A novel Ag/ZnO core-shell structure for efficient sterilization synergizing antibiotics and subsequently removing residuals

The massive use of antibiotics has led to the aggravation of bacterial resistance and also brought environmental pollution problems.This poses a great threat to human health.If the dosage of antibiotics is reduced by increasing its bactericidal performance,the emergence of drug resistance is certainly delayed,so that there's not enough time for developing drug resistance during treatment.Therefore,we selected typical representative materials of metal Ag and semiconductor ZnO nano-bactericides to design and synthesize Ag/ZnO hollow core-shell structures(AZ for short).Antibiotics are grafted on the surface of AZ through rational modification to form a composite sterilization system.The research results show that the antibacterial efficiency of the composite system is significantly increased,from the sum(34.7%+22.8%-57.5%)of the antibacterial efficiency of AZ and gentamicin to 80.2%,net synergizes 22.7%,which fully reflects the effect of 1+1>2.Therefore,the dosage of antibiotics can be drastically reduced in this way,which makes both the possibility of bacterial resistance and medical expenses remarkably decrease.Subsequently,residual antibiotics can be degraded under simple illumination using AZ-self as a photocatalyst,which cuts off the path of environmental pollution.In short,such an innovative route has guiding significance for drug resistance.

MXene:From synthesis to environment remediation

A new burgeoning family of two-dimensional(2D)transition metal carbides/nitrides,better known as MXenes,have received extensive attention because of their distinct properties,such as metallic conductivity,good hydrophilicity,large surface area,good mechanical stability,and biodegradability.About 40 different MXenes have been synthesized,and dozens more structures and properties have been theoretically predicted.However,the recent progress in MXenes development is not well covered in chronological order based on different applications.This review article focuses on emerging synthesis methods,the properties of MXenes,and mainly the applications of MXenes and MXene-based material family in environmental remediation,a comprehensive review of gaseous and aqueous pollutants treatment.

Oxidation of Partially Hydrolyzed Polyacrylamide from Polymer Flooding Processes Using Fenton Reagents

The degradation of partially hydrolyzed polyacrylamide(HPAM) found in alkaline/surfactant/polymer flooding sewage was investigated using Fenton-type reagents. Different Fenton reagent treatments for HPAM degradation were compared. The effects of pH, hydrogen peroxide(H_(2)O_(2)), ferrous ion(Fe^(2+)), and tartaric ion(C_(4)H_(4)O_(6)^(2-)) concentrations were studied. The degradation reaction occurred within a wide range of pH(3–9). The HPAM degradation performance of photo-Fenton processes using solar light and UV were compared with that of the Fenton process. The degradation rate was found to be strongly dependent on the H_(2)O_(2)/Fe^(2+)/C_(4)H_(4)O_(6)^(2-)molar ratio. The HPAM degradation efficiency was 90%, and the chemical oxygen demand removal efficiency was 85%. HPAM could be degraded into a compound with a lower molecular weight, but it was difficult to achieve complete mineralization to CO_(2). The presence of intermediate products hindered further oxidation in the Fenton process.

Green synthesis of three-dimensional magnesium ferrite/titanium dioxide/reduced graphene from Garcinia mangostana extract for crystal violet photodegradation and antibacterial activity

In this study,three-dimensional porous magnesium ferrite/titanium dioxide/reduced graphene oxide(Mg Fe_2O_(4)-GM/TiO_(2)/rGO(MGTG))was successfully synthesized via green and hydrothermal-supported co-precipitation methods using the extract of Garcinia mangostana(G.mangostana)as a reducing agent.The characterization results indicate the successful formation of the nano/micro Mg Fe_(2)O_(4)(MFO)and TiO_(2) on the structure of the reduced graphene oxide(rGO),which can also act as efficient support,alleviating the agglomeration of the nano/micro MFO and TiO_(2).The synergic effects of the adsorption and photodegradation activity of the material were investigated according to the removal of crystal violet(CV)under ultraviolet light.The effects of catalyst dosage,CV concentration,and p H on the CV removal efficiency of the MGTG were also investigated.According to the results,the CV photodegradation of the MGTG-200 corresponded to the pseudo-first-order kinetic model.The reusability of the material after 10 cycles also showed a removal efficiency of 92%.This happened because the materials can easily be recollected using external magnets.In addition,according to the effects of different free radicals·O_(2)^(-),h^(+),and·OH on the photodegradation process,the photocatalysis mechanism of the MGTG was also thoroughly suggested.The antibacterial efficiency of the MGTG was also evaluated according to the inhibition of the Gram-positive bacteria strain Staphylococcus aureus(S.aureus).Concurrently,the antibacterial mechanism of the fabricated material was also proposed.These results confirm that the prepared material can be potentially employed in a wide range of applications,including wastewater treatment and antibacterial activity.

