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1.
Artigo em Inglês | MEDLINE | ID: mdl-38861065

RESUMO

Highly active catalysts with salt and acid/alkali resistance are desired in peroxymonosulfate (PMS) activation processes and marine environment applications. F- and Cl-doped graphene (F-GN and Cl-GN) were prepared via electronegative and atom radius adjustment for tetracycline hydrochloride (TCH) pollution removal to satisfy these requirements. The introduction of special F and Cl functionalities into graphene exhibits superior electron transfer properties for PMS activation, considering the experimental and density functional theory (DFT) calculation results. The TCH degradation efficiency reached up to 80% under various pH and salt disturbance conditions with F-GN and Cl-GN. Cl-GN exhibited an activity superior to F-GN due to the higher electron polarization effect of C atoms adjacent to Cl atoms. The presence of more positive charged C sites in Cl-GN (around Cl doping) is more favorable for PMS attachment and sequence radical generation than F-GN. In addition, the main active species functionalized during reaction included ·OH and SO4-·, and the stability of F-GN and Cl-GN was confirmed to be over 60% by recycle test. Final research results provide an effective strategy for designing and preparing PMS activators resistant to salt, acid, and alkali, thereby expanding their application potential.

2.
Bioresour Technol ; 403: 130883, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38788807

RESUMO

Electrodes with superior stability and sensitivity are highly desirable in advancing the toxicity detection efficiency of microbial fuel cells (MFCs). Herein, boron-doped reduced graphene oxide (B-rGO) was synthesized and utilized as an efficient cathode candidate in an MFCs system for sensitive sodium dodecylbenzene sulfonate (SDBS) detection. Boron doping introduces additional defects and improves the dispersibility and oxygen permeability, thereby enhancing the oxygen reduction reaction (ORR) efficiency. The B-rGO-based cathode has demonstrated significantly improved output voltage and power density, marking improvements of 75 % and 58 % over their undoped counterparts, respectively. Furthermore, it also exhibited remarkable linear sensitivity to SDBS concentrations across a broad range (0.2-15 mg/L). Notably, the cathode maintained excellent stability within the test range and showed significant reversibility for SDBS concentrations between 0.2 and 3 mg/L. The highly sensitive and stable B-rGO-based cathode is inspiring for developing more practical and cost-effective toxicant sensing devices.


Assuntos
Fontes de Energia Bioelétrica , Boro , Eletrodos , Grafite , Grafite/química , Boro/química , Benzenossulfonatos/química , Oxirredução , Óxidos/química
3.
J Colloid Interface Sci ; 663: 358-368, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38412721

RESUMO

Ligand functionalization is an effective way to endow Metal-organic frameworks (MOF) with versatility for multiple applications by introducing or displaying substituents without changing the origin framework. In this work, the original MIL-101(Fe) was modified by functional groups, including -NH2, -NO2, -CH3, and -Cl substituents. The Bader charge results and electron localization function (ELF) quantitatively indicated that the functional ligands with different properties can regulate the electron structure of transition-metal centers through interface-charge redistribution. Accompanying the higher adsorption and utilization rate of peroxymonosulfate (PMS), more than 96% of acetaminophen (APAP) was degraded with a mineralization rate of 40.17% under the NH2-BDC/PMS system. In terms of mechanism, the amino group not only accelerated the regeneration of Fe(II) via the NCFe electron-transfer path, but also stimulated the appearance of high-valent Fe species. Meanwhile, the degradation pathways of APAP were proposed by integrating the results of liquid chromatograph-mass spectrometry (LC-MS) and Frontier molecular-orbital theory. Finally, the NH2-BDC/PMS system reveals long-term stability, nonselectivity, low biotoxicity as well as secondary pollution for pollutant degradation, which is a considered candidate for further environmental applications.

4.
Chemosphere ; 349: 140849, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38043619

RESUMO

As a hot candidate for marine pollution control, electrocatalytic oxidation strongly depends on the characteristics of anode materials. Even though emerging 2D metal-organic frameworks (2D-MOFs)/graphene oxide (GO) complex has satisfied the conductive and tunable requirements of anode, electrocatalytic efficiency still needs to be improved by maximizing the electron carriers or shuttles. Herein, we capitalized upon crosslinking heteroatoms as pointcut to adjust the electron distribution, mobility, and transfer orientation in 2D-MOFs/GO. As a result, Ni3(BHT)2/2GO (metal centers: Ni; crosslinking heteroatoms: S), which was much higher than materials with metal centers of Cu or crosslinking heteroatoms of N, achieved superior conductivity and 100% tetracycline hydrochloride removal within 12 min. In Ni3(BHT)2/2GO, Ni ions and S atoms cooperated as electron shutters rather than isolated active center and granted accelerated electron transfer from 2D-MOFs to GO layers. Furthermore, Ni sites and S crosslinking heteroatoms exhibited superior activity for ⋅O2- and ⋅OH generation, whereas 1O2 depended more on C and O substrates. All experiments, theory calculations, and application expanding approved the practice feasibility of 2D-MOFs/GO in electrocatalytic oxidation by adjusting crosslinking heteroatoms. All these results provided new perspectives on the micro-molecular regulation for improving electrocatalytic efficiency.


Assuntos
Estruturas Metalorgânicas , Tetraciclina , Elétrons , Oxirredução , Transporte de Elétrons , Íons
5.
Environ Sci Pollut Res Int ; 30(52): 112252-112266, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37831265

RESUMO

Cu and graphene oxide composites (Cu-GO) were designed by anchoring Cu+ via oxygen groups in GO based on the heavy co-relationships of copper (Cu) anode electrocatalytic activity with Cu valence state. With the consumption of oxygen groups under various pyrolysis temperatures, the Cu valence state changed from Cu ions (as CuCl2 and CuCl) to Cu oxide (CuO and Cu2O) and the final metallic Cu. In which the Cu+ in CuCl was more favorable for electrocatalytic oxidation than other Cu valence states. Due to the dramatic contribution of 1O2 and active chlorine, 100% degradation efficiency was achieved using tetracycline hydrochloride (TCH) as the target pollutant. Cu+ showed a selective preference for 1O2 and active chlorine triggering, rather than metallic Cu. Under the attack of 1O2 and active chlorine, the degradation intermediates of TCH were then provided by LC-MS results. The final results not only prove the feasibility of the Cu-GO/electrocatalysis system for pollution control but also shed light on the anode design via Cu valence state modulation.


Assuntos
Grafite , Tetraciclina , Cloro , Oxigênio
6.
Chemosphere ; 338: 139444, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37442382

RESUMO

Electron-transfer properties, as great contributors for electrocatalytic oxidation on the anode, are crucial to pollution degradation. The strong relationship between electron-transfer properties and active species (such as radicals) generation of anode catalysts suggests a new strategy for pollution-degradation efficiency improvement. In this study, a novel composite of Cu3(hexaamino triphenylhexane)2 [Cu3(HITP)2] and reduced graphene oxide (RGO) was synthesized to construct electron-transfer pathways between the two layers. Benefiting from the connection formed through RGO-O-N-Cu, the electron transfer from RGO to Cu3(HITP)2 was accelerated. The resettled charge distribution led the C atoms in the RGO layer, and the Cu and C atoms in Cu3(HITP)2 layer acted as the main surface active sites. O2•-, 1O2, and reactive chlorine were then triggered to boost the degradation of acetaminophen. The source of O2•- and 1O2 was more likely from surface oxygen groups rather than dissolved O2. Overall, this research provided a perspective proof of conductive Cu3(HITP)2/RGO composite construction with 2D/2D structure for electrocatalytic-oxidation improvement.


Assuntos
Acetaminofen , Elétrons , Oxirredução , Transporte de Elétrons , Oxigênio
7.
Environ Pollut ; 333: 121986, 2023 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-37315885

RESUMO

The consumption of disinfectants increased dramatically with the outbreak of the COVID-19 epidemic. Benzalkonium chloride (DDBAC), a cationic surfactant disinfectant for import and export cargoes, is used for effective degradation method. For DDBAC effective degradation, polyhedral Fe-Mn bimetallic catalyst of Prussian blue analogue (FeMn-CA300) was novelty developed for rapid peroxymonosulfate (PMS) activation. Results showed that the Fe/Mn redox and surface hydroxyl groups in the catalyst played an important role in the DDBAC-enhanced degradation. The removal effectiveness of 10 mg L-1 DDBAC was up to 99.4% in 80 min under the initial pH = 7, catalyst dosage of 0.4 g L-1, and PMS concentration of 15 mmol L-1. In addition, FeMn-CA300 had a wide pH applicability range. The results indicated that hydroxyls, sulfate radicals, and singlet oxygen could effectively improve the degradation efficiency, where sulfate radicals played a crucial role. Finally, the corresponding degradation path of DDBAC was further provided according to GC-MS results. The results of this study provide new insights into the degradation of DDBAC, thereby highlighting the great potential of FeMnca300/PMS to control refractory organic compounds in the aqueous phase.


