جستجوی مقالات مرتبط با کلیدواژه « co » در نشریات گروه « علوم پایه »

Continuous need for fossil fuels as a source of energy around the world and gradual velocity of renewable energy development, increasing greenhouse gases, including  in the atmosphere. For this purpose, strategies to counter global warming and environmental change are important. Over the last two decades, technology developments of  capture and storage in underground formations has been considered aquifer reservoirs are a good method to  storage because of high potential. By dissolution of  supercritical  in aquifer reservoir due to salinity, pressure and temperature, brine density increased from 0.1 to 1 percent and it causes the emergence of instability and fingering in the environmental flow system and convectional mixing phenomenon. In this article, focusing on effect of aperture and fracture orientation parameters on  storage in aquifer reservoir, two_dimensional simulation has been investigated by COMSOL multiphysics 4.3 software. Improving  storage over a 40 years period is significant as the fracture aperture increases. Also, by reducing fracture orientation relative  to vertical, fingerings will advance into aquifer and increase storage safety.

Industrialization, urbanization, and population growth are considered as the main causes of urban air pollution that is responsible for millions of deaths per year worldwide. Besides, the impact of urban air pollution on health is considerable. Respiratory, lung diseases, and heart attacks are largely due to urban air pollution. However, there is a lack of air pollution monitoring stations (hereafter simply stations) in most cities worldwide because of their high expenses, and, thus, access to high spatial and temporal coverage of air pollutants and their distribution is limited. To address this issue, the main purpose of this study was to estimate CO concentration in Isfahan, Iran, based on air pollution monitoring stations and Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2018 to 2019.

In the present work, we used ANFIS and Random Forest (RF) algorithms to estimate the CO concentration level. To implement the ANFIS algorithm, based on collected air pollution data from the stations and Aerosol Optical Depth (AOD) data from MODIS imagery, the basic fuzzy rules were extracted. Further, with the integration of fuzzy rules and artificial neural network algorithm, ANFIS algorithm was implemented to model the dispersion of CO level in Isfahan city. To model the dispersion of CO using the RF algorithm, air pollution data and AOD data were used. Since the number of trees and the number of variables in each node are two basic parameters in the success of the RF algorithm, a 10-fold cross-validation method was used to identify value for these two variables.

Our findings indicated that the RF algorithm was more efficient and accurate in spatial modeling the dispersion of CO because it achieved better RMSE and MAE results than the ANFIS algorithm. The RMSE error value of the RF and ANFIS algorithms were 0.724 and 0.809 ppm, respectively. Furthermore, the MAE error value of the RF and ANFIS algorithms were 0.636 and 0.792 ppm, respectively. In the case of spatial dispersion of CO pollutants, the ANFIS algorithm showed that the amount of this pollutant varies in the city. For example, the central and northern regions of Isfahan had the most pollution and the eastern and western regions of Isfahan had the least pollution based on the ANFIS algorithm. Regarding the RF algorithm, it was observed that by moving from the southeast to the northwest of Isfahan, the amount of CO pollutant increases, and the northwestern regions of Isfahan had the highest CO pollution. The examination of numerical values obtained from the ANFIS algorithm showed that the lowest amount of CO pollution in Isfahan city was equal to 1.43 ppm and the highest amount was 2.13 ppm. In contrast, obtained results from the RF algorithm showed that the lowest amount of CO pollution in the city was equal to 0.57 ppm and the highest amount was 2.27 ppm.

Overall, it can be concluded that since ANFIS and RF algorithms are appropriate and accurate methods in modeling environmental problems due to their nonlinear modeling, the ability to reduce the negative effects of outgoing data, and less sensitivity to the local minimum problem. It should be noted that a significant part of the error observed in the results of ANFIS and RF methods was related to the intrinsic properties of MODIS imagery (i.e., cloud cover and mixed pixel problem due to the coarse resolution of MODIS imagery), point measurements of air pollution data collected from the stations, and recorded data error at the stations.

Determination of pollutant emission factors by time is the most important initial data in air pollution modeling. EPA's AP 42 documents provide the most comprehensive emission factor system for all industries based on process type, fuel, and control types. Target of this study, wasto investigate concentrations, emission factors of SO2, NO2 and CO in Ilam gas refinery.

In this study, concentrations of SO2, NO2 and CO and other required parameters such as temperature, pressure, flow rate and diameter of the 6 main stacks were measured by direct field measurements by Testo 350 XL. By results of these measurements and measurements of previous years in the refinery, the mean average for the two normal scenarios and the worst condition, and then the emission values ​​were calculated. Data analysis was carried out with a confidence level of 95%.

The estimated secondry, hourly, daily, monthly, and annual emissions from Ilam gas refinery was calculated and analyzed based on 2 normal and worst-case scenarios. Field measurement of flue concentrations showed that the highest concentrations of carbon monoxide (3565 ppm) and sulfur dioxide (5099 ppm) relates to SRU1 unit, the highest produced nitrogen dioxide (188 ppm) produced by SRU2, 1396 were the most polluted year according to the measured gases. The results of environmental measurements showed that CO at the sewage station is, 4/12 ppm and in Mehran road with an undetectable amount, the lowest amount of NO2 in the Chegae with 0.6 and Mehran road with the undetectable, the lowest amount, the amount of SO2 at the laboratory point with a maximum of 0.13 ppm and in the housing camp with an undetectable amount, the lowest It was.

Considering that the amount of environmental pollution and concentration of pollutants in the production units are more significant. So, planning for corrective actions to reduce emission of pollutants in production units, seems to be necessary. As well as the recovery and reduction of feed of flaring, can have a significant impact on the emission of pollutants.

