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1.
    
Homogeneous and vertically aligned silicon nanowires (SiNWs) were successfully fabricated using silver assisted chemical etching technique. The prepared samples were characterized using scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Photocatalytic degradation properties of graphene oxide (GO) modified SiNWs have been investigated. We found that the SiNWs morphology depends on etching time and etchant composition. The SiNWs length could be tuned from 1 to 42 µm, respectively when varying the etching time from 5 to 30 min. The etchant concentration was found to accelerate the etching process; doubling the concentrations increases the length of the SiNWs by a factor of two for fixed etching time. Changes in bundle morphology were also studied as function of etching parameters. The SiNWs diameter was found to be independent of etching time or etchant composition while the size of the SiNWs bundle increases with increasing etching time and etchant concentration. The addition of GO was found to improve significantly the photocatalytic activity of SiNWs. A strong correlation between etching parameters and photocatalysis efficiency has been observed, mainly for SiNWs prepared at optimum etching time and etchant concentrations of 10 min and 4:1:8. A degradation of 92% was obtained which further improved to 96% by addition of hydrogen peroxide. Only degradation efficiency of 16% and 31% has been observed for bare Si and GO/bare Si samples respectively. The obtained results demonstrate that the developed SiNWs/GO composite exhibits excellent photocatalytic performance and could be used as potential platform for the degradation of organic pollutants.  相似文献   

2.
    
Nickel (hydr)oxide (NiOH) is known to be good co-catalyst for the photoelectrochemical oxidation of water, and for the photocatalytic oxidation of organics on different semiconductors. Herein we report a greatly improved activity of Bi2MoO6 (BMO) by nickel hexammine perchlorate (NiNH). Under visible light, phenol oxidation on BMO was slow. After NiNH, NiOH, and Ni2+ loading, a maximum rate of phenol oxidation increased by factors of approximately 16, 8.8, and 4.7, respectively. With a BMO electrode, all catalysts inhibited O2 reduction, enhanced water (photo-)oxidation, and facilitated the charge transfer at solid-liquid interface, respectively, the degree of which was always NiNH > NiOH > Ni2+. Solid emission spectra indicated that all catalysts improved the charge separation of BMO, the degree of which also varied as NiNH > NiOH > Ni2+. Furthermore, after a phenol-free aqueous suspension of NiNH/BMO was irradiated, there was a considerable Ni(III) species, but a negligible NH2 radical. Accordingly, a plausible mechanism is proposed, involving the hole oxidation of Ni(II) into Ni(IV), which is reactive to phenol oxidation, and hence promotes O2 reduction. Because NH3 is a stronger ligand than H2O, the Ni(II) oxidation is easier for Ni(NH3)6+ than for Ni(H2O)6+. This work shows a simple route how to improve BMO photocatalysis through a co-catalyst.  相似文献   

3.
    
The membrane fouling caused by extracellular organic matter (EOM) and algal cells and organic matter removal of two typical cyanobacteria (M. aeruginosa and Pseudoanabaena sp.) during ultrafiltration (UF) process were studied in this work. The results showed that EOM had a broad molecular weight (Mw) distribution and the irreversible membrane fouling was basically caused by EOM. Moreover, humic acid and microbial metabolites were major components of EOM of two typical cyanobacteria. Since EOM could fill the voids of cake layers formed by the algal cells, EOM and algal cells played synergistic roles in membrane fouling. Fourier transform infrared spectroscopy analysis indicated that the CH2 and CH3 chemical bonds may play an important role in membrane fouling caused by EOM. Interestingly, the cake layer formed by the algal cells could trap the organic matter produced by algae and alleviate some irreversible membrane fouling. The results also showed that although the cake layer formed by the algal cells cause severe permeate flux decline, it could play a double interception role with UF membrane and increase organic matter removal efficiency. Therefore, when using UF to treat algae-laden water, the balance of membrane fouling and organic matter removal should be considered to meet the needs of practical applications.  相似文献   

4.
    
Chlorine dioxide (ClO2),an alternative disinfectant to chlorine,has a superior ability to inactivate microorganisms,in which protein damage has been considered as the main inactivation mechanism.However,the reactivity of ClO2 with amino acid residues in oligopeptides and proteins remains poorly investigated.In this research,we studied the reaction rate constants of ClO2 with tryptophan residues in five heptapeptides and four proteins using stopped-flow or competi...  相似文献   

5.
    
Bi2O2CO3(BOC)/Bi4O5Br2(BOB)/reduced graphene oxide (rGO) Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method.Ultra-thin nanosheets of BOC and BOB were grown in situ on r GO.The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies (OVs) effectively leads to lower negative electron reduction potential of BOB as well as higher positive h...  相似文献   

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7.
    
Millions of people in poor areas are still under the threat of fluoride contamination.How to effectively separate fluorine in water is an important step to reduce the ecological risk.In this paper,we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl-and MgAl-LDHs.The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination,because of the better electronic structure.After the defluorination,the LiAl-LDHs with adso...  相似文献   

8.
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The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots (BQDs) doped TiO2 with nitrogen doped graphene oxide (NGO) nanocomposite (NGO/BQDs-TiO2) was fabricated. It was used for degradation of organic pollutants like 2,4-dichlorophenol (2,4-DCP) and stable dyes, i.e. Rhodamine B and Congo Red. X-ray diffraction (XRD) profile of NGO showed reduction in oxygenic functional groups and restoring of graphitic crystal structure. The characteristic diffraction peaks of TiO2 and its composites showed crystalline anatase TiO2. Morphological images represent spherical shaped TiO2 evenly covered with BQDs spread on NGO sheet. The surface linkages of NO?O?Ti, C?O?Ti, Bi?O?Ti and vibrational modes are observed by Fourier transform infrared spectroscopy (FTIR) and Raman studies. BQDs and NGO modified TiO2 results into red shifting in visible region as studied in diffused reflectance spectroscopy (DRS). NGO and BQDs in TiO2 are linked with defect centers which reduced the recombination of free charge carriers by quenching of photoluminescence (PL) intensities. X-ray photoelectron spectroscopy (XPS) shows that no peak related to C?O in NGO/BQDs-TiO2 is observed. This indicated that doping of nitrogen into GO has reduced some oxygen functional groups. Nitrogen functionalities in NGO and photosensitizing effect of BQDs in ternary composite have improved photocatalytic activity against organic pollutants. Intermediate byproducts during photo degradation process of 2,4-DCP were studied through high performance liquid chromatography (HPLC). Study of radical scavengers indicated that O2·? has significant role for degradation of 2,4-DCP. Our investigations propose that fabricated nanohybrid architecture has potential for degradation of environmental pollutions.  相似文献   

9.
    
Microplastic pollution has become one of the most concerned focuses in the world. Among many treatment methods, photocatalysis is considered to be one of the most environmentally friendly methods. In this work, the photodegradation behavior of polyamide microplastics is studied by using polyamide 6 PA6) as model microplastics and FeCl3 as catalyst. It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl3 is irradiated in water. The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl3 aqueous solution, indicating that it is promising to use this new method to solve the problem of PA6 type microplastics. In addition, the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS), which provides a new insight for the study of polymer degradation mechanism.  相似文献   

10.
    
Porous materials as emerging potential adsorbents have received much more attention because they are capable of capturing various pollutants with fast adsorption rate, high adsorption capacity, good selectivity and excellent reusability.In order to prepare porous materials with decent porous structure, Pickering emulsion template method has been proved to be one of the most effective technologies to create pore structure.This paper reviewed comprehensively the latest research progress on the pre...  相似文献   

11.
    
Fluence rate (FR) distribution (optical field) is of great significance in the optimal design of ultraviolet (UV) reactors for disinfection or oxidation processes in water treatment. Since the 1970s, various simulation models have been developed, which can be combined with computational fluidic dynamic software to calculate the fluence delivered in a UV reactor. These models strive for experimental validation and further improvement, which is a major challenge for UV technology in water treatment. Herein, a review of the simulation models of the FR distribution in a UV reactor and the applications of the current main experimental measurement approaches including conventional flat-type UV detector, spherical actinometer, and micro-fluorescent silica detector (MFSD), is presented. Moreover, FR distributions in a UV reactor are compared between various simulation models and MFSD measurements. In addition, the main influential factors on the FR distribution, including inner-wall reflection, refraction and shadowing effects of adjacent lamps, and turbidity effect are discussed, which is helpful for improving the accuracy of the simulation models and avoiding dark regions in the reactor design. This paper provides an overview on the simulation models and measurement approaches for the FR distribution, which is helpful for the model selection in fluence calculations and gives high confidence on the optimal design of UV reactors in regard to present methods.  相似文献   

12.
    
Global environmental problems have been increasing with the growth of the world economy and have become a crucial issue. To replace fossil fuels, sustainable and eco-friendly catalysts are required for the removal of organic pollutants. In this study, nickel ferrite (NiFe2O4) was prepared using a simple wet-chemical synthesis, followed by calcination; bismuth phosphate (BiPO4) was also prepared using a hydrothermal method. Further, NiFe2O4/BiPO4 nanocomposites were prepared using a hydrothermal technique. Numerous characterization studies, such as structural, morphology, surface area, optical, photoluminescence, and photoelectrochemical investigations, were used to analyze NiFe2O4/BiPO4 nanocomposites. The morphology analysis indicated a successful decoration of BiPO4 nanorods on the surface of NiFe2O4 nanoplate. Further, the bandgap of the NiFe2O4/BiPO4 nanocomposites was modified owing to the formation of a heterostructure. The as-prepared NiFe2O4/BiPO4 nanocomposite exhibited promising properties to be used as a novel heterostructure for tetracycline (TC) and Rhodamine B (RhB) removal. The NiFe2O4/BiPO4 nanocomposite degrades TC (98%) and RhB (99%) pollutants upon solar-light irradiation within 100 and 60 min, respectively. Moreover, the trapping experiments confirmed the Z-scheme approach of the prepared nanocomposites. The efficient separation and transfer of photogenerated electron-hole pairs rendered by the heterostructure were confirmed by utilizing electrochemical impedance spectroscopy, photocurrent experiments, and photoluminescence. Mott–Schottky measurements were used determine the positions of the conduction and valence bands of the samples, and the detailed mechanism of photocatalytic degradation of toxic pollutants was projected and discussed.  相似文献   

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14.
    
Exposure to engineered nanomaterials(ENMs), such as graphene oxide(GO), can potentially induce the response of various molecular signaling pathways, which can mediate the protective function or the toxicity induction.Wnt signaling pathway is conserved evolutionarily in organisms.Using Caenorhabditis elegans as an in vivo assay model, we investigated the effect of GO exposure on intestinal Wnt signaling.In the intestine, GO exposure dysregulated Frizzled receptor MOM-5, Disheveled protein DSH-2, GSK-3(a component of APC complex), and two β-catenin proteins(BAR-1 and HMP-2), which mediated the induction of GO toxicity.In GO exposed nematodes, a Hox protein EGL-5 acted as a downstream target of BAR-1, and fatty acid transport ACS-22 acted as a downstream target of HMP-2.Functional analysis on HMP-2 and ACS-22 suggested that the dysregulation of these two proteins provides an important basis for the observed deficit in functional state of intestinal barrier.Our results imply the association of dysregulation in physiological and functional states of intestinal barrier with toxicity induction of GO in organisms.  相似文献   

15.
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Formaldehyde is a pollutant that significantly affects the indoor air quality.However,conventional remediation approaches can be challenging to deal with low-concentration formaldehyde in an indoor environment.In this study,Photocatalysts of Ag/graphitic carbon nitride (g-C3N4)/Ni with 3D reticulated coral structure were prepared by thermal polymerization and liquid phase photo-deposition,using nickel foam (NF) as the carrier.Experiments demonstrated that when the Ag concen...  相似文献   

16.
    
In order to better understand the contribution of nutrients regeneration pathway, release potential and transformation pattern to cyanobacterial growth and succession, 7 sampling sites in Lake Chaohu with different bloom degree were studied every two months from February to November 2018. The carbon, nitrogen (N) and phosphorus (P) forms or fractions in surface, interstitial water and sediments as well as extracellular enzymatic activities, P sorption, specific microbial abundance and community composition in sediments were analyzed. P regeneration pathway was dominated by iron-bound P desorption and phosphorus-solubilizing bacteria solubilization in severe-bloom and slight-bloom area respectively, which both resulted in high soluble reactive phosphorus (SRP) accumulation in interstitial water. However, in severe-bloom area, higher P release potential caused the strong P release and algal growth, compared to slight-bloom area. In spring, P limitation and N selective assimilation of Dolichospermum facilitated nitrate accumulation in surface water, which provided enough N source for the initiation of Microcystis bloom. In summer, the accumulated organic N in Dolichospermum cells during its bloom was re-mineralized as ammonium to replenish N source for the sustainable development of Microcystis bloom. Furthermore, SRP continuous release led to the replacement of Dolichospermum by Microcystis with the advantage of P quick utilization, transport and storage. Taken together, the succession from Dolichospermum to Microcystis was due to both the different forms of N and P in water column mediated by different regeneration and transformation pathways as well as release potential, and algal N and P utilization strategies.  相似文献   

17.
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Finely modulated light-induced charge separation and transfer is a central challenge to achieve efficient photocatalysis.Although progress has been made in this field,most of the previous research works focused on the separation or migration of photogenerated carriers but did not build a bridge between the two.How to realize the strong driving and precise migration of carriers has become the focus of our work.We report an ingeniously designed ternary heterojunction.Taking NiFe-MOF as the“parent ...  相似文献   

18.
    
Efficient and robust photocatalysts for environmental pollutants removal with outstanding stability have great significance. Herein, we report a kind of three dimensional (3D) photocatalyst presented as Z-scheme heterojunction, which combining TiO 2 and Zn x Cd 1- x S with graphene aerogel to contrast TiO 2 -Zn x Cd 1- x S graphene aerogel (TSGA, x = 0.5) through a moderate hydrothermal process. The as-prepared Z-scheme TSGA was used to remove aqueous Cr(VI) via a synergistic effect of adsorption and visible light photocatalysis. The adsorption equilibrium can be reached about 40 min, then after about 30 min irradiation under visiblelight (wavelength ( λ) > 420 nm) the removal rate of Cr(VI) almost reached 100%, which is much better than the performance of pristine TiO 2 and Zn 0.5 Cd 0.5 S, as well as TiO 2 graphene aerogel (TGA) and Zn 0.5 Cd 0.5 S graphene aerogel (SGA). The virulent Cr(VI) was reduced to Cr(III) with hypotoxicity after photocatalysis on TSGA, meanwhile the as-synthesized TSGA presented a good stability and reusability. The reduced graphene oxide (rGO) sheets between TiO 2 and Zn 0.5 Cd 0.5 S played a role as charge transfer mediator, promoting the photoinduced electrons transfer and photocatalysis ability of TSGA was enhanced significantly. Hence,such photocatalyst exhibits a potential application on removing heavy metals with high efficiency and stability from polluted aqueous environment.  相似文献   

19.
    
Photo-responsive adsorption-photocatalysis nanocomposites are generally used in water and wastewater decontamination; however, the prolonged adsorption capacity of composites and the role of adsorption in concomitant photocatalysis are typically neglected. These composites can be regenerated under light irradiation as their adsorption capacity decreases. Herein, a novel adsorption-photocatalysis bifunctional nanocomposite, Bi-doped TiO2 supported on powdered activated carbon (Bi2O3/TiO2/PAC), was prepared using the sol-impregnation-hydrothermal procedure. Bi2O3/TiO2/PAC with a secondary calcination temperature of 700°C under a nitrogen atmosphere was selected for maximum adsorption capacity on Methyl Orange (MO). The composite displayed an excellent adsorption capacity and was easily separated and recycled. The results demonstrate that 71.2% photocatalytic regeneration efficiency could be attained under visible light irradiation for 1 hr at an intensity of 750?W/m2 and pH 7. Characterization of the as-prepared Bi2O3/TiO2/PAC nanocomposite (700°C) indicates that it possesses a highly specific surface area and great optical properties, showing bifunctional adsorption-photocatalysis characteristics. The p-n heterojunction of the composite played a dominant role in the photocatalytic regeneration process, and effective degradation of MO could be achieved along with composite regeneration.  相似文献   

20.
    
Plasmids play a critical role in the dissemination of antimicrobial resistance genes (ARGs), however, a systematical understanding of ARGs originated from plasmids in swine production is currently lacking. Herein, quantitative polymerase chain reaction was applied to determine the prevalence of ten ARGs and the class1 integron gene intI1 of plasmid source in swine manure from 44 farms in Sichuan, Hubei and Hebei provinces, China. All assayed ARGs were observed in plasmid DNA samples, and the average absolute abundance of aac(6’)-Ib-cr, blaNDM, blaCTX-M, optrA, ermB, floR, mcr-1, qnrS, tetM, sul1 and intI1 were 7.09, 2.90, 4.67, 6.62, 7.55, 7.14, 4.08, 4.85, 7.16, 7.11 and 8.07 of 10 log copies/gram, respectively. IntI1 showed a high correlation (r > 0.8, P < 0.01) with the abundance of aac(6’)-Ib-cr and sul1 in swine manure. Moreover, the farm scale (i.e., herd population) and geographical location were not found to be critical factors influencing the absolute abundance of ARGs of plasmid DNA in swine farms. However, the concentrations of florfenicol, Cu, Zn, Fe, total phosphorus (TP) and total potassium (TK) demonstrated a significant correlation with the abundance of several ARGs. Particularly, Cu and Zn had high correlations with optrA and blaCTX-M, respectively. Our results demonstrated that antibiotics, heavy metals and environmental nutrients are likely jointly contributing to the long-term persistence of ARGs in swine production. This study provides insights into the abundance and influencing factors of ARGs from swine manure, which is of significance for assessing and reducing the public health risks in livestock production.  相似文献   

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