Investigation into the impact of CeO2 morphology regulation on the oxidation process of dichloromethane.

Four distinct CeO2 catalysts featuring varied morphologies (nanorods, nanocubes, nanoparticles, and nano spindle-shaped) were synthesized through a hydrothermal process and subsequently employed in the oxidation of dichloromethane (DCM). The findings revealed that the nano spindle-shaped CeO2 exhibited exposure of crystal faces (111), demonstrating superior catalytic oxidation performance for DCM with a T90 of 337 °C and notably excellent low-temperature catalytic activity (T50 = 192 °C). The primary reaction products were identified as HCl and CO2. Through obvious characterizations, it showed that the excellent catalytic activity presented by CeO2-s catalyst might be related to the higher oxygen vacancy concentration, surface active oxygen content, and superior redox performance caused by specific exposed crystal planes. Meanwhile, CeO2-s catalyst owned outstanding stability, reusability, and water inactivation regeneration, which had tremendous potential in practical treatment.

Nitrogen-Fluorine co-doped TiO2/SiO2 nanoparticles for the photocatalytic degradation of acrylonitrile: Deactivation and regeneration.

In this study, we investigated the deactivation kinetics and mechanism of N-F-TiO2/SiO2 nanopowder as a model photocatalyst for the purpose of facilitating the photocatalytic degradation of acrylonitrile (AN) in aqueous environment. Prior research has already displayed the proficient degradation of AN through the utilization of N-F-TiO2/SiO2 catalysts, revealing a degradation efficiency of 81.2% within a span of 6 min at an initial AN concentration of 10 mg/L. Multiple variables including the initial AN concentration, illumination intensity, and initial pH value were extensively analyzed during the degradation process. The kinetics of photocatalytic degradation of AN, facilitated by the N-F-TiO2/SiO2 photocatalyst, were modeled by fitting the pseudo first-order reaction kinetics to each individual factor. Furthermore, the adverse effect of catalyst poisoning during the photocatalytic breakdown of AN using the N-F-TiO2/SiO2 photocatalyst was analyzed through a range of different techniques including SEM, XPS, BET, XRD, TG, and NH3-TPD. The incorporation of findings from these diverse techniques revealed that, the primary factors contributing to the photocatalyst's poisoning were as follows: (i) During the degradation process, the build-up of intermediate molecules on active sites hindered their functionality, leading to a decrease in the efficiency of the photocatalytic reaction, (ii) Carbonaceous deposits formed when the catalyst's pore structure was obstructed by pollutants or intermediate products that had not undergone timely photocatalytic breakdown and (iii) The persistent erosion of active sites due to hydraulic forces resulted in inadequate performance of the N-F-TiO2/SiO2 photocatalyst in aqueous solutions. A comprehensive analysis of the deactivation kinetics was conducted, deciding in the formulation of a detailed poisoning mechanism for the N-F-TiO2/SiO2 photocatalyst. Additionally, we explored the catalysts regeneration, involving thermal treatment, ultrasonic irradiation, and catalyst reloading. This study not only advances our insight into the waning performance of catalysts in aqueous media but also establishes a conceptual framework for extrapolating analogous deactivation dynamics in other catalysts, grounded in precedent experimental knowledge. This research contributes to the development of a deactivation model for catalysts in the aqueous environment, based on existing experimental research, providing a theoretical framework for understanding the deactivation process of photocatalysts.

Applications of two-dimensional ion chromatography for analytes determination in environmental matrix: A review.

Ion chromatography (IC) has grown in usage rapidly since its first introduction in 1975. However, IC is still sometimes unable to separate target analytes from coexisting components well with identical elution time, due to the limited resolution and column capacity, especially in the presence of high-level salt matrix. These limitations hence drive IC to develop two-dimensional IC (2D-IC). In this review, we capture the 2D-IC applications in environmental samples via the perspective of coupling different IC columns, which aim to summarize where these 2D-IC methods fit in. In sequence, we firstly review the principles of 2D-IC and emphasize one-pump column-switching IC (OPCS IC) because it is a simplified 2D-IC that only uses one set of IC system. We then compare typical 2D-IC and OPCS IC performances in terms of application scope, method detection limit, drawbacks, and expectations. Finally, we propose some challenges of current methods and opportunities for future research. For instance, it is challenging to couple anion exchange column and capillary column in OPCS IC due to the incompatibility between flow path dimensions and suppressor; coupling ion exclusion column and mixed-bed column may be promising to simultaneously determine anions and cations in weak acids or salts. The details of this study may help practitioners to better understand and implement 2D-IC methods and meanwhile motivate researchers to fill in the knowledge gap in the future.

