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Showing 9 results for Absorption
Study of Heavy Metals in the Atmospheric Deposition in Zanjan, Iran
Z Farahmand Kia, M.r Mehrasbi, M.s Sekhawatju, A.sh Hasanalizadeh, Z Ramezanzadeh,
Volume 2, Issue 4 (3-2010)
Abstract

Backgrounds and Objectives : Heavy metals in dust can enter to the human body through ingestion andinhalation. They can pollute the water and soil resources via atmospheric precipitation and accumulate in the plants tissue and enter human body by water and food. The aim of this study was measurement of the heavy metals in wet and dry atmospheric precipitation and effects of pollution sources at the ground surface on the concentration of heavy metals in the atmospheric precipitations.
Materials and Methods: In this study the zanjan city was divided into 5 zones and wet and dry precipitations were collected in autumn, winter and spring (2008- 2009) from zones. The concentrations of Pb, Cd, Cr and Zn the collected precipitations were determined by Atomic Absorption spectroscopy method.
Results: The averages of concentrations of Pb, Cd, Cr and Zn were 0.082, 0.286, 0.018, and 0.009 (mg/m 2.d)respectively. The correlation coefficients between Pb-Zn was 0.8 (P<0.01) and for Cr-Cd, Cd-Pb, and Cr-Pb were 0.89, 0.58 and 0.61 respectively.
Conclusion: The results showed that the industrial sources of heavy metals play the main role in concentration of heavy metals in wet and dry atmospheric precipitation in Zanjan.The correlation coefficients showed that the lead and zinc result from a common source. This source can be the lead and zinc factories locating around the city. The measurement of heavy metals in atmospheric precipitation shows the effects of anthropogenic sources in air quality. The heavy metals concentration in atmospheric precipitation can be use as air pollution index.


Determination of Pb,Cd,Cr and Ni concentration in Imported Indian Rice to Iran
M Malakootian, K Yaghmaeian, M Meserghani, A.h Mahvi, M Danesh Pajouh,
Volume 4, Issue 1 (5-2011)
Abstract

Background and Objectives: Heavy metal pollution has always been a major cause contamination of environment and considered as a major concern for food health. Rice is the most popular food among Iranians and presence of heavy metals in trace level in rice has received special attention because they are directly related to health.The aim of this research was to investigate the concentration of Pb, Cd, Cr, Ni in rice prevalent in the market of Iran.
Materials and Methods: 20 of the most widely consumed brands of Iranian rice were purchased from local market in Iran. 3 samples of each brand were collected and certain volumes of each sample were digested with acid. Heavy metal contents in the digested samples were determined by atomic absorption spectrometry.
Results :The results showed that mean concentration Pb , Cr , Ni in rice samples respectively was 0.387 , 0.683, 0.019 ( mg/kg )
Conclusion: Notably the Ni and Cr content in the rice samples was found to be below the food sanitary standards in India rice . In the other hand 50% samples content Pb was found to be upper the food sanitary (Pb: 0.3 mg/kg). The result indicated that weekly intake of heavy metal by rice was below the provisional tolerable weekly intake recommended by WHO/FAO. However, risk assessments needs considerable attention and better prevention this low pollution.


Forecasting Some of the Qualitative Parameters of Rivers Using Wavelet Artificial Neural Network Hybrid (W-ANN) Model (Case of study: Jajroud River of Tehran and Gharaso River of Kermanshah)
Hossein Banejad, Mahsa Kamali, Kimia Amirmoradi , Ehsan Olyaie,
Volume 6, Issue 3 (12-2013)
Abstract

Background and Objectives: Rivers are the most important resources supplying drinking, agricultural, and industrial water demand. Their quality fluctuates frequently due to crossing from different regions and beds as well as their direct relationship with their peripheral environments. Thus, it is essential to be considered the surveying and predicating changes in the water qualitative parameters in a river. In this study, in order to estimate some of the qualitative parameters (Total dissolved solids, electrical conductivity and sodium absorption rate) for Tehran Jajroud and Kermanshah Gharasu rivers, we used wavelet-artificial neural network (W-ANN) hybrid model during a statistical period of 24 years. Methods: We compared W-ANN model with ANN model in order to evaluate its capability in detecting signals and separating error signals for estimating water quality parameters of the abovementioned rivers. The evaluation of both models was performed by the statistical criteria including correlation coefficient, the Nash-Sutcliffe model efficiency coefficient (NS), the root mean square error (RMSE) and the mean absolute error (MAE). Results: The results showed that the optimized W-ANN with correlation coefficient of 0.9 has high capability to estimate SAR parameter in the stations studied. Moreover, we found that W-ANN had less error and higher accuracy in the case of EC and TDS parameters rather than ANN model. Conclusion: W-ANN proved high efficiency in forecasting of the water quality parameters of rivers, therