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1.
J Nat Prod ; 2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33216556

RESUMO

Eleven metabolites, six echinosporins (1-6), four dibenzoyls (7-10), and an aromatic compound (11), were isolated from the fermentation broth of lichen-associated Amycolatopsis hippodromi. The structures of the new compounds (1-5, 8-11) were elucidated by comprehensive spectroscopic analysis including data from experimental and calculated ECD spectra. Amycolasporins A-C (1-3) demonstrated antibacterial activities against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli with MIC values of 25 or 100 µg/mL. Amycolasporin C (3) and the known dibenzoyl (7) attenuated the production of NO due to the suppression of the expression of nitric oxide synthase (iNOS) in LPS-induced RAW 264.7 cells in a dose-dependent manner.

2.
ACS Appl Mater Interfaces ; 12(45): 50610-50618, 2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33136368

RESUMO

Monolayer MoS2 (ML-MoS2) with various polymorphic phases attracts growing interests for device applications in recent years. Herein, a field-effect transistor (FET) gas sensor is developed on the basis of monolayer MoS2 with a heterophase of a 1T metallic phase and a 2H semiconducting phase. Lithium-exfoliated MoS2 nanosheets own a monolayer structure with rich active sites for gas adsorption. With thermal annealing from 50 to 300 °C, the initial lithium-exfoliated 1T-phase MoS2 gradually transforms into the 2H phase, during which the 1T and 2H heterophases can be modulated. The 1T/2H heterophase MoS2 shows p-type semiconducting properties and prominent adsorption capability for NO2 molecules. The highest response is observed for 100 °C annealed MoS2 of a 40% 1T phase and a 60% 2H phase, which shows a sensitivity up to 25% toward 2 ppm NO2 at room temperature in a very short time (10 s) and a lower limit of detection down to 25 ppb. This study demonstrates that the gas detection capability of ML-MoS2 could be boosted with the heterophase construction, which brings new insights into transition-metal dichalcogenide gas sensors.

3.
ACS Appl Mater Interfaces ; 12(29): 32970-32978, 2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32584022

RESUMO

MXenes, a group of emerging two-dimensional (2D) transition metal carbides or nitrides, have attracted wide interest due to their unique structures and properties. Their stability and applicability in different media especially in an alkaline environment are directly associated with their potential applications and are not yet explored. Herein, a field-effect transistor (FET) is fabricated with single/double-layer Ti3C2Tx MXene. The Ti3C2Tx FET indicator shows a fast (∼1 s), sensitive, and selective response to alkali. Moreover, the device can work even in a high-salinity (2 M NaCl) environment, suggesting its high anti-interference ability for alkali in a high-ionic-strength environment. Using an in situ morphological image evolution study, it is demonstrated that the response signal results from alkali-induced denaturation of Ti3C2Tx nanosheets. The Ti3C2Tx-based alkali FET indicator and systematic evaluation on alkali-induced structure evolution of Ti3C2Tx provide essential insights into MXene-based FETs and future applications of MXene in alkaline environments.

4.
ACS Appl Mater Interfaces ; 12(17): 19607-19615, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32282182

RESUMO

Although graphitic carbon nitride (g-C3N4) has been identified as a promising photocatalyst, pristine g-C3N4 has a limited light absorption, insolubility, small specific surface area, and rapid electron-hole pair recombination. In this study, hydroxyl-grafted oxygen-linked tri-s-triazine-based polymer (HGONTP) is achieved through the polycondensation of hydrothermally pretreated dicyandiamide (DCDA). The content of C-O-C linkers and terminal OH groups in HGONTP can be regulated by the cyclization and hydrolysis degrees of DCDA through the replacement of the pendant NH2 groups with OH groups. The HGONTP photocatalyst exhibits an outstanding light absorption from UV to near-IR, possessing a narrow band gap of 2.18 eV, a hydrophilic surface, a large specific surface area of 96.1 m2 g-1, and reduced charge recombination. As a result, HGONTP exhibits a hydrogen evolution rate 27.7-fold higher than that for pristine g-C3N4 (6.54 vs 0.236 mmol g-1 h-1). The apparent quantum yield reaches 12.6% at 420 nm and 4.1% at 500 nm. In addition, the photocatalytic conversion efficiency of CO2 to CO reaches as high as 3.3 µmol g-1 h-1 without cocatalysts and sacrificial agents. The selectivity of CO2 to CO achieves 88.4%. The proposed strategy paves a new avenue to design high-performance polymeric photocatalysts used in water.

5.
Water Res ; 173: 115563, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32059129

RESUMO

In mercury (Hg)-polluted eutrophic waters, algal blooms are likely to aggravate methylmercury (MeHg) production by causing intensified hypoxia and enriching organic matter at the sediment-water interface. The technology of interfacial oxygen (O2) nanobubbles is proven to alleviate hypoxia and may have potential to mitigate the risks of MeHg formation. In this study, incubation column experiments were performed using sediment and overlying water samples collected from the Baihua Reservoir (China), which is currently suffering from co-contamination of Hg and eutrophication. The results indicated that after the application of O2 nanobubbles, the %MeHg (ratio of MeHg to total Hg) in the overlying water and surface sediment decreased by up to 76% and 56% respectively. In addition, the MeHg concentrations decreased from 0.54 ± 0.15 to 0.17 ± 0.01 ng L-1 in the overlying water and from 56.61 ± 9.23 to 25.48 ± 4.08 ng g-1 in the surface sediment. The decline could be attributed to the alleviation of anoxia and the decrease of labile organic matter and bioavailable Hg. In addition, hgcA gene abundances in the overlying water and surface sediment decreased by up to 69% and 44% after the addition of O2 nanobubbles, as is consistent with MeHg occurrence in such areas. Accordingly, this work proposed a promising strategy of using interfacial oxygen nanobubbles to alleviate the potentially enhanced MeHg production during algal bloom outbreaks in Hg-polluted eutrophic waters.


Assuntos
Mercúrio , Compostos de Metilmercúrio , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Oxigênio
6.
Nanotechnology ; 31(16): 165403, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-31891915

RESUMO

Flexible all-solid-state supercapacitors (ASSSs) have caught the scientific attention to meet the explosive demand for portable and wearable electronic devices. However, it is difficult for flexible electrode materials to obtain a high areal capacitance at a high mass loading, which limits their commercial applications. In this study, vanadium oxide (V2O5) nanoparticles are introduced into Ti3C2 flakes with the aid of cetyltrimethylammonium bromide (CTAB). The intercalation of V2O5 particles in the interlayer of Ti3C2 establishes a hierarchical structure and facilitates the electrolyte penetration. As a result, the prepared CT-Ti3C2@V2O5 composite electrode achieves a high areal capacitance of 2065 mF cm-2 at 3 mA cm-2 and superior active mass loading (15 mg cm-2). Meanwhile, over 93% capacitance is maintained after 6000 cycles at 18 mA cm-2. The ASSS based on CT-Ti3C2@V2O5 delivers a high areal capacitance of 477 mF cm-2 at 1 mV s-1 and exhibits stable performance at different bending states, which reaches to the advanced level for the ASSSs based on MXenes.

7.
J Hazard Mater ; 384: 121248, 2020 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-31585294

RESUMO

Photoelectrocatalytic (PEC) especially continuous flow PEC process for organic wastewater treatment greatly depends on both catalytic capacity and practical availability of electrode materials. In this study, g-C3N4 nanosheets are implanted into TiO2 nanotube arrays mesh (TCNs) through direct calcination of TiO2 nanotube array mesh loading melamine precursor. The TCNs photoelectrodes exhibit excellent PEC activity in organic pollutant degradation. Typically, almost 100% of tetracycline (TC, an emerging refractory antibiotic pollutant) is removed in 2 h and TOC removal reaches to 93% in 3 h under simulated solar irradiation at 1 V vs. Ag/AgCl. Theoretical calculations are performed to predict the primary reactive sites for radical species attack and the intermediates are identified. Meanwhile, the ecotoxicity of TC-containing wastewater greatly decrease after PEC treatment. Impressively, because of the mesh screen effect and high catalytic capacity of the photoelectrode, continuous flow PEC process keeps 80% removal efficiency of TC in real wastewater in the absence of additional background electrolyte. After prolonging 20 h, the level of treatment is highly stable. This work would set an example for potential large-scale treatment of organic wastewater using PEC process.

8.
Ecotoxicol Environ Saf ; 188: 109888, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31706242

RESUMO

Eutrophication can induce hypoxia/anoxia and rich organic matter at the sediment-water interface in surface waters. When eutrophic waters are impacted with mercury (Hg) pollution, methylmercury (MeHg) production ability (MPA) of surface sediment would increase and more MeHg might be produced. To tackle this risk, this study firstly collected samples of surface sediment and overlying water from a typical eutrophic lake-Taihu Lake. Then from a sediment-water simulation system, we demonstrated that eutrophic waters were able to methylate Hg spontaneously, and that sediment is the major Hg sink in the system. After the addition of HgCl2 solution (approximately 1 mg L-1 in the slurry), MeHg concentrations in the sediment increased by 11.7 times after 48 h. The subsequent column experiments proved that O2 nanobubbles could significantly decrease the MPA of surface sediment, by up to 48%. Furthermore, we found that O2 nanobubbles could remediate anoxia mainly by increasing dissolved oxygen (from 0 to 2.1 mg L-1), oxidation-reduction potentials (by 37% on average), and sulfate (by 31% on average) in the overlying water. In addition, O2 nanobubbles could also help decrease organic matter concentration, as was revealed by the decline of dissolved organic carbon in the overlying water (by up to 57%) and total organic carbon in surface sediment (by up to 37%). The remediation of anoxia and reduction of organic matter could contribute to the decrease of hgcA gene abundance (by up to 86%), and thus result in the reduction of MPA after the addition of O2 nanobubbles. This study revealed the risk of MeHg production in case Hg pollution occurs in eutrophic waters and proposed a feasible solution for MeHg remediation.


Assuntos
Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/química , Compostos de Metilmercúrio/química , Oxigênio/química , Poluentes Químicos da Água/química , Eutrofização , Lagos/química , Mercúrio/análise , Mercúrio/química , Compostos de Metilmercúrio/análise , Compostos Orgânicos/análise , Compostos Orgânicos/química , Oxirredução , Oxigênio/análise , Poluentes Químicos da Água/análise
9.
Front Public Health ; 8: 620023, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33553099

RESUMO

The mental health problems might have been increased owing to the COVID-19 pandemic with the commencement of the year 2020, therefore, an epidemiological survey appraising the burden of mental health issues among the general population is imperative. This cross-sectional study attempts to reveal the underlying mental health conditions, such as Post-Traumatic Stress Symptoms (PTSS), depression, and insomnia, relating to the pandemic situation, and to further examine the combined effects of gender and age on the COVID-19 related mental health consequences. An online survey was conducted among 2,992 adults in China from February 1st 2020 to February 10th 2020. The study uses binary logistic regression to analyze the potential factors associated with PTSD, depression, and insomnia. The results indicate that the prevalence of PTSS, depression, and insomnia are 19.5, 26.9, and 19.6% respectively during the COVID-19. Men and women show different rates of PTSS and depression, whereas no insomnia is found in both males and females. The females above 50 years of age have a lower level of depressive symptoms (OR = 0.448, 95%CI: 0.220-0.911, Cohen's d = -0.443) as compared with females aged 18-25; while the highest effect sizes for PTSS (OR = 2.846, 95%CI: 1.725-4.695, Cohen's d = 0.537) and the depression (OR = 2.024, 95%CI: 1.317-3.111, Cohen's d = 0.314) are seen in males aged 26 to 30. Besides gender, education, living conditions, direct exposure to COVID-19, the post mental and the physical health condition is related to PTSS, depression, and insomnia. Our study suggests that high-risk groups, especially those having two or more related factors and young men, should be the focus of mental health intervention.