Assuntos
Compostos de Benzalcônio , COVID-19 , Humanos , Peróxidos/química , Radical Hidroxila , Sulfatos
8.
J Colloid Interface Sci ; 629(Pt B): 667-682, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36183646

RESUMO

The highly conductive Ni-metal-organic framework/reduced graphene oxide (Ni-MOG/rGO) heterostructure shows an excellent catalytic activity through the modification of active sites, considerably enabling the electron transfer between rGO and Ni-MOF. However, the detailed mechanisms, i.e., the functions of separate metal sites and organic ligands and electron transfer orientation between Ni-MOFs and rGO, remain to be discussed. Here, the electrocatalytic mechanism of Ni-MOF/rGO was experimentally analyzed on the basis of the density functional theory. The dominant active sites of radical and nonradical generation were determined. Findings indicated that radicals (O2•- and •OH) and nonradicals (1O2 and active chlorine) contributed to paracetamol (APAP) degradation. Moreover, metal sites (Ni) were favorable to generate O2•- and partly •OH to initiate the reaction. By contrast, organic frameworks in Ni-MOF and rGO basement favored to generate •OH and nonradicals (1O2 and active chlorine). In this case, N sites (in Ni-MOF), which seized electrons from Ni sites, acted as the primary bonding bridge to accelerate the electron transfer from rGO to Ni-MOF. This study provided essential information to decipher the mechanism of Ni-MOF/rGO heterostructure applicable to the electrocatalytic system.

9.
Water Res ; 226: 119287, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36323210

RESUMO

Enhancing anaerobic treatment efficiency of waste activated sludge (WAS) toward preferable resource recovery would be an important requirement for achieving carbon-emission reduction, biosolids minimization, stabilization and security concurrently. This study demonstrated the synergic effect of potassium ferrate (PF) and nitrite on prompting WAS solubilisation and acidogenic fermentation toward harvesting volatile fatty acids (VFAs). The results indicated the PF+NaNO2 co-pretreatment boosted 7.44 times and 1.32 times higher WAS solubilisation [peak soluble chemical oxygen demand (SCOD) of 2680 ± 52 mg/L] than that by the single nitrite- and PF-pretreatment, respectively, while about 2.77 times and 2.11 times higher VFAs production were achieved (maximum VFAs accumulation of 3536.25 ± 115.24 mg COD/L) as compared with the single pretreatment (nitrite and PF)-fermentations. Afterwards the WAS dewaterability was improved simultaneously after acidogenic fermentation. Moreover, a schematic diagram was established for illustrating mechanisms of the co-pretreatment of PF and nitrite for enhancing the VFAs generation via increasing key hydrolytic enzymes, metabolic functional genes expression, shifting microbial biotransformation pathways and elevating abundances of key microbes in acidogenic fermentation. Furthermore, the mechanistic investigations suggested that the PF addition was conducive to form a relatively conductive fermentation environment for enhancing electron transfer (ET) efficiency, which contributed to the VFAs biotransformation positively. This study provided an effective strategy for enhancing the biodegradation/bioconversion efficiency of WAS organic matters with potential profitable economic returns.


Assuntos
Nitritos , Esgotos , Fermentação , Concentração de Íons de Hidrogênio , Ácidos Graxos Voláteis , Ácidos
10.
Environ Sci Pollut Res Int ; 29(53): 80281-80296, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35715674

RESUMO

Electrocatalytic oxidation is an effective technology for treatment of refractory organic pollutants, and its performance strongly depends on anode materials. Among all anode materials, graphene (GN) owns the advantages of high stability and lack of secondary pollution. The catalytic performance of GN can be further improved through heteroatom doping. Here, P/N-codoped graphene (PN-GN) materials were optimized and used as an anode material for 4-acetamidophenol (APAP) electrocatalytic degradation. Result indicated that PN-GN had lower internal resistance, larger specific surface area, and higher electrochemical activity than single-doped graphene materials. The catalytic activity of GN was greatly improved by P/N codoping. When PN-GN (P8.4%-N7.6%-500 °C) was used as catalyst (current of 20 mA, initial pH of 7, reaction time of 60 min), the degradation efficiency of APAP reached 98.2% ± 1.8%, which was 17.9% ± 3.6% higher than P-codoped graphene (P-GN), 14.7% ± 4.6% higher than N-codoped graphene (N-GN), and 54.0% ± 5.2% higher than GN. After 180 min of reaction, the degradation efficiency of total organic carbon (TOC) was 78.5%. The reaction conditions were optimized and the degradation pathway of APAP was estimated to elucidate the catalytic mechanism. The main active substances generated in the system were identified as active chlorine and O2•-.


Assuntos
Poluentes Ambientais , Grafite , Grafite/química , Acetaminofen , Cloro , Eletrodos
11.
Bioresour Technol ; 345: 126488, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34871722

RESUMO

Polyoxyethylene dehydration sorbitol monooleate (polysorbate-80) pretreatment enhanced volatile fatty acids (VFAs) production of waste activated sludge (WAS) in acidogenic fermentation. The results showed that polysorbate-80 ameliorated WAS solubilization obviously with a soluble chemical oxygen demand (SCOD) increasing to 1536 mg/L within 4 h. Within 2 days of acidogenic fermentation, the maximal VFAs arrived to 2958.35 mg COD/L via polysorbate-80-pretreatment. The polysorbate-80 pretreatment boosted microbial diversity and richness in fermentation process. The Clostridium, Macellibacteroides and Acidocella strengthened microbial cooperation for the metabolic functions enhancement (e.g. amino acid metabolism and carbohydrate metabolism) for VFAs generation from WAS organics. Overall, the polysorbate-80 could play positive roles on the transformation of organic matter from sludge solid matters to VFAs, which was turned out to become an effective enhancing strategy for future WAS treatment / bioresource recovery with relatively low cost.


Assuntos
Polissorbatos , Esgotos , Metabolismo dos Carboidratos , Ácidos Graxos Voláteis , Fermentação , Concentração de Íons de Hidrogênio , Interações Microbianas
12.
Chemosphere ; 287(Pt 1): 132070, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34478967

RESUMO

This paper presents the use of B and N co-doped reduced graphene oxide (BN-GN) as an electrode for paracetamol electrochemical degradation. The reaction mechanism, focused on active sites in the atom level and dominant radical species generated through the reaction, was analyzed by characterization, density functional theory (DFT) calculation, quenching experiments, and electron paramagnetic resonance analysis. The characterization results indicated that the introduction of N and B functionalities into GN improved catalytic activity due to the generation of new surface defects, active sites, and improvement of conductivity. Results of experiments and DFT showed that co-doping of B and N greatly improved the catalytic activity, and the B atoms in C-N-B groups were identified as main active sites. The main active substances of BN-GN generated in the electrocatalytic oxidation of paracetamol in the solution were O2•- and active chlorine. The influence of O2•- and active chlorine on the efficiency/path of catalytic oxidation and the proposed mechanism were also determined for paracetamol degradation. This study provides an in-depth understanding of the mechanism of BN-GN catalysis and suggests possibilities for practical applications.


Assuntos
Acetaminofen , Grafite , Catálise , Oxirredução
13.
J Nanosci Nanotechnol ; 21(12): 6073-6081, 2021 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-34229806

RESUMO

The application of electrochemical catalytic oxidation in wastewater treatment with powerful Cldoped graphene as an anode has been discussed as a novel approach to degrade acetaminophen effectively. The characteristics of Cl-doped graphene that were related to Cl loading content and microscopic morphology were analyzed by using several instruments, and the defects created by Cl doping were identified. Quenching experiments and electron paramagnetic resonance detection were proposed to clarify the mechanism underlying the production of active free radicals by Cldopedgraphene. The degradation results indicated that efficiency increased with the percentage of Cl atoms doped into the graphene. The best degradation efficiency of acetaminophen could reach 98% when Cl-GN-12 was used. In the process of electrocatalytic oxidation, O•-2, and active chlorine, as the main active species, persistently attacked acetaminophen into open-ring intermediates, such as 4-chlororesorcinol, and finally into CO2 and H²O.


Assuntos
Grafite , Acetaminofen , Catálise , Cloro , Eletrodos , Oxirredução
14.
Chemosphere ; 280: 130939, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34162110

RESUMO

To avoid the generally deteriorated dewaterability of sludge in waste activated sludge (WAS) anaerobic acidogenesis, the combination of varied calcium oxide (CaO) dosage (i.e., 0.01-0.07 g/g TS) and freezing/thawing pretreatment (5 F/T cycles) was investigated for concurrently improving the production of volatile fatty acids (VFAs) and dewatering performance of sludge. The highest release of soluble chemical oxygen demand (SCOD) (1836 ± 96 mg/L) and accumulation of VFAs (448.0 mg COD/g VS) were reached through the co-pretreatment of CaO (0.07 g/g TS) and F/T (50 h at -24 °C) (i.e., 0.07 CaO-F/T). Meanwhile, optimal dewaterability of sludge was also achieved in 0.07 CaO-F/T co-pretreated WAS fermentation, which was reflected by large particle size (98.32 µm), low capillary suction time (41.6 s), decreased specific resistance to filtration (SRF, reduced 47.5% against blank) and high zeta potential (-9.59 mV). Co-pretreatment of CaO and F/T reduced the species number of total microbial population, but improved the abundance of acid-producing bacteria. Increased abundance of Bacteroides, Macellibacteroides, Petrimonas, Prevotella, Clostridium, and Megasphaera was positively relevant to the high yields of VFAs. The economic analysis indicated that CaO-F/T was economically acceptable with considerable estimated net profits, which provided a feasible and efficient alternative for further WAS treatment at large scale.


Assuntos
Ácidos Graxos Voláteis , Esgotos , Anaerobiose , Compostos de Cálcio , Fermentação , Congelamento , Concentração de Íons de Hidrogênio , Óxidos
15.
Bioresour Technol ; 320(Pt A): 124287, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33120057

RESUMO

This first-attempted study illustrated the calcium oxide (CaO) agentia-pretreatment for prompting waste activated sludge (WAS) solubilization and enhancing volatile fatty acids (VFAs) bio-production through acidogenic fermentation. The 15-h CaO pretreatment was capable to produce a soluble chemical oxygen demand (SCOD) yield of ca. 153.17 mg COD/g VS and VFAs generation efficiency of 327.8 mg COD/g VS with adding dosage of 0.07 g/g TS. The relative frequencies corresponded to metabolic functions profiling were promoted obviously by CaO pretreatment and contributed to biosolid decomposition/VFAs production in sludge fermentation. Main genera of Azonexus, Arcobacter, Acinetobacter, Thauera, Petrimonas, Clostrium and Macellibacteroides cooperated synergically toward triggering concurrent VFAs generation/biosolid biodegradation. Finally, the CaO-pretreatment displayed positive merits in terms of sludge biosolid decomposition/recoverable resource harvest as compared with other alkali pretreatments. This study might shed lights on enriching intensification strategy for WAS management toward high-efficiency of recoverable resource harvest with lower cost.


Assuntos
Ácidos Graxos Voláteis , Esgotos , Compostos de Cálcio , Fermentação , Concentração de Íons de Hidrogênio , Interações Microbianas , Óxidos
16.
Huan Jing Ke Xue ; 41(6): 2736-2745, 2020 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608789

RESUMO

High crystallinity Mn-Fe LDH was synthesized by improved co-precipitation combined with the hydrothermal method and was utilized as a catalyst for peroxymonosulfate (PMS) activation to degrade reactive black 5. The high crystal purity and clear lamellar structure were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The operating parameters such as Mn/Fe molar ratio, catalyst dosage, PMS concentration, and initial pH value on the absorption efficiency, catalytic degradation, and reaction kinetics of RBK5 were also investigated. The results demonstrated that high crystallinity Mn-Fe LDH has good adsorption capacity and high catalytic efficiency. The degradation efficiency of RBK5 (20 mg·L-1) could reach 86% within 90 min when the Mn/Fe molar ratio was 1, the catalyst dosage was 0.2 g·L-1, the PMS concentration was 1 mmol·L-1, and the initial pH value was 7.0. The reaction process follows pseudo-first-order reaction kinetics (R2>0.9). In addition, the quenching experiment indicated that SO4-·and·OH were the main active species that degraded RBK5 from the Mn-Fe LDH/PMS system. The XPS analysis of the catalyst before and after the reaction confirmed the synergistic effect between Mn and Fe. The charge balance between Mn(Ⅱ) and Fe(Ⅲ) on the LDH surface and CO32- in layers stabilized the structure, thus promoting the synergistic effect of Mn and Fe on the lamellar surface and improving the activation efficiency of PMS by Mn-Fe LDH. Three-dimensional fluorescence and the UV-Vis scanning spectral analysis were preliminarily discussed to understand the degradation process of RBK5.

17.
Bioresour Technol ; 311: 123469, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32408194

RESUMO

This first-attempted study demonstrated endogenous redox-mediators harvest/application from waste activated sludge (WAS) through freezing/thawing (F/T) pretreatment-enhanced anaerobic acidogenesis coupled with microbial fuel cells (MFCs). A total of 2.57 kWh electricity was produced from per kg soluble chemical oxygen demand (SCOD) via MFCs just in 2 d with about 90% organics removal, which contained 1.152 kWh/kg COD from F/T liquid together with 1.418 kWh/kg COD from fermentation liquid. The fermentation liquor-MFCs fostered higher anodic biodiversity and more power output as compared with the F/T liquid-MFCs. Essentially, the completely endogenous redox mediators-like substances with relatively high redox activities could be retained after MFC electrogenesis from F/T liquid and played electron shuttle-roles sufficiently in enlarging bio-energy production of MFCs, which seemed to be an effective option for harvesting endogenous redox mediators from sludge. This study might inspire progressive thinking toward aims of high-efficiency of resource recycle/bioenergy production from WAS.


Assuntos
Fontes de Energia Bioelétrica , Anaerobiose , Eletricidade , Congelamento , Oxirredução , Esgotos
18.
Bioresour Technol ; 302: 122869, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32006928

RESUMO

This study investigated the association of volatile fatty acid (VFA) production with microbial mechanism in waste activated sludge (WAS) anaerobic acidogenesis enhanced by freezing/thawing (F/T) pretreatment. WAS solubilization was enhanced with 955.4 ± 10.0 mg/L soluble chemical oxygen demand (SCOD) release by a 50-h F/T pretreatment at -24 °C. The highest level of VFAs (4852 ± 156 mg COD/L) was obtained after a 12-day fermentation. Moreover, phyla of Proteobacteria, Bacteroidetes, Firmicutes, and Ignavibacteriae played vital roles in VFA generation, while high genera abundance of Clostridium, Macellibacteroides, Prevotella, and Megasphaera were positively associated with high yields of short-chain (C2-C5) fatty acids. A schematic diagram was drawn to illustrate the microbial mechanism of enhanced VFA generation by F/T pretreatment during WAS fermentation. This study provides an in-depth exploration of promoting bio-resource recycling from WAS with a low-cost approach (specially in high latitudes) and bring about some new thinking on future WAS management.


Assuntos
Ácidos Graxos Voláteis , Esgotos , Anaerobiose , Fermentação , Congelamento , Concentração de Íons de Hidrogênio
19.
Sci Total Environ ; 715: 136730, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32007871

RESUMO

Although graphene exhibited excellent performance, its capability of electrochemical catalytic oxidation would significantly improve by modification via sulfur (S)-doping. However, due to the complicated doping species of heteroatoms, the detailed mechanism was still remained open for discussion. Thus, this first-attempt study tended to decipher such mechanism behind the direct and indirect oxidation by analyzing S species in S-graphene. The density functional theory (DFT) was adopted for reactive center calculation and confirmation of secondary active species, to discuss the degradation pathway. As the experimental and calculation results, the thiophene structure S was more favorable for electron acceptation in direct oxidation. Chloride reactive species, as the most effective secondary functionalities (rather than •OH), were favorably generated on the edge doped S position than thiophene structured S in defects, to further trigger the indirect oxidation. However, the extensive contents of reactive functionalities could act as trap for self-annihilation of chloride reactive species, resulting in poor electrocatalytic degradation of the pollutants. This study deepened the understanding of heteroatoms doping for electrochemical catalytic oxidation.


Assuntos
Grafite/química , Acetaminofen , Catálise , Oxirredução , Enxofre
20.
J Nanosci Nanotechnol ; 20(5): 3287-3294, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31635677

RESUMO

As the characterizations of electrode are meaningful for electric catalytic efficiency and mechanism, the improvement of electrode have raised considerable public concern in recent decades. However, the metal electrode have the drawbacks of high price and easy for toxicity, nano electrode restricted by difficulties for electrode coating, possibility of agglomeration, and abscission during reactions. Focus on those defects, the proposed study is going to establish a useful technique for polymer combined nano-electrode preparation. The morphology, functional groups, and other characterization of the Pt/TiO2/graphene particles and organic composite nano Pt/TiO2/graphene sheets were analyzed by transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), electrochemical impedance spectroscopy (EIS). To identify the stability of self-prepared electrodes, parameters such as catalysts dosage, current density and pH will be analyzed by using RBK5 as target pollutions. The results shows that after treatment for 50 min under optimized conditions (20 mA, 1 g/L NaCl), the degradation rate of acetaminophen almost reached 100%. After five times recycle, the self-prepared electrode could still maintained a high removal rate of 90%.

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