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1.
Environ Pollut ; 261: 114039, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32220747

RESUMO

Environmentally persistent free radicals (EPFRs) are easily generated in the combustion processes of municipal solid waste (MSW) and can cause adverse effects on human health. This study focuses on understanding the toxicity of EPFR particles (ZnO/MCB containing EPFRs) to human bronchial epithelial cell lines BEAS-2B and 16HBE, murine macrophages Raw264.7, and the lung of BALB/c mice after a short exposure (7 days). Exposure of BEAS-2B, 16HBE, and Raw264.7 cells to ZnO/MCB particles significantly increased the reactive oxygen species (ROS) production and perturbed levels of intracellular redox conditions (decreased the intracellular GSH level and the activity of cytosolic SOD, and stimulated oxidative stress related proteins such as HO-1 and Nrf2). EPFR particles decreased the mitochondrial membrane potential (MMP) and induced cell apoptosis, including the activation of Caspase-3, Bax, and Bcl-2 apoptotic signalling pathways. A signature inflammatory condition was observed in both cell models and the mouse model for lung lesions. Our data suggest that EPFRs in particles have greater toxicity to lung cells and tissues that are potential health hazards to human lung.

2.
Bioresour Technol ; 304: 123005, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32070840

RESUMO

Petrochemical wastewaters treatment represents a serious challenge due to the high toxicity and complex chemical components. In this study, the biodegradability, mineralization behaviors and methane productivity of eight different types of petrochemical wastewaters were evaluated in series of semi-continuous bioreactors. Methane production strongly depended on the characteristics of wastewaters and chemical constituents. The highest methane yield of 305.9 ± 2.7 mL/g-COD was achieved by purified terephthalic acid wastewater, followed by ethylene glycol, polyester, etc. Comparatively, one-step-SCN- wastewater produced the lowest methane yield (4.7 ± 0.7 mL/g-COD) owing to high toxicity and low biodegradability. Modified Gompertz model confirmed that purified terephthalic acid, ethylene glycol and polyester wastewaters had a short lag-phase of 1.2, 1.7 and 0.2 days, respectively. Nonetheless, the formation of by-products such as proteins, polysaccharides and ammonia nitrogen throughout anaerobic digestion reflected the high activity of anaerobic microorganisms, confirming the technical feasibility of anaerobic biotechnology in treating petrochemical wastewaters.


Assuntos
Reatores Biológicos , Águas Residuárias , Amônia , Anaerobiose , Metano
3.
Water Environ Res ; 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31975564

RESUMO

The injection of oxidants is one of the useful remediation technologies for eliminating hydrogen sulfide (H2 S) and ammonia (NH3 / NH 4 + ) in aquatic sediments. In the current work, the impact of calcium nitrate injection on the release of heavy metals associated with phosphate was evaluated in a column test of sediment with overlying water at a volume ratio of 1:1 for 131 days. Sulfide was significantly oxidized by calcium nitrate, as its amount was reduced substantially by 85% from the 20th to the 30th day, with a decrease in the oxidation-reduction potential to -68 mV and a simultaneous increase in pH to 9.83. Over 50% of the mobile Zn, Pb, and Cu were reprecipitated in the sediment when the phosphate was partially released. It is proposed that the heavy metal immobilization was related to the phosphate content in the pore water due to the precipitation of heavy metals and phosphorus on the surface of Fe hydroxide particles after oxidation. This is supported by chemical fraction analysis of the heavy metals in the sediment, which indicated increased residual fractions of heavy metals. Our results provide an insight into the remediation of sediment by oxidation with a self-stabilization of heavy metals and phosphate. PRACTITIONER POINTS: Effective removal of sulfide after calcium nitrate injection was achieved. Metal immobilization was related to the phosphate content in pore water. Over 50% of mobile Zn, Pb, and Cu might be reprecipitated in sediment. Oxidizable fraction of heavy metal predominantly transformed to its residual fraction.