How pollutants enter, as well as the speed of releasing pollutants into the atmosphere, affect air pollution. Pollutants may be freed freely, periodically or periodically, either from a source or from several sources or from point and point sources. Also, the dispersion of pollutants depends on how they enter the atmosphere. Lack of information on the distribution of pollutants makes it difficult to determine the impact of their dissemination outside the boundaries of the site and in surrounding residential areas (Shin et al, 2005). Mobarakeh Steel Complex in Iran, due to the production of large amounts Pm10 and Co, the focus of many environmental scientists has attracted. In the presence of amounts of sulfur dioxide gas in the atmosphere, fine particles in the air react with PM10 and become toxic and dangerous substances, which is one of the main causes of urban air quality problems in Mobarakei province of Isfahan. The CALPUFF model is approved by USEPA as an appropriate model for modeling non-uniform and complex currents, including those with complicated earth conditions, as well as in locations where flow and recurrence flow are important. The modeling system consists of three main parts: CALMET, CALPUFF and CALPOST. CALMET is a meteorological meteorological model that calculates meteorological meteorological data from meteorological meteorological models and calculates values for smaller scales using more accurate network layout data using land-use and land-use data. CALPUFF: In fact, a uniform model Lagrangian fluid motion -Gvsy the following procedures for networking time changes, weather conditions in three dimensions, the effects of terrain, wet and dry sessions, interaction plume of smoke and Terrain, broadcast and distribution on the marine environment, Currents are at the bottom of the buildings. CALPOST: Use this section to preprocess output and process simulation files(USEPA(A), 2004). AERMOD is a Gaussian plume model for steady state and for near-site objects based on the structure and implications of planetary boundary layer turbulence. In addition to the AERMOD's primary processor, it is a meteorological pre-processor called AERMET and a ground-based pre-processor, and air pollution is one of the challenges facing the industrial area (USEPA (B), 2004). In this research, the performance estimation of the models has been done in two ways: First, by comparing the observational data of the output models, at the receiver points determined for the models (based on the UTM coordinates), the accuracy of the modeling is obtained at each point in the time periods considered. In the second step, The performance of models is compared with each other.

Today pollution in the large cities has become a basic challenge for the environment. In Ahwaz, 60% of the pollution is related to the mobile sources which produce a huge amount of various pollutants including CO and PM10 that affect the life of the residents in Ahwaz. CO is an important pollutant emitted to the atmosphere from traffic. Generally, pollutant emission to the air has a significant effect on air pollution control. Therefore, the of this study was to investigate the dispersion and density of CO and PM10 from mobile sources.
In this study, at first the study area was zonned (3×3 Km). Then, in each net the number of cars were estimated according to the types of car and hours of traffic. Consequently, the whole diffusion of CO and PM10 concentration in each net was estimated according to gram per second for each car considering the diffusion factors, type of consumed fuel and the distance drived. Finally, for better illustration of places, graphic exhibition, distribution way of the mentioned pollutant and diffusion, GIS a software was used.
The pattern of pollutant diffusion for CO and PM10 emitted from cars, which is calculated by the model, shows that most of the polluted areas are the business and administrative centers. These pollutants were calculated to be very low and even zero at the outskirts of the city.

Due to electrical charge and high specific surface area, clay minerals, such as sepiolite, are widely used for the removal of heavy metals from environment. However, limited information is available to identify their ability for heavy metals removal from multi-ionic solutions. This study was conducted to determine the ability of Fariman sepiolite for the removal of Cd, Co, and Zn from aqueous solutions, and the effect of different factors, such as contact time and initial solution pH, as well as application of heating pretreatments (150 and 250 Cᵒ) on adsorption process of the mentioned elemnts. .
All the experiments were done in 11 contact times from 5 to 2880 minutes, in three replications and at pH values of 4 and 5. After determining the remained amounts of each heavy metal in the centrifuged suspension solutions by atomic absorption machine, the experimental data were fitted by pseudo first order, pseudo second order, and intraparticle diffusion kinetic models.
Findings: The results showed that the adsorption potential of the heavy metals depended on contact time, solution pH, and physicochemical characteristics of the elements. Accordingly, by increasing the contact time and pH of solutions, adsorption rate of the heavy metals increased in an order of Co>Zn>Cd. Moreover, the results illustrated that application of heat treated sepiolite particles, compared to natural sepiolite, increases the removal efficiency of the heavy metals from aqueous solutions.
Results illustrated that application of heating pretreated sepiolite leads to greater removal of heavy metals in the solutions studied. Besides, greater efficiency in removal of heavy metals would be attained in pH= 5 as compared to pH=4.

In this researcher, the MnxFe0.7-xZn0.3Fe2O4 ferrite nanoparticles prepared by co-precipitation method. In these compositions the value of x varies from 0 to 0.7. Structural and magnetic properties of synthesized powder were characterized by X-ray diffraction XRD, Far-Infrared spectroscopy Far-FTIR, Transmission Electron Microscopy TEM and vibration sample magnetometer VSM. The XRD results show that all of the samples have single phase spinel structure. The average crystallite size estimated of about 12 to 7 nm, using Scherrer´s formula. The Far-FTIR measurements show, two frequency bonds within the rang 300 to 600 cm-1 indicate the presence of cation-anion interactions in the octahedral and tetrahedral sites, respectively.Also Transmission Electron Microscope images show particles size uniform distribution. The VSM results show that the saturation magnetization for all the samples decrease by increasing the manganese content.