جستجوی مقالات مرتبط با کلیدواژه « آلاینده های آب » در نشریات گروه « پزشکی »

Various absorbents have been studied for removing heavy metals from water. One of the most effective removals is iron oxide nanoparticles. In recent years many studies have been carried out for modifying the surface of the nanoparticles and increasing its effectiveness and efficiency.
In this paper coated iron oxide nanoparticles were prepared using Polylophium involucratum extract. To examine the structure of the absorbent the infrared spectrometer instrument and SEM were used to check the size of nanoparticles. the average size of them were determined 60 nm.
The synthesized coated nanoparticles were used to eliminate lead and cadmium after optimization conditions (pH of 6, absorbent weight of 20 mg, and time of 4 minutes) in water samples. Magnetic green coated nanoparticles have many advantages such as non-toxicity, biocompatibility, shorter extraction time, avoiding the use of organic solvents, low cost, ease of use, high accuracy, recovery and adsorption capacity due to the nanostructure and high ratio of surface to volume.
Functionalized nanoparticles by extract of the plant is able to link up with heavy metal ions and increase the efficiency of the nanoparticles in the removal of these two heavy metals.

Introduction and Phenol is one of the common pollutants found in many industrial effluents , which affects the environment and human health due to its special features like high toxicity and carcinogenic properties. The use of adsorbents is one of the most effective strategies for the removal of phenol. In this study, we investigated the efficiency of Citrullus colocynthis shell ash as a natural adsorbent in phenol removal from aqueous solutions.
This was an experimental study, where the effect of different variables such as the initial phenol concentrations (i.e., 10, 20, 50, 80, and 100 ppm), contact time (i.e., 2, 5, 10, and 30 min), adsorbent dose (i.e., 0.5, 1, 3, 5, 7, and 10 g/L) and pH (2-12) were studied. Then, the adsorption process was described with Freundlich and Langmuir isotherms at controlled temperatures. Excel software was used for data analysis.
The results revealed that the highest removal rate of phenol was obtained at pH of 2 (79.8%), primary phenol concentration of 20 ppm (66.4%), adsorbent dose of 5 g/l (86.8%), and contact time of 10 minutes. Also, the correlation coefficients of isotherms (Freundlich and Langmuir) showed that phenol adsorption by Citrullus colocynthis shell ash had more accordance with the Freundlich model than the Langmuir model.
We found that Citrullus colocynthis shell ash can be used as a lowcost and accessible adsorbent for phenol removal from aqueous solutions.

Nowadays, according to growth of industry and increasing population, water resources are seriousely shortened. This lack of water resources will require special management to be considered in industry and agriculture. Among the various sources of water, surface waters are more susceptible to infection. The most important of these sources of pollution are industrial pollution, detergent, pesticides, radioactive materials, heat and salt concentration.
In this article, at first the importance of each pollutant will be evaluated base on the effects and its results and then quality evaluation of surface water will be studied. In order to assess the relative importance of these pollutants primarily using TOPSIS software, prioritize these factors as one of the hierarchical analysis and then is modeled with decision tree method using Weka software, the importance of each factor is evaluated and if it does not meet the minimal importance of the decision tree will be removed.
The results obtained from the Topsis fuzzy analysis indicate that surface water and groundwater are exposed to pollution about 74% and 26% respectively among the six pollutants examined in this study. In addition, results obtaned from the hierarchical tree in software Weka has shown that the heat factor, soluble salts and industrial pollutants give impac factor or purity about 0.1338, 0.0523 and 1.2694 respectively.
Surface water is at greater risk of being polluted compared with groundwater. The heat factor and low concentration of dissolved salts have the low impact and industrial pollutants are considered as the most influential factors in surface water pollution.

Because of heavy metals toxicity for the environmental، heavy metals are considered as environmental pollutants. The hexavalent chromium is one of the heavy metals that toxic and soluble in water. This study to remove of hexavalent chromium from aqueous solution by pomegranate seed powder has been done. This study was performed in laboratory scale and experimental. The adsorbent prepared in laboratory scale and pulverized by standard ASTM sieves (40-100 mesh). In this research، the effect of pH (2، 3، 4، 6)، adsorbent dose (0. 2 to 0. 6 g/100 ml)، contact time (15 to 180 min) at initial Cr (VI) concentrations of 2 and 10 mg/L، was studied. The results of adsorption equilibrium were analyzed to Langmuir and Freundlich isotherm models. The unknown Concentration of Hexavalent Chromium by spectrophotometer set (UV/VisibleSP-3000 Plus-Japan) at 540 nm based on standard methods for testing water and wastewater book determined. The results showed that increasing the adsorbent dose and contact time led to increasing of the removal efficiency and increasing pH and initial chromium concentration led to reducing of removal efficiency. According to the results، the best removal efficiency occurred at acidic pH and adsorption equilibrium time was 120 min. In the absorbed dose of 0. 6gr/100ml، pH = 2 and hexavalent chromium concentration 2 mg/l، the removal efficiency was achieved equal to 99. 5%. In this study، chromium ions adsorption by pomegranate seed powder is follows Freundlich isotherm model. The obtained results showed that pomegranate seed powder is suitable natural adsorbent for the removal of chromium (VI).

Background and Çadmium is one of the toxic elements which contaminate water resources through industrial, domestic, agricultural effluents and un hygienic burdening of industrial and urban waste materials. Studies shows that surface and subsurface waters in some areas near to the pollutant sources are contaminated with cadmium 0.1 to 1.0 mg/l. No study has been done about omiting the low concentrations of cadmium (poresent in the contaminated resources) with the help of activated carbon, determination of isotherms and the influencing factors on it. The aim of this study was to determine cadmium absorption isotherm on activated granular carbon GÂÇ, and also determine the effect of temperature and water pH on absorption isotherms. Ând finally determine the rate of efficacy of using activated carbon column in omition of cadmium from water. Çertain weights of activated carbon (0.05-0.07 gram) were added seperately to 250 ml of water with certain concentration of cadmium present in flask and pH was adjested, the flasks were kept in refrigerated incubater equiped with shaker, temperature was edjusted. Ïn order to determine the time equilibrium of abserption, the flasks were shaked with duration of 30 minutes to 6 hours in incubator. Ât each time interval the concentration remained cadmium in solution after fillration of the samples were measured according to the standard by atomic absorption mwthod. With the help of data concerning experiments on determination of isotherms, synthetic of cadmium absorption on sctivated carbon, the effect of activated carbon on the speed of absorption, effect of initial cadmium concetration on coefficient of absorption. Âs well as the effect of temperature changes and pH on isotherms was determined. The rate of cadmium absorption on activated carbon column at work conditions, was comared with the expected rate on isotherm. Break through curves related to cadmium containing water for concontration of D.26 mg/L. for at the of ËBÇT for 30 minuts and for the Çoncentration of 0.59 mg/Li for at two contact time of 30 and 60 minuts were plotted. The rate of cadmium absorption on activted carbon increased with increasing in pH and temperature. Though by increasing initial concentration of cadmium the rate of its absorption on Ünit Weight of autivated carbon(9) increased. But removing efficiency Çertain amount of activated Çaobon declined. Çadmium absorption on activated Çarbon Fllew the first order of kinetic. By increasing the rate of cutivated Çarbon, absorption of Çadmium increased. For Çoncentration of of Çadmium, the break through offer passing water was 55 folds more on bed volume and for Çocentration of 0.59 mg/Lifor after Passing was 40 fold of volume accured The rate of Çadmium uptake on Çolumn of Gac was more than the expected rate of isotherm. Çonclusion: Though Çomplate removal of 0.26 mg/Lifor and 0.59 mg/Lifer of Çadmium of water through activated Çarbon column is possible. But the break through in the plot related to the performance of the Çolumn is partially happens soon.