Enhanced visible-light photocatalytic activity of Z-scheme graphitic carbon nitride/oxygen vacancy-rich zinc oxide hybrid photocatalysts

With the objectives of enhancing the stability,optical properties and visible-light photocatalytic activity of photocatalysts,we modified oxygen vacancy-rich zinc oxide（Vo-ZnO） with graphitic carbon nitride（g-C3N4）. The resulting g-C3N4/Vo-ZnO hybrid photocatalysts showed higher visible-light photocatalytic activity than pure Vo-ZnO and g-C3N4. The hybrid photocatalyst with a g-C3N4 content of 1 wt% exhibited the highest photocatalytic degradation activity under visible-light irradiation（λ≥ 400 nm）. In addition,the g-C3N4/Vo-ZnO photocatalyst was not deactivated after five cycles of methyl orange degradation,indicating that it is stable under light irradiation. Finally,a Z-scheme mechanism for the enhanced photocatalytic activity and stability of the g-C3N4/Vo-ZnO hybrid photocatalyst was proposed. The fast charge separation and transport within the g-C3N4/Vo-ZnO hybrid photocatalyst were attributed as the origins of its enhanced photocatalytic performance.

Fabrication and photodegradation properties of TiO_2 nanotubes on porous Ti by anodization

Both Ti foil and porous Ti were anodized in 0.5%HF and in ethylene glycol electrolyte containing 0.5%NH4F(mass fraction) separately. The results show that TiO2 nanotubes can be formed on Ti foil by both processes, whereas TiO2 nanotubes can be formed on porous Ti only in the second process. The overhigh current density led to the failure of the formation nanotubes on porous Ti in 0.5%HF electrolyte. TiO2 nanotubes were characterized by SEM and XRD. TiO2 nanotubes on porous Ti were thinner than those on Ti foil. Anatase was formed when TiO2 nanotubes were annealed at 400 °C and fully turned into rutile at 700 °C. To obtain good photodegradation, the optimal heat treatment temperature of TiO2 nanotubes was 450 °C. The porosity of the substrates influenced photodegradation properties. TiO2 nanotubes on porous Ti with 60% porosity had the best photodegradation.

Microwave-hydrothermal preparation of flower-like ZnO microstructure and its photocatalytic activity

The flower-like ZnO microstructure was prepared by a straightforward microwave-hydrothermal technique using zinc chloride and arginine solution as reactants. The as-synthesized crystal structure and morphology were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and the optical properties of the ZnO nanostructure were studied by Raman and photoluminescence （PL） spectra, which confirms the high crystal quality of ZnO microstructure. The as-synthesized ZnO flowers exhibit a significant enhancement of photocatalytic capability toward degrading methyl blue （MB） under UV light, the photodegradation of MB reaches 95.60%, only within 2 h of adding the as-synthesized ZnO in the MB solution under UV irradiation. Furthermore, the photodegradation could be described as the pseudo-first-order kinetics with degradation rate constant of 1.0675-1.6275 h-1, which is relative to the morphology of the structures.

Characterization of V_2O_5/MoO_3 composite photocatalysts prepared via electrospinning and their photodegradation activity for dimethyl phthalate

Vanadium pentoxide（V2O5）/molybdenum trioxide（MoO 3） composites with different molar ratios of vanadium（V） to molybdenum（Mo） were synthesized via a simple electrospinning technique. The photocatalytic activity of the composites were evaluated by their ability to photodegrade methylene blue and dimethyl phthalate（DMP） under visible-light irradiation. Compared with pure V2O5 and MoO 3,the V2O5/MoO 3 composites showed enhanced visible-light photocatalytic activity because of a V 3d impurity energy level and the formation of heterostructures at the interface between V2O5 and MoO 3. The optimal molar ratio of V to Mo in the V2O5/MoO 3 composites was found to be around 1/2. Furthermore,high-performance liquid chromatographic monitoring revealed that phthalic acid was the main intermediate in the photocatalytic degradation process of DMP.

Fabrication and Photocatalysis of TiO2 Flower-like Nanostructures

TiO2 nanostructures were fabricated by a reaction of Ti foils in H2O2 solution at mild temperature, Porous TiO2 nanostructurcs, well adhered to Ti foil surfaces, were formed at 80 ℃ in 10 rain, and then flower- like and rod nanostructures formed in succession after a longer reaction time. Samples prepared at 80 ℃ for 4 h arc amorphous, and anatase-dominated crystal phase emerged in the sample prepared for as long as 10 h. Almost pure anatase phase were obtained in TiO2 nanostructures by annealing the samples at a temperature of 300 ℃. Photoeatalysis of the TiO2 nanostructures was characterized by the degradation of RhB dye molecules in an aqueous solution exposed to ultraviolet light. Results show a 7 cm^2 annealed TiO2 flower-like nanostrueture having the degradation rate of RhB as fast as 29.8 times that of the dye solution exposed to ultraviolet light alone.

Aqueous oxytetracycline degradation and the toxicity change of degradation compounds in photoirradiation process

The extensive use of antibiotics has been a worldwide environmental issue.In this study the fate of oxytetracycline (OTC),under photoirradiation,was investigated.The results showed that OTC photolysis followed first order model kinetics.Direct photolysis rate was found to be dependent on the initial OTC concentration,with k value ranging from 0.0075 to 0.0141 min^(-1),in the OTC concentration from 40 to 10 mg/L.OTC photolysis was highly pH-dependent and strongly enhanced at a high pH value,with a k value of...

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper （Cu） ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied. Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time, the analysis of the extracts from the soil was carded out using gas chromatography （GC）. The photodegradation of pyrethroids in water system was conducted under UV irradiation. The effect of Cu^2＋ on the pesticides degradation was measured with half life 00.5） of degradation. It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed. But Cu^2＋ could accelerate photodegradation of the pyrethroids in water. The t0.5 for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil. As for photodegradation, t0.5 for cyhalothrin reduced from 173.3 to 115.5 min and for cypermethrin from 115.5 to 99.0 min. The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms. However, it had catalyst tendency for photodegradation in water system. The difference for the degradation efficiency of pyrethroid isomers in soil was also observed. Copper could obviously accelerate the degradation of some special isomers.

氧化铈纳米粒子光催化降解亚甲基蓝的动力学和机理(英文)

CeO2 nanocrystals were synthesized by a simple precipitation method and calcination at 600℃.(NH4)2Ce(NO3)6 and ammonia were used as precursors.The CeO2 nanoparticles were characterized by X-ray diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,and N2 adsorption.The photodegradation of methylene blue catalyzed by CeO2 nanoparticles was studied under UV and sunlight irradiation.The highest degradation was obtained with 1.0 g/L CeO2 at pH 11 within 125 min.The pseudo first order rate constants of dye bleaching were calculated as 16.2×10-3 and 15.7×10-3 min-1 under UV and sunlight irradiation,respectively.The effect of iso-PrOH,iodide ion,and H2O2 was studied to predict the pathway of dye degradation.The obtained results indicate the effect of photogenerated holes in the degradation mechanism of the dye.Also,the photocatalytic activity of the prepared photocatalyst was studied in the presence of several negative ions.

