جستجوی مقالات مرتبط با کلیدواژه « organic pollutants » در نشریات گروه « شیمی »
تکرار جستجوی کلیدواژه «organic pollutants» در نشریات گروه «علوم پایه»-
در این پژوهش، سنتز و شناسایی نانوکامپوزیت اصلاح شده Sr-Ce-ZnO/Hap در تخریب آلاینده رودامین B تحت تابش مریی مورد بررسی قرار گرفت. ساختار نانوکامپوزیت Sr-Ce-ZnO/HAp با استفاده از طیف سنجی تبدیل فوریه فروسرخ (FT-IR)، پراش پرتو ایکس (XRD)، میکروسکوپ الکترونی روبشی (SEM)، طیف سنجی پراش انرژی پرتو ایکس (EDX) ، دستگاه طیف سنجی مریی فرابنفش (UV-Vis)، طیف بازتاب پخشی (DRS) و اندازه گیری تخلخل سنجی جذب و واجذب با آنالیز BET تایید شد. ارزیابی ها نشان دادند که آلایش با کاتیون های فلزی و حضور هیدروکسی آپاتیت منجر به کاهش شکاف انرژی، افزایش سطح، افزایش جذب و کاهش بازترکیب الکترون روزنه می شود. همچنین نتیجه ها نشان دادند که مقدار بیش از 91 درصد رودامین B طی مدت زمان 90 دقیقه پس از آغاز واکنش حذف شد. سنتیک واکنش مرتبه اول و ثابت سرعت min-1 023/0 به دست آمد.
کلید واژگان: روی اکسید, Sr-Ce-ZnO, HAp, رودامین B, نانوکامپوزیت, کاتالیست نوری, آلاینده آلی}In this study, the synthesis and characterization of Sr-Ce-ZnO/HAp nanocomposite in the degradation of rhodamine B under visible light was investigated. Structure of Sr-Ce-ZnO/HAp nanocomposite identified by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy diffraction (EDX) spectroscopy (visible-spectrophotometer) UV-Vis and adsorption/desorption porosimetry were confirmed by BET analysis. Evaluations showed that adopted with metal cations and the presence of hydroxyapatite reduced energy gap, increased surface area, increased adsorption and decreased electron-hole recombination. As a result, it significantly increases the photocatalytic activity of Sr-Ce-ZnO/HAp nanocomposite compared to other prepared nanoparticles. The results also showed that more than 91% of rhodamine B was removed within 90 minutes after the start of the reaction. The first-order reaction constant and the rate constant of 0.023 min-1 were obtained.
Keywords: Zinc oxide, Sr-Ce-ZnO, HAp, Rhodamine B, Nanocomposite, photocatalyst, Organic pollutants} -
هدف از این پژوهش تهیه و بررسی قدرت فتوکاتالیستی نانو کامپوزیت هیبریدی پایه فلزی با روکش آنتی باکتریال به صورت نانوکامپوزیت فسفات نقره/برمید نقره/اکسید روی/ مگنتیت با ساختار شیمیایی (Fe3O4@ZnO@AgBr@Ag3PO4) می باشد. برای ارزیابی قدرت تخریبی آلاینده های آلی مانند تری فلورالین،دیمیتوآت و قرمز کنگو در راستای تصفیه آب های آلوده به مواد شیمیایی از این نانوکامپوزیت هیبریدی استفاده شد. وجود نانو ذره های فرومغناطیس سبب افزایش جذب نور مریی، کاهش گاف انرژی و قابلیت جمع آوری این نانوکامپوزیت های هیبریدی توسط اعمال یک میدان مغناطیسی ساده شده است. نانو کامپوزیت Fe3O4@ZnO@AgBr@Ag3PO4 به ترتیب از روش های سلوترمال، هیدروترمال و هم رسوبی طی مرحله های متوالی تهیه شده و با استفاده از روش های متداول آنالیز مانند پراش پرتو ایکس، طیف سنجی فروسرخ، میکروسکوپ الکترونی روبشی شناسایی شدند. با استفاده از طیف سنجی فرابنفش و مریی، ویژگی های فتوکاتالیستی آ ن ها بررسی شد. نتیجه ها نشان دادند که نانوساختارهای تهیه شده دارای ویژگی های فتوکاتالیستی بسیار مناسبی برای حذف آلاینده های آلی می باشند و تا 98 درصد ترکیب های آلی را در بار اول حذف نمودند. همچنبن آزمایش های مربوط به عملکرد نشان داد که پس از 4 بار بازیابی، قدرت فتوکاتالیستی نانوکامپوزیت های استفاده شده حدود 90 درصد می باشد.کلید واژگان: نانوکامپوزیت, نانوفتوکاتالیست, تصفیه پساب, شناسایی, آلاینده های آلی}The goal of this research was related to the investigation of the photocatalytic activity of hybrid nanocomposite based on a metal substrate coated with antibacterial materials as a nanocomposite of silver phosphate/silver bromide/Zinc oxide and magnetite with a chemical structure of Fe3O4@ZnO@AgBr@Ag3PO4, in order to evaluate of degradation efficiency of organic contamination like Trifluralin, Dimethoate, and Congo red in chemical and microbial polluted waters. The nanocomposite was prepared from the solvothermal, hydrothermal, and co-precipitation methods respectively. The prepared sample was characterized with a Scanning Electron Microscope (SEM)‚ Fourier transform infrared spectroscopy and X-Ray Diffraction (XRD) and the particle sizes and the morphology of the prepared material were determined. the photocatalytic properties of the samples were characterized by UV-Vis spectroscopy. obtained results showed that the prepared nanostructures have suitable photocatalytic activities and remove the 98% of organic contaminants in the first usage. Also, the performance test results revealed that after 4 times of usage, the recovery of the photocatalytic activity was more than 90%.Keywords: Nanocomposite, nano-photo-catalyst, sewage treatment, Characterization, Organic pollutants}
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در این پژوهش نانو کامپوزیت روی اکسید آلاییده با نقره و سریم/پلی آنیلین(Ag-Ce-ZnO/PANI) به عنوان فوتوکاتالیست، برای تخریب هم زمان دو آلاینده آلی پارانیتروفنول و متیلن بلو در حضور نور فرا بنفش سنتز شد. آنالیزهای XRD ، FESEM و UV-Vis برای تعیین ویژگی های فیزیکی، شیمیایی و اپتیکی نمونه های سنتز شده مورد استفاده قرارگرفت. آزمایش های فوتوکاتالیستی نشان از عملکرد بهتر نانوکامپوزیت Ag-Ce-ZnO/PANI درمقایسه با سایر نمونه ها داشت. نتیجه ها نشان داد که با گذشت 60 دقیقه از آزمایش، حدود 88 % متیلن بلو و 56 % پارانیتروفنول توسط این نانوکامپوزیت تخریب شده است. عملکرد خوب فوتوکاتالیستی برای نانوکامپوزیت Ag-Ce-ZnO/PANI را می توان به کاهش بازترکیب الکترون حفره، افزایش هدایت الکتریکی و افزایش جذب نسبت داد. فعالیت فوتوکاتالیستی پایدار و کارآمد نانوکامپوزیت تهیه شده آن را به عنوان یک فوتوکاتالیست موثر در تخریب آلاینده های آلی به صورت تکی یا هم زمان معرفی می کند.
کلید واژگان: روی اکسید, پلی آنیلین, نانوکامپوزیت, فوتوکاتالیست, آلاینده های آلی}In this study, Ag, Ce codoped ZnO/polyaniline nanocomposites were synthesized as photocatalysts for the simultaneous degradation of organic pollutants para nitrophenol and methylene blue under UV light. XRD, FESEM, and UV-Vis analyzes were used to determine the physical, chemical, and optical properties of the synthesized samples. Photocatalytic experiments showed better performance of Ag-Ce-ZnO/PANI nanocomposite compared to other samples. The results showed that after 60 minutes, about 88% of methylene blue and 56% of para nitrophenol were degraded by this nanocomposite. The good photocatalytic performance of Ag-Ce-ZnO/PANI nanocomposites can be attributed to the reduction of electron-hole recombination, increased electrical conductivity, and increased adsorption. The stable and efficient photocatalytic activity of the prepared nanocomposite identifies it as an effective photocatalyst in the degradation of organic pollutants solely or simultaneously.