Recent advances in sterilization and disinfection technology: A review.

Sterilization and disinfection of pollutants and microorganisms have been extensively studied in order to address the problem of environmental contamination, which is a crucial issue for public health and economics. Various form of hazardous materials/pollutants including microorganisms and harmful gases are released into the environment that enter into the human body either through inhalation, adsorption or ingestion. The human death rate rises due to various respiratory ailments, strokes, lung cancer, and heart disorders related with these pollutants. Hence, it is essential to control the environmental pollution by applying economical and effective sterilization and disinfections techniques to save life. In general, numerous forms of traditional physical and chemical sterilization and disinfection treatments, such as dry and moist heat, radiation, filtration, ethylene oxide, ozone, hydrogen peroxide, etc. are known along with advanced techniques. In this review we summarized both advanced and conventional techniques of sterilization and disinfection along with their uses and mode of action. This review gives the knowledge about the advantages, disadvantages of both the methods comparatively. Despite, the effective solution given by the advanced sterilization and disinfection technology, joint technologies of sterilization and disinfection has proven to be more effective innovation to protect the indoor and outdoor environments.

Efficient One-Pot Synthesis of TiO2/ZrO2/SiO2 Ternary Nanocomposites Using Prunus × Yedoensis Leaf Extract for Enhanced Photocatalytic Dye Degradation.

A simple, efficient, and ecofriendly method was employed to synthesize TiO2/ZrO2/SiO2 ternary nanocomposites using Prunus × yedoensis leaf extract (PYLE) that shows improved photocatalytic and antibacterial properties. The characterization of the obtained nanocomposites was done by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopic (EDS) analysis. The synthesized ternary nanocomposites with nanoscale pore diameters were investigated for the elimination of Reactive Red 120 (RR120) dye. The obtained results showed about 96.2% removal of RR120 dye from aqueous solution under sunlight irradiation. Furthermore, it shows promising antibacterial activity against Staphylococcus aureus and Escherichia coli. The improved photocatalytic and antibacterial activity of TiO2/ZrO2/SiO2 may bring unique insights into the production of ternary nanocomposites and their applications in the environment and biomedical field.

Fe(II)-activated persulfate oxidation to degrade iopamidol in water: parameters optimization and degradation paths.

Iodinated contrast media (ICM), which was widely used in medical imaging and was difficult to remove by conventional wastewater treatment methods, attained much attention due to its potential environmental impacts. Herein, iopamidol (IPM), one typical compound of ICM, was found to be rapidly degraded by ferrous activated persulfate oxidation (Fe(II)/PS) as compared with PS or Fe(II) alone. With a persulfate concentration of 1 mmol L-1, n(Fe(II))/n(PS) of 1:10, and a pH of 3.0, 78% IPM was degraded within 60 min, with a degradation rate of 0.1266 min-1. It was demonstrated that IPM degradation and deiodination were favored by a high temperature, while affected positively by acidic and neutral conditions. Radical quenching experiments and Electron Paramagnetic Resonace (EPR) spectra showed that the combined effects of SO4-· and ·OH contributed dominantly to degrade IPM, while the ·OH played an essential role during the degradation reaction. Through the Discrete Fourier Transform quantum chemical calculation, the possible reaction pathways for the oxidation of IPM by ·OH are as follows: IPM-TP651-TP667-TP541-TP557, IPM-TP651-TP525-TP557, IPM-TP705-TP631-TP661, and IPM-TP705-TP735. The obtained results showed that IPM could be degraded effectively by Fe(II)/PS system, giving a promising technique for IPM removal from water.

Photocatalytic degradation of industrial acrylonitrile wastewater by F-S-Bi-TiO2 catalyst of ultrafine nanoparticles dispersed with SiO2 under natural sunlight.

