The Nanofluid includes suspensions containing nanoparticles, which are dispersed in the base fluid homogeneously. In this study, nanoparticles called multi-walled carbon nanotubes (MWCNT) were dispersed in a pure water-based fluid. The shape, size, and arrangement of carbon nanotubes were displayed by the transmittance electron microscope (TEM) and scanning electron microscope (SEM) techniques. The thermal conductivity and viscosity of the resulting nanofluid were measured experimentally. The carbon nanotubes within the nanofluid were stabilized using Sodium dodecyl benzene sulphate. The effect of carbon nanotubes on shear stress, thermal conductivity and viscosity of fluids has investigated. The results showed that at 308K the thermal conductivity was increased from 0.6 to 0.94 w/m.ºC with an increase in the volumetric concentration of MWCNTs from 0 to 0.015%. And the thermal conductivity was increased from 0.74 to 0.94 w/m.ºC with increase in temperature from 298 to 308K. The shear stress was increased from 10.8 to 11.9 N/m2 at 298K by increase in the volumetric concentration of MWCNTs from 0 to 0.015% and it was reduced from 11.9 to 9.2 N/m2 with enhance in temperature from 298 to 308K, respectively. پرونده مقاله

In this project, the removal of Acid Red 114(AR 114) that is a mono Azoo dye with global usage in aqueous environment was explored by nano photo catalytic process. The ZnO was supported on Bentonite and used at suspension state in a batch photo reactor. The catalyst was synthesized by co precipitation methods and characterized by Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FT-IR) spectra. The effect of operational variables including pH, initial concentration of Acid red 114, amounts of catalysts and temperature were investigated on the removal efficiency of AR114. The optimum conditions were achieved at 1g/l of catalyst, 30 mg/l of AR 114, pH of 9 and temperature at 35℃. The removal of AR 114 in UV, UV/ZnO, and UV/ZnO/Bentonite process were 26.5, 55 and 92.5% after 2 h of treatment, respectively. The photo catalytic degradation mechanism was described and the efficiency of the process increased considerably by modification of photo catalyst. پرونده مقاله

In this research, a synthesized nano photocatalyst was prepared by supporting ZnO nanoparticle on Lightweight expanded clay aggregate (LECA). The catalyst was synthesized by co-precipitation method. The SEM, FT-IR and XRD tests were used to characterize ZnO/LECA, which was employed for photocatalytic removal of Cr (VI) from aqueous solution in batch photoreactor. The full factorial experimental design (FFD) was used for the statistical analysis of data. The influence of catalyst amounts, pH, and initial concentration of Cr (VI) was investigated on the reduction of Cr (VI) to Cr (III). The number of active site was increased with increase in the concentration of catalyst to some extent. Also, the selection of other factors in optimized amount was important. The optimal conditions were obtained at 0.75 g/l of photocatalyst, pH at 5 and 20 mg/l of Cr(VI). The experimental and predicted reduction efficiency by FFD at optimal conditions were 97.6 and 96.18%, respectively. The comparison of experimental and predicted data showed a good agreement between them. پرونده مقاله

The Photocatalytic degradation of chemical pollutants such as dyes, especially by Nano catalysts is an effective method to protect the environment and water resources. In this study, through Forced Hydrolysis and Reflux Condensation (FHRC) method the nanospherical α-Fe2O3 particles were synthesized and supported on the surface of silica sand by Solid-State Dispersion (SSD) method with the average crystallite size of 27.5 nm. The characterization of catalyst and catalyst support was done using FTIR spectroscopy, SEM images, XRD patterns and BET surface area. In this paper, α-Fe2O3/SiO2 nanophotocatalyst was used for the removal of methyl red (MR) under ultraviolet (UV) light. After running different tests, the effective parameters such as the concentration of MR, pH, and mass of catalyst on pollutant degradation were optimized by single-variable method. The results showed that the optimum conditions for achieving 98.46 % of degradation were pH at 5, initial concentration of MR at 10 mg/l, and 2.0 g of α-Fe2O3/SiO2 nano photo catalyst. پرونده مقاله

Ever-increasing environmental pollutions and water scarcity are highly challenging issues that pose formidable obstacles to human beings on all fronts. Hetero-photocatalytic methods which utilized semiconductors as photocatalysts are highly promising and green technologies for the degradation of recalcitrant organic pollutants which cannot be completely removed by conventional treatment processes. In the view of the current scenario, zinc oxide nanostructures have been demonstrated to be predominant photocatalyst candidates for photodegradation because of their cost-effectiveness, non-toxicity, strong oxidation capability, flexibility in synthesizing, earth-abundance nature, easy crystallization, and high performance in the absorption over an extensive fraction of solar spectrum in comparison with titanium dioxide. Nevertheless, bare zinc oxide possesses several intrinsic limitations, like high recombination rate of the photogenerated charge carriers, limited solar light application, photo corrosion, broad bandgap and limited visible light absorption. Moreover, photocatalysts separation from remediated solutions restricts their large-scale applications. In this review paper, the authors briefly discussed basic principles of the zinc oxide photocatalytic process besides various modifications such as coupling with low bandgap semiconductors like metal and non-metal doping, synthesizing with graphene oxide, or reduced graphene oxide and their integration in magnetic materials to successfully addressing aforesaid disconcerting challenges. Moreover, hybridized photocatalytic and membrane systems are explored. Finally, challenges and future research directions are proposed for giving profound and well-defined insights toward reaching fully exploited zinc oxide-based nanoparticles in the field of water and wastewater treatments. پرونده مقاله

In this study, through the application of TiO2/ZnS as a novel nano photocatalyst, the degradation of AR18 in synthetic wastewater was explored. The nano photocatalyst was synthesized by the co-precipitation method and characterized by Scanning electron microscopy (SEM), Fourier transfer infrared (FTIR), and X-ray powder diffraction (XRD) techniques. The average size of ZnS/TiO2 nano photocatalyst was 79nm. For experimental design and statistical analysis of each factor including AR18 concentration, pH, catalyst dosage, and treatment time on the degradation rate of AR18 (response) by Central Composite Design (CCD) was used. The analysis of variance (ANOVA) demonstrates a second-order regression model with R2 = 0.9995, adjusted R2=0.9991, and predicted R2=0.9982) for the removal of AR18. The optimum conditions for each operating factor were as the following: AR18 concentration at 30 mg.L-1, catalyst dosage at 1.2 g.L-1, pH at 5, and treatment time at 120 min. In this condition, the actual and predicted AR18 removal was 94% and, 93.07%, respectively. پرونده مقاله

The wastewater containing Tert- Butyl alcohol (TBA) contains water-soluble polymer discharged from different chemical and textile industries. In this study, through the application of the UV/ZnFe2O4 approach in a batch photoreactor, the decomposition of synthetic wastewater including TBA was investigated. The co-precipitation method was utilized for synthesizing the ZnFe2O4 nano photocatalyst. Using FTIR spectroscopy, XRD, and SEM images, the characterization of catalyst was ascertained. For evaluation and exploration of the stability of nano photocatalyst particles, the Zeta potential was utilized. The influence of different crucial factors including the concentration of catalyst, the initial dosage of contaminants, and pH, on the mineralization of TBA was studied. At optimal situations (pH at 6, 25 mg/l of TBA, and 0.9 g/l of catalyst) and after 120 min of remediation time, around 58% of Chemical Oxygen Demand (COD) and 93.5% of TBA was eliminated. The main reason for the generation of active radicals in the photocatalytic method is the electron-hole mechanism. According to the Langmuir Hinshelwood model, the kinetic of the TBA decomposition was elucidated hence, the half-life of the reaction and the apparent rate of the pseudo-first-order reaction, (t_(1/2)=35 min) and (K_app=1.98×10^(-2) min^(-1)) was obtained, respectively. پرونده مقاله

In this study, TiO2/Ag nano photocatalyst was synthesized by sol-gel method and used for degradation of Chloridazon (CLZ) in aqueous media. The prepared catalyst was characterized using powder X-ray diffractometry (XRD), Fourier transform infra-red (FTIR), and field emission scanning electron microscopy (FESEM) techniques. The Crystallite size of pure TiO2 and Ag/TiO2 nanoparticles was 20 and 60 nm, respectively. The Central Composite Design (CCD) was employed for experimental design and statistical analysis of independent operational parameters. According to the results of Response Surface Methodology (RSM) plots of Design-Expert software, the optimal conditions for each critical variable were as the follows: time at 113 min, pH at 6.8, initial concentration of CLZ at 40 mg/l, and catalyst concentration at 0.83gr/l. The maximum effectiveness in the experimental and predicted CLZ removal was 94.2 and 93.5%, respectively. The outcomes of Analysis of variance (ANOVA) demonstrated high determination coefficient quantities (R2 = 0.9997, Predicted R2=0.9989, and Adjusted R2=0.9994) which validated the reliability of the second-order regression model. پرونده مقاله

The Photocatalytic degradation of chemical pollutants such as dyes, especially by Nano catalysts is an effective method to protect the environment and water resources. In this study, through Forced Hydrolysis and Reflux Condensation (FHRC) method the nanospherical α-Fe2O3 particles were synthesized and supported on the surface of silica sand by Solid-State Dispersion (SSD) method with the average crystallite size of 27.5 nm. The characterization of catalyst and catalyst support was done using FTIR spectroscopy, SEM images, XRD patterns and BET surface area.In this paper, α-Fe2O3/SiO2 nano photocatalyst was used for the removal of methyl red (MR) under ultraviolet (UV) light. After running different tests, the effective parameters such as the concentration of MR, pH, and mass of catalyst on pollutant degradation were optimized by single-variable method. The results showed that the optimum conditions for achieving 98.46 % of degradation were pH at 5, initial concentration of MR at 10 mg/l, and 2.0 g of α-Fe2O3/SiO2 nano photo catalyst. پرونده مقاله

In this research, a synthesized nano photocatalyst was prepared by supportingZnO nanoparticle on Lightweight expanded clay aggregate (LECA). The catalystwas synthesized by the co-precipitation method. The SEM, FT-IR, and XRD testswere used to characterize ZnO/LECA, which was employed for photocatalyticremoval of Cr (VI) from an aqueous solution in a batch photoreactor. The fullfactorial experimental design (FFD) was used for the statistical analysis of data.The influence of catalyst amounts, pH, and initial concentration of Cr (VI) wasinvestigated on the reduction of Cr (VI) to Cr (III). The number of active sites wasincreased with an increase in the concentration of catalyst to some extent. Also,the selection of other factors in the optimized amount was important. The optimalconditions were obtained at 0.75 g/l of photocatalyst, pH at 5 and 20 mg/l ofCr(VI). The experimental and predicted reduction efficiency by FFD at optimalconditions were 97.6 and 96.18%, respectively. The comparison of experimentaland predicted data showed a good agreement between them. پرونده مقاله

In this project, the removal of Acid Red 114(AR 114) that is a mono Azoo dye withglobal usage in an aqueous environment was explored by nano photocatalyticprocess. The ZnO was supported on Bentonite and used at suspension state ina batch photoreactor. The catalyst was synthesized by co precipitation methodsand characterized by Scanning Electronic Microscopy (SEM), X-Ray Diffraction(XRD), and Fourier Transform Infrared (FT-IR) spectra. The effect of operationalvariables including pH, initial concentration of Acid red 114, amounts of catalystsand temperature were investigated on the removal efficiency of AR114. Theoptimum conditions were achieved at 1g/l of catalyst, 30 mg/l of AR 114, pH of9 and temperature at 35oC. The removal of AR 114 in UV, UV/ZnO, and UV/ZnO/Bentonite process were 26.5, 55 and 92.5% after 2 h of treatment, respectively.The photo catalytic degradation mechanism was described and the efficiency ofthe process increased considerably by modification of photocatalyst. پرونده مقاله

The Nanofluid includes suspensions containing nanoparticles, which are dispersedin the base fluid homogeneously. In this study, nanoparticles called multi-walledcarbon nanotubes (MWCNT) were dispersed in a pure water-based fluid. The shape,size, and arrangement of carbon nanotubes were displayed by the transmittanceelectron microscope (TEM) and scanning electron microscope (SEM) techniques.The thermal conductivity and viscosity of the resulting nanofluid were measuredexperimentally. The carbon nanotubes within the nanofluid were stabilized usingSodium dodecyl benzene sulphate. The effect of carbon nanotubes on shearstress, thermal conductivity and viscosity of fluids has investigated. The resultsshowed that at 308K the thermal conductivity was increased from 0.6 to 0.94w/m.ºC with an increase in the volumetric concentration of MWCNTs from 0 to0.015%. And the thermal conductivity was increased from 0.74 to 0.94 w/m.ºCwith increase in temperature from 298 to 308K. The shear stress was increasedfrom 10.8 to 11.9 N/m2 at 298K by increase in the volumetric concentrationof MWCNTs from 0 to 0.015% and it was reduced from 11.9 to 9.2 N/m2 withenhance in temperature from 298 to 308K, respectively. پرونده مقاله

یکی از آلاینده های مهم و سرطان زای موجود در پساب تعدادی از صنایع شیمیایی ارتو تولوییدین است. در این پروژه حذف ارتو تولوییدین با فرایندهای UV/H2O2 و UV/US/H2O2 در واکنشگاه های ناپیوسته چرخشی مورد مطالعه و بررسی قرار گرفته است. در فرایند UV/H2O2 در دمای ثابت 25 درجه سانتی گراد سه عامل مهم شامل غلظت اولیه ارتو تولوییدین، مقدار آب اکسیژنه و pH به عنوان متغیرهای تاثیرگذار بر فرایند مورد بررسی قرار گرفته است و شرایط بهینه شامل 40 میلی مول بر لیتر از آب اکسیژنه، 50 میلی گرم بر لیتر ارتو تولوییدین و pH برابر با 9 به دست آمد. با اضافه شدن امواج فراصوت به فرایند UV/H2O2 ثابت سرعت واکنش افزایش یافته است. فرایند UV/US/H2O2 در دماهای 25 ،30 و 35 درجه سانتی گراد مورد بررسی قرار گرفت و بیشترین بازده در دمای 35 درجه سانتی گراد مشاهده شده است. با استفاده از مطالعات سینتیکی در واکنش حذف ارتو تولوییدین با فرایندهای UV/H2O2و UV/US/H2O2ثابت سرعت شبه درجه اول به ترتیب برابر با 1-mm 0442/0 (شرایط بهینه) و 1-mm 0593/0 به دست آمده است. مقدار حذف کل کربن آلی(TOC) پس از 100 دقیقه از واکنش در فرایندهای UV/H2O2 و UV/US/H2O2 به ترتیب برابر با 38 و5/52 درصد بود. هم چنین اثر حجم و دبی حجمی پساب چرخشی و روابط سینتیکی در واکنشگاه مورد استفاده نیز بررسی شده است به طوری که با افزایش حجم پساب در گردش بازده کاهش و با افزایش دبی حجمی پساب گردشی بازده تخریب آلاینده در واکنشگاه افزایش یافته است. پرونده مقاله

در این پژوهش، حذف 4-نیتروفنل در محیط‌های آبی با روش الکتروپرسولفات و الکتروفنتون با الکترود آهن در یک واکنشگاه ناپیوسته الکتروشیمیایی در مقیاس آزمایشگاهی مجهز به چهار الکترود و منبع برق مستقیم بررسی شد. نتایج نشان داد که درصد حذف 4-نیتروفنل در فرایند الکتروپرسولفات و الکتروفنتون، در زمان60 دقیقه و شرایط بهینه به ترتیب 2/99 و 0/94 درصد بود. شرایط عملیاتی بهینه در pH برابر با 3، غلظت اولیه 4-نیتروفنل برابر با 100 میلی‌گرم در لیتر، 5/0 میلی‌مولار از هیدروژن پراکسید و پرسولفات و با چگالی 1/0 آمپر در دسی‌مترمربع به‌دست آمد. فرایند‌های الکتروپرسولفات و الکتروفنتون برای حذف 4-نیتروفنل بازده حذف یکسانی در محیط اسیدی داشتند. به‎طور کلی تلفیق فرایند الکتروشیمیایی با پرسولفات و هیدروژن پراکسید به منظور تولید الکتریکی آهن و فعال‌سازی پرسولفات و هیدروژن پراکسید توانایی بیشتری از به‎کارگیری جداگانه این فرایند‌ها داشتند. در نمونه واقعی پساب شامل COD برابر با 5000 میلی‌گرم بر لیتر، حذف COD در فرایند الکتروفنتون و الکتروپرسولفات به ترتیب 82 و 86 درصد بود. پرونده مقاله

استانیلید یکی از مهم‌ترین مواد شیمیایی واسطه در صنایع داروسازی است که به‎عنوان تب‌بر و پاددرد استفاده می‌شود. تاکنون برای تصفیه و تخریب پساب حاوی این آلاینده هیچ کار پژوهشی انجام نشده است. در این پژوهش، برای نخستین بار پساب تهیه ‎شده حاوی استانیلید با فرایند ازون‌زنی موردتصفیه قرارگرفت. اثر متغیرهای فرایندی با روش طراحی آزمایش باکس بنکن در واکنشگاه نیم‎پیوسته بررسی شد. مقدار ازون برابر با 15 میلی‌گرم بر لیتر، pH برابر با 9 و غلظت اولیه استانیلید برابر با 50 میلی‌گرم بر لیتر به‎عنوان شرایط بهینه به‎دست آمد و در این شرایط در مدت 30 دقیقه، 100 % از آلاینده و 5/61 % از اکسیژن موردنیاز شیمیایی (COD) حذف شد. مهم‌ترین عامل تاثیرگذار بر فرایند pH بود. به‎علت تشکیل رادیکال هیدروکسیل، بازده تخریب آلاینده در محیط قلیایی بیشتر بود. به‎علت تولید ترکیبات حد واسط کربوکسیلیک اسیدی، مقدار تخریب استانیلید بسیار بیشتر از سرعت معدنی‎سازی و حذف اکسیژن موردنیاز شیمیایی بود. معادله سرعت تخریب آلاینده از نوع شبه‎درجه اول بود و ثابت سرعت و زمان نیمه-‎عمر واکنش تخریب، به ترتیب برابر با 1-min 3-10 ×2/155 و 55/4 دقیقه تعیین شد. پرونده مقاله

In this research degradation and mineralization of Ortho-Toluidine (OT) in the wastewater of petrochemical industries was investigated by UV/TiO2 process in a batch recirculating photo reactor. The influence of different variables such as initial pH, amount of TiO2 and initial concentration of OT on the reaction rate was investigated. In optimum conditions (1.75 g/l of catalyst, pH at 7 and initial concentration of OT at 20 mg/l), 93.5% of pollutant and 57% of COD were removed in 180 min of reaction. The reaction rate represented by the mechanism of Langmuir-Hinshelwood was found to follow pseudo first-order kinetics. Degradation and mineralization of the OT were tested by HPLC and COD tests. پرونده مقاله

In this project decolorization and mineralization of synthetic wastewater containing acid red 33 (AR33) was investigated by Fenton and photo Fenton processes in a batch photo reactor. A comparative assessment using Fenton and photo Fenton processes was performed after initial optimization studies such as varying pH, the concentration of pollutant, peroxide and iron. The color removal and mineralization efficiency of AR33 were calculated by Spectrophotometric and chemical oxygen demand (COD) tests. The degradation efficiency in photo Fenton process (98.5% in 10 min of reaction) was higher than Fenton ones (97.5% in 30 min). After 60 min of reaction, the removal of COD in photo Fenton and Fenton processes was 71% and 37.5%, respectively. Therefore, photo Fenton was the most effective process in partial mineralization of AR33. Kinetic constants were evaluated using pseudo first order equations to obtain the rate constant, K. پرونده مقاله