4.
J Hazard Mater ; 389: 122051, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32000123

RESUMO

Efficient activation of peroxydisulfate (PDS, S2O82-) was achieved in this study by a hybrid of reduced graphene oxide (rGO) and layered double hydroxide (LDH). The peroxydisulfate was intercalated into the interlayers of LDH that was combined with rGO. This sample contributed to 92.4 % of phenol (PhOH) removal at 25 °C with a PDS loading amount of 0.4 mmol/g, which is better than its LDH-PDS counterpart. A high activation of PDS in rGO/LDH-PDS was also observed during the oxidation of 4-bromophenol (4-BrPhOH), 2,4-dibromophenol (2, 4-BrPhOH), 2,6-dibromophenol (2, 6-BrPhOH) and bisphenol A (BPA). As a redox reaction of PDS in LDH, this result determined that the composite of rGO/LDH caused more PDS to be activated than LDH. As the defective rGO sites activated the PDS on the surface or edges of LDH layers, the breaking of the OO bond in PDS generated SO4·- radicals from intercalated peroxydisulfate. This result was supported by the radical scavenger experiment, electron paramagnetic resonance measurements, and the increased number of oxygen functional groups in the reacted rGO. Our work thus provided a novel strategy for PDS activation to use in environmental remediation.

5.
J Environ Manage ; 258: 109946, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31929044

RESUMO

Environmental pollutants generated by waste incineration plants, such as heavy metals and dioxin, make surrounding residents very sensitive to the construction of such facilities. This sensitivity and anxiety of residents may induce group events, which further leads to the emergence of social risks. Based on risk perception theory, a total of 320 questionnaires was designed and handed out to residents neighboring to Jiangqiao Waste Incineration Plant in Shanghai, China to detect the factors affecting risk attitude toward such plants. Using ordered logit model, it is found that there are four decisive factors including impact on health, information cognitive, objective characteristics, and the attitude of the neighbors. These factors have different influence on resident risk attitudes, in which the attitude of the neighbors is of most significance, followed by the economic-geography characteristics of residents, the information cognitive has minimal impact.


Assuntos
Dioxinas , Eliminação de Resíduos , Gerenciamento de Resíduos , Atitude , China , Incineração , Risco
6.
Chemosphere ; 241: 125038, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31610455

RESUMO

The use of humic acid (HA) and fulvic acid (FA) as reinforcing agents to improve the efficiency of electrokinetic remediation (EKR) were investigated for the first time using an artificially contaminated soil. A series of soil leaching tests and bench-scale EKR experiments were performed to elucidate the mechanisms of As removed from artificially contaminated soil. The characterization of total reducing capacity (TRC) and functional group were carried out to reveal the difference of HA and FA. The observations demonstrated that with 0.1 M NaOH and KCl as the anolyte, using both HA and FA enhanced the efficiency of EKR. After 25 days of EKR, the removal efficiency of TAs in HA/FA-enhanced EKR was about 2.0-3.0 times greater than when unenhanced. Compared to HA, more As was removed in EKR with FA, which has more TRC and oxygen-containing groups. These EKR experimental results, with the support of data obtained from soil leaching test, indicate that competitive adsorption, reductive dissolution and complexation were the reasons why HA and FA promoted the release of As in the soil and further enhanced the remediation efficiency.


Assuntos
Arsênico/isolamento & purificação , Benzopiranos/farmacologia , Técnicas Eletroquímicas/métodos , Recuperação e Remediação Ambiental/métodos , Substâncias Húmicas/análise , Poluentes do Solo/isolamento & purificação , Adsorção , Poluentes do Solo/análise , Temperatura Ambiente
7.
J Hazard Mater ; 381: 120935, 2020 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-31401458

RESUMO

Manganese slag is a hazardous waste, which lacks proper treatment. For the first time, an effective catalyst for selective catalytic reduction of nitric oxide was synthesized from manganese slag by a sol-gel method. The obtained catalyst had an excellent low-temperature activity and high hydrothermal stability. It removed 46.3% of nitric oxide (990 ppm) at a temperature as low as 100 °C; its removal increased to 100% at 220 °C, which lasted for more than 2000 min. Moreover, hydrothermal treatment at 400 °C showed little influence on its activity. Even after hydrothermal treatment at 900 °C, the catalyst still removed 39.7% of NO at 220 °C, 22.7% higher than another catalyst synthesized from pure reagents. The hydrothermal stability was attributed to an amorphous layer of MnSixOy. This layer covered the catalyst surface, protected active metal species, pore size and pore volume from steam attacking. Manganese slag thus realized the high-value-added utilization by synthesizing a catalyst with the high hydrothermal stability.

8.
Water Res ; 171: 115379, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31869692

RESUMO

Sewage sludge is a primary pathway for microplastics (MPs) entering into terrestrial ecosystems. However, a standardized method to analyze MP in sludge is lacking due to its high organic matter. This study investigated the extraction efficiency of six MPs in five solid matrices, i.e. sewage sludge, cattle manure, soil, sediment and silicon dioxide. Results show lower extraction efficiency of 87.2% for MPs in sludge compared with that in other matrices, especially polyethylene terephthalate (PET) (only 27.8%). The possible reason was that the presence of extracellular polymeric substances within the sludge hinders the MPs to float. Therefore, five protocols, i.e. hydrogen peroxide (H2O2), Fenton, nitric acid (HNO3), hydrochloric acid (HCl) and sodium hydroxide (NaOH) were used to pretreat the sludge and optimize the MP extraction. The sludge pretreated by H2O2, Fenton and 1 M of acids had higher MP extraction efficiency than the raw sludge due to higher extraction of the PET. The MP extraction efficiency in the sludge first increased, and subsequently decreased with the soluble chemical oxygen demand (SCOD) content, implying that moderate dissolution of sludge organic matter is beneficial to the MP extraction. Quantitative analysis of the changes in the MP physicochemical characteristics after the pretreatments indicated that polyamide (PA) and PET are not resistant to acid and alkali treatment, respectively. Principal component analysis shows that the effect of pretreatments on the MPs follows a decreasing sequence: alkali > high concentration of acids > low concentration of acids > H2O2 and Fenton. Additionally, the susceptibility of the MPs to the pretreatments follows a decreasing sequence: PET, PA and polymethyl methacrylate (PMMA) > polystyrene (PS) > polyethylene (PE) and polypropylene (PP). The findings supply novel insights into the effect of chemical pretreatments on MP extraction in sewage sludge.


Assuntos
Plásticos , Esgotos , Animais , Bovinos , Ecossistema , Peróxido de Hidrogênio
9.
Mol Ther Nucleic Acids ; 19: 208-217, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31841993

RESUMO

Nuclear factor κB (NF-κB) acts as a nuclear factor that is composed of five main subunits. It is a pluripotent and crucial dimer transcription factor that has a close relationship with many serious illnesses, especially its influences on cell proliferation, inflammation, and cancer initiation and progression. NF-κB acts as part of the signaling pathway and determines its effect on the expression of several other genes, such as epidermal growth factor receptor (EGFR), p53, signal transducer and activator of transcription 3 (STAT3), and non-coding RNA (ncRNA). Continuous activation of the NF-κB signaling pathway has been seen in many cancer types. While the NF-κB signaling pathway is tightly regulated in physiological settings, quite frequently it is constitutively activated in cancer, and the molecular biology mechanism underlying the deregulated activation of NF-κB signaling remains unclear. In this review, we discuss the regulatory role and possible clinical significance of ncRNA (microRNA [miRNA] and long non-coding RNA [lncRNA]) in NF-κB signaling in cancer, including in the conversion of inflammation to carcinogenesis. Non-coding RNA plays an essential and complex role in the NF-κB signaling pathway. NF-κB activation can also induce the ncRNA status. Targeting NF-κB signaling by ncRNA is becoming a promising strategy of drug development and cancer treatment.

10.
Environ Monit Assess ; 191(12): 771, 2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31773378

RESUMO

Shanghai is one of the largest metropolitan areas in the world, during the rapid urbanization of the past decades, impervious surface expanded dramatically and became a main factor influencing surface water quality. Thus, exploring the driving forces of impervious surface has great implications in such metropolitan area. In this study, an impervious surface coefficient method (ISC) was used to measure the percentage of total impervious area (PTIA) of Shanghai; regression analysis was conducted to define the relationship between PTIA and three socio-economic factors, population density, unit area gross domestic product, and unit area industrial output at the city and district scale. Results showed that the industrial land use generated the highest ISC value, followed by high-density residential. Strong correlations were showed between PTIA and socio-economic indicators, in which population density was the most significant. Threshold effect was presented that when population density was higher than 15000 per/km2, this relationship would become less significant and PTIA remained stable. Similar effects were found when unit area gross domestic product exceeded 125 million yuan/km2. Scale effect was also discussed that the relationship was more significant at city scale than district. An improved understanding of the threshold effect and scale effect will help guide future urban planning and design new urban ecosystem policies.


Assuntos
Ecossistema , Propriedades de Superfície , Urbanização , China , Cidades , Planejamento de Cidades , Movimentos da Água
11.
Chemosphere ; 235: 1015-1021, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561290

RESUMO

Phosphate is one of the main contaminations in water, so an effective method of decreasing or removing phosphate is needed. The main purpose of this paper is to synthesize CaFe-LDHs and MgFe-LDHs from the mixture of calcined dolomite and ferric chloride to remove orthophosphate and pyrophosphate. The study showed that removal of orthophosphate was attributed to the precipitation by Ca2+ and adsorption by MgFe-LDHs, where the former played a main role. As for pyrophosphate, it was mainly removed by precipitation at the initial pyrophosphate concentration ranging from 3.228 to 17.04 mmol/L. When the initial concentrations became relatively higher, the removal efficiency of pyrophosphate decreased because the complexation effects by Fe3+, Ca2+ and Mg2+ took place.


Assuntos
Carbonato de Cálcio/química , Cloretos/química , Difosfatos/análise , Compostos Férricos/química , Hidróxidos/química , Magnésio/química , Fosfatos/análise , Poluentes Químicos da Água/análise , Difosfatos/isolamento & purificação , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
12.
Sci Total Environ ; 695: 133875, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31421340

RESUMO

The surface functional group plays an important role in H2S catalytic oxidization. However, the specific effect of each group species has seldom been investigated. For the first time, we revealed by experimental and theoretical methods that the pyrone group was the most valuable group. An increase in the pyrone-group amount obviously decreased the kinetic reaction order of H2S catalytic oxidization. The catalyst with the largest amount of pyrone group (0.1321 mmol·g-1) showed the lowest reaction order (0.5896) and activation energy (16.25 kJ·mol-1). By comparison, a catalyst with 0.0008 mmol·g-1 of pyrone group had a reaction order of just 1.1852 and an activation energy of 81.22 kJ·mol-1. The contribution of pyrone content to the kinetic reaction order had a negative correlation coefficient of -8.0665, which was three and five times larger than that of the quinone (-2.5568) and acidic groups (-1.7454), respectively. Moreover, density functional theory calculations showed that the pyrone group had the lowest energy gap (0.156 eV), far less than that (1.921 eV) of the carboxyl group. After H2S was adsorbed, the pyrone group had a Mulliken atomic charge of 0.510, which was larger than that (0.236) of the carboxyl group. In other words, the pyrone group showed the best ability to facilitate electron transfer. As a result, the catalyst with 0.1321 mmol·g-1 of the pyrone group removed 100% of the H2S (450 ppm). This amount was 42% higher than a catalyst with 0.0008 mmol·g-1 of the pyrone group. The main results of this work help to explain the mechanism of carbon material in various types of catalysis.