Highly active photocatalyst, having certain anti-ionic interfering function, of F, S and Bi doped TiO2/SiO2 was used for the first time to degrade the organic pollutants in acrylonitrile industrial wastewater under natural sunlight. The photocatalyst were prepared and characterized by UV-Vis, XRD, TEM, EDS, Nitrogen physical adsorption and XPS technique. UV-Vis analysis revealed addition of F, S and Bi into the lattice of TiO2 led to the expansion of TiO2 response in the visible region and hence the efficient separation of charge carrier. The photocatalytic potential of as prepared catalyst to degrade acrylonitrile wastewater under simulated and natural sunlight irradiation was investigated. The extent of degradation of acrylonitrile wastewater was evaluated by chemical oxygen demand (CODCr). CODCr in wastewater decreased from 88.36 to 7.20 mgL-1 via 14 h irradiation of simulated sunlight and achieved regulation discharge by 6 h under natural sunlight, illuminating our photocatalyst effectiveness for refractory industrial wastewater treatment. From TEM results, we found that SiO2 could disperse the photocatalyst with different component distributions between the surface and the bulk phase that should also be responsible for the light absorption and excellent photocatalytic performance. The XPS analysis confirmed the presence of surface hydroxyl group, oxygen vacancies.

Efficient photocatalytic degradation of acrylonitrile by Sulfur-Bismuth co-doped F-TiO2/SiO2 nanopowder.

In this study, a simple sol-gel method was applied for preparing effectual photocatalyst of S-Bi co-doped F-TiO2/SiO2 (S-Bi-F-TiO2/SiO2) nanopowder. Optimal preparation conditions were obtained by optimizing the calcination temperature and the ratio of S and Bi. The synthesized powder was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), brunauer-emmett-teller (BET), UV-Visible diffuse-reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL) and ammonia adsorption and temperature-programmed desorption (NH3-TPD). The photocatalytic activity was evaluated by the degradation of acrylonitrile under simulated visible light irradiation. S-Bi-F-TiO2/SiO2 nanopowder possess excellent photocatalytic properties under visible light for the degradation of acrylonitrile, when the calcination temperature was 450 °C for 2 h and the ratio of S and Bi was 0.02: 0.007. The degradation efficiency of acrylonitrile reached to 81.9% within 6 min of visible light irradiation. Compared with F-TiO2/SiO2 sample, NH3-TPD and PL results revealed the higher photocatalytic activity for S-Bi-F-TiO2/SiO2, which is mainly due to the increase strength and number of surface acid site with S doping. The co-doping with S & Bi improved the separation of electron-hole pairs and enhanced the photocatalytic oxidizing species. The UV-Vis DRS showed stronger absorption in S-Bi co-doped F-TiO2/SiO2 catalyst as compared to F-TiO2/SiO2 catalyst. XPS results demonstrated the presence of various surface species viz. oxygen vacancies, Ti3+, Ti4+, O2- and OH group.

Visible and UV photo-detection in ZnO nanostructured thin films via simple tuning of solution method.

This study demonstrates significant visible light photo-detection capability of pristine ZnO nanostructure thin films possessing substantially high percentage of oxygen vacancies [Formula: see text] and zinc interstitials [Formula: see text], introduced by simple tuning of economical solution method. The demonstrated visible light photo-detection capability, in addition to the inherent UV light detection ability of ZnO, shows great dependency of [Formula: see text] and [Formula: see text] with the nanostructure morphology. The dependency was evaluated by analyzing the presence/percentage of [Formula: see text] and [Formula: see text] using photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) measurements. Morphologies of ZnO viz. nanoparticles (NPs), nanosheets (NSs) and nanoflowers (NFs), as a result of tuning of synthesis method contended different concentrations of defects, demonstrated different photo-detection capabilities in the form of a thin film photodetector. The photo-detection capability was investigated under different light excitations (UV; 380~420 nm, white ; λ > 420 nm and green; 490~570 nm). The as fabricated NSs photodetector possessing comparatively intermediate percentage of [Formula: see text] ~ 47.7% and [Formula: see text] ~ 13.8% exhibited superior performance than that of NPs and NFs photodetectors, and ever reported photodetectors fabricated by using pristine ZnO nanostructures in thin film architecture. The adopted low cost and simplest approach makes the pristine ZnO-NSs applicable for wide-wavelength applications in optoelectronic devices.

Formation of oxygen vacancies and Ti(3+) state in TiO2 thin film and enhanced optical properties by air plasma treatment.

This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti(3+), Ti(4+), O(2-), oxygen vacancies, OH group and optical properties was studied using X-ray photon spectroscopy (XPS) and UV-Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti(3+) and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 seconds. With the increasing treatment time, Ti(3+) and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was observed in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift.