Preparation of photocatalytic ZnO nanoparticles and application in photochemical degradation of betamethasone sodium phosphate using taguchi approach

In this study, ZnO nanoparticles were prepared by a sol-gel method for the first time. Taguchi method was used to identify the several factors that may affect degradation percentage of betamethasone sodium phosphate in wastewater in UV/K₂S₂O₈/nano-ZnO system. Our experimental design consisted of testing five factors, i.e., dosage of K₂S₂O₈, concentration of betamethasone sodium phosphate, amount of ZnO, irradiation time and initial pH. With four levels of each factor tested. It was found that, optimum parameters are irradiation time, 180 min; pH 9.0; betamethasone sodium phosphate, 30 mg/L; amount of ZnO, 13 mg; K₂S₂O₈, 1 mM. The percentage contribution of each factor was determined by the analysis of variance (ANOVA). The results showed that irradiation time; pH; amount of ZnO; drug concentration and dosage of K₂S₂O₈ contributed by 46.73, 28.56, 11.56, 6.70, and 6.44%, respectively. Finally, the kinetics process was studied and the photodegradation rate of betamethasone sodium phosphate was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.     

Synthesis of ZnO nanoparticles and its application in photocatalytic degradation of LABS by the trial-and-error and Taguchi methods

In the work ZnO nanoparticles were prepared by sol-gel method. The catalyst was characterized by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM). The photocatalytic oxidation of anionic surfactant in detergent industries was studied using ZnO nanoparticles with diameter size 20 nm as catalyst on irradiation with UV light. Analysis of kinetic showed that the amount of surfactant photocatalytic degradation can be fitted with pseudo-first-order model and studied photochemical elimination of Linear alkyl benzene sulfonates by the trial-and-error and Taguchi methods. Our experimental design consisted of testing five factors, i.e. dosage of K₂S₂O₈, concentration of surfactant, amount of ZnO, irradiation time, and initial pH. The results showed that photocatalytic degradation of linear alkyl benzene sulfonates was strongly influenced by these parameters.     

Statistical modeling of <Emphasis Type="Italic">p</Emphasis>-nitrophenol degradation using a response surface methodology (RSM) over nano zero-valent iron-modified Degussa P25-TiO<Subscript>2</Subscript>/ZnO photocatalyst with persulfate

Zero-valent iron-modified Degussa P25-TiO₂/ZnO nanocomposites (denoted as P25/Fe⁰/ZnO) were designed and prepared via Fe⁰ impregnation of P25-TiO₂/ZnO and then were employed in the visible-light photocatalytic degradation of p-nitrophenol (PNP) in the presence of [K₂S₂O₈]. Central composite design was applied for response surface modeling (RSM) to understand the influence of selected factors (pH, [Fe⁰] wt% and [K₂S₂O₈] concentration) on the degradation of PNP and to determine the interaction between the factors. The maximal PNP degradation efficiency (86.9%) was obtained with P25/1.5 wt% Fe⁰/ZnO at 3 mg/L of [K₂S₂O₈] concentration and pH 7.5. In addition, the RSM showed a satisfactory correlation between the experimental and predicted values of PNP degradation. The P25/Fe⁰/ZnO photocatalyst performance was also examined degrading methyl orange and phenol and high degradation efficiency, 82 and 99%, was achieved, respectively. The structure, morphology, light absorption and photocatalytic properties of as-prepared P25/Fe⁰/ZnO were studied using TEM, BET, XRD, FTIR and DRS.     

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.     