Assuntos
/epidemiologia , Depressão/epidemiologia , Distúrbios do Início e da Manutenção do Sono/epidemiologia , Transtornos de Estresse Pós-Traumáticos/epidemiologia , Adulto , Fatores Etários , China/epidemiologia , Estudos Transversais , Surtos de Doenças , Feminino , Humanos , Masculino , Saúde Mental , Pessoa de Meia-Idade , Prevalência , Fatores Sexuais , Inquéritos e Questionários , Adulto Jovem
10.
Environ Sci Technol ; 53(24): 14612-14619, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31738519

RESUMO

Removal of uranium from groundwater is of great significance as compared to in situ bioimmobilization technology. In this study, a novel direct electro-reductive method has been developed to efficiently remove and recover uranium from carbonate-containing groundwater, where U(VI)O2(CO3)34- and Ca2U(VI)O2(CO3)3 are the dominant U species. The transferred electron calculations and XPS, XRD analyses confirmed that U(VI) was reduced to U(IV)O2 and accumulated on the surface of the Ti electrode (defined as Ti@U(IV)O2 electrode) with high current efficiencies (over 90.0%). Moreover, over 98.0% of the accumulated U(IV)O2 could be recovered by soaking the Ti@U(IV)O2 electrode in the dilute nitric acid. Results demonstrated that the accumulated U(IV)O2 on the surface of the Ti electrode played a key role in the removal of U(VI), which can promote the electro-reduction of U(VI). Therefore, the electrode could be used repeatedly and has a high removal capacity of U(VI) due to the continuous accumulation of active U(IV)O2 on the surface of the electrode. Significantly, the uranium in both real and high salinity groundwater can be efficiently removed. This study implies that the proposed direct electro-reductive method has great potential for the removal and recovery of uranium from groundwater and uranium-containing wastewater.


Assuntos
Água Subterrânea , Urânio , Poluentes Radioativos da Água , Eletrodos , Oxirredução
11.
Water Res ; 167: 115107, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31563708

RESUMO

Although Fe-based biochar adsorbents are attractive for removing arsenic from water due to their advantages of costing little and being producible at a large scale, the practical applications of these granular adsorbents are mainly limited by low Fe utilization and slow adsorption kinetics. In this study, iron oxide nanoneedle array-decorated biochar fibers (Fe-NN/BFs) adsorbents have been prepared through a simple hydrothermal reaction. The vertical growth of iron oxide nanoneedle arrays on the surface of biochar fibers maximizes Fe utilization and shortens As diffusion distance, thereby increasing As removal kinetics and capacity. Batch experiments show that the adsorption capacities of Fe-NN/BFs for As(V) and As(III) reach to 93.94 and 70.22 mg/g-Fe at pH 7.0, respectively. As(V) levels (275 µg/L) in groundwater are rapidly reduced (less than 5 min) to below 10 µg/L using Fe-NN/BFs (1 g/L) at pH 6.7. Similar As(III) levels can be reduced to below 10 µg/L within 30 min by Fe-NN/BFs (1.5 g/L). In fixed-bed experiments, the treatment volumes of As(V) and As(III) spiked groundwater reach to 2900 BV (26.2 L) and 2500 BV (22.6 L), respectively, using two columns packed with Fe-NN/BFs in tandem (C0 = 275 µg/L, 2 g of adsorbents in each column). When the As concentration in the influent is reduced to 50 µg/L (As(V): 25 µg/L + As(III): 25 µg/L), the treatment volume using one column reaches up to 11000 BV. The Fe-NN/BFs packed column can be easily regenerated and reused many times. After four regenerations, the treatment volume of As(V) and As(III) were reduced by 10.4% and 22.8%, respectively.


Assuntos
Arsênico , Água Subterrânea , Poluentes Químicos da Água , Purificação da Água , Adsorção , Carvão Vegetal , Compostos Férricos , Cinética
12.
Biosens Bioelectron ; 145: 111711, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31563801

RESUMO

Although aptamer has been demonstrated as an important probe for antibiotic determination, the selective sensing of different antibiotics is still a challenge due to their structure similarities and wide folding degrees of aptamer. Herein, a field-effect transistor using MoS2 nanosheet as the channel and an aptamer DNA (APT) with its configuration shaped by a complementary strand DNA (CS) is employed for kanamycin (KAN) determination. This probe structure contributes to an enhanced selectivity and reliability with reduced device-to-device variations. This MoS2/APT/CS sensor shows time-dependent performance in antibiotic sensing. Prolonged detection time (20 s-300 s) leads to an enhanced sensitivity (1.85-4.43 M-1) and a lower limit of detection (1.06-0.66 nM), while a shorter detection time leads to a broader linear working range. A new sensing mechanism relying on charge release from probe is proposed, which is based on the "replacement reaction" between KAN and APT-CS. This sensor exhibits an extremely high selectivity (selectivity coefficient of 12.8) to kanamycin over other antibiotics including streptomycin, tobramycin, amoxicillin, ciprofloxacin and chloramphenicol. This work demonstrates the merits of probe engineering in label-free antibiotic detection with FET sensor, which presents significant promises in sensitive and selective chemical and biological sensing.


Assuntos
Antibacterianos/isolamento & purificação , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais , Leite/química , Animais , Antibacterianos/química , Bovinos , Cloranfenicol/química , Cloranfenicol/isolamento & purificação , DNA Complementar/química , Dissulfetos/química , Ouro/química , Humanos , Canamicina/química , Canamicina/isolamento & purificação , Nanopartículas Metálicas/química , Molibdênio/química , Estreptomicina/química , Estreptomicina/isolamento & purificação , Tobramicina/química , Tobramicina/isolamento & purificação
13.
Environ Sci Technol ; 53(20): 11932-11940, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31497953

RESUMO

Efficient elimination of antibacterial activity of halogenated antibiotics by dehalogenation pretreatment is desired for a biochemical treatment process. In this study, crystalline cobalt phosphide nanosheet arrays on a Ti plate (C-CoP/Ti) are fabricated by a simple electrodeposition and phosphorization process. The crystalline structure greatly promotes atomic hydrogen (H*) generation. Moreover, the nanosheet arrays can provide abundant active sites and accelerate electron transfer and mass transport. As a result, the dehalogenation rate of florfenicol (FLO, an emerging organic pollutant) on C-CoP/Ti is 11.1, 2.97, and 13.6 times higher than that on amorphous CoP/Ti, Pd/Ti, and bare Ti, respectively. The C-CoP/Ti electrode achieves 97.4% dehalogenation of FLO (20 mg L-1) within 30 min at -1.2 V (vs Ag/AgCl). Nearly 100% of Cl and 20% of F are broken away within 120 min, showing the highest electrocatalytic defluorination efficiency reported so far. Both experimental results and theoretical calculations reveal that the dehalogenation of FLO on C-CoP/Ti is synergistically accomplished via direct reduction of electron transfer and indirect reduction of H*. This study develops a highly efficient non-noble metal electrode material for dehalogenation of halogenated organic compounds.


Assuntos
Tianfenicol , Eletrodos , Halogenação , Tianfenicol/análogos & derivados , Titânio
14.
Water Res ; 159: 102-110, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31082641

RESUMO

Benzophenone derivatives, including benzophenone-1 (C13H10O3, BP1), benzophenone-3 (C14H12O3, BP3) and benzophenone-8 (C14H12O4, BP8), that used as UV filters are currently viewed as emerging contaminants. Degradation behaviors on co-exposure benzophenone derivatives using UV-driven advanced oxidation processes under different aqueous environments are still unknown. In this study, the degradation behavior of mixed benzophenone derivatives via UV/H2O2 and UV/peroxydisulfate (PDS), in different water matrices (surface water, hydrolyzed urine and seawater) were systematically examined. In surface water, the attack of BP3 by hydroxyl radicals (HO∙) or carbonate radicals (CO3∙-) in UV/H2O2 can generate BP8, which was responsible for the relatively high degradation rate of BP3. Intermediates from BP3 and BP8 in UV/PDS were susceptible to CO3∙-, bringing inhibition of BP1 degradation. In hydrolyzed urine, Cl- was shown the negligible effect for benzophenone derivatives degradation due to low concentration of reactive chlorine species (RCS). Meanwhile, BP3 abatement was excessively inhibited during co-exposure pattern. In seawater, non-first-order kinetic behavior for BP3 and BP8 was found during UV/PDS treatment. Based on modeling, Br- was the sink for HO∙, and the co-existence of Br- and Cl- was the sink for SO4∙-. The cost-effective treatment toward target compounds removal in different water matrices was further evaluated using EE/O. In most cases, UV/H2O2 process is more economically competitive than UV/PDS process.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Benzofenonas , Peróxido de Hidrogênio , Cinética , Oxirredução , Raios Ultravioleta , Água
15.
Environ Sci Pollut Res Int ; 26(17): 17707-17718, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31028624

RESUMO

Methylmercury (MeHg) in sediment is difficult to be determined due to its low concentration and binding compounds like sulfide and organic matter. Moreover, wet sediment samples have been suggested to behave differently from certified reference materials in MeHg analysis. Optimal pretreatment procedure for MeHg determination in sediments has not been ascertained and whether the procedure could apply to sediment samples with complex matrix merits further research. This work firstly compared recovery results of five pretreatment procedures for MeHg determination using ERM-CC580. Using the optimal pretreatment procedure, recovery results were analyzed in different sediment samples after manipulation of moisture content, organic matter, and acid volatile sulfide. The procedure using CuSO4/HNO3 as leaching solutions and mechanical shaking as extraction method was proved to produce the most satisfactory recovery results (100.67 ± 6.75%, mean ± standard deviation). And when moisture content varied from 20 to 80%, average recovery results in sediment samples ranged from 100 to 125%. Furthermore, before and after the manipulation of organic matter or acid volatile sulfide, spiking recovery results varied little and were all within acceptable limit (85~105%). Therefore, the procedure of CuSO4/HNO3-mechanical is proposed as a universal pretreatment method for MeHg determination in sediment samples with various characteristics.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Compostos de Metilmercúrio/análise , Poluentes Químicos da Água/análise , Mercúrio/análise
16.
J Hazard Mater ; 373: 97-105, 2019 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-30904817

RESUMO

Although Fe-chitosan adsorbents are attractive for removing arsenite from water, the practical applications of these granular adsorbents are mainly limited by slow adsorption kinetics. In this study, radially porous Fe-chitosan beads (P/Fe-CB) were prepared using freeze-casting technique. The P/Fe-CB particles possess radially aligned micron-sized tunnels from the surface to the inside as well as excellent acid resistance. Kinetic studies show that the adsorption equilibrium time of P/Fe-CB to 0.975 mg/L As(III) (within 240 min) is considerably shorter than that of compact Fe-chitosan beads (over 600 min). The maximal adsorption capacity of P/Fe-CB for As(III) is 52.7 mg/g. It can work effectively in a wide pH range from 3 to 9, and the coexisting sulfate, carbonate, silicate and humic acid have no significant effect on As(III) removal. The addition of H2O2 can further accelerate and promote the As(III) removal except at high pH (11) and phosphate concentration (50 mg/L). The fixed-bed experiments demonstrate that the P/Fe-CB column can effectively treat about 3000 bed volume (BV) of simulated As(III)-containing groundwater to meet the drinking water standard (<10 µg As/L). This study would extend the potential applicability of porous Fe based chitosan adsorbent and millimeter-sized adsorbent combined with H2O2 to a great extent.

17.
Chemosphere ; 222: 258-266, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30708160

RESUMO

Bulk adsorbents for fast and deep removal of arsenic in water is highly demanded for practical treatment process, especially fixed-bed column process. In this study, a superior bulk adsorbent of porous Fe2O3 nanocubes-impregnated porous graphene aerogel (PGA/PFe2O3) is prepared using a simple template engineering. The maximum capacity for As(III) and As(V) reaches as high as 172.27 and 217.34 mg g-1 of Fe2O3, respectively. The adsorption equilibrium times of As(III) and As(V) on PGA/PFe2O3 are only 30 and 5 min, respectively (m/V = 0.5 g L-1, C0 = 5 mg L-1). Significantly, the high concentrations of As(III) and As(V) can be reduced below 10 µg L-1 within only 60 and 5 min, respectively. The aerogel is conducive to fast diffusion of arsenic and porous Fe2O3 nanocubes provide abundant adsorption sites. Moreover, the adsorbent exhibits an outstanding reusability. The adsorbent also shows a strong anti-interference to aquatic environment. A real realgar tailing wastewater (C0 = 3.076 mg L-1 for As(III) and 3.225 mg L-1 for As(V)) can be deep treated (below 10 µg L-1) within 4 h (m/V = 0.6 g L-1). The bulk adsorbent of PGA/PFe2O3 presents a high column treatment capacity of arsenic-containing groundwater (4750 BV for As(III), 5730 BV for As(V)), producing only 12 BV eluent. This work develops a superior bulk adsorbent for large-scale treatment of arsenic-containing wastewater.


Assuntos
Arsênico/isolamento & purificação , Compostos Férricos/química , Grafite/química , Águas Residuárias/química , Purificação da Água/métodos , Adsorção , Difusão , Porosidade , Poluentes Químicos da Água/isolamento & purificação
18.
J Colloid Interface Sci ; 533: 95-105, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30149224

RESUMO

Exploring and designing an efficient and robust photocatalyst toward the degradation of organic pollutants under nature sunlight irradiation is a challenging research topic. The ability to maintain the photocatalytic activity in the entire daytime will be the ultimate goal for further widespread application of solar energy-driven semiconductor photocatalysis. Here, an all-day-active Z-scheme photocatalytic system is reported by employing Ag@AgI nanoparticles decorated Ag3PO4 cubes (C-Ag3PO4@Ag@AgI). By coupling the pronounced carrier separation as well as increased stability, the C-Ag3PO4@Ag@AgI is capable of performing efficient Rhodamine B (RhB) and bisphenol A (BPA) degradation under sunlight irradiation, and still persist noticeable activity when the light is very weak. The RhB (20 mg/L, 50 mL) can be completely degraded by C-Ag3PO4@Ag@AgI (30 mg) within 1 h with the average luminous power of 117.5 mW (3.14 cm2). Dramatically, the as-prepared samples can still maintain photocatalytic activity even in a cloudy day (0.2-6.7 mW). This work has offered a valuable concept of continuous pollutant removal under nature sunlight irradiation in the entire daytime, which may serve as a model system for the wide environment applications, such as the removal of low-level pollutants under weak light irradiation.

19.
Water Res ; 150: 182-190, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30513412

RESUMO

Although oxidation of As(III) to As(V) is deemed necessary to promote arsenic removal, the oxidation process usually involves toxic byproducts, well-defined conditions, energy input or sludge generation. Moreover, extra operations are required to remove the resulting As(V). A heterogeneous catalytic process of CuFe2O4 with peroxymonosulfate (PMS) is established for As(III) oxidation and adsorption. The PMS can be activated by CuFe2O4 to generate radical species for As(III) oxidation. The CuFe2O4/PMS has a stronger affinity for arsenic than CuFe2O4 alone. Oxidation and adsorption promote each other. As a result, the heterogeneous catalytic process is more efficient for As(III) removal than a preoxidation of As(III) followed by adsorption. The adsorption capacity for As on CuFe2O4/PMS reached up to 63.9 mg/g, which is much higher than that of As(III) (36.9 mg/g) or As(V) (45.4 mg/g) on CuFe2O4 alone. The process can work effectively over a wide range of pH values (3-9) and temperatures (10-40 °C). Coexisting ions such as sulfate, carbonate, silicate and humic acid have an insignificant effect on As(III) removal. The As(III) (1415 µg/L) can be completely oxidized to As(V) and rapidly removed to below 10 µg/L (less than 15 min) using CuFe2O4(0.2 g/L)/PMS(100 µM). Moreover, the As(III) (50 µg/L) can be completely oxidized and removed within 1 min. The proposed process is easily applicable for the remediation of As(III)-contaminated water under ambient conditions.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Adsorção , Concentração de Íons de Hidrogênio , Oxirredução , Peróxidos , Água
20.
Front Psychol ; 9: 2197, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30487768

RESUMO

Using the conservation of resources theory and social exchange theory as our conceptual frameworks, the current study examined how employee surface acting relates to their sabotage to customers through the mediating role of emotional exhaustion and explored the moderating roles of coworker exchange (CWX) and leader-member exchange (LMX). We collected two-wave time-lagged data from 540 clinical nurses and found that emotional exhaustion mediated the positive relationship between surface acting and employee sabotage to customers. In addition, we found that CWX buffered the positive effect of surface acting on emotional exhaustion, while LMX buffered the positive effect of emotional exhaustion on employee sabotage to customers, such that the effects were weaker when CWX and LMX were higher, respectively. These findings shed light on the effect of surface acting on employee harmful behaviors, the potential underlying mechanism, and boundary conditions to mitigate the negative consequences of surface acting.

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