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Chlorpyrifos (CP) is an organophosphorus pesticide used to control pests in agriculture. Brilliant green (BG) is a cationic dye widely used in textile and dyeing industry. However, the presence of pollutants in the aquatic environment has harmful effects on the environment and humans. Photocatalytic degradation can be appropriate method for water purification. Therefore, the Fe 3 O 4 /CdS–ZnS magnetic nanocomposite was synthesized and characterized by Brunauer-Emmett-Teller (BET) surface area analysis, Energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), UV–Vis-diffuse reflectance spectroscopy (DRS), and field emission scanning electron microscopy (FESEM) analyses and was used to degrade pollutants such as chlorpyrifos pesticide and brilliant green dye under visible light with source 300 W. Parameters that may be effective on photocatalytic degradation include pH, photocatalyst amount, contaminant concentration, photocatalyst and contaminant contact temperature and duration, light intensity as well as distance of light source from the reaction vessel. In the present study, the parameters that have the most influence on the degradation process were experimentally optimized, including pH, photocatalyst amount, photocatalyst reuse, and initial concentration. The study of the photocatalytic degradation rate of chlorpyrifos and brilliant green in optimal conditions (pH = 7, the concentration of pollutants = 10 ppm, volume of pollutants = 5 mL, and photocatalyst amounts for CP and BG were 0.0100 and 0.0015 g respectively) was obtained by Langmuir-Hinshelwood model. According to this model, the k app value for CP and BG were respectively 0.0315 and 0.0119 min−1 respectively. It has been concluded that the composition of CdS and ZnS caused inhibition of the recombination of photogenerated charge carriers, leading to high catalytic efficiency. Based on the results, the synthesized nanocatalyst showed that it has the ability to photocatalytic degradation of chlorpyrifos and brilliant green in aqueous solutions. [ABSTRACT FROM AUTHOR]

A novel, inexpensive and sensitive type of magnetic nanosorbent based on the functionalized silica-coated Fe 3 O 4 nanoparticles was prepared and used for the adsorption of trace amounts of nitrite and nitrate ions. The work is based on selective ion-pairing complex formation of nitrate and nitrite with Cu(I)-neocuproine which are covalently bounded on nanoparticles. Nitrite was determined according to its reaction with barbituric acid to give violuric acid and determination of nitrate was based on its reduction to nitrite in the presence of Zn/NaCl. After formation of violuric acid, the absorbance was measured spectrophotometrically at 310 nm. The quantitative recoveries were obtained at pH 5.5 for the analytes. Under optimum conditions, the limits of detection in the original solutions were 0.49 μg L −1 and 0.40 μg L −1 for nitrate and nitrite, respectively. The linearity ranges were found to be 1.5 to 2.8 × 10 3  μg L −1 (NO 3 − ) and 1.2 to 1.9 × 10 3  μg L −1 (NO 2 − ). The preconcentration factor was 120 for nitrate and 150 for nitrite. This method has been successfully applied to the determination of trace amounts of nitrite and nitrate in various water and food samples and also accuracy was confirmed by the analysis of the spiked recovery test. [ABSTRACT FROM AUTHOR]

This work presents a fast route for the preparation of a new Ta(V) metal-organic framework nanostructure with high surface area, significant porosity, and small size distribution. X-ray diffraction (XRD), scanning electron microscopy (SEM), Transition electron microscopy (TEM), energy dispersive spectrometer (EDS), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), CHNS/O elemental analyser, and Brunauer-Emmett-Teller (BET) surface area analysis were applied to characterize the synthesized product. Moreover, the influences of ultrasonic irradiation including temperature, time, and power on different features of the final products were systematically studied using 2 k-1 factorial design experiments, and the response surface optimization was used for determining the best welding parameter combination. The results obtained from analyses of variances showed that ultrasonic parameters affected the size distribution, thermal behaviour, and surface area of Ta-MOF samples. Based on response surface methodology, Ta-MOF could be obtained with mean diameter of 55 nm, thermal stability of 228 °C, and high surface area of 2100 m 2 /g. The results revealed that the synthesized products could be utilized in various applications such as a novel candidate for CO 2 adsorption. [ABSTRACT FROM AUTHOR]

An effective solid phase extraction method was developed using magnetic nanofiber of polyvinyl alcohol-triethoxysilane modified Fe 3 O 4 @SiO 2 nanoparticles synthesized by electrospinning method. These nanocomposites were characterized by various method. The suggested method was applied for the extraction of some antibiotics that have amino group in their structures, such as sulfamethoxazole and trimethoprim. Moreover, some of the important parameters that effect on the extraction yield of both drugs were investigated and optimized. Limits of detection and quantitation, linear ranges, and absolute extraction recovery were calculated as 0.0317 and 0.104 ​mg/L, 0.1–40 ​mg/L, and 95.1% for sulfamethoxazole and 0.0748 and 0.247 ​mg/L, 0.3–50 ​mg/L, and 98.2% for trimethoprim, respectively. In addition, the obtained results showed that the adsorption isotherm and kinetics follow the Freundlich model and Pseudo-Second-Order , respectively. This sample preparation (pre-concentration) method combined with UV–VIS was successfully used to the extraction of antibiotics in water samples. Image 1 • The electrospun nanofiber of Fe 3 O 4 @SiO 2 /polymer had been synthesized. • The proposed nanofiber was selected as the sorbent. • This sorbent efficiency is higher than magnetic nanoparticles for polymer swelling. • The affected parameters on sorbent performance of nanocomposite were investigated. [ABSTRACT FROM AUTHOR]

Through a critical review and systematic analysis of pavement life cycle assessment (LCA) studies published over the past two decades, this study shows that the available information regarding the environmental impacts of pavement infrastructure is not sufficient to determine what pavement type is more environmentally sustainable. Limitations and uncertainties related to data, system boundary and functional unit definitions, consideration of use and maintenance phase impacts, are identified as the main reasons for inconsistency of reported results in pavement LCA studies. The study outcomes also highlight the need for advancement of knowledge pertaining to: (1) utilization of performance-adjusted functional units, (2) accurate estimation of use, maintenance, and end-of-life impacts, (3) incorporation of the dynamic and uncertain nature of pavement condition performance in impact assessment; (4) development of region-specific inventory data for impact estimation; and (5) consideration of a standard set of impact categories for comparison of environmental performance of different pavement types. Advancing the knowledge in these areas is critical in providing consistent and reliable results to inform decision-making toward more sustainable roadway infrastructure. [ABSTRACT FROM AUTHOR]