Photocatalytic decolorization of methyl orange solution with potassium peroxydisulfate

Increasing environmental pollution caused by toxic dyes due to their hazardous nature is a matter of great concern. It has been generally agreed that methyl orange (MO) can be effectively degraded in aerated K₂S₂O₈ homogeneous reaction system using near-UV irradiation. In this paper photocatalytic degradation of MO solutions with K₂S₂O₈ was investigated, with particular attention on the possible underlying mechanisms. This report has shown decolorization efficiency of MO increases with the increasing of the dosage of the catalyst. There is no optimal amount of catalyst in our case, where special attention was paid on the nature of the photocatalyst itself. The current research revealed that the decolorization reaction is a pseudo first-order reaction when the concentration of MO is below 20 mg L⁻¹ and the decolorization reaction is zero-order reaction when the concentration of MO is above 100 mg L⁻¹, but the Langmuir-Hinshewood kinetic model does not describe this. The influence of IO₄⁻, BrO₃⁻ and H₂O₂ were investigated in detailed. Several observations indicate that the mechanism is not involved in hydroxyl radical attacks in MO degradation with K₂S₂O₈ by UV irradiation. The possible underlying mechanisms are direct oxidation of the MO by S₂O₈²⁻ and hydrogen attraction by SO₄^•−.      

Synthesis of KIT-5 decorated by Bi2S3-Fe3O4 photocatalyst for degradation of parathion pesticide in aqueous media: Offering a degradation model and optimization using response surface methodology (RSM)

In this research, a novel KIT-5/Bi₂S₃-Fe₃O₄ nanocomposite was prepared. The structure and morphology properties of the nanocomposite were well characterized by XRD, FESEM-EDS-mapping, TEM, and N₂ adsorption–desorption. Benefiting from the visible light, the as-prepared KIT-5/Bi₂S₃-Fe₃O₄ nanocomposite exhibit significantly improved photocatalytic performance for the degradation of parathion. The optimum photocatalytic efficiency of KIT-5/Bi₂S₃-Fe₃O₄ nanocomposite was investigated with the central composite design using Design Expert software. The four critical variables affecting parathion degradation such as the concentration of parathion, pH, irradiation time, and amount of KIT-5/Bi₂S₃-Fe₃O₄ nanocatalyst. A polynomial function corresponding to degradation percent was obtained for the experimental data. The results showed that this catalyst has a good performance for the degradation of parathion.     

Straightforward Synthesis of Mn3O4/ZnO/Eu2O3-Based Ternary Heterostructure Nano-Photocatalyst and Its Application for the Photodegradation of Methyl Orange and Methylene Blue Dyes

Zinc oxide-ternary heterostructure Mn₃O₄/ZnO/Eu₂O₃ nanocomposites were successfully prepared via waste curd as fuel by a facile one-pot combustion procedure. The fabricated heterostructures were characterized utilizing XRD, UV–Visible, FT-IR, FE-SEM, HRTEM and EDX analysis. The photocatalytic degradation efficacy of the synthesized ternary nanocomposite was evaluated utilizing model organic pollutants of methylene blue (MB) and methyl orange (MO) in water as examples of cationic dyes and anionic dyes, respectively, under natural solar irradiation. The effect of various experimental factors, viz. the effect of a light source, catalyst dosage, irradiation time, pH of dye solution and dye concentration on the photodegradation activity, was systematically studied. The ternary Mn₃O₄/ZnO/Eu₂O₃ photocatalyst exhibited excellent MB and MO degradation activity of 98% and 96%, respectively, at 150 min under natural sunlight irradiation. Experiments further conclude that the fabricated nanocomposite exhibits pH-dependent photocatalytic efficacy, and for best results, concentrations of dye and catalysts have to be maintained in a specific range. The prepared photocatalysts are exemplary and could be employed for wastewater handling and several ecological applications.     

纳米Ag@AgBr表面敏化K_2Ti_4O_9可见光催化剂的微波合成、表征和光催化活性(英文)

利用微波法合成纳米尺寸Ag@AgBr表面敏化K2Ti4O9的复合光催化剂(Ag@AgBr/K2Ti4O9),并通过SEM、X-射线能量色散谱(EDX)、TEM、选定区域电子衍射(SAED)、XRD、紫外-可见漫反射(UV-VisDiffuseReflectance)、XPS等对其进行了表征,同时在可见光下测定催化剂对有机物降解的光催化活性。结果表明,粒径为0.2~0.5μm的Ag@AgBr均匀分散在K2Ti4O9表面,Ag@AgBr/K2Ti4O9对可见光有很好的吸收且Ag@AgBr的担载量影响可见光的吸收。当Ag@AgBr的担载量为25wt%时,复合光催化剂具有最高的光催化活性,光照1h对罗丹明B(RhB)的降解率可达97%。另外,催化剂的担载量和稳定性也做了考察。催化剂较高的光催化活性主要归因于Ag纳米粒子的表面等离子体效应和有效的光生电子-空穴的分离。     

纳米Ag@AgBr表面敏化K2Ti4O9可见光催化剂的微波合成、表征和光催化活性

利用微波法合成纳米尺寸Ag@AgBr表面敏化K₂Ti₄O₉的复合光催化剂（Ag@AgBr/K₂Ti₄O₉）,并通过SEM、X-射线能量色散谱（EDX）、TEM、选定区域电子衍射（SAED）、XRD、紫外-可见漫反射（UV-Vis Diffuse Reflectance）、XPS等对其进行了表征,同时在可见光下测定催化剂对有机物降解的光催化活性。结果表明,粒径为0.2~0.5μm的Ag@AgBr均匀分散在K₂Ti₄O₉表面,Ag@AgBr/K₂Ti₄O₉对可见光有很好的吸收且Ag@AgBr的担载量影响可见光的吸收。当Ag@AgBr的担载量为25wt%时,复合光催化剂具有最高的光催化活性,光照1h对罗丹明B（RhB）的降解率可达97%。另外,催化剂的担载量和稳定性也做了考察。催化剂较高的光催化活性主要归因于Ag纳米粒子的表面等离子体效应和有效的光生电子-空穴的分离。     

Synthesis of visible light-driven Eu, N co-doped TiO2 and the mechanism of the degradation of salicylic acid

Europium and nitrogen co-doped TiO₂ was successfully synthesized by the precipitation–peptization method. The structure and properties of the catalysts were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectra. The photocatalytic efficiency was evaluated by monitoring the photocatalytic degradation of salicylic acid under visible light irradiation. It was verified that TiO₂ co-doped with nitrogen and 1% europium showed the highest photocatalytic activity. The adsorption isotherms were obtained by measuring the salicylic acid concentration before and after the dark adsorption at different original solution concentrations. The results illustrated that the doping of Eu was beneficial to the adsorption of salicylic acid. The probable degradation mechanism of salicylic acid was examined by the addition of NaF, Na₂S₂O₃, and K₂S₂O₈ as the probe molecules. It was verified that salicylic acid was first adsorbed on the surface of the catalysts, followed by the degradation by the photogenerated holes (h _vb ⁺ ).     

TiO2/clay as a heterogeneous catalyst in photocatalytic/photochemical oxidation of anionic reactive blue 19

A TiO₂-coated Tunisian clay (TiO₂–clay) was synthesized by a typical impregnation method. The physicochemical characterization points to a successful impregnation of titania on the clay surface. The activity of this structured catalyst was studied in the photocatalytic/photochemical oxidation of anionic reactive blue 19 (RB 19). The effect of UVA and solar irradiation (UV-solar) was studied at room temperature. TiO₂–clay demonstrated an effective degradation of RB 19 under both types of irradiation. Moreover, in this study, the effects of various oxidants such as hydrogen peroxide (H₂O₂), potassium peroxodisulfate (K₂S₂O₈) and sodium carbonate (Na₂CO₃) were thoroughly investigated. H₂O₂ was a promising oxidant for promoting RB 19 degradation under UV_A. The kinetics of discoloration of RB 19 followed a pseudo-first-order rate law. We can remark that 20 min of UV irradiation was enough to achieve 100% discoloration of the aqueous solution. However, under UV–Vis, HPLC and chemical oxygen demand measurements indicated, that a longer reaction time (of around 45 min) was required for achieving the complete dye mineralization. The findings clearly demonstrated the applicability of this TiO₂/clay catalyst for the photocatalytic oxidation of RB 19.     

Improved photocatalytic degradation of reactive blue 81 using NiO-doped ZnO–ZrO2 nanoparticles

In this study, the photocatalytic degradation of Reactive Blue 81 (RB81) using synthesized NiO-doped ZnO–ZrO₂ nanoparticles under UV irradiation was investigated. Then, the products were characterized by Scanning electron microscope (SEM), X-ray diffraction (XRD), and diffuse reflectance spectroscopy (DRS). The removal rate of RB81 using ZnO–ZrO₂ after 180?min of irradiation was 96.7%. Nickel oxide (NiO) was used as an additive to ZnO–ZrO₂ for improvement of RB81 degradation via photocatalysis process. Photodegradation of RB81 was achieved to 100% using ZnO–ZrO₂–NiO nanoparticles with ratio of 1:2:0.3 after 180?min of irradiation. There was a red shift in absorption bands (from 410?nm to 435?nm) observed in increasing of NiO to ZnO–ZrO₂ nanoparticle, that it might lead to a higher photocatalytic activity under visible light. Response surface methodology (RSM) was used for optimization of experimental and these results were obtained: solution pH = 3, ZnO–ZrO₂–NiO dosage = 15?mg/L, and the initial RB81 concentration = 5?mg/L. The photodegredation of RB81 followed pseudo-first order kinetic according to the Langmuir–Hinshelwood model.     

Reclamation of Water Polluted with Flubendiamide Residues by Photocatalytic Treatment with Semiconductor Oxides

The photodegradation of flubendiamide (benzenedicarboxamide insecticide), a relatively new insecticide was investigated in aqueous suspensions binary (ZnO of and TiO₂) and ternary (Zn₂TiO₄ and ZnTiO₃) oxides under artificial light (300–460 nm) irradiation. Photocatalytic experiments showed that the addition of semiconductors, especially ZnO and TiO₂, in tandem with an electron acceptor (Na₂S₂O₈) enhances the degradation rate of this compound in comparison with those carried out with catalyst alone and photolytic tests. The photocatalytical degradation of flubendiamide using ZnO/Na₂S₂O₈ and TiO₂/Na₂S₂O₈ followed first‐order kinetics. In addition, desiodo‐flubendiamide was identified during the degradation of flubendiamide. Finally, application of these reaction systems in different waters (tap, leaching and watercourse) showed the validity of the treatments, which allowed the removal of flubendiamide residues in these drinking and environmental water samples.     

Photodegradation of aromatic amines by Ag-TiO2 photocatalyst

The photocatalytic degradation of ortho, para and meta-nitroanilines (ONA, PNA and MNA) was investigated by Ag-TiO₂ suspension. The effect of some parameters such as the amount of photocatalyst, irradiation time of UV light, flow rate of O₂, pH, and temperature for the Ag-TiO₂ photocatalyst was also examined. Degradation of amines was small when the reaction was carried out in the absence of photocatalyst, and negligible in the absence of the UV light. Degradation rate of aniline derivatives decreases with increasing O₂ in the system. The effect of pH indicated that effective degradation occurred in alkaline conditions. Degradation kinetics of these aromatic amines can be described by Langmuir-Hinshelwood equation and shows pseudo-first order law.     

Determination of bifonazole and identification of its photocatalytic degradation products using UPLC‐MS/MS

The main goal of the presented work was to investigate the effect of ZnO or/and TiO₂ on the stability of bifonazole in solutions under UVA irradiation. To this end, a simple and reproducible UPLC method for the determination of bifonazole in the presence of its photocatalytic degradation products was developed. Linearity was studied in the range of 0.0046–0.15 mg mL⁻¹ with a determination coefficient of 0.9996. Bifonazole underwent a photocatalytic degradation process under the experimental conditions used. Comparative studies showed that combination of TiO₂/ZnO (1:1 w /w) was a more effective catalyst than TiO₂ or ZnO with a degradation rate of up to 67.57% after 24 h of irradiation. Further, kinetic analyses indicated that the photocatalytic degradation of bifonazole in the mixture of TiO₂/ZnO can be described by a pseudo‐first order reaction. Statistical comparison clearly indicated that the presence of TiO₂/ZnO also affected the stability of bifonazole from a cream preparation after 15 h of UVA exposure (p < 0.05). Ten photodegradation products of bifonazole were identified for the first time and their plausible fragmentation pathways, derived from MS/MS data, were proposed. The main pathway in the photocatalytic transformation of bifonazole in the presence of ZnO or/and TiO₂ involves hydroxylation of the methanetriyl group and/or adjacent phenyl rings and cleavage of the imidazole moiety.     

Enhanced photocatalytic activities of ZnO thin films: a comparative study of hybrid semiconductor nanomaterials

Nanostructure single ZnO, SnO₂, In₂O₃ and composite ZnO/SnO₂, ZnO/In₂O₃ and ZnO/SnO₂/In₂O₃ films were prepared using sol?Cgel method. The obtained composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV?CVis spectroscopy. The photocatalytic activities of composite films were investigated using phenol (P), 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP) and 4-aminophenol (4-AP) as a model organic compounds under UV light irradiation. Hybrid semiconductor thin films showed a higher photocatalytic activity than single component ZnO, SnO₂ and In₂O₃ films. The substituted phenols degrade faster than phenol. The ease of degradation of phenols is different for each catalyst and the order of catalytic efficiency is also different for each phenol. The use of multiple components offered a higher control of their properties by varying the composition of the materials and related parameters such as morphology and interface. It was also found that the photocatalytic degradation of phenolic compounds on the composite films and single films followed pseudo-first order kinetics.     

Accelerated chemical degradation of polyacrylamide

The chemical degradation of polyacrylamide(PAM) at low temperature in aqueous medium was initiated by peroxides. The degradation degree of the polymer rose with the reaction time. The degradation degree of PAM depended not only on peroxide characteristic but also on the concentration of polyacrylamide and potassium persulfate, degradation temperature and original molecular weight of PAM. The results showed that the order of degradation degree of PAM in three peroxides is K₂S₂O₈ > K₂S₂O₈ — Na₂S₂O₃ > H₂O₂. The degradation degree of PAM grew as reaction temperature, molecular weight of PAM, concentration of potassium persulfate and PAM increased.     

Photodegradation of Congo red in aqueous solution on ZnO as an alternative catalyst to TiO2

In this research, the efficiency of ZnO and TiO₂ was compared by photocatalytic degradation of Congo red azo dye. The effects of some parameters such as pH, dye concentration and irradiation time on the degradation rate of dye solution were also examined. In addition, the aggregation feature of Congo red was studied by using UV-Vis spectroscopy techniques. The recovery of the ZnO catalyst was also investigated.     

ZnO修饰提升花状BiOBr的可见光催化降解罗丹明B性能

以Bi(NO₃)₃·5H₂O、Zn(CH₃COO)₂·2H₂O和NaBr为前驱体,采用简单溶剂热法制备BiOBr/ZnO三维花状微纳米复合材料。采用X射线衍射、扫描电子显微镜、X射线光子能谱、N₂吸附-脱附、光致发光和电子顺磁共振等分析技术对其理化性质进行了表征。通过可见光催化降解罗丹明B(RhB)的实验测试了复合材料的光催化性能。结果表明ZnO含量为5%的BiOBr/ZnO光催化活性最优,RhB降解率在50 min后达到98.3%,其降解速率常数是纯ZnO和BiOBr的6.3倍和3.4倍,并且具有较高的稳定性。复合材料光催化性能增强的可能原因为ZnO的引入增强了可见光的吸收和光生载流子的电荷分离效率。