Solvothermal synthesis of EDTA-functionalized magnetite-carboxylated graphene oxide nanocomposite as a potential magnetic solid phase extractor of p-phenylenediamine from environmental samples

The use of carboxylated graphene oxide (CGO) in the removal of organic pollutants from aquatic life is a recent and significant issue. In this study, EDTA-functionalized magnetite-carboxylated graphene oxide nanocomposite (EDTA-MCGO) was first used for the adsorptive removal of p-phenylenediamine (PDA) from industrial wastewaters. Based on the great surface area of the magnetic nanocomposite and the huge number of carboxyl groups from CGO and EDTA, multiple interactions to adsorb PDA can be anticipated. The maximum adsorption capacity of EDTA-MCGO was 994.75?mg g^?1 at pH 7.8 and this value was decreased to 94.7% after seven cycles. The adsorption process was spontaneous and fits the pseudo-second-order kinetic model. PDA strongly deposited on the EDTA-MCGO surface via different electrostatic interactions and hydrogen bonding. The PDA removal efficiency from different environmental wastewaters was 98.6?±?0.6%. All the results demonstrate that the EDTA-MCGO nanocomposite is a potential magnetic extractor of aromatic contaminants from aquatic life.GRAPHICAL ABSTRACT     

Removal of Phenol Dyes Using a Photocatalytic Reactor with SnO2/Fe3O4 Nanoparticles

In this study, we present kinetics of phenol dyes removal by SnO₂/Fe₃O₄ nanoparticles in a photocatalytic reactor for optimization of this process. The effect of different concentrations of SnO₂ 5, 10, 15, 20% w/w on the photocatalytic reactor during removal of phenol red was investigated. The SnO₂/Fe₃O₄ nanoparticles were synthesized by core–shell method. The results of XRD and TEM showed the successful synthesis of these nanoparticles. Several other methods were applied to synthesis of these nanoparticles but none of them succeeded. This process composed of two-stage. The first stage was absorption by iron oxide nanoparticles and second stage was photocatalytic by tin oxide nanoparticles that followed pseudo-second-order kinetic and first-order kinetic, respectively. Optimization of this process was done corresponding to the parameters affecting the process with design expert software. In order to determine the optimal values of each of the parameters and the optimal conditions of the process, parameters were introduced to response surface methodology.     

Euphorbia polygonifolia extract assisted biosynthesis of Fe3O4@CuO nanoparticles: Applications in the removal of metronidazole,ciprofloxacin and cephalexin antibiotics from aqueous solutions under UV irradiation

In this study, a new, economical and green method was reported for synthesizing Fe₃O₄@CuO nanoparticles without adding any surfactants using Euphorbia polygonifolia extract as a renewable, mild and safe reducing agent and effective stabilizer. The green synthesized NPs were analyzed by various methods such as XRD, FESEM, FT-IR, EDS, VSM, UV–visible, DRS, BET and TGA-DTA. Based on the BET analysis, the Fe₃O₄@CuO NP had a surface area of 69.20 m²/g. The FTIR analysis verified the existence of different functional groups of phytochemicals from Euphorbia polygonifolia extract which were accountable for the NPs formation. The catalytic performance of the catalyst for the degradation of metronidazole, ciprofloxacin and cephalexin antibiotics was examined in aqueous mediums at room temperature. The results showed an extraordinary catalytic performance, easy reusability and long-term stability of the composite for reducing antibiotic pollution. In this process, the effects of environmental conditions such as initial pH of the environment, initial concentration of antibiotics, the concentration of modified photocatalyst and reaction time were studied. According to the results, at the optimal conditions, the highest removal efficiency for metronidazole, ciprofloxacin and cephalexin antibiotics using Fe₃O₄@CuO nanoparticles, were 89%, 94%, and 96%, respectively. Also, it was observed that even after recycling, the NPs presents good nanocatalytic stability for the degradation of antibiotics. Using the NPs for five cycles did not significantly alter the photocatalyst efficiency, showing that the photocatalytic stability of the NPs was excellent.     

Photocatalytic Degradation of Styrene in Aqueous Solution: Central Composite Design Optimization

In this study, the response surface methodology was first applied to optimize the photocatalytic degradation of styrene in aqueous phase under UV/TiO₂ system. Twenty experiments were done by adjusting three parameters (styrene concentration, TiO₂ dose, and pH) at five levels. Optimal experimental conditions for arbitrary aqueous styrene concentration (115 mg L^?1) were found: initial pH 7 and TiO₂ loading 2 g L^?1 with photocatalytic degradation efficiency of 79.2%. Furthermore, the main degradation intermediate produced was identified by GC/MS. The total organic carbon results revealed that the photocatalysis process could be effectively mineralized. Kinetics of the photocatalytic reaction followed a pseudo-first-order model.     

Bifunctional copper modified graphitic carbon nitride catalysts for efficient tetracycline removal: Synergy of adsorption and photocatalytic degradation

In order to efficiently remove tetracycline in wastewater through the synergistic effect of adsorption and photocatalytic degradation, a series of novel composite materials (Cu doped g-C₃N₄) were synthesized by two-pot hydrothermal method. It was found that the composite materials with optimized ratio (Cu/CN-1) displayed outstanding adsorption and photocatalytic performance as compared with pure g-C₃N₄ photocatalyst. The removal efficiency of tetracycline (TC, 50 mg/L) reached almost 99% within 30 min by Cu/CN-1 through the synergy of adsorption and photocatalysis under visible-light irradiation, which was the highest removal efficiency ever reported. The adsorption kinetics and isotherms of TC on the Cu/CN-1 were well fitted with the pseudo-second-order kinetic model and Langmuir model, respectively. Moreover, it was confirmed that the main effective reactive groups were O₂⁻ and h⁺ in photocatalytic process. The Cu/CN-1 exhibited high stability and excellent reusability after five cycle experiments. Finally, the mechanism of synergy between Cu and g-C₃N₄ was proposed: on the one hand, the decoration of Cu particles significantly increased the adsorption sites of Cu/CN-1 to tetracycline, on the other hand, the modification of Cu particles effectively inhibits charge recombination and broadens the visible light absorption range of the photocatalyst.This study provided a promising photocatalyst to be used for TC removal in the actual wastewater.     

光催化甲胺磷降解效率和降解机理的研究

本文以自制的纳米TiO2为光催化剂,研究了光催化条件(溶液pH值、催化剂浓度及甲胺磷浓度)对甲胺磷在水中降解率的影响。结果表明:通过优化催化条件,可以大大提高甲胺磷的降解率。在甲胺磷浓度为20 mg/L,反应液起始pH为10.00,催化剂用量为0.5 g/L,光照时间为3 h的条件下,甲胺磷的降解效率可达到71.8%。通过化学计算模拟了甲胺磷的分子构型,并结合离子色谱的检测结果初步探讨了甲胺磷光催化降解的反应机理。     

Sunlight-induced photocatalytic degradation of acetaminophen over efficient carbon doped TiO2 (CTiO2) nanoparticles

Carbon doped titanium oxide (CTiO₂) photocatalyst was successfully synthesized by the sol–gel method. The crystal structure, surface morphology, and optical properties of CTiO₂ have been characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area (S_BET), scanning electron microscope, UV–Vis, X-ray spectroscopy (EDS), Fourier transform infrared and X-ray photoelectron spectroscopy. The photocatalytic degradation of acetaminophen (AMP) in aqueous solution, seawater, and polluted seawater has been investigated by using the synthesized photocatalyst under irradiation of UV and natural sunlight. The effectiveness of CTiO₂ compared to pure TiO₂ toward the photocatalytic removal of AMP was significantly observed. The optimized conditions including catalyst dose, initial concentration of AMP and solution pH were also studied for effective photocatalytic removal. The highest degradation rate was obtained when 2.0 g L^?1 of the catalyst was used at pH 7. The kinetic results revealed that the photocatalytic degradation of AMP using CTiO₂ obeyed a pseudo-first-order reaction kinetics.

     

三维电极电助光催化降解直接湖蓝水溶液的研究

 以500W高压汞灯为光源,在TiO2光催化剂和电催化剂同时存在下,联合多相三维电极技术与光催化技术,对直接湖蓝5B水溶液进行了电助光催化降解的研究．实验结果表明,浓度为0．5mmol／L的直接湖蓝5B水溶液经30min的光电催化降解,其大环结构可迅速破坏,颜色可迅速褪去,色度去除率高达96．8％,COD去除率可达66．7％．考察了空气流速、光催化剂加入量、底物的初始浓度、电解槽电压、pH值、电导率、以及曝气量等因素对直接湖蓝5B脱色率及COD去除率的影响．     

Removal of Pararosaniline Hydrochloride Dye (Basic Red 9) from Aqueous Solution by Electrocoagulation: Experimental,Kinetics, and Modeling

In this work, the removal of pararosaniline hydrochloride (Basic red 9) dye from aqueous solutions by electrocoagulation was investigated. The effect of parameters such as current density, initial pH, electrolysis time, inter-electrode distance, initial dye concentration and salt concentration on dye removal efficiency were investigated. The experimental results showed that 99% dye removal was observed after 30 minutes of electrolysis for an initial dye concentration of 100 mg/L, current density of 111.1 A/m² and initial pH of 7.0. It was observed that an increase in current density, time of operation and decrease in inter-electrode distance improved the dye removal efficiency. The optimum pH range for highest dye removal was 5.0–10.25. It was also observed that increase in salt concentration in the solution reduces the specific electrical energy consumption. The kinetic study inferred that the dye removal primarily follows a first order reaction. Finally, phenomenological models were proposed to illustrate the dependence of dye removal rate constant and specific electrical energy consumption on current density, inter-electrode distance, initial dye concentration and salt concentration.     

Photocatalytic degradation of methylene blue and phenol on Fe-doped sulfated titania

Fe-doped sulfated titania (FST) photocatalysts with high photocatalytic activity were prepared from industrial titanyl sulfate solution and characterized using X-ray diffraction (XRD), thermogravimetry analysis?Cdifferential scanning calorimeter (TGA-DSC), Fourier transform infrared spectroscopy (FT-IR), and nitrogen adsorption?Cdesorption techniques. The photocatalytic activity of the FST photocatalyst was evaluated using the photodegradation of methylene blue (MB) and the photooxidation of phenol in aqueous solutions in the presence of UV irradiation, respectively. The effect of various parameters, such as calcining temperature, calcination time, initial concentration of substrate, amount of catalyst and pH value on the photocatalytic activity of FST photocatalyst was investigated. Among the parameters studied, calcining temperature, initial concentration of substrate, and amount of catalyst have a very similar effect on the activity of FST photocatalyst for both the photodegradation of MB and the photooxidation of phenol, while the others have distinct differences. The optimal calcination conditions were 500?°C, 1.5?h and 650?°C, 2.5?h; the optimal catalyst concentration were 1.0 and 1.2?g?L^?1; the optimal pH values were 8 and 4 for the photodegradation of MB and the photooxidation of phenol, respectively. In addition, the mechanism for the high photocatalytic efficiency of FST photocatalyst has also been put forward.     

Photochemical degradation of an anionic surfactant by TiO<Subscript>2</Subscript> nanoparticle doped with C,N in aqueous solution

Novel C,N-doped TiO₂ nanoparticles were prepared by a solid phase reaction. The catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that crystallite size of synthesized C,N-doped TiO₂ particles were in nanoscale. UV light photocatalytic studies were carried out using sodium naphthalenesulfonate formaldehyde condensate (SNF) as a model pollutant. The effects of initial concentration of surfactant, catalyst amount, pH, addition of oxidant on the reaction rate were ascertained and optimum conditions for maximum degradation was determined. The results indicated that for a solution of 20 mg/L of SNF, almost 98.7% of the substance were removed at pH ~ 4.0 and 0.44 g/L photocatalyst load, with addition of 1 mM K₂S₂O₈ and irradiation time of 90 min. The kinetics of the process was studied, and the photodegradation rate of SNF was found to obey pseudo-first-order kinetics equation represented by the Langmuir–Hinshelwood model.     

碳纳米管/FeS类Fenton催化剂的制备及催化性能

以浮动催化热分解法制备碳纳米管(CNTs), 采用氧化-还原-硫化的方法制备了CNTs/FeS催化剂, 采用X射线衍射(XRD)、 透射电子显微镜(TEM)和热重(TG)分析等技术对催化剂进行了结构表征. 将CNTs/FeS作为类Fenton催化剂用于水中环丙沙星的去除, 研究了降解过程中H₂O₂浓度、 CNTs/FeS催化剂的投加量、 环丙沙星浓度及pH等因素对催化降解性能的影响. 结果表明, CNTs/FeS类Fenton催化反应在H₂O₂浓度为20 mmol/L和CNTs/FeS催化剂的投加量为10 mg的条件下具有最优的降解效果, 其催化反应过程符合一级动力学方程, 且具有更加宽泛的pH适应范围(pH=3~8), 同时, CNTs/FeS类Fenton催化剂在使用寿命方面也具有一定的优势.     

A Sharp Jump in Photocatalytic Activity of Elemental Sulfur for Dye Degradation in Alkaline Solution

Elemental sulfur is a low-cost and abundant substance as one of the largest by-products of the oil industry which was widely used in many industrial activities. Cyclo-octasulfur (S₈) is one of the sulfur allotropes that is a very stable substance in standard conditions. In this study, we report a low-cost and fast method for the degradation of methyl violet in water under visible light and also sunlight by using elemental sulfur (S₈). The results show that sulfur is a good photocatalyst which operates under visible light and can be utilized for degradation of methyl violet. The photocatalytic degradation of methyl violet in acidic, neutral, and alkaline media was investigated, and it was found that the photocatalytic efficiency increases dramatically in alkaline solution. The effects of the initial concentration of the dye, photocatalyst dosage, solution pH, and photocatalyst reusability were investigated. The kinetics of the reaction were studied in detail, and the photocatalytic rate equation was presented.     

Visible light induced photocatalytic degradation of phenol by polymer-modified semiconductors: Study of the influencing factors and the kinetics

To investigate the influencing factors and the kinetics of photocatalytic degradation of phenol, experiments were carried out using conjugated polymer poly(fluorene-co-thiophene) (PFT) sensitized TiO₂ and ZnO under LED (light-emitting diode) lights of the wavelength of 450–475 nm. Influencing factors, such as initial phenol concentration, photocatalyst dosage and pH value on the photocatalytic degradation of phenol were studied in detail. The reaction kinetics was found to follow pseudo first-order law.     

Synthesis of ZnO photocatalyst modified with activated carbon for a perfect degradation of ciprofloxacin and its secondary pollutants

The proposed research, presents the synthesis, characterization, and photocatalytic accomplishment of ZnO nanoplate (ZnOs) modified with activated carbon derived from Konar bark. The obtained nanocomposite (photocatalyst) was characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). First, the ZnO photocatalyst and activated carbon (AC) were prepared separately; then, the ZnO photocatalyst was modified with activated carbon. Various parameters namely pH, degradation time, and photocatalyst dose were optimized and studied in multivariate method by design expert7 software. The synergic efficiency of ZnO‐AC (adsorbent/photocatalyst) exhibited a good rate of ciprofloxacin (CIP) removal under visible irradiation. In addition, first pseudo order kinetic and isotherms equations were calculated. Moreover, the identification of degradation products was performed by ultra performance liquid chromatography‐tandem mass spectrometer (UPLC‐MS/MS). It is for the first time that a ZnO photocatalyst modified with activated carbon (ZnO‐AC) applied for CIP degradation.     

Photocatalytic degradation of norfloxacin and its intermediate degradation products using nitrogen‐doped activated carbon–CuS nanocomposite assisted by visible irradiation

We have synthesized a nitrogen‐doped activated carbon (NAC) derived from oak using KOH and N₂ thermal treatment at 400 °C as well as CuS nanoparticles. The NAC was decorated with the synthesized CuS to apply as a photocatalyst for degradation of norfloxacin (NOR). Before its application for photodegradation, the adsorbent/photocatalyst structural properties were investigated using X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy. The photocatalytic degradation of NOR was successfully done under visible light using NAC–CuS. The results revealed that the investigated fluoroquinolone degraded very efficiently and pseudo‐first‐order kinetics was adopted for the photodegradation process. In addition, isothermal studies showed that the adsorption process in darkness followed the Langmuir model. The degradation characteristics of the NAC–CuS photocatalyst were studied for 120 min and 15 h under visible light for degradation of NOR, exhibiting a good efficiency for NOR removal. During 120 min of degradation, some intermediate degradation products that can be considered as secondary pollutants were produced. Then, to degrade these pollutants the radiation time was increased up to 15 h. The results displayed a perfect degradation of NOR and its secondary pollutants. The effective variables including pH, degradation time and photocatalyst dosage were optimized and studied in a multivariate method using Design Expert 7. Determination of photodegradation products was carried out using liquid chromatography–mass spectrometry. The results are of significance for estimating the environmental fate of NOR in aqueous media.     

超声水热法制备高可见光催化活性的BiOCl-Bi12O17Cl2纳米复合材料去除染料和药物废水（英文）

光催化作为一种环境友好型、低能耗的技术,在环境净化等领域倍受关注.传统光催化剂,如TiO2,ZnO,V2O5和WO3等具有较高的光敏性,其价格低廉,自然无毒,常用于光电反应的应用当中.然而,这些催化剂具有较宽的禁带宽度,只能在紫外光下响应.为此,设计一种较窄带隙的高可见光活性的光催化剂具有一定的意义.近年来,氯氧化铋光催化剂受到了越来越多的关注,其在紫外光下具有非常优异的光催化性能.并且,研究者们已成功合成出非化学计量比的氯氧化铋,如Bi3O4Cl(2.60 eV),Bi12O17Cl2(2.10 eV),Bi12O15Cl6(2.86 eV)和Bi24O31Cl10(2.70 eV)等光催化剂.研究表明,较低的Cl/O比可能会减小催化剂的带隙宽度,并提高其光催化性能;其中Bi12O17Cl2的Cl/O比最小,是最有潜力的氯氧化铋光催化剂.然而,Bi12O17Cl2具有较高的光生电子空穴复合率,会极大的减弱其光催化活性.因此,将Bi12O17Cl2与具有高稳定性,结构相似且空穴复合率低的Bi OCl相结合,将会极大提高在可见光下Bi12O17Cl2的光催化活性.本文采用了超声水热法成功制备了具有高可见光催化活性的Bi OCl-Bi12O17Cl2纳米复合材料,用于去除染料和药物废水.扫描电子显微镜和比表面积分析仪的结果表明,纳米复合材料具有良好的分散性,结构为花瓣形状,其平均厚度为20至50 nm,且具有较高的比表面积.紫外-可见漫反射和光致发光光谱分析表明,纳米复合材料具有良好的可见光吸收性能,并且光生电子空穴复合率远低于Bi12O17Cl2.其在可见光下降解罗丹明B(/环丙沙星)的动力学常数分别约为Bi12O17Cl2,BiOCl和P25的8.14(/4.94),64.66(/11.91)和42.63(/36.07)倍.合适的形态,结构和光电性能是此纳米复合光催化剂具有优异光催化性能的原因.此外,该催化剂还显示出较宽的pH适用范围和优异的可重复利用性,有利于实际利用.机理研究表明,降解罗丹明B的主要活性物质是光生空穴和超氧自由基.总之,本文开发了一种绿色、稳定、高效的可见光光催化剂,对BiOCl基的光催化剂的研究作出了一定的贡献.     

Assessment of operating parameters for photocatalytic degradation of a textile dye by Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiO<Subscript>2</Subscript>/clinoptilolite nanocatalyst using Taguchi experimental design

In the current study, a nanophotocatalyst doped with of TiO₂ and Fe₂O₃ nanoparticles supported on Iranian clinoptilolite was synthesized and characterized by XRD, XRF, SEM, and EDX analyses. The results suggested the successful loading of TiO₂ and Fe₂O₃ nanoparticles onto the surface of clinoptilolite. The SEM images confirmed the average size of nanoparticles deposited on zeolite, which was about 20–40 nm. Furthermore, application of the synthesized photocatalyst in photocatalytic degradation of Acid Black 172 dye was studied using the Taguchi method and the chosen parameters were as follows: pH (2–7), dye concentration (50–200 mg/l), irradiation time (30–120 min), and catalyst dosage (0.5–1.5 g/l). The results indicate that dye concentration, pH, and irradiation time are respectively the most effective factors in these experiments while with the minimum dosage of the catalyst (0.5 g/l), up to 90 % removal efficiency could be achieved. The optimum value for each parameter was pH = 2, dye concentration = 50 mg/l, catalyst dosage = 1 g/l and irradiation time = 60 min, and the dye removal efficiency reached up to 100 % at these optimal conditions. Furthermore, after five-times recycling and reusing the catalyst, the efficiency of the photocatalytic degradation was reduced from 91.5 to 65.9 %, which is still an acceptable value.     

Process optimization and kinetics study for photocatalytic ciprofloxacin degradation using TiO2 nanoparticle: A comparative study of Artificial Neural Network and Surface Response Methodology

The photocatalytic degradation of ciprofloxacin was investigated by developing a predictive mathematical model using response surface methodology and an artificial neural network. The four independent variables involve solution pH, reaction time, catalyst dose, and initial antibiotic concentration considered as factors in central composite design to observe the response in the form of antibiotic degradation. Accordingly, at an optimum antibiotic concentration of 5.02 mg/L, catalyst dose of 44.51 mg/L, solution pH of 5.04, and reaction time of 75.80 min, the photocatalysis method achieved a ciprofloxacin degradation of 88.30%. The experimental outputs were very much consistent along with the predicted output of experiments through response surface methodology (R² = 0.9969) and artificial neural network (R² = 0.975). The adsorption isotherm and kinetic study reveal that Langmuir isotherm and pseudo-second-order kinetic models respectively were best fitted for degradation of ciprofloxacin through photocatalysis. The finding provides a novel method for evaluating the photocatalysis process for the optimization of ciprofloxacin antibiotic removal from pharmaceutical waste using experiments and computer simulation tools.     

Facile synthesis of ZnO/CuO/Eu heterostructure photocatalyst for the degradation of industrial effluent

Zinc oxide-based ternary heterostructure ZnO/CuO/Eu(1%, 3%, and 5% of Eu) nanoparticles were effectively produced by employing Vigna unguiculata (cowpea)waste skin extract as fuel in a simple one-pot combustion process. The as-synthesized heterostructure was analyzed by X-ray diffraction studies, ultraviolet-visible spectroscopy, Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscopy, and High-Resolution Transmission Electron Microscopy techniques. Besides, the photocatalytic degradation efficiency of the as-obtained ternary nanocomposite was evaluated under UV light for the degradation of model organic pollutants including methylene blue (MB), Rhodamine-B (RB), and an effluent sample collected from the textile industrial waste. During this study, the effect of a variety of parameters on the photodegradation activity of the photocatalysts has been thoroughly evaluated, such as light source, catalyst dose, irradiation period, dye concentration, solution pH, etc. Under UV irradiation(100 mins), the ternary ZnO/CuO/Eu photocatalyst demonstrated excellent degradation activity of ～99 and ～93% for MB and RB, respectively, while for the industrial effluent, a decent degradation activity of 42% has been recorded. Further experiments have revealed a pH and concentration-dependent photocatalytic behavior of the heterostructure photocatalyst. Therefore, the results suggest that the heterostructure photocatalyst can be potentially applied for wastewater treatment and other environmental applications.