio/química , Gás Natural/análise , Ozônio/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , China , Eletrodos , Floculação , Fraturamento Hidráulico , Oxirredução , Águas Residuárias/química
5.
Chemosphere ; 262: 128316, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182136

RESUMO

Resin acids in pulp and paper mills wastewater are potentially partitioned in the solids in post-primary clarification due to higher hydrophobicity with log Kow ∼1.74-5.80. They are known to adversely affect anaerobic digestion (AD) process, although the effect has not been quantified deterministically in control studies. The objective of the present work was to determine the effect of untreated and ozonated spiked resin acids on AD of primary sludge. Batch adsorption tests were conducted to determine the solid-liquid partition coefficient (Kd) of resin acids on the primary sludge. Higher Kd was obtained at pH 4; however, it was decreased by 78-98% at pH 8. Thereafter, batch AD of model resin acids in primary sludge using food to microorganism ratio (S0/X) of 0.5gtCOD/gVSSindicated only 15-20% removal of resin acids in the liquid phase anaerobically. While, ozonation in pure water using 0.74-1.48 mg O3/mg tCOD showed >90% reduction of the test resin acids, an ozone dose of 0.52 mg O3/mg tCOD reduced 50-70% spiked resin acids' load to the digester. However, no further removal of resin acids occurred during AD over 30 days. About 42% reduction in methane production compared to the control digestor occurred in the presence of 150 mg/L of resin acids. When treated with 0.52 mg O3/mg tCOD, methane production improved and was comparable to the control digestor, indicating that resin acids may not be detrimental to AD at a concentration range of 45-75 mg/L.


Assuntos
Abietanos/análise , Diterpenos/análise , Ozônio/química , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Adsorção , Anaerobiose , Cinética , Metano/análise , Resinas Vegetais/química , Águas Residuárias/química
6.
Chemosphere ; 262: 128073, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182155

RESUMO

Due to the multi-catalysis of the WO3 and excellent properties of the graphene (GO), a series of rGO-WO3 nanocomposites were prepared through the hydrothermal synthesis procedure by changing the material ratio, the reaction temperature and the reaction time in this paper, and then added it into a dielectric barrier discharge plasma (DBDP) system for investigating the bisphenol A (BPA)'s degradation and corresponding catalytic mechanism of the rGO-WO3 in the DBDP system. The obtained results show that there was an optimum dosage of the rGO-WO3 (40 mg/L) as well as the preparation conditions (5:1000 mass ratio of the GO and the WO3, 18 h reaction time and 120 °C reaction temperature) for achieving the highest catalytic effect, and the highest degradation rate constant of the BPA was 0.03129 min-1. The determined higher TOC removal, higher COD removal as well as UV-Vis analysis also demonstrated the catalysis of the rGO-WO3. The measurement of the change of the O3 and the H2O2 concentrations in the reaction system with or without the rGO-WO3 and with or without the BPA proved the catalysis of the rGO-WO3 on the ·OH formation, while the combination of the GO had the positive effect for enhancing the catalytic effect. A figure on the catalysis and degradation procedure of the BPA in the DBDP/rGO-WO3 system was provided in the paper.


Assuntos
Compostos Benzidrílicos/análise , Grafite/química , Nanocompostos/química , Óxidos/química , Fenóis/análise , Tungstênio/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Catálise , Peróxido de Hidrogênio/química , Modelos Teóricos , Oxirredução , Ozônio/química
7.
J Prev Med Hyg ; 61(3): E301-E303, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33150218

RESUMO

The new SARS-CoV-2/COVID-19 emergency has imposed new disinfection and sanitation measures of work environments also to beauty and health professional workers and in this context ozone shows growing interest. Ozone has proven to be highly effective in killing bacteria, fungi, and molds and inactivating viruses both on the surfaces and suspended in the air. Ozone is proven to be effective also for the inactivation of the SARS virus, while for the novel SARS-CoV-2 it is supposed that it be equally effective but specific studies are needed.


Assuntos
Betacoronavirus , Infecções por Coronavirus/prevenção & controle , Infecção Hospitalar/prevenção & controle , Desinfecção/métodos , Controle de Infecções/métodos , Ozônio/química , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Humanos , Raios Ultravioleta
8.
Artigo em Inglês | MEDLINE | ID: mdl-32731444

RESUMO

In order to investigate the adsorption characteristics of activated carbon fibers (ACFs) with improved surface morphologies towards volatile organic compounds (VOCs), a commercial low-grade ACF was surface modified by successive surface treatment (ST) and chemical activation (CA) process. O3 was used as an ST agent for the formation of oxygen-containing functional groups on the carbon matrix of ACFs. CA was carried out after ST, using a KOH solution. After the successive ST-CA process, Brunauer-Emmett-Teller (BET) surface area and average pore diameter of ACFs were increased from 1483 m2/g to 2743 m2/g and enlarged from 1.931 nm to 2.512 nm, respectively. The successive ST-CA process also resulted in the adsorption capacities of benzene, toluene, and xylene of the ACFs to increase from 0.22 g-Ben./g-ACFs, 0.18 g-Tol./g-ACFs, and 0.19 g-Xyl/g-ACFs up to 0.37 g-Ben./g-ACFs, 0.35 g-Tol./g-ACFs, and 0.38 g-Xyl/g-ACFs, respectively.


Assuntos
Carvão Vegetal , Gases/química , Metais Alcalinos , Ozônio/química , Adsorção , Fibra de Carbono
9.
Chemosphere ; 260: 127598, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32693258

RESUMO

Cork boiling wastewaters (CBW) are strongly coloured complex aqueous solutions with high organic load of biorecalcitrant and toxic nature. The feasibility and efficiency of a CBW treatment process combining ozonation as pre- and post-treatment of a horizontal subsurface flow constructed wetland (HSFCW) was assessed. Over an extended monitoring period of 390 days, two lab-scale HSFCW units were tested; one planted with P. australis (CWP) and one unplanted-control (CWC) operated at average organic loads rates (OLR) of 5 and 10 g COD/m2/d. CWP always outperformed the control unit. The ozonation trials were run at pH values of 8.15-8.21 and 5.39-5.45 (without adjustment) at ozone to COD ratios of 0.25-0.29 and 0.24-0.59 when implemented as pre- and post-treatment, respectively. Average removals (calculated through mass balance basis) were 78-88%, 86-91%, 71-89% and 43-89% for COD, BOD5, Total Phenols (TPh) and colour when ozonation was implemented as post-treatment. For ozonation as pre-treatment, respective figures were 77-80%, 79-92%, 78-85% and 19-73%. Regardless of the treatment scheme and OLR, ozonation was very effective in biodegradability increase (i.e., BOD5/COD) from 0.18 to 0.42 when applied as pre-treatment, and decolourization after the HSFCW increased from 21% to 91% (post-treatment) with respective ozone consumed yields of 67-69% and 72-85%. The best results were obtained for the scheme CWP + Ozonation at OLR of 5.33 g COD/m2/d with COD reductions from 1950 mg/L to 81-88 mg/L in the effluent and TPh from 125 mg/L to 5-6 mg/L at limited ozone amounts of 0.21-0.45 g O3/m2/d.


Assuntos
Ozônio/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Purificação da Água/métodos , Áreas Alagadas , Biodegradação Ambiental , Estudos de Viabilidade , Oxirredução , Casca de Planta/química , Poaceae/crescimento & desenvolvimento , Quercus/química
10.
Ecotoxicol Environ Saf ; 203: 110945, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32684517

RESUMO

The high-concentration wastewater produced in the industrial reverse osmosis (RO) process contains a large amount of refractory organic matters, which will have serious impacts on the natural environment and human health. Among them, contaminants can be transformed by humus-reducing bacteria based on humus. In this study, O3- assisted UV-Fenton method was applied as pretreatment. Biological activated carbon (BAC) technology in which humus-reducing bacteria were the dominant bacteria, enhanced by electron donor and Fe3+, was used to dispose of RO concentrate (ROC). The results showed that water treatment process combining oxidation with biological filtration had a positive effect on the removal of stubborn contaminants in ROC. The system was strengthened by adding electron donor and Fe3+, and the chemical oxygen demand (COD) removal efficiency was up to 80.1%. However, when the removal efficiency of UV254 absorbing pollutants reached optimal value (87.3%), that means only Fe3+ was added.


Assuntos
Carvão Vegetal/análise , Compostos Férricos/química , Substâncias Húmicas , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Filtração/métodos , Substâncias Húmicas/análise , Substâncias Húmicas/microbiologia , Hidrocarbonetos Halogenados/análise , Peróxido de Hidrogênio/química , Ferro/química , Osmose , Oxirredução , Ozônio/química , Raios Ultravioleta , Águas Residuárias/análise , Águas Residuárias/microbiologia
11.
J Environ Sci Health B ; 55(10): 929-939, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32715921

RESUMO

The aim of this study is to investigate the synergetic effect of ozonation on ultraviolet irradiation on the degradation of carbaryl (CBL) (1-naphthyl-N-methylcarbamate) in aqueous solutions (40 mg L-1). The degradation of CBL and the intermediates formed during ozonation were determined by gas chromatography-mass spectrometer. The change in formaldehyde, dissolved oxygen, pH, and total acidity were determined as a function of ozonation time. It was found that the dissolved oxygen and total acidity were increased with the increasing ozonation time but the pH was decreased with the increasing ozonation time. The aliphatic acids formed during ozonation were followed by ion chromatography as a function of ozonation time. It was found that the effect of ozonation is highly effective on the degradation of CBL. The complete degradation of CBL has occurred at 75-second ozonation time. As a consequence of the obtained results the possible degradation pathway was proposed. The results confirmed that ozonation is an effective method for the degradation of CBL.


Assuntos
Carbaril/análise , Inseticidas/análise , Ozônio/química , Fotólise , Raios Ultravioleta , Cromatografia Gasosa-Espectrometria de Massas
12.
Chemosphere ; 258: 127216, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535436

RESUMO

The degradation of fluopyram (FLP) was investigated under ozone-microbubble treatment (OMBT). Kinetic models were established to study the influence of three treatments: ozonated water, microbubbles (MCB), and OMBT. FLP degraded completely in OMBT, and a clearance rate of 89.8-100% was achievable. Three direct transformation products [product 1 (F1), product 2 (F2), and product 3(F3)] were isolated and identified using a hybrid ion trap-orbitrap mass spectrometer. Moreover, a transformation theory of FLP degradation was developed according to targeted fragmentation, accurate mass measurements, and degradation profiles. These analyses showed that the products originated from a series of chemical reactions involving dechlorination, hydroxyl substitution, cleavage and oxidation, and were further confirmed based on molecular electrostatic potential and molecular orbital theory. In addition, the stability and toxicity of FLP and its transformation products were tested using the Toxicity Estimation Software Tool (T.E.S.T.) and the Ecological Structure Activity Relationships (ECOSAR) program. Products F1, F2 and F3 were found to be toxic substances, but their toxicity to aquatic organisms was lower than that of FLP. However, they were more toxic to rats than FLP, and their physicochemical properties were more stable. Overall, OMBT is a highly effective method for FLP removal during wastewater treatment.


Assuntos
Benzamidas/análise , Microbolhas , Ozônio/química , Piridinas/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Animais , Organismos Aquáticos/efeitos dos fármacos , Benzamidas/toxicidade , Radical Hidroxila/química , Cinética , Dose Letal Mediana , Oxirredução , Piridinas/toxicidade , Ratos , Testes de Toxicidade Aguda , Águas Residuárias/química , Poluentes Químicos da Água/toxicidade
13.
Chemosphere ; 253: 126767, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464763

RESUMO

Herein, the potential of bimetallic MOFs in catalytic ozonation was investigated for the first time. Three novel ozonation catalysts, i.e. cobalt-based, nickel-based and cobalt/nickel-based metal-organic frameworks (Co-MOF, Ni-MOF and Co/Ni-MOF), were synthesized, characterized by XRD, SEM, N2 sorption-desorption isotherms, FTIR and XPS, and applied in catalytic ozonation for atrazine removal. It was found that the catalysts showed outstanding performance in the catalytic ozonation, especially Co/Ni-MOF which was attributed to multiple metal sites, higher coordination unsaturation, metal centers with larger electron density, and better efficiency in electron transfer than its single-metal counterparts. Under specific experimental conditions, 47.8%, 67.0%, 75.5%, and 93.9% of atrazine were removed after adsorption and degradation in the ozonation system without catalyst, and the catalytic ozonation systems with Co-MOF, Ni-MOF and Co/Ni-MOF, respectively. Higher removal rates could be achieved by growing initial pH, increasing oxidant dosage and reducing pollutant concentration, while an excess of Co/Ni-MOF was not favorable for the catalytic ozonation. Surface hydroxyl groups and acid sites were considered as the critical catalytic sites on Co/Ni-MOF. From the results of EPR tests, O2·-, 1O2 and ·OH were ascertained as the main reactive species in the degradation. It was suspected that O2·- and H2O2 played important roles in the formation of ·OH and the cycle of Co(II)/Co(III) and Ni(II)/Ni(III). Additionally, Co/Ni-MOF displayed good stability and reusability in cycling experiments, ascribed to the enhancement of the porosity and pore hydrophobicity. Finally, based on MS/MS analysis at different reaction times, major degradation pathways for atrazine were proposed.


Assuntos
Atrazina/química , Adsorção , Catálise , Cobalto/química , Transporte de Elétrons , Peróxido de Hidrogênio , Estruturas Metalorgânicas/química , Níquel/química , Oxidantes , Ozônio/química , Espectrometria de Massas em Tandem
14.
Chemosphere ; 255: 126963, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32413797

RESUMO

Coal gasification wastewater (CGW) has attracted considerable industrial attention because of its high toxicity and poor biodegradability. Ozonation is a promising process for CGW treatment. In this study, the effects of ozone concentration, pH, and ozonation time on CGW treatment were investigated. The results confirmed that CGW was degraded effectively and that the chemical oxygen demand (COD) was reduced from 1057 to 362 mgL-1, utilizing 50 mgL-1 ozone for 90 min. Further, the color of CGW changed from brown to clear and colorless, and the pH decreased from 8.5 to 4.7. Importantly, molds were observed in the oxidized CGW after 14 d at room temperature (23 ± 2 °C), indicating that CGW is significantly biodegradable by ozonation. The CGW components were extracted with three different organic solvents (chloroform, n-hexane, and benzene), and their compositions were analyzed by gas chromatography-mass spectrometry (GC-MS) before and after ozonation. The results proved that considerable amounts of highly toxic refractory compounds in CGW, such as phenolic compounds, polynuclear aromatic hydrocarbons (PAHs), and nitrogenous heterocyclic compounds (NHCs), were degraded to compounds that included olefins, carboxylic acids, and cycloalkanes, or minerals, which are relatively environmentally benign. Moreover, the number of substances in CGW decreased significantly from 127 to 74 after ozonation. Summarily, ozonation is a promising approach for the treatment of highly toxic refractory wastewater, such as CGW.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Carvão Mineral/análise , Oxirredução , Estresse Oxidativo , Ozônio/química , Fenóis/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Águas Residuárias/química
15.
Chemosphere ; 253: 126625, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32289602

RESUMO

In this study, the removal performance of a hybrid ozonation-coagulation (HOC) process using AlCl36H2O (Al-HOC) and FeCl36H2O (Fe-HOC) as coagulants for the treatment of wastewater treatment plant (WWTP) effluent and ibuprofen (IBP) was investigated. Compared with the conventional coagulation process and pre-ozonation-coagulation process, much better organic matter removal performance can be achieved for both the Al-HOC and Fe-HOC processes. The Fe-HOC process showed an obviously higher dissolved organic carbon (DOC) removal efficiency than that of the Al-HOC process. Surface hydroxyl groups were determined to be the active sites in generating OH in the HOC process, and the hydrolysed Fe species possessed a higher content of surface hydroxyl groups than the hydrolysed Al species according to fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectra (XPS) analyses. In addition, the hydrolysed Fe species contained a higher portion of tetrahedral sites that were more likely to be stronger Lewis acid sites to react with ozone to generate OH. Furthermore, peroxone reactions in the HOC process were other possible way to enhance the OH generation, and higher H2O2 generation was observed in the Fe-HOC process due to higher O2- generation. Therefore, better removal performance of the Fe-HOC process can be obtained due to the increased OH generation in the Fe-HOC process.


Assuntos
Modelos Químicos , Ozônio/química , Poluentes Químicos da Água/química , Peróxido de Hidrogênio/química , Hidrólise , Ibuprofeno/química , Espectroscopia de Infravermelho com Transformada de Fourier , Águas Residuárias , Poluentes Químicos da Água/análise , Purificação da Água/métodos
16.
Chemosphere ; 253: 126737, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302908

RESUMO

Bioaerosols have widely been a concern due to their potential harm to human health caused by the carrying and spreading of harmful microorganisms. Biofiltration has been generally used as a green and effective technology for processing VOCs. However, bioaerosols can be emitted into the atmosphere as secondary pollutants from the biofiltration process. This review presents an overview of bioaerosol emissions from gas bioreactors. The mechanism of bioaerosols production and the effect of biofiltration on bioaerosol emissions were analyzed. The results showed that the bioaerosol emission concentrations were generally exceeded 104 CFU m-3, which would damage to human health. Biomass, inlet gas velocity, moisture content, temperature, and some other factors have significant influences on bioaerosol emissions. Moreover, as a result of the analysis done herein, different inactivation technologies and microbial immobilization of bioaerosols were proposed and evaluated as a potential solution for reducing bioaerosols emissions. The purpose of this paper is to make more people realize the importance of controlling the emissions of bioaerosols in the biofiltration process and to make the treatment of VOCs by biotechnology more environmentally friendly. Additionally, the present work intends to increase people's awareness in regards to the control of bioaerosols, including microbial fragment present in bioaerosols.


Assuntos
Microbiologia do Ar/normas , Poluentes Atmosféricos/análise , Poluição do Ar/prevenção & controle , Reatores Biológicos/microbiologia , Desinfecção/métodos , Aerossóis , Poluentes Atmosféricos/efeitos da radiação , Atmosfera/química , Biomassa , Química Verde , Humanos , Peróxido de Hidrogênio/química , Oxirredução , Ozônio/química , Raios Ultravioleta
17.
Chemosphere ; 253: 126744, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302911

RESUMO

p-Coumaryl alcohol (p-CMA), as the simplest lignin precursor, was determined in the process of lignin polymer degradation and wood smoke. However, its transformation and migration in the atmosphere have not been well clarified. In this work, the gas-phase reaction mechanisms and kinetic parameters of ozone-initiated removal of p-CMA were performed by using quantum chemical calculations. Seven primary addition reaction pathways were summarized. A more comprehensive and detailed reaction routes of the favorable Criegee intermediate (IM9) were presented, including the reactions with small molecules, as well as its own isomerization and decomposition reactions. p-Hydroxybenzaldehyde (P1) is the most dominant product in the further reactions of IM9 and the subsequent ozonolysis mechanisms of P1 also were elucidated. All thermodynamic calculations were investigated on the density functional theory (DFT) method at the M06-2X/6-311 + G (3df, 2p)//M06-2X/6-311 + G (d,p) level. The overall and individual rate constants have estimated by using the KiSThelP under typical atmospheric temperature (198-338 K) and pressure. The total rate constant is 3.37 × 10-16 cm3 molecule-1 s-1 at 298 K and 1 atm. In addition, the atmospheric lifetime of p-CMA by ozone-determined is 1.18 h under the average ozone concentration of 7 × 1011 molecules cm-3. The short lifetime indicates that the degradation processes of p-CMA determined by O3 cannot be ignored, especially in areas where the tip concentration of O3 molecules is high. The present study provides a synthetical investigation on ozonolysis of p-CMA for the first time and enriches our understanding of atmospheric oxidation processes of other lignin compounds.


Assuntos
Poluentes Atmosféricos/análise , Modelos Químicos , Ozônio/química , Propionatos/análise , Atmosfera/química , Cinética , Oxirredução , Temperatura , Termodinâmica
18.
Chemosphere ; 252: 126596, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32240859

RESUMO

Minimizing bromate formation by adding H2O2 is one major option for bromide-containing source water when applying ozone in drinking water. However, difference in background water quality can have a significant influence on bromate depression. In this study, three bromide-bearing source waters (YZ, HR and HP) were selected to investigate bromate depression during the H2O2-ozonation process. The results showed that there was strong correlation between bromate formation and molecular ozone consumption during ozonation process for the three waters. Compared to YZ and HR, ozone was consumed quickly within about 10 min for HP water, inducing lower bromate formation during ozonation process. In the initial step of bromide oxidation, molecular ozone oxidation was responsible for more than 80% of oxidation, much higher than that by hydroxyl radicals. Specifically, 94% of the oxidation of bromide occurred with ozone for YZ water, which might be attributed to the low concentration of organic matter in the water. The residual molecular ozone would be a restrictive factor and affect the bromate formation significantly. For YZ and HP water, as H2O2/O3 (g/g) increased to 0.5, the ozone decomposition rate increased 61 times and 7.2 times respectively, which resulted in difference in bromate depression performance when applying H2O2. Humic acid and tyrosine in water were confirmed to have effects on bromate formation and depression after H2O2 addition. This study could elucidate the different bromate depression effects occurring in different source waters when adding H2O2, which will provide an informative guide for bromate control in drinking water treatment.


Assuntos
Bromatos/química , Peróxido de Hidrogênio/química , Ozônio/química , Poluentes Químicos da Água/química , Animais , Brometos , Transtorno Depressivo , Substâncias Húmicas , Radical Hidroxila , Oxirredução , Tardígrados , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Qualidade da Água
19.
Ecotoxicol Environ Saf ; 196: 110547, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32244119

RESUMO

Large molecular weight pig biogas slurry (L-PBS) and small molecular weight pig biogas slurry (S-PBS) were separated from original pig biogas slurry (O-PBS) using a 100 kDa membrane. The original bioavailability and biosafety of L-PBS was very low. In order to enhance the total bioavailable dissolved organic nitrogen (TB-DON) and total bioavailable dissolved organic phosphorus (TB-DOP), optimum catalytic ozonation of L-PBS conditions were determined using Box-behnken design models (P < 0.0001) and intersection tests. The optimal values for ozone concentration, pH value, active catalyst concentration and reaction time were 2.63 mg·L-1, 6.48, 1.43 g·L-1 and 40 min, respectively. Catalytic ozonation can effectively decompose and transform 68.07% of L-PBS into S-PBS to improve content organic bioavailability, with a molecular weight distribution of 0-1 kDa (13.53%), 1-5 kDa (16.62%), 5-10 kDa (11.16%), 10-30 kDa (11.73%), 30-100 kDa (15.04%). Catalytic ozonation of L-PBS can reduce protein levels from 85.28% to 47.18%, but increases the proportion of fulvic and humic components from 10.22% to 32.67% and 4.51%-20.15%, respectively. Because catalytic ozonation changes the internal components and molecular weights of L-PBS, both saw increases in TB-DON and TB-DOP from 3.33% to 41.12% and 2.43%-37.88%, respectively, with a large number of TB-DON and TB-DOP derived from hydrophilic organic components during catalytic ozonation. These important internal mechanisms changed by catalytic ozonation can effectively reduce the ecotoxicity (IR, from 76.5% to 33.1%) and phytotoxicity (GI, enhanced from 35.4% to 70.3%) of L-PBS. Therefore, catalytic ozonation combined with membrane separation is a choice technology in improving the nutrition of biogas slurry and reduce its ecological risk.


Assuntos
Biocombustíveis , Ozônio/química , Animais , Catálise , Peso Molecular , Nitrogênio/análise , Fósforo/análise , Suínos
20.
Chemosphere ; 250: 126283, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32120148

RESUMO

On 3rd to May 24, 2018, volatile organic compound (VOC) samples were collected four times a day by using stainless steel canisters at an urban site in Zhengzhou, China. The concentrations, compositions, sources, ozone (O3) formation potential (OFP), and health risk assessment of VOCs were discussed based on the measurements of 103 VOC species. Results show that the average mixing ratio of VOCs was 29.11 ± 15.33 ppbv, and the dominant components comprised oxygenated VOCs (OVOCs) and alkanes, followed by halocarbons, alkenes, aromatics, and a sulfide. Various groups of VOCs had typical diurnal variation characteristics. Alkenes, alkanes, and aromatics contributed most to the OFP. Five sources identified by the positive matrix factorization model revealed solvent utilization as the largest contributor, followed by industrial production, long-lived and secondary species, vehicular emission, and biogenic emission. Solvent utilization and vehicular emission were important sources to OFP. During O3 episode days, the mixing ratios of alkanes, alkenes, halocarbons, OVOCs, aromatics, and TVOCs decreased to varying degrees; the source contribution of solvent utilization decreased significantly while industrial production showed the opposite trend. VOC species and sources posed no non-carcinogenic risk while five species and all sources except for biogenic emission had carcinogenic risks to exposed population. Industrial emission was the largest contributor to both non-carcinogenic and carcinogenic risks. These results will help to provide some references for O3 pollution research and prevention and control of pollution sources.


Assuntos
Monitoramento Ambiental/métodos , Ozônio/toxicidade , Saúde da População Urbana/normas , Compostos Orgânicos Voláteis/análise , Poluentes Atmosféricos/análise , Alcanos/análise , China , Humanos , Ozônio/análise , Ozônio/química , Medição de Risco
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA