mohammad ali baghapour
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Introduction
Air pollution from industrial sources is a growing problem increasing the amount of air pollution by emitting various gaseous pollutants such as Nitrogen Oxides (NOx ). This study analyzed Nitrogen dioxide (NO2 ) emissions using American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) from the stacks and flares of a gas refinery in the Middle East.
Materials and methodsThe NO2 emissions were measured from the stacks and flare of the refinery (231 samples). The distribution of emissions was investigated over a statistical period of 1 year for an average time of 1 h using the AERMOD dispersion model in an area of 25×25 km2 . The predicted concentrations were compared with national and international standards and are plotted for the desired zones.
ResultsComparison of simulation results with national and international clean air standards showed that NO2 emission modeled in all periods of 4 seasons is higher than the standard. Examination of NO2 emission and distribution maps also showed that the maximum concentration of NO2 pollutants occurred in the central parts and the area close to the refinery. The highest maximum concentration of 1-h NO2 was 3744.3716 μg/m3 in summer in the west and south of the refinery. Validation results also showed a high correlation between the predicted and actual results.
ConclusionThe power of resources in emission and distribution, topographic conditions, and meteorological characteristics of the region are three important and influential factors in the distribution of NO2 pollutants. So pollution reduction strategies are needed due to the different types of use, surrounding residential areas, personnel, and people involved in the gas refining company
Keywords: Air pollution modeling, AERMOD, Nitrogen dioxide (NO2) -
BackgroundNatural Organic Matters (NOMs) react in the presence of residual chlorine in distribution network pipes, producing such byproducts as Trihalomethanes which are carcinogenic and mutagenic. The present study was conducted to investigate the quality of drinking water in Shiraz.MethodsIn this cross-sectional study, 54 samples were taken from 27 locations in both summer and winter. For each sample, temperature, residual chlorine, pH, and NOM were measured during the two seasons. Residual chlorine and temperature measurement were performed at the sampling sites, but pH and NOM were measured in the laboratory.ResultsAccording to the results, the mean concentrations of Total NOM (TNOM), residual chlorine, pH, and temperature varied from 0.9 to 5 m-1, 0 to 1.2 mg/L, 7.4 to 8 and 18 to 23.5 ᵒC in summer and from 0.3 to 1.5 m-1, 0 to 0.8 mg/L, 7.6 to 8.2 and 9.7 to 10.8 ᵒC in winter, respectively. In addition, the concentrations of all measured parameters, except for pH, were reported to be higher in summer than in winter.ConclusionAs a result, since the amount of NOM in the drinking water distribution network of Shiraz was not zero, regular monitoring of these compounds in the distribution networks is recommended to be done by engineers.Keywords: Distribution network, Water, NOM, Residual Chlorine, pH
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A vast variety of pesticides are used for agricultural pests in Iran. The release of these persistent organic pollutants into water supplies leaves adverse effects on both the environment and public health. This study aimed to compare the photo-degradation of atrazine in the aquatic environment using UV and UV/Fe (III)-TiO2 processes. The effects of parameters including pH, the initial concentration of atrazine, and reaction time on the removal of atrazine in the aqueous phase using ultraviolet radiation (1020 μW/cm2 ) and UV/Fe (III)-TiO2 were investigated. Residual concentrations were determined using HPLC. Finally, the data were analyzed using SPSS software (version 16) and the graph was made by MATLAB software. The results demonstrated that the atrazine removal rate in both processes was significantly increased in acidic and alkaline conditions. By increasing initial atrazine concentrations, the removal rate was increased in both processes as well. Data showed that at the lower initial concentration of atrazine (0.1 and 1mg/l) the removal rate in UV/ Fe (III) - TiO2 process was more than the UV process. However, at higher concentration, both processes were almost the same and the maximum removal efficiency (99.2% at UV and 99.11% at UV /Fe (III) - TiO2) occurred at pH=11, initial Atrazine concentration of 10mg/L and the reaction time 30 min In conclusion, UV and Fe+3 -TiO2/UV process was an appropriate method to reduce atrazine in contaminated water resources.
Keywords: Atrazine, UV, Fe (III)-TiO2, Photodegradation -
مقدمه و هدف
غلظت برخی از آلاینده ها اغلب در محیط های داخلی بیشتر از محیط های بیرونی تشخیص داده شده است؛ بنابراین، آلودگی هوای خانگی در حال حاضر به عنوان یکی از مهم ترین نگرانی های سلامت عمومی در سراسر جهان در نظر گرفته می شود. مطالعه حاضر با هدف اندازه گیری غلظت آلاینده های بنزن، تولوین، اتیل بنزن و زایلن در هوای منازل شهر خشت در استان فارس و ارزیابی خطر سرطان زایی و غیر سرطان زایی این ترکیبات در هوای تنفسی زنان خانه دار طراحی شد.
روش کاردر این مطالعه، از هوای 30 منزل در شهر خشت نمونه گرفته شد. نمونه های هوا برای اندازه گیری ترکیبات BTEX بر اساس روش شماره 1501 NIOSH جمع آوری و با دستگاه GC-FID اندازه گیری شد. خطر سرطان زایی و غیر سرطان زایی این ترکیبات در هوای تنفسی زنان خانه دار طول یک سال محاسبه شد. تجزیه وتحلیل داده ها با استفاده از آزمون های همبستگی اسپیرمن و من وینتی و نرم افزار SPSS نسخه 23 با سطح اطمینان 95 درصد انجام شد.
یافته ها:
نتایج نشان داد غلظت بنزن، تولوین و زایلن به ترتیب 1/76-0/06، 0/96-0/1 و 0/97-0/01 میکروگرم در مترمکعب بود. مقادیر اتیل بنزن در تمامی نمونه ها کمتر از حد تشخیص دستگاه گزارش شد. رابطه خطی و مثبت معناداری بین غلظت بنزن و تولوین مشاهده شد (0/05 <p). خطر افزایش سرطان محاسبه شده در طول یک سال (ILCR) برای بنزن در تمام نمونه ها کمتر از حد استاندارد (6-10×1) توصیه شده توسط آژانس حفاظت از محیط زیست ایالات متحده (EPA) و سازمان بهداشت جهانی گزارش شد. همچنین میزان ضریب خطر (HQ) محاسبه شده به منظور ارزیابی خطرات غیر سرطان زایی برای بنزن، تولوین و زایلن کمتر از یک گزارش شد.
نتیجه گیری:
با توجه به اینکه سازمان بهداشت جهانی هیچ محدوده امنی برای مواجهه با بنزن، به خصوص در هوای داخلی که افراد مدت زمان بیشتری را سپری می کنند، در نظر نگرفته است، درنتیجه غلظت ناچیز این آلاینده در محیط های داخلی نیز برای سلامتی افراد به خصوص زنان خانه دار نگران کننده است؛ بنابراین، به منظور کاهش غلظت این آلاینده و سایر ترکیبات BTEX، کاهش یا حذف آن دسته از فعالیت های انسانی که ترکیبات BTEX آزاد می کنند و همچنین استفاده از روش های تهویه مناسب توصیه می شود.
کلید واژگان: آلودگی هوای داخلی، ارزیابی خطر، ترکیبات آلی فرار، ترکیبات BTEXIntroduction and purposeThe concentration of some indoor pollutants is often recognized as higher than that in the outdoor. Accordingly, household air pollution is currently considered one of the most important public health concerns worldwide. Therefore, this study aimed to measure the concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) pollutants in the air of houses in Khesht, Fars Province, Iran. Moreover, it was attempted to evaluate the carcinogenic and non-carcinogenic risks of these compounds in respiratory air for housewives.