13.
Waste Manag ; 95: 644-651, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31351652

RESUMO

Phosphorus (P) is an essential nutrient for all organisms, and the recovery of P from sewage sludge (SS) has been the focus of recent research. The effect of temperature and chlorine-based additives (MgCl2 and CaCl2) on P recovery and heavy metal (Cu, Zn, and Cr) removal during SS incineration were investigated. The results showed that temperature and chlorine-based additives increased the P fixation and improved the P-bioavailability. The fixation rate of P reached a maximum of 98.5% in SS using 3% Mg (MgCl2) at 900 °C and 97.8% in SS using 5%Ca (CaCl2) at 800 °C. Additionally, the mechanism of P associated with aluminum oxides/hydroxides (Al-P) transferring to that of magnesium oxides/hydroxides (Mg-P) and calcium oxides/hydroxides (Ca-P) was also investigated. The results indicated that Mg3(PO4)2 was formed via the reaction between AlPO4 and MgCl2 during incineration, which increased the P solubility in 2% citric acid. When AlPO4 was incinerated with CaCl2, Ca2PO4Cl which has a higher P-bioavailability than AlPO4 was formed. In addition, the mass fraction and leaching concentration of Cu and Zn in treated SS greatly decreased during SS incineration, while no reduction in Cr. These findings suggest that chlorine-based additives can be used to treat SS at high temperatures to obtain an ideal material for P-fertilizer production.


Assuntos
Incineração , Metais Pesados , Cloro , Fósforo , Esgotos
14.
Environ Int ; 131: 105024, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31357090

RESUMO

Activated persulfate (PS) oxidation is promising for contaminant removal but a lack of controllable activation can lead to a loss of reagents and thus low contamination degradation. Herein, we have proposed and investigated an innovative method to control PS activation by introducing ion exchange membrane into electrochemically activated PS. This electrochemical membrane reactor (EMR) could precisely control PS activation by adjusting electrical current for slow release of Fe2+, and also avoid direct contact between PS and a sacrificial anode electrode (iron electrode)/an alkaline cathode solution. It was found that the PS decomposition rate constant was linearly increased by increasing the applied current (R2 = 0.988). The rate of the released Fe2+ also exhibited a linear relationship with the applied current (R2 = 0.995). Compared to one-time dosage of Fe2+, the EMR-based slow-release process had higher contamination degradation and better PS utilization (molar ratio of the decomposed PS to the migrated Fe, 1.04 ±â€¯0.01:1), thereby minimizing the waste of both reaction reagents and generated radicals. The EMR was also employed to degrade a representative dye contaminant in a controllable manner and achieved 95.7 ±â€¯0.7% removal percentage with PS dosage of 3.0 g L-1 within 20 min. This study is among the earliest to explore effective approaches for precisely controlling PS activation and subsequent oxidation of contaminants.


Assuntos
Ferro/química , Sulfatos/química , Eletroquímica , Recuperação e Remediação Ambiental/métodos , Membranas Artificiais , Oxirredução , Poluentes Químicos da Água/química
15.
Environ Int ; 130: 104926, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31228790

RESUMO

It has been reported that microbial reduction of sulfate, nitrite/nitrate and iron/manganese could be coupled with anaerobic oxidation of methane (AOM), which plays a significant role in controlling methane emission from anoxic niches. However, little is known about microbial chromate (Cr(VI)) reduction coupling with AOM. In this study, a microbial consortium was enriched via switching nitrate dosing to chromate feeding as the sole electron acceptor under anaerobic condition in a membrane biofilm reactor (MBfR), in which methane was continuously provided as the electron donor through bubble-less hollow fiber membranes. According to long-term reactor operation and chromium speciation analysis, soluble chromate could be reduced into Cr(III) compounds by using methane as electron donor. Fluorescence in situ hybridization and high-throughput 16S rRNA gene amplicon profiling further indicated that after feeding chromate Candidatus 'Methanoperedens' (a known nitrate-dependent anaerobic methane oxidation archaeon) became sole anaerobic methanotroph in the biofilm, potentially responsible for the chromate bio-reduction driven by methane. Two potential pathways of the microbial AOM-coupled chromate reduction were proposed: (i) Candidatus 'Methanoperedens' independently utilizes chromate as electron acceptor to form Cr(III) compounds, or (ii) Candidatus 'Methanoperedens' oxidizes methane to generate intermediates or electrons, which will be utilized to reduce chromate to Cr(III) compounds by unknown chromate reducers synergistically. Our findings suggest a possible link between the biogeochemical chromium and methane cycles.

16.
Colloids Surf B Biointerfaces ; 181: 585-592, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31195314

RESUMO

The search for effective alternatives to traditional antibiotics to avoid antibiotic resistant bacteria is growing worldwide. ZnO nanoparticles are found to effectively inhibit growth and proliferation of bacteria, and ZnO-based layered double hydroxides (ZnO-based LDHs) have been intensively investigated for this purpose. However, the nanocomposites are made in a multi-step preparation process with severe agglomeration and limited bactericidal ability. In this research, ZnO-dotted nanohybrids using Zn3Al-LDHs as precursors (ZnO-dotted LDHs or ZnO/LDHs) were synthesized under facile hydrothermal conditions. An understanding of the transformation of the LDH precursors to the ZnO/LDHs was conducted with TEM/HRTEM/XRD/FTIR. ZnO/LDHs can be transformed from ZnAl-LDHs, with more ZnO nanodots generated upon heating at 150 and 200 °C for 2 h (Zn3Al-150, Zn3Al-200). Zn3Al-200 nanohybrids showed potent antibacterial activity towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) at 100-300 µg/mL for 4 days. Antibacterial activity of Zn3Al-200 may be attributed to the synergistic effects (ROS, leached Zn2+ and physical interaction). This research thus suggests a potential economic approach to prepare ZnO/LDH nanocomposites for avoiding the antibiotic resistant bacteria in environmental engineering or clinic fields.


Assuntos
Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Temperatura Alta , Nanocompostos/química , Staphylococcus aureus/efeitos dos fármacos , Alumínio/química , Alumínio/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Hidróxidos/química , Hidróxidos/farmacologia , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Propriedades de Superfície , Zinco/química , Zinco/farmacologia , Óxido de Zinco/química , Óxido de Zinco/farmacologia
17.
ACS Appl Mater Interfaces ; 11(18): 16538-16545, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-30983330

RESUMO

An economic and facile method was urgently required for the degradation of SF6 to replace the high-energy excitation treatment. Both theoretical calculations and experimental observations were conducted to reveal the synergy of Cr/Fe/Si composites on a new technique of SF6 degradation through reacting silicon dioxide. Density functional theory (DFT) calculations show that strong adsorption of SF6 on Cr2O3, and then the fast F/O exchange between CrF3 and Fe2O3 (energy barrier was 1.45 eV) as well as FeF3 and SiO2 (energy barrier was 1.69 eV) enhanced mediated efficiency from SF6 to SiF4. The fluorine (F) migration between solid interfaces in Cr2O3&Fe2O3@SBA15 was responsible for efficient SF6 removal. The F migration route was composed of SF6 to CrF3, CrF3 to FeF3, and FeF3 to SiF4 with the lowest thermodynamic driving. Enhanced specific accumulative converted amount (SACA) of SF6 on Cr2O3&Fe2O3@SBA15 was achieved and the highest SACA was 13.98 mmol/g within 7 h, significantly higher than that on Fe2O3@SBA15 (5.74 mmol/g) and Cr2O3@SBA15 (2.71 mmol/g). Moreover, X-ray diffractometry and X-ray photoelectron spectroscopy were performed to support DFT calculations, including ion intensities detected using mass spectroscopy and composition analysis of the mediator during the reaction. Therefore, our work put forward a novel approach for economic and efficient SF6 decomposition through reacting with silicon dioxide under the mediation of Cr2O3&Fe2O3. This method was also potentially used in effective degradation of refractory non-metal halides.

18.
J Environ Manage ; 239: 90-95, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30889522

RESUMO

Manganese slag is a solid waste produced by the steel industry and usually lacks a proper recycling. In this paper, the manganese slag was used to synthesize a catalyst via microwave assistant method and applied in selective catalytic reduction of nitric oxide. As a result, the catalyst exhibited an excellent low-temperature activity. It removed 78.31% of nitric oxide at 100 °C, 44.44% higher than that of a slag-derived catalyst synthesized by ammonia impregnation, and 63.18% higher than that of a commercial catalyst. Even after a hydrothermal treatment, the catalyst still showed a removal of 69.26% at 150 °C. After a detailed characterization, the low-temperature activity was attributed to an increased amount of oxygen vacancies, which were generated during the microwave synthesis. The generated oxygen vacancies provided adsorption sites for chemisorbed oxygens, which then promoted the electron transfer for reduction of nitric oxide. The main result of this work will help to develop a low-cost catalyst and obtain a high-value-added utilization of manganese slag at the same time.


Assuntos
Manganês , Óxido Nítrico , Amônia , Catálise , Oxigênio
19.
Bioresour Technol ; 281: 457-468, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30827730

RESUMO

Due to abundant biomass and eco-friendliness, biochar is exemplified as one of the most promising candidates to mediate the degradation of environmental contaminants. Recently, environmentally persistent free radicals (EPFRs) have been detected in biochars, which can activate S2O82- or H2O2 to generate reactive oxygen species for effective degradation of organic and inorganic contaminants. Comprehending the formation mechanisms of EPFRs in biochars and their interactions with contaminants is indispensable to further develop their environmental applications, e.g., direct and indirect EPFR-mediated removal of organics/inorganics by biochars. With reference to the information of EPFRs in environmental matrices, this article critically reviews the formation mechanisms, characteristics, interactions, and environmental applications of EPFRs in biochars. Synthesis conditions and loading of metals/organics are considered as key parameters controlling their concentrations, types, and activities. This review provides new and important insights into the fate and emerging applications of surface-bound EPFRs in biochars.


Assuntos
Carvão Vegetal/química , Radicais Livres/química , Peróxido de Hidrogênio/química
20.
J Environ Manage ; 238: 144-152, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30851552

RESUMO

Municipal solid waste incineration fly ash is directly landfilled after solidification in the industry. The rapid evaluation of contaminant leaching is required before the landfill of fly ash. In order to reduce the time to evaluate the effect of solidification, a set of rapid evaluation method was developed through the determination of characteristic index, heavy metal leaching analysis, principal component analysis, and mathematical model construction. It was found that f-CaO, acid neutralizing capacity, pH and soluble calcium were negatively correlated with heavy metal leaching. The soluble chlorine was positively correlated with heavy metal leaching. The effect of each feature indicators on heavy metal leaching was evaluated using principal component analysis and mathematical analysis software R.3.4.4. Furthermore, R.3.4.4 was used to detect the optimal model and the excess probability formula by stepwise linear regression and logistic regression analysis method. By introducing the measured value of feature indicator into the excess probability formula, the rate of excess-standard of heavy metals leaching can be preliminarily determined. Based on the above ideas, a rapid detection and evaluation system could be developed according to the local leaching standards and the components of fly ash selected locally.


Assuntos
Metais Pesados , Eliminação de Resíduos , Carbono , Cinza de Carvão , Incineração , Minerais , Material Particulado , Resíduos Sólidos
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