Keywords: ZnO, PANI, Nanocomposite, Photocatalysts, Organic pollutants} -
In recent years, with the increase in the growing speed of industries and population, water pollution and environmental pollution is a major challenge for the scientific community, which needs a serious and real solution in the world. Because the discharge of wastewater containing toxic substances, solid waste or flue gases from factories is known as a serious problem for the sustainable development of human society. Therefore, in this paper, which is a review of recent studies on this subject, first, an introduction to the catalytic degradation of pollutants is provided, and then the researcher's studies are reviewed, and finally, a conclusion is provided. In conclusion, it is found that in photocatalytic processes, the catalyst dosage is very effective on the rate of pollutant degradation. As the catalyst dosage increases, the number of active sites absorbing the pollutant at the catalyst surface also increases. The increasing trend of dye removal with catalyst dosage can be attributed to the increase in surface area and the availability of more absorption sites. This process continues until it increases light absorption and the production of hydroxyl radicals. However, it is also noteworthy that at values above the optimum, the reaction rate decreases. In other words, if the catalyst dosage is too high, not only it is not effective on the dye removal process, but also causes more turbidity of the solution, which in turn prevents the penetration of light and the effectiveness of the photocatalytic process.Keywords: Synthesis, Photocatalyst, Organic pollutants, wastewater}
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A quantitative structure–retention relation (QSRR) study was conducted on the retention times of 160 pesticides and 25 environmental organic pollutants in wine and grape. The genetic algorithm was used as descriptor selection and model development method. Modeling of the relationship between selected molecular descriptors and retention time was achieved by linear (partial least square; PLS) and nonlinear (kernel PLS: KPLS and Levenberg-Marquardt artificial neural network; L-M ANN) methods. The QSRR models were validated by cross-validation as well as application of the models to predict the retention of external set compounds, which did not have contribution in model development steps. Linear and nonlinear methods resulted in accurate prediction whereas more accurate results were obtained by L-M ANN model. The best model obtained from L-M ANN showed a good R2 value (determination coefficient between observed and predicted values) for all compounds, which was superior to those of other statistical models. This is the first research on the QSRR of the compounds in wine and grape against the retention time using the GA-KPLS and L-M ANN.Keywords: grape, Wine, Pesticide Residue, Organic pollutants, GC×GC–TOFMS, Quantitative structure–retention relationships}
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The ZnO/SiO2 semiconductor nanophotocatalysis was synthesized via sol-gel method. Also, the platinum particles were loaded on the ZnO/SiO2 nanoparticles by photoreductive method. The structure of catalyst was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM) andfourier transform infrared spectroscopy (FT-IR). The XRD patterns of ZnO particles displayed the nanoparticles have a wurtzite structure (hexagonal phase). The crystallite sizes were calculated using Scheerers equation and were around 32nm. For photocatalytic test, decomposition of Malachite Green oxalate (MG), as an organic pollutant was carried out by synthesized catalyst. A comparison of degradation between bare catalyst and platinum loaded ZnO/SiO2nanoparticle under UV-Vis light irradiation shows that the Pt-ZnO/SiO2 photocatalyst is more efficient than ZnO/SiO2 nanoparticles. Also, the activity of ZnO/SiO2nanoparticles in the visible light are minimal, while loading of Pt in zinc oxide network displaced the band gap toward longer wavelengths (visible light) and increased the photocatalysis activity of ZnO/SiO2 in the range of visible light.Keywords: Photocatalyst, Malachite Green, UV-Vis, ZnO, Organic pollutants}
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Water pollution is a major global problem which requires ongoing evaluation and revision of water resource policy at all levels (international down to individual aquifers and wells. It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily. Genetic algorithm-partial least square (GA-PLS), Kernel partial least square (GA-KPLS) and Levenberg-Marquardt artificial neural network (L-M ANN) techniques were used to investigate the correlation between retention time (RT) and descriptors for 150 organic contaminants in natural water and wastewater which obtained by gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-TOF MS). The L-M ANN model gave a significantly better performance than the other models. This indicates that L-M ANN can be used as an alternative modeling tool for quantitative structure–retention relationship (QSRR) studies.Keywords: Water Pollution, Hazardous chemicals, Organic pollutants, Gas Chromatography, Time-of-flight mass spectrometry, chemometrics, Levenberg-Marquardt artificial neural network}
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In this work, ZnO/SiO2 nanoparticles were prepared using sol-gel method, and platinum particles were loaded on ZnO/SiO2 nanoparticles by photoreductive method. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The XRD patterns showed that the zinc oxide samples have a wurtzite structure (hexagonal phase). The crystallite size calculated by Scheerer’s equation is ~ 32 nm. For photocatalytic test, decomposition of Rhodamine B (RB), as an organic pollutant, was carried out. A comparison of degradation between bare catalyst and platinum loaded ZnO/SiO2 nanoparticle under UV-Vis light irradiation shows that the Pt- ZnO/SiO2 photocatalyst is more efficient than ZnO/SiO2 nanoparticles. Also, the activity of ZnO/SiO2 nanoparticles in the visible light are minimal, while loading of Pt in zinc oxide network displaced the band gap toward longer wavelengths (visible light) and improved the photocatalysis activity of ZnO/SiO2 in the range of visible light.Keywords: Photocatalyst, Rhodamine B, UV, Vis, ZnO, Organic pollutants}
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