Formation of BiOI/g-C_3N_4 nanosheet composites with high visible-light-driven photocatalytic activity

Constructing binary heterojunctions is an important strategy to improve the photocatalytic performance of graphitic carbon nitride(g‐C3N4).In this paper,a novel g‐C3N4 nanosheet‐based composite was constructed via in situ growth of bismuth oxyiodide(BiOI)nanoplates on the surface of g‐C3N4 nanosheets.The crystal phase,microstructure,optical absorption and textural properties of the synthesized photocatalysts were analyzed by X‐ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),ultraviolet‐visible(UV‐vis)diffuse reflectance spectroscopy(DRS),and nitrogen adsorption‐desorption isotherm measurements.The BiOI/g‐C3N4 nanosheet composite showed high activity and recyclability for the photodegradation of the target pollutant rhodamine B(RhB).The conversion of RhB(20 mg L?1)by the photocatalyst was nearly 100%after 50 min under visible‐light irradiation.The high photoactivity of the BiOI/g‐C3N4 nanosheet composite can be attributed to the enhanced visible‐light absorption of the g‐C3N4 nanosheets sensitized by BiOI nanoplates as well as the high charge separation efficiency obtained by the establishment of an internal electric field between the n‐type g‐C3N4 and p‐type BiOI.Based on the characterization and experimental results,a double‐transfer mechanism of the photoinduced electrons in the BiOI/g‐C3N4 nanosheet composite was proposed to explain its activity.This work represents a new strategy to understand and realize the design and synthesis of g‐C3N4 nanosheet‐based heterojunctions that display highly efficient charge separation and transfer.

Photochemical behavior of benzo[a]pyrene on soil surfaces under UV light irradiation

The rates of photodegradation and photocatalysis of benzo [a]pyrene （BaP） on soil surfaces under UV light have been studied. Different parameters such as temperature, soil particle sizes, and soil depth responsible for photodegradation, catalyst loads and wavelength of UV irradiation blamed for photocatalysis have been monitored. The results obtained indicated that BaP photodegradation follows pseudo-first-order kinetics. BaP photodegradation was the fastest at 30℃ . The rates of BaP photodegradation at different soil particle size followed the order： less than 1 mm〉less than 0.45 mm〉less than 0.25 mm. When the soil depth increased from 1 mm to 4 ram, the half-life increased from 13.23 d to 17.73 d. The additions of TiO2 or Fe2O3 accelerated the photodegradation of BaP, and the photocatalysis of BaP follows pseudo-first-order kinetics. Changes in catalyst loads of TiO2 （0.5%, 1%, 2%, and 3% （wt）） or Fe203 （2%, 5%, 7%, and 10% （wt）） did not significantly affect the degradation rates. Both BaP photocatalysis in the presence of TiO2 and Fe2O3 were the fastest at 254 nm UV irradiation.

MoO_3-TiO_2纳米晶体复合材料光降解糖蜜(英文)

A MoO3-TiO2 nanocrystalline composite material was prepared by a simple solgel method.The synthesized material was charac-terized by X-ray diffraction,scanning electron microscopy with an electron dispersion spectroscopy,transmission electron microscopy,and Fourier transform infrared spectroscopy.Melanoidin is a dark brown pigment found in wastewater from the sugar industry and it pollutes water.This polluted water is generally referred to as molasses and it undergoes fermentation and is solely responsible for water,soil,and air pollution.The synthesized catalytic material was found to be effective in degrading molasses under UV-visible radiation.Analysis of treated and untreated molasses was carried out by measuring its color,chemical oxygen demand,biological oxygen demand,pH,and total dissolved solid.Results from these analyses indicate the effective photodegradation of the molasses.This methodology has several advantages such as high photocatalytic activity,non-toxicity,cleanliness,and reusability of the catalytic material.

Mechanism study on UV-induced photodegradation of nonylphenol ethoxylates by intermediate products analysis

Photodegradation of nonylphenol ethoxylates （NPloEO） was investigated in laboratory scale under UV irradiation. The intermediate photodegradation products were analyzed by LC-ESI-MS. Three kinds of intermediate products including aldehydic compounds, carboxylic compounds and cyclohexanyl compounds were identified. Five main degradation routes involving the oxidation of the alkyl chain and ethoxylate unit, shortening of the alkyl chain and ethoxylate unit, hydrogenation of the benzene ring were proposed.

Sn/n3O4-x heterostructure rich in oxygen vacancies with enhanced visible light photocatalytic oxidation performance

Sn3O4, a common two-dimensional semiconductor photocatalyst, can absorb visible light.However, owing to its rapid recombination of photogenerated electron-hole pairs, its absorption is not sufficient for practical application.In this work, a Sn nanoparticle/Sn3O4-x nanosheet heterostructure was prepared by in situ reduction of Sn3O4 under a H2 atmosphere.The Schottky junctions formed between Sn and Sn3O4-x can enhance the photogenerated carrier separation ability.During the hydrogenation process, a portion of the oxygen in the semiconductor can be extracted by hydrogen to form water, resulting in an increase in oxygen vacancies in the semiconductor.The heterostructure showed the ability to remove Rhodamine B.Cell cytocompatibility experiments proved that Sn/Sn3O4-x can significantly enhance cell compatibility and reduce harm to organisms.This work provides a new method for the fabrication of a Schottky junction composite photocatalyst rich in oxygen vacancies with enhanced photocatalytic performance.

Photoreductive degradation of sulfur hexafluoride in the presence of styrene

Sulfur hexafluoride （SF6） is known as one of the most powerful greenhouse gases in the atmosphere. Reductive photodegradation of SF6 by styrene has been studied with the purpose of developing a novel remediation for sulfur hexafluoride pollution. Effects of reaction conditions on the destruction and removal efficiency （DRE） of SF6 are examined in this study. Both initial styrene-to-SF6 ratio and initial oxygen concentration exert a significant influence on DRE. SF6 removal efficiency reaches a maximum value at the initial styrene-to-SF6 ratio of 0.2. It is found that DRE increases with oxygen concentration over the range of 0 to 0.09 mol/m^3 and then decreases with increasing oxygen concentration. When water vapor is fed into the gas mixture, DRE is slightly enhanced over the whole studied time scale. The X-ray Photoelectron Spectroscopy （XPS） analysis, together with gas chromatography-mass spectrometry （GC-MS） and Fourier Transform Infrared spectroscopy （FT-IR） analysis, prove that nearly all the initial fluorine residing in the gas phase is in the form of SiF4, whereas, the initial sulfur is deposited in the form of elemental sulfur, after photodegradation. Free from toxic byproducts, photodegradation in the presence of styrene may serve as a promising technique for SF6 abatement.

Photodegradation of acetochlor in water and UV photoproducts identified by mass spectrometry

The sunlight photodegradation half-lives of 20 mg/L acetochlor were 151, 154 and 169 days in de-ionized water, river water and paddy water, respectively. When exposed to ultraviolet (UV) light, acetochlor in aqueous solution was rapidly degraded. The half-lives were 7.1, 10.1, and 11.5 min in de-ionized water, river water and paddy water, respectively. Photoproducts of acetochlor were identified by gas chromatography/mass spectrometry(GC/MS) and found at least twelve photoproducts resulted from dechlorination with subsequent hydroxylation and cyclization processes. The chemical structures of ten photoproducts were presumed on the basis of mass spectrum interpretation and literature data. Photoproducts are identified as 2-ethyl-6-methylaniline; N,N-diethylaniline; 4,8-dimethyl-2-oxo-1,2,3,4- tetrahydroquino-line; 2-oxo-N-(2-ethyl-6-methylphenyl)-N-(ethoxymethyl)acetamide; N-(ethoxymethyl)-2′-ethyl-6′-methylformanilide;1-hydroxyacetyl-2-ethoxyl-7-ethylind ole; 8-ethyl-1-ethoxymethyl-2-oxo-1,2,3,4-tetrahydroquinoline; 4,8-dimethyl-1-ethoxymethyl-2-oxo-1,2,3,4-tetrahydroquinoline; 2-hydroxy-2′-ethyl-6′-methyl-N-(ethoxymethyl)acetanilide and a compound related to acetochlor. The other two photoproducts were detected by GC/MS although their chemical structure was unknown.

Calculation method of quantum efficiency to TiO_2 nanocrystal photocatalysis reaction

The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to the TiO 2/UV photocatalysis system. Furthermore, for the immobility system (IS), the formulation of the faction of light absorbed by the TiO 2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity (T). For the suspension system(SS), due to the difficulty to obtain the absorption coefficient ( α ) of TiO 2 particulates, the quantum efficiency is calculated by means of the relative photonic efficiency ( ζ r) and the standard quantum yield ( Φ standard ).