MethodsAir samples were taken from 30 houses according to the National Institute for Occupational Safety and Health Manual of Analytical Method no. 1501 and were analyzed using the gas chromatography/flame ionization detector to measure BTEX compounds. In addition, carcinogenic and non-carcinogenic risks of target compounds in respiratory air for housewives during one year were assessed in this study. Mann Whitney U and Spearman correlation tests were applied to analyze the data in SPSS software (version 23). A p-value less than 0.05 was considered statistically significant.
ResultsAccording to the results, the benzene, toluene, and xylenes concentrations varied from 0.06 to 1.76, 0.1 to 0.96, and 0.01 to 0.97 µg / m3, respectively. Moreover, ethylbenzene levels in all samples were below the detection limit. A significant linear and positive relationship was observed between benzene and toluene concentrations (P<0.05). Furthermore, the Incremental Lifetime Cancer Risk for benzene in all samples was reported to be significantly lower than the standard (1×10-6) recommended by the US Environmental Protection Agency and the World Health Organization (WHO). Moreover, the calculated hazard quotient for benzene, toluene, and xylene was less than one in this study.
ConclusionThe WHO has not considered any safe restrictions on exposure to benzene, especially indoors in which people spend more time. However, even the low concentrations of these indoor pollutants are dangerous to human health, especially housewives. Therefore, in order to reduce the concentration of these pollutants and other BTEX compounds, it is recommended to reduce or eliminate those human activities that release BTEX compounds and use appropriate ventilation methods.
Keywords: BTEX compounds, Indoor air pollution, Risk assessment, Volatile organic compounds -
Drinking water quality monitoring is a prerequisite for macro planning of development programs in metropolitans, improvement in health, and water resources management. Since WQIs (Water Quality Index) are known as comprehensive tools for interpretation of water quality, this study benefitted from this tool to determine the drinking water quality trends in Shiraz, Iran in a five year period from 2011 to 2015 and figure out the factors affecting its changes in this city. For this aim, annual data of 9 water quality parameters including DO, Fecal Coliforms, pH, BOD5, NO3, PO4, temperature deviation, turbidity, and TS were collected for 45 drinking water wells located in 4 zones (Dokuhak, Derak, Sabzpushan, and Chamran) to calculate the WQI. Pairwise comparison of years in terms of WQI values was analyzed statically using post-HOC analysis in Univariable repeated measure test. The results showed that the highest and the lowest water quality level both for annual and long term evaluations belonged to Derak and Chamran zones, respectively. All the studied wells in the five years were classified in "good" quality group. According to statistically analyze the highest significant change in water quality (p-valueKeywords: Water quality, Drinking, NSFWQI, Shiraz
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In developing a specific WQI (Water Quality Index), many quality parameters are involved with different levels of importance. The impact of experts different opinions and viewpoints, current risks affecting their opinions, and plurality of the involved parameters double the significance of the issue. Hence, the current study tries to apply a consensus-based FOWA (Fuzzy Ordered Weighting Average) model as one of the most powerful and well-known Multi-Criteria Decision- Making (MCDM) techniques to determine the importance of the used parameters in the development of such WQIs which is shown with an example. This operator has provided the capability of modeling the risks in decision-making through applying the optimistic degree of stakeholders and their power coupled with the use of fuzzy numbers. Totally, 22 water quality parameters for drinking purposes were considered in this study. To determine the weight of each parameter, the viewpoints of 4 decision-making groups of experts were taken into account. After determining the final weights, to validate the use of each parameter in a potential WQI, consensus degrees of both the decision makers and the parameters are calculated. The highest and the lowest weight values, 0.999 and 0.073 respectively, were related to Hg and temperature. Regarding the type of consumption that was drinking, the parameters weights and ranks were consistent with their health impacts. Moreover, the decision makers highest and lowest consensus degrees were 0.9905 and 0.9669, respectively. Among the water quality parameters, temperature (with consensus degree of 0.9972) and Pb (with consensus degree of 0.9665), received the highest and lowest agreement with the decision-making group. This study indicated that the weight of parameters in determining water quality largely depends on the experts opinions and approaches. Moreover, using the FOWA model provides results accurate and closer- to-reality on the significance of each of the water quality parameters. Thus, using this operator can be a precise and appropriate method to determine the parameters weights and importance in order to develop specific WQIs for drinking, industrial, and agricultural purposes.Keywords: MCDM, FOWA Model, Consensus, Fuzzy Number, Water Quality Index
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BackgroundMonitoring the water quality and analyzing its changes over time is an important aspect of sustainable management and development of water resources. The purpose of the present study was to analyze the trend of temporal variations in the quality of drinking water supplied from groundwater sources in Shiraz, using IRWQI (Iran Water Quality Index) as well as statistical analysis.MethodologyThis study was conducted on groundwater resources in Shiraz, Iran from 2011 to 2015. 10 water quality parameters were used in this index including NO3, Fecal Coliform, EC, TH, SAR, BOD5, PO4, COD, pH, and DO, with their own weights. Repeated measure test was used in order to analyze the differences between IRWQI values between the study years.ResultsThe results showed that IRWQI varied between 89/96 (very good quality) and 49/51 (average quality) in the study years. The main causes of water quality decline were average to relatively high levels of hardness and nitrate. The general pattern of the changes in water quality has been accompanied by an increase and decrease, so that the water quality has improved from 2011 to 2013 but then declined until the end of the study.ConclusionRegarding the necessity of clarifying the water quality condition and its changes and the importance of using IRWQI as an emerging national indicator, water quality analysis in different parts of the country, taking advantage of this indicator and statistical analyses will help the country promote and accelerate the integrated management of water resources quality.Keywords: Water Quality, Groundwater, IRWQI, Drinking, Shiraz
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BackgroundAtrazine is used extensively in many parts of the world for controlling a variety of weeds, primarily in the production of corn. Its widespread use in water has caused environmental concern because of its frequent detection in aquatic systems where this herbicide has been spilled.ObjectivesThe purpose of this study was to focus on evaluating the feasibility of using titanium catalyst doped with iron (FeTiO2) to remove atrazine from the aqueous phase and to determine its removal efficiency in ideal conditions.Materials And MethodsThe influence of different parameters was considered. Three different levels of pH (3 - 11), initial concentration of atrazine at three different levels (0.1 - 10 mg/L), and reaction time at five different levels (0 - 120 minutes) in the removal of atrazine in an aqueous-phase titanium catalyst doped with iron (FeTiO2) at three different levels (0 - 25) were investigated. Finally, the data were analyzed using SPSS software (version 16).ResultsThe results demonstrated that the atrazine removal rate increased by decreasing the initial atrazine concentration and the maximum rate of atrazine removal (41.72%) was at pH = 11, atrazine concentration = 0.1 mg/L, and catalyst concentration = 25 at 120 minutes.ConclusionsAccording to the results, it can be concluded that the titanium catalyst doped with iron (FeTiO2) processes is an appropriate method for reducing atrazine in polluted water resources.Keywords: Atrazine, Liquid Solution, Catalyst, Removal
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BackgroundAtrazine is one of the most widely used triazine herbicides which has been used for controlling broadleaf and grassy weeds for many years. Its widespread use in water has caused environmental concern because of frequent detection of atrazine in aquatic systems where this herbicide has been spilled. Therefore, the purpose of this study was to determine the herbicide removal efficiency at the optimal conditions.MethodsThe effect of different parameters including pH at three different levels (3-11), the initial concentration of atrazine at three different levels (0.1-10 mg/L), and reaction time at five different levels (0-120 min) on the removal of atrazine in the aqueous phase using ultraviolet radiation (1020 μw/cm2) was investigated. Finally, the data were analyzed using SPSS software (version 16).ResultsThe results demonstrated that atrazine removal rate increased by increasing pH, initial atrazine concentration, and reaction time. The maximum rate of atrazine removal (99.2%) at optimal condition occurred in pH=11, atrazine concentration=10 mg/L at 30 min.ConclusionAccording to the findings, it can be concluded that the UV-A process is an effective and commodious method for reducing atrazine in polluted water resources.Keywords: Herbicide, Atrazine, Ultraviolet radiation, Photodegradation
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BackgroundThe consumption of healthy food is considered as an essential need to devoid the physical, chemical, and biological hazards. The importance of this issue is more conspicuous in places such as hospitals where people with somehow compromised immune systems are under treatment. Therefore, this research aimed to evaluate the microbiological quality of food contact surfaces in a kitchen in one of the hospitals of Shiraz University of Medical Sciences.MethodsIn the present study, samples were taken from 48 food contact surfaces according to ISO 18593:2004(E) and placed into the bags containing diluting solution; they were then transferred to the laboratory for microbial analysis in the cold chain. The microbial analysis was carried out according to ISO 4833-1:2013 and BS ISO 4832:2006 for enumeration of total bacterial count and coliform.ResultsBased on the results presented here, 39.6% and 85.7% of the samples showed acceptable contamination with regard to the enumeration of total bacterial and coliform count. Besides, 18.2% and 72.7 % of work surfaces groups (cutting board, table, and hand) showed acceptable contamination with regard to the enumeration of total bacterial count and coliform in comparison to the standards. Furthermore, 45.9% and 89.2% of other surfaces showed acceptable total bacterial and coliform count, respectively.ConclusionThe results showed that safe management of the kitchen, education of the staff and also improvement of the equipment used are necessary.Keywords: Total bacterial count, Coliform, Food contact surfaces, Hospital
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BackgroundGroundwater nitrate pollution is an important environmental problem in water resources management. In this regard, specific measures aiming at prevention of water pollution will be helpful to managers and decision-makers. Identification of aquifers’ vulnerable areas and determination of groundwater protection zones using most widely used models, such as DRASTIC and CD, are one of the most useful approaches in water resources’ hygiene.ObjectiveThe present study aimed to assess the vulnerability of Shiraz plain’s unconfined aquifer using the above-mentioned models.MethodsThe main hydro-geologic factors affecting the transmission of pollution, including depth to water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone, aquifer hydraulic conductivity, and land use parameters were rated, weighted, and integrated using GIS 9.3. Finally, the maps of Shiraz plain’s unconfined aquifer vulnerability were prepared.ResultsThe vulnerability maps based on these two indexes showed very similar results, identifying the southeastern part of the aquifer, around Maharlu Lake, as the vulnerable zone. The observed nitrate concentrations from the wells in the underlying aquifer were in accordance with these findings. The results of sensitivity analyses indicated the depth parameter as the most effective parameter in vulnerability assessment of Shiraz plain.ConclusionAs Shiraz plain has been covered with fine-grained sediments, except for some central and south-east regions which have moderate vulnerability and high nitrate concentration, its vulnerability is low. Given the intensive agricultural activities and also the rise in groundwater level in southeastern regions, more attention should be paid to these areas.Keywords: Vulnerability, Shiraz aquifer, DRASTIC, CD index, Nitrate
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BackgroundModeling aims at simulation or optimization of a process in various environments and is an essential tool that allows researchers to gain a better understanding of processes. Also, modeling helps to predict the scientific events. In spite of the great advantages of antibiotics, these compounds enter into the environments through various pathways, change and destroy different ecosystems, and lead to bacterial resistance. Amoxicillin is widely used as an antibiotic in modern medicine. Due to its certain physicochemical characteristics, it leaks into aquatic environments. Up to now, many physical and chemical methods have been recommended for removing amoxicillin from soil and aquatic environments. However, these methods are very costly..ObjectivesThe present study aimed to evaluate and model the capability of the biological aerated filters (BAFs) in degradation of amoxicillin from aquatic environments in different concentration levels of amoxicillin and hydraulic retention times (HRTs)..Materials And MethodsIn this study, biodegradation of amoxicillin by BAF was evaluated in the aquatic environment. In order to assess amoxicillin removal from the aquatic environment, this bioreactor was fed with synthetic wastewater at four amoxicillin concentration levels and three HRTs..ResultsThe results showed that maximum amoxicillin and chemical oxygen demand (COD) removals by aerated biofilter were 50.7% and 45.7%, respectively..ConclusionsThe study results showed that Stover-Kincannon model had a great fitness (R2 > 99%) for loading this biofilter with amoxicillin..Keywords: Amoxicillin, Anti, Bacterial Agents, Biodegradation, Environmental, Waste Water
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BackgroundModeling aims at simulation or optimization of a process in various environments and is an essential tool that allows researchers to gain a better understanding of processes. Also, modeling helps to predict the scientific events. In spite of the great advantages of antibiotics, these compounds enter into the environments through various pathways, change and destroy different ecosystems, and lead to bacterial resistance. Amoxicillin is widely used as an antibiotic in modern medicine. Due to its certain physicochemical characteristics, it leaks into aquatic environments. Up to now, many physical and chemical methods have been recommended for removing amoxicillin from soil and aquatic environments. However, these methods are very costly..ObjectivesThe present study aimed to evaluate and model the capability of the biological aerated filters (BAFs) in degradation of amoxicillin from aquatic environments in different concentration levels of amoxicillin and hydraulic retention times (HRTs)..Materials And MethodsIn this study, biodegradation of amoxicillin by BAF was evaluated in the aquatic environment. In order to assess amoxicillin removal from the aquatic environment, this bioreactor was fed with synthetic wastewater at four amoxicillin concentration levels and three HRTs..ResultsThe results showed that maximum amoxicillin and chemical oxygen demand (COD) removals by aerated biofilter were 50.7% and 45.7%, respectively..ConclusionsThe study results showed that Stover-Kincannon model had a great fitness (R2 > 99%) for loading this biofilter with amoxicillin..Keywords: Amoxicillin, Anti, Bacterial Agents, Biodegradation, Environmental, Waste Water
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BackgroundAmoxicillin is widely used as an antibiotic in the modern medicine. Due to its chemical structure, polarity, activity level, antibiotic specifications, and environmental sustainability, Amoxicillin leaks into the groundwater, surface waters, and drinking water wells. Many physical and chemical methods have been suggested for removing Amoxicillin from aquatic environments. However, these methods are so costly and have many performance problems.MethodsIn this study, biodegradation of Amoxicillin by submerged biological aerated filter (SBAF) was evaluated in the aquatic environment. In order to assess the removal of Amoxicillin from the aquatic environment, this bioreactor was fed with synthetic wastewater based on sucrose and Amoxicillin at 3 concentration levels and 4 hydraulic retention times (HRTs).ResultsThe maximum efficiency for Amoxicillin and Soluble Chemical Oxygen Demand (SCOD) removal was 50.8% and 45.3%, respectively. The study findings showed that Stover- Kincannon model had very good fitness in loading Amoxicillin in the biofilter (R2 > 9 9%). T here w as n o a ccumulation o f Amoxicillin in the biofilm and the loss of Amoxicillin in the control reactor was negligible. This shows that removal of Amoxicillin from the system was due to biodegradation.ConclusionsIt can be concluded that there was no significant inhibition effect on mixed aerobic microbial consortia. It was also observed that Amoxicillin degradation was dependent on the amount of Amoxicillin in the influent and by increasing the initial Amoxicillin concentration, Amoxicillin biodegradation increased, as well.Keywords: Amoxicillin, Antibiotic, Biodegradation, Submerge Aerated Filter, Aquatic Environment
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زمینه و هدفافزایش تولید لاستیک های مستعمل بحث بازیافت این پسماند را به امری مهم در جهان امروز تبدیل کرده است، ازطرفی به نظر می رسد در جوامع در حال توسعه آلودگی آب های زیرزمینی به مواد نفتی از جمله بنزین به تحدیدی جدی برای سلامت انسان تبدیل شده است، هدف مطالعه حاضر تولید کربن فعال از لاستیک مستعمل و استفاده از آن برای حذف بنزین از محیط آبی است.روش بررسیدر این مطالعه از نمک پتاسیم هیدرواکساید برای فعال سازی شیمیایی لاستیک مستعمل استفاده گردید. به منظور جلوگیری از اکسیداسیون پیش ماده مورد استفاده از گاز آرگون استفاده شد. برای تعیین خصوصیات بافت کربن فعال تولید شده جذب گاز N2 و ایزوترم BET به کار برده شد. همچنین جهت تعیین خصوصیات جذب بنزین بر روی جاذب تولید شده از مدل های ایزوترمی و سینتیکی و برای تعیین اثر دما از مطالعه ترمودینامیکی استفاده گردید.یافته هانتایج نشان داد میزان SBET و VTOTAL به ترتیب برابر با 111/702 g/m2 و 0/124 cc/g است. مدل لانگمیر و شبه درجه دوم نیز به ترتیب بهترین مدل های ایزوترمی و سینتیکی جهت پیش بینی رفتار جاذب در جذب بنزین تعیین گردیدند. مقادیر تغییرات انرژی آزاد گیبس نیز در تمامی دماها منفی بود.نتیجه گیریکربن فعال تولید شده دارای مساحت سطحی مطلوب و ظرفیت جذب مناسب برای حذف بنزین در محیط های آبی است و به نظر می رسد تولید کربن فعال از لاستیک مستعمل ارزان، موثر و دوستار محیط زیست باشد.
کلید واژگان: لاستیک مستعمل، کربن فعال، حذف بنزین، ایزوترم جذب، سینتیک جذبBackground And ObjectivesIncreasing waste tiers production has made the recycling of this solid waste a critical issue in the world. On the other hand، it seems contamination of groundwater to the petroleum pollutant like gasoline is a great threat to the health of societies in developing countries. The main objective of this study was gasoline removal from aquatic environment by waste tire derived activated carbon.Materials And MethodsIn this study for preparation of activated carbon from waste tires، KOH was used for chemical activation process. We used argon gas to prevent precursor oxidation. We applied N2 gas and BET isotherm for characterization of the prepared activated carbon texture. Isothermal and kinetic models were used for defining gasoline adsorption characteristic to adsorbent، and thermodynamic studies were used to determine the effect of temperature.ResultsCharacterization results revealed that SBET and VTOTAL were 111. 702m2/g and 0. 124cc/g respectively. Langmuir and pseudo-second order models were the best isotherm and kinetic models for prediction of the adsorbent behaviors to adsorb gasoline. The Gibbs free energy changes were negative at all temperatures applied.ConclusionProduced activated carbon has desired surface area and adsorptive capacity for gasoline adsorption in aquatic environments and it seems preparation activated carbon from waste tiers is cheap، effective and environment friendly.Keywords: Waste tires, Activated carbon, Gasoline removal, Adsorption isotherm, Adsorption kinetic, Adsorption thermodynamic -
BackgroundDyes are one of the most important industrial pollutants, especially in textile industries. Many methods have been proposed in order to remove color from wastewater among which, adsorption is more acceptable due to the ability for its use in the large scale..ObjectivesThe objective of this study was to investigate pumice as an inexpensive adsorbent for removal of Methylene Blue from aqueous solutions..Materials And MethodsIn this work the Modified Pumice Stone has been applied for removal of the Methylene Blue dye from aqueous environments. The effect of pH, contact time, initial concentration and amount of adsorbent were considered. In order to investigate the mechanism of the adsorption process, several kinetic models including pseudo-first order, pseudo-second order and intra-particle diffusion were used. In addition, equilibrium data was fitted on to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models..ResultsResults showed that the adsorption of the Methylene Blue was enhanced with increasing initial dye concentration, pH and contact time. The optimum pH was 10. The qmax for adsorption of methylene blue dye from the Langmuir model was 15.87 mg/g. Considering the values of R2 (0.999) and χ2, Freundlich isotherm model and pseudo-second order kinetic model had the best fitness..ConclusionsThis study has demonstrated that the modified Pumice stone with HCl can be employed as effective and inexpensive adsorbent for the removal of Methylene Blue from aqueous environments..Keywords: Pumice, Methylene Blue, Adsorption
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BackgroundIndustrial effluents the major contaminants of the environment and colored wastewaters from the textile industries are the main sources of environmental pollution..ObjectivesThe present study aimed to determine the appropriate MWCNTs dosage to adsorb RR-198 and identify the thermodynamic parameters such as the free energy (ΔG °), entropy (ΔS °), and enthalpy (ΔH °) changes during adsorption process at various temperatures..Materials And MethodsThe present laboratory research investigated the effect of pH, adsorbent dose, temperature, initial dye concentration, and contact time on the adsorption process of RR-198 by MWCNTS. The values of thermodynamic parameters were determined to establish the adsorption mechanism. Also, the isotherm model has been investigated..ResultsThe RR-198 absorption rates were 33.26 and 222.88 mg/g, respectively for 20, and 200 mg/L dye concentration, at pH of 3, 600 mg/L dose of adsorbent, and 120 minutes time. In addition, the maximum absorption was observed at 600 mg/L dose of MWCNTs. Also, the studied dye absorption isotherm was fitted Freundlich model (R2 = 0.996 at 298K) and, the maximum adsorption capacities calculated by Freundlich model was 169.73 mg/g at 298K. All ΔG ° values were negative. The values of enthalpy (ΔH °) and entropy (ΔS °) were 38.119 KJ/mol, and 134.93 KJ/mol, respectively..ConclusionsThe study results showed that by increasing the initial dye concentration and contact time, the adsorption capacity increased, as well. Moreover, the thermodynamic parameters (ΔH °, ΔG °, and ΔS °) revealed the endothermic sorption of RR-198 onto MWCNTs..Keywords: Adsorption, Textile Industry, Thermodynamics
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Background And ObjectivesActivated carbon is an adsorbent which is mostly employed in order to remove dye from aqueous solutions; however, commercial activated carbon is expensive and this is considered as an obstacle for its usage. Therefore, the present study aimed to use waste paper as an inexpensive precursor to produce activated carbon.Materials And MethodsIn the present study, KOH was used for the chemical activation process; in order to prevent the precursor oxidation during the carbonization process, a completely sealed furnace was used. In order to determine the characteristics of the prepared activated carbon texture, N2 gas adsorption and BET isotherm were used. Moreover, Langmuir, Freundlich, Temkin, and Redlich-Peterson isotherm models as well as Pseudo-first order, Pseudo-second order, and intra-particle diffusion kinetic models were used to determine the characteristics of Methylene Blue adsorption on the prepared adsorbent.ResultsAccording to the results, SBET and VTOTAL were 66.01m2/g and 0.063cc/g, respectively. Ferudlich and pseudo-second order models were the best isotherm and kinetic models for prediction of the Methylene Blue adsorption on the produced adsorbent. Furthermore, the qmax constant from the Langmuir model was obtained as 68.03 mg/g.ConclusionIn comparison to other studies, the produced activated carbon in the present study had a desirable surface area and adsorptive capacity for methylene blue adsorption in aquatic environments. Moreover, it seems that preparing activated carbon from waste newspaper is inexpensive, effective, and environment friendly.Keywords: Waste paper, Activated carbon, Methylene Blue, Removal, Adsorption kinetic
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