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1.
TiO 2 supported on active carbon fiber (TiO 2/ACF), an absorbable photocatalyst, is a new kind of material applied in air purification. In this paper, the influence of environmental temperature (T) and relative humidity (RH) on the gas-solid adsorption of toluene and the photocatalytic oxidation (PCO) efficiency of adsorbed toluene on TiO 2/ACF were studied, and then, the purification capability of TiO 2/ACF was estimated. PCO results showed that although the PCO efficiency increased under high RH and T levels, the amount of adsorption of toluene decreased. Moreover, quantitative analysis results of intermediates indicated that more environmental risk emerged when PCO of toluene was carried out at higher environmental T and RH levels because more toxic intermediates would be accumulated on the TiO 2/ACF. So, it is significant to control the environmental T and RH conditions in the application of the PCO technique. T = 25°C and RH530% is the optimal condition for purifying toluene in our experimental system. 相似文献
2.
The aim of this study was to identify the intermediates in clofibric acid degradation under various advanced oxidation processes, namely ultraviolet (UV), UV/H 2O 2, vacuum ultraviolet (VUV), VUV/H 2O 2, and solar/TiO 2 processes, as well as to assess the toxicity of these intermediates. Eleven intermediates have been detected by gas chromatography-mass spectrometer, most of which were reported for the first time to our best knowledge. Combining the evolution of the dissolved organic carbon, Cl - and specific ultraviolet absorption at 254 nm, it could be deduced that cleavage of aromatic ring followed by dechlorination was the mechanism in solar/TiO 2 process, while dechlorination happened first and accumulation of aromatic intermediates occurred in the other processes. Different transformation pathways were proposed for UV-, VUV-assisted and solar/TiO 2 processes, respectively. The acute toxicity was evaluated by means of Photobacterium phosphoreum T 3 spp. bioassay. It was believed that aromatic intermediates increased the toxicity and the ring-opening pathway in solar/TiO 2 process could relieve the toxicity. 相似文献
3.
We examined influence of phosphate on transport of TiO2 NPs in soil. Deposition was reduced at higher pH and by adsorption of phosphate in soil. Release was more for NPs initially deposited at higher pH. Release was more for NPs initially deposited in the presence of phosphate. Surface roughness and charge heterogeneity play a role in the deposition/ release. ![]() The widespread use of TiO 2 nanoparticles (NPs) makes inevitable their release into the soil. Phosphate is also widespread within soil, and is likely copresent with TiO 2 NPs. However, the influence of phosphate on deposition/release— and thereby on transport— of TiO 2 NPs in soil is yet to be elucidated. In this study we conducted saturated column experiments to systematically examine the transport of TiO 2 NPs in soil amended with phosphate at different ionic strengths (ISs) (1, 10, 100 mmol/L NaCl) and pHs (4 and 9). Results show that the deposition of TiO 2 NPs decreased with decreasing IS, increasing pH, and when soil absorbed phosphate. These observations are qualitatively in agreement with Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy calculations, because the repulsive energy barrier is larger and secondary minimum depth is smaller at a lower IS, higher pH, and in the presence of phosphate. Accordingly, both primary- and secondary-minimum deposition were inhibited. Interestingly, although the deposition was less at higher pH and in the presence of phosphate, the subsequent spontaneous detachment and detachment by reduction of solution IS in these cases were greater. In addition, the presence of phosphate in the solution can cause a small quantity of attached TiO 2 NPs to detach, even without perturbations of physical and chemical conditions. Our study was the first to investigate the influence of phosphate on detachment of TiO 2 NPs and the results have important implication for accurate prediction of fate and transport of TiO 2 NPs in subsurface environments. 相似文献
4.
Three adsorbents including TiO 2, Ti-Ce, and Ti-La hybrid oxides were prepared to remove fluoride from aqueous solution. The Ti-Ce and Ti-La hybrid adsorbents obtained by the hydrolysis-precipitation method had much higher sorption capacity for fluoride than the TiO 2 adsorbent prepared through hydrolysis. Rare earth (Ce and La) oxides and TiO 2 exhibited a synergistic effect in the hybrid adsorbents for fluoride sorption. The sorption equilibrium of fluoride on the three adsorbents was achieved within 4 h, and the pseudo-second-order model described the sorption kinetics well. The sorption isotherms fitted the Langmuir model well, and the adsorption capacities of fluoride on the Ti-Ce and Ti-La adsorbents were about 9.6 and 15.1 mg·g -1, respectively, at the equilibrium fluoride concentration of 1.0 mg·L -1, much higher than the 1.7 mg·g -1 on the TiO 2. The sorption capacities of fluoride on the three adsorbents decreased significantly when the solution pH increased from 3 to 9.5. The electrostatic interaction played an important role in fluoride removal by the three adsorbents, and Fourier transform infrared (FTIR) analysis indicated that the hydroxyl groups on the adsorbent surface were involved in fluoride adsorption. 相似文献
5.
● Bimetallic oxide composite catalyst was designed for the urea-based SCR process. ● Surface chemical state and typical microstructure of catalyst was determined. ● Reaction route was improved based on intermediates and active site identification. ● TiO2@Al2O3 presents an obvious promotion for urea hydrolysis. As a promising option to provide gaseous NH 3 for SCR system, catalytic urea hydrolysis has aroused great attention, and improving surface area and activity of catalysis are the crucial issues to be solved for efficient urea hydrolysis. Therefore, a composite metal oxide (TiO 2@Al 2O 3) catalyst was prepared by a simple hydrothermal method, with mesoporous alumina (γ-Al 2O 3) as substrate. The results verify the mesoporous structure and submicron cluster of TiO 2@Al 2O 3, with exposed crystal faces of (101) and (400) for TiO 2 and γ-Al 2O 3, respectively. The electronegativity difference of Ti 4+ and Al 3+ changes the charge distribution scheme around the interface, which provides abundant acid/base sites to boost the urea hydrolysis. Consequently, for an optimal proportioning with nano TiO 2 content at 10 wt.%, the hydrolysis efficiency can reach up to 35.2 % at 100 °C in 2 h, increasing by ~7.1 % than that of the blank experiment. 13C NMR spectrum measurements provide the impossible intermediate species during urea hydrolysis. Theoretical calculations are performed to clarify the efficient H 2O decomposition at the interface of TiO 2@Al 2O 3. The result offers a favorable technology for energy-efficiency urea hydrolysis. 相似文献
6.
• Bi doping in TiO2 enhanced the separation of photo-generated electron-hole. • The performance of photocatalytic degradation of MC-LR was improved. • Coexisting substances have no influence on algal removal performance. • The key reactive oxygen species were h+ and •OH in the photocatalytic process. The increase in occurrence and severity of cyanobacteria blooms is causing increasing concern; moreover, human and animal health is affected by the toxic effects of Microcystin-LR released into the water. In this paper, a floating photocatalyst for the photocatalytic inactivation of the harmful algae Microcystis aeruginosa ( M. aeruginosa) was prepared using a simple sol-gel method, i.e., coating g-C 3N 4 coupled with Bi-doped TiO 2 on Al 2O 3-modified expanded perlite (CBTA for short). The impact of different molar ratios of Bi/Ti on CBTA was considered. The results indicated that Bi doping in TiO 2 inhibited photogenerated electron-hole pair recombination. With 6 h of visible light illumination, 75.9% of M. aeruginosa (initial concentration= 2.7 × 10 6 cells/L) and 83.7% of Microcystin-LR (initial concentration= 100 μg/L) could be removed with the addition of 2 g/L CBTA-1% (i.e., Bi/Ti molar ratio= 1%). The key reactive oxygen species (ROSs) in the photocatalytic inactivation process are h + and •OH. The induction of the Bi 4+/Bi 3+ species by the incorporation of Bi could narrow the bandgap of TiO 2, trap electrons, and enhance the stability of CBTA-1% in the solutions with coexisting environmental substances. 相似文献
7.
• UVA pre-irradiation to TiO2 NPs enhanced its toxicity toward plant A. cepa. • UVA TiO2 NPs increased intracellular ROS, resulting in more cell damage. • Cell death enhanced cell permeability and increased uptake of NPs. • Being highly toxic (EC50 = 0.097 µmol/L), TC did not increase ROS generation. • Even at a low dose, TC enhanced the toxic potential of TiO2 NPs significantly. ![]() Usage of titanium dioxide nanoparticles (TiO 2 NPs) and tetracycline (TC) has increased significantly in the present era. This leads to their release and accumulation in the environment. Both the compounds, individually, can have adverse toxic effects on the plants. Their binary mixtures can increase this degree of damage. The present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures in Allium cepa. Further, the toxicity of TiO 2 NPs upon UVA pre-irradiation was also measured. Results showed that UVA pre-irradiated NPs (UVA-TiO 2 NPs) had a significant decrease in cell viability than their non-irradiated counterparts (NI-TiO 2), denoting an increase in photocatalytic activity upon UVA pre-irradiation. Very low concentrations of TC ( EC10 = 0.016 µmol/L) mixed with TiO 2 NPs significantly increased the toxicity for both UVA-TiO 2 and NI-TiO 2 NPs. Intracellular ROS generation was significantly high for UVA-TiO 2 NPs. However, TC did not have any effects on ROS production. Both the compounds exhibited genotoxic potential in A. cepa. Different chromosomal abnormalities like anaphase bridges, telophase bridges, laggard chromosomes, binucleate cells, etc. were observed. The binary mixture of UVA-TiO 2 NPs and TC showed the highest chromosomal aberrations (64.0%±1.26%) than the mixture with NI-TiO 2 or the individual contaminants. This decreased significantly after recovery (46.8%±1.92%), denoting the self-repair processes. This study proved that UVA-TiO 2 NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of TC. This work will help to assess the risk of both compounds in the environment. 相似文献
8.
A solution of atrazine in a TiO 2 suspension, an endocrine disruptor in natural water, was tentatively treated by microwave-assisted photocatalytic technique. The effects of mannitol, oxygen, humic acid, and hydrogen dioxide on the photodegradation rate were explored. The results could be deduced as follows: the photocatalytic degradation of atrazine fits the pseudo-first-order kinetic well with k = 0.0328 s −1, and ·OH was identified as the dominant reactant. Photodegradation of atrazine was hindered in the presence of humic acid, and the retardation effect increased as the concentration of humic acid increased. H 2O 2 displayed a significant negative influence on atrazine photocatalysis efficiency. Based on intermediates identified with gas chromatography-mass spectrometry (GC-MS) and Liquid chromatography-mass spectrometry (LC-MS/MS) techniques, the main degradation routes of atrazine are proposed. 相似文献
9.
● TiO2/ZSM-11 was prepared by a facile solid state dispersion method. ● Mechanism for photocatalytic degradation of dyes was investigated. ● Both experimental and MD simulations were conducted. ● Chemisorption instead of electrostatic interaction played a critical role. Photocatalytic degradation is a promising way to eliminate dye contaminants. In this work, a series of TiO 2/ZSM-11 (TZ) nanocomposites were prepared using a facile solid state dispersion method. Methyl orange (MO), methylene blue (MB), and rhodamine B (RhB) were intentionally chosen as target substrates in the photocatalytic degradation reactions. Compared to pristine TiO 2, negative effect was observed on MO degradation while promoted kinetics were collected on MB and RhB over TZ composites. Moreover, a much higher photocatalytic rate was interestingly achieved on RhB than MB, which indicated that a new factor has to be included other than the widely accepted electrostatic interaction mechanism to fully understand the selective photodegradation reactions. Systematic characterizations showed that TiO 2 and ZSM-11 physically mixed and maintained both the whole framework and local structure without chemical interaction. The different trends observed in surface area and the photo-absorption ability of TZ composites with reaction performance further excluded both as the promotion mechanism. Instead, adsorption energies predicted by molecular dynamics simulations suggested that differences in the adsorption strength played a critical role. This work provided a deep mechanistic understanding of the selective photocatalytic degradation of dyes reactions, which helps to rationally design highly efficient photocatalysts. 相似文献
10.
The new properties of engineered nanoparticles drive the need for new knowledge on the safety, fate, behavior and biologic effects of these particles on organisms and ecosystems. Titanium dioxide nanoparticles have been used extensively for a wide range of applications, e.g, self-cleaning surface coatings, solar cells, water treatment agents, topical sunscreens. Within this scenario increased environmental exposure can be expected but data on the ecotoxicological evaluation of nanoparticles are still scarce. The main purpose of this work was the evaluation of effects of TiO 2 nanoparticles in several organisms, covering different trophic levels, using a battery of aquatic assays. Using fish as a vertebrate model organism tissue histological and ultrastructural observations and the stress enzyme activity were also studied. TiO 2 nanoparticles (Aeroxide® P25), two phase composition of anatase (65%) and rutile (35%) with an average particle size value of 27.6±11 nm were used. Results on the EC 50 for the tested aquatic organisms showed toxicity for the bacteria, the algae and the crustacean, being the algae the most sensitive tested organism. The aquatic plant Lemna minor showed no effect on growth. The fish Carassius auratus showed no effect on a 21 day survival test, though at a biochemical level the cytosolic Glutathione-S-Transferase total activity, in intestines, showed a general significant decrease ( p<0.05) after 14 days of exposure for all tested concentrations. The presence of TiO 2 nanoparticles aggregates were observed in the intestine lumen but their internalization by intestine cells could not be confirmed. 相似文献
11.
GO/TiO2 membrane was prepared by assembling GO nanosheets and TiO2 nanotubes. The intercalation of TiO2 nanotubes enlarged the space of GO interlayers and modified the surface morphology. Hydrophilic/underwater superoleophobic property of GO/TiO2 membrane was obtained. Water permeability, hydrophilicity, oleophobicity and antifouling ability of GO-based membrane were all enhanced by intercalating TiO2 nontubes. ![]() Membrane technology for oil/water separation has received increasing attention in recent years. In this study, the hydrophilic/underwater superoleophobic membrane with enhanced water permeability and antifouling ability were fabricated by synergistically assembling graphene oxide(GO) nanosheets and titanium dioxide (TiO 2) nanotubes for oil/water separation. GO/TiO 2 membrane exhibits hydrophilic and underwater superoleophobic properties with water contact angle of 62° and under water oil contact angle of 162.8°. GO/TiO 2 membrane shows greater water permeability with the water flux up to 531 L/(m 2·h·bar), which was more than 5 times that of the pristine GO membrane. Moreover, GO/TiO 2membrane had excellent oil/water separation efficiency and anti-oil-fouling capability, as oil residual in filtrate after separation was below 5 mg/L and flux recovery ratios were over 80%.The results indicate that the intercalation of TiO 2 nanotubes into adjacent GO nanosheets enlarged the channel structure and modified surface topography of the obtained GO/TiO 2 membranes, which improved the hydrophilicity, permeability and anti-oil-fouling ability of the membranes, enlightening the great prospects of GO/TiO 2 membrane in oil-water treatment. 相似文献
12.
• A novel and multi-functional clay-based oil spill remediation system was constructed. • TiO2@PAL functions as a particulate dispersant to break oil slick into tiny droplets. • Effective dispersion leads to the direct contact of TiO2 with oil pollutes directly. • TiO2 loaded on PAL exhibits efficient photodegradation for oil pollutants. • TiO2@PAL shows a typical dispersion-photocatalysis synergistic remediation. ![]() Removing spilled oil from the water surface is critically important given that oil spill accidents are a common occurrence. In this study, TiO 2@Palygorskite composite prepared by a simple coprecipitation method was used for oil spill remediation via a dispersion-photodegradation synergy. Diesel could be efficiently dispersed into small oil droplets by TiO 2@Palygorskite. These dispersed droplets had an average diameter of 20–30 mm and exhibited good time stability. The tight adsorption of TiO 2@Palygorskite on the surface of the droplets was observed in fluorescence and SEM images. As a particulate dispersant, the direct contact of TiO 2@Palygorskite with oil pollutants effectively enhanced the photodegradation efficiency of TiO 2 for oil. During the photodegradation process, •O 2−and •OH were detected by ESR and radical trapping experiments. The photodegradation efficiency of diesel by TiO 2@Palygorskite was enhanced by about 5 times compared with pure TiO 2 under simulated sunlight irradiation. The establishment of this new dispersion-photodegradation synergistic remediation system provides a new direction for the development of marine oil spill remediation. 相似文献
13.
The effect of ion-doping on TiO 2 nanotubes were investigated to obtain the optimal TiO 2 nanotubes for the effective decomposition of humic acids (HA) through O 3/UV/ion-doped TiO 2 process. The experimental results show that changing the calcination temperature, which changed the weight fractions of the anatase phase, the average crystallite sizes, the Brunauer-Emmett-Teller surface area, and the energy band gap of the catalyst, affected the photocatalytic activity of the catalyst. The ionic radius, valence state, and configuration of the dopant also affected the photocatalytic activity. The photocatalytic activities of the catalysts on HA removal increased when Ag +, Al 3+, Cu 2+, Fe 3+, V 5+, and Zn 2+ were doped into the TiO 2 nanotubes, whereas such activities decreased as a result of Mn 2+- and Ni 2+-doping. In the presence of 1.0 at.% Fe 3+-doped TiO 2 nanotubes calcined at 550°C, the removal efficiency of HA was 80% with a pseudo-first-order rate constant of 0.158 min −1. Fe 3+ in TiO 2 could increase the generation of ·OH, which could remove HA. However, Fe 3+ in water cannot function as a shallow trapping site for electrons or holes. 相似文献
14.
• Photocatalytic activity was improved in TiO2 thin film by rapid thermal annealing. • Photoreactor was designed for TiO2 thin film. • Considerable reusability and durability of prepared photocatalysts were studied. ![]() Un-biodegradable pharmaceuticals are one of the major growing threats in the wastewaters. In the current study, TiO 2 thin film photocatalysts were designed by nanocrystal engineering and fabricated for degradation of the acetaminophen (ACE) in a photocatalytic reaction under UV light irradiation in batch and continuous systems. The photocatalyst was prepared by sputtering and then engineered by thermal treatment (annealing at 300℃ (T300) and 650℃ (T650)). The annealing effects on the crystallinity and photocatalytic activity of the TiO 2 film were completely studied; it was found that annealing at higher temperatures increases the surface roughness and grain size which are favorable for photocatalytic activity due to the reduction in the recombination rate of photo-generated electron-hole pairs. For the continuous system, a flat plate reactor (FPR) was designed and manufactured. The photocatalytic performance was decreased with the increase of flow rate because the higher flow rate caused to form the thicker film of the liquid in the reactor and reduced the UV light received by photocatalyst. The reusability and durability of the samples after 6 h of photocatalytic reaction showed promising performance for the T650 sample (annealed samples in higher temperatures). 相似文献
15.
• PANI/Ti(OH)n(4–n)+ exhibited excellent adsorption capacity and reusability. • Adsorption sites of Cr(VI) were hydroxyl, amino/imino group and benzene rings. • Sb(V) was adsorbed mainly through hydrogen bonds and Ti-O-Sb. • The formation of Cr-O-Sb in dual system demonstrated the synergistic adsorption. • PANI/TiO2 was a potential widely-applied adsorbent and worth further exploring. Removal of chromium (Cr) and antimony (Sb) from aquatic environments is crucial due to their bioaccumulation, high mobility and strong toxicity. In this work, a composite adsorbent consisting of Ti(OH) n(4–n)+ and polyaniline (PANI) was designed and successfully synthesized by a simple and eco-friendly method for the uptake of Cr(VI) and Sb(V). The synthetic PANI/TiO 2 composites exhibited excellent adsorption capacities for Cr(VI) and Sb(V) (394.43 mg/g for Cr(VI) and 48.54 mg/g for Sb(V)), wide pH applicability and remarkable reusability. The adsorption of Cr(VI) oxyanions mainly involved electrostatic attraction, hydrogen bonding and anion-π interactions. Based on X-ray photoelectron spectroscopy and FT-IR analysis, the adsorption sites were shown to be hydroxyl groups, amino/imino groups and benzene rings. Sb(V) was adsorbed mainly through hydrogen bonds and surface complexation to form Ti-O-Sb complexes. The formation of Cr-O-Sb in the dual system demonstrated the synergistic adsorption of Cr(VI) and Sb(V). More importantly, because of the different adsorption sites, the adsorption of Cr(VI) and Sb(V) occurred independently and was enhanced to some extent in the dual system. The results suggested that PANI/TiO 2 is a promising prospect for practical wastewater treatment in the removal of Cr(VI) and Sb(V) from wastewater owing to its availability, wide applicability and great reusability. 相似文献
16.
Adsorption is the most widely used technology for the removal of indoor volatile organic compounds (VOCs). However, existing adsorbent-based technologies are inadequate to meet the regulatory requirement, due to their limited adsorption capacity and efficiency, especially under high relative humidity (RH) conditions. In this study, a series of new porous clay heterostructure (PCH) adsorbents with various ratios of micropores to mesopores were synthesized, characterized and tested for the adsorption of acetaldehyde and toluene. Two of them, PCH25 and PCH50, exhibited markedly improved adsorption capability, especially for hydrophilic acetaldehyde. The improved adsorption was attributed to their large micropore areas and high micropore-to-mesopore volume ratios. The amount of acetaldehyde adsorbed onto PCH25 at equilibrium reached 62.7 mg·g −1, eight times as much as the amount adsorbed onto conventional activated carbon (AC). Even at a high RH of 80%, PCH25 removed seven and four times more of the acetaldehyde than AC and the unmodified raw PCHs did, respectively. This new PCH optimized for their high adsorption and resistance to humidity has promising applications as a cost-effective adsorbent for indoor air purification. 相似文献
17.
以锐钛矿TiO 2(P25)为载体采用原位生长法负载锰氧化物制备了Mn/TiO 2催化剂,再以等体积浸渍-煅烧法对该催化剂掺杂氧化铈制备Ce(x)Mn/TiO 2-y催化剂用以烟气低温SCR脱硝.在固定锰负载量(质量分数为8%)的基础上,考察了铈掺杂量(铈锰摩尔比)、煅烧温度对催化剂SCR脱硝性能的影响.采用TEM、BET、XRD和XPS等手段表征了催化剂的理化结构特性.结果发现,当Ce/Mn的摩尔比例为1.0,煅烧温度为300℃时,Ce(1.0)Mn/TiO 2-300催化剂在150—300℃温度范围内、10500—27000 h -1的空速范围内,能够保持90%以上的NO转化率.理化性能分析结果表明,煅烧温度对催化剂的微观形貌影响显著,随着煅烧温度的升高,Ce(1.0)Mn/TiO 2-500催化剂活性物种颗粒集聚明显、比表面积降低,且锰氧化物价态分布偏向于低价态;铈的掺杂有助于Ce(1.0)Mn/TiO 2-300催化剂活性物种在载体表面的均匀分散,可以促进产生更多的Mn4+物种和更多的吸附氧,有利于催化剂低温SCR脱硝性能的提升. 相似文献
18.
This research investigates the performances of RuO 2/ZrO 2-CeO 2 in catalytic ozonation for water treatment. The results show that RuO 2/ZrO 2-CeO 2 was active for the catalytic ozonation of oxalic acid and possessed higher stability than RuO 2/Al 2O 3 and Ru/AC. In the catalytic ozonation of dimethyl phthalate (DMP), RuO 2/ZrO 2-CeO 2 did not enhance the DMP degradation rate but significantly improved the total organic carbon (TOC) removal rate. The TOC removal in catalytic ozonation was 56% more than that in noncatalytic ozonation. However this does not mean the catalyst was very active because the contribution of catalysis to the overall TOC removal was only 30%. The adsorption of the intermediates on RuO 2/ZrO 2-CeO 2 played an important role on the overall TOC removal while the adsorption of DMP on it was negligible. This adsorption difference was due to their different ozonation rates. In the catalytic ozonation of disinfection byproduct precursors with RuO 2/ZrO 2-CeO 2, the reductions of the haloacetic acid and trihalomethane formation potentials (HAAFPs and THMFPs) for the natural water samples were 38%–57% and 50%–64%, respectively. The catalyst significantly promoted the reduction of HAAFPs but insignificantly improved the reduction of THMFPs as ozone reacts fast with the THMs precursors. These results illustrate the good promise of RuO 2/ZrO 2-CeO 2 in catalytic ozonation for water treatment. 相似文献
19.
• Aquatic plants are more likely to absorb TiO2 NPs that are beneficial to them. • Ag NPs inhibited the growth of aquatic plants under both 5- and 60-day exposure. • CeO2 NPs had positive/negative impact on plant in 5/60-day exposure, respectively. • TiO2 NPs presence could enhance the photosynthesis and increase the plant biomass. • The ENPs changed plant activity, which resulted in changes of wetland performance. Engineered nanoparticles (ENPs) threaten the environment through wastewater discharging. Generally, constructed wetlands (CWs) are efficient methods for ENPs removal. However, the biotoxicity of ENPs on plants in CWs is unclear. Here, we investigated the distribution and bio-impacts of different ENPs (Ag NPs, TiO 2 NPs, and CeO 2 NPs) in plants under 5- and 60-day exposure to 1 and 50 mg/L concentrations. Results showed that ENPs appeared in the vascular bundle and mesophyll cell space, which induced the variation in antioxidase activities (e.g., superoxide dismutase [SOD], peroxidase [POD], and catalase [CAT] activities) as well as overproduction of malondialdehyde (MDA). Additionally, Ag NPs inhibited photosynthesis rate and root activity during two exposure phases. CeO 2 NPs had positive and negative impacts on plants in 5- and 60-day exposure, respectively. Inversely, TiO 2 NPs enhanced photosynthesis and root activity under 60-day exposure. Finally, the contents of the C, N, and P elements in plants fluctuated in response to ENPs stress. All results have a positive correlation with the wetland performance under ENPs exposure except for TiO 2 NPs treatment. Overall, our study systematically reveals aquatic plants' responses to ENPs and provides a reference for building ecological treatment systems to purify wastewater containing ENPs. 相似文献
20.
• Cu0.15-ACF performs the best for H2S and PH3 simultaneous removal. • 550°C and 90°C are separately calcination and reaction temperatures. • The reason why Cu0.15/ACF shows better performance was found. • The accumulation of H2PO4− and SO42−(H2O)6 is the deactivation cause of Cu0.15/ACF. Poisonous gases, such as H 2S and PH 3, produced by industrial production harm humans and damage the environment. In this study, H 2S and PH 3 were simultaneously removed at low temperature by modified activated carbon fiber (ACF) catalysts. We have considered the active metal type, content, precursor, calcination, and reaction temperature. Experimental results exhibited that ACF could best perform by loading 15% Cu from nitrate. The optimized calcination temperature and reaction temperature separately were 550°C and 90°C. Under these conditions, the most removal capacity could reach 69.7 mg/g and 132.1 mg/g, respectively. Characterization results showed that moderate calcination temperature (550°C) is suitable for the formation of the copper element on the surface of ACF, lower or higher temperature will generate more cuprous oxide. Although both can exhibit catalytic activity, the role of the copper element is significantly greater. Due to the exceptional dispersibility of copper (oxide), the ACF can still maintain the advantages of larger specific surface area and pore volume after loading copper, which is the main reason for better performance of related catalysts. Finally, increasing the copper loading amount can significantly increase the crystallinity and particle size of copper (oxide) on the ACF, thereby improving its catalytic performance. In situ IR found that the reason for the deactivation of the catalyst should be the accumulation of generated H 2PO 4− and SO 42−(H 2O) 6 which could poison the catalyst. 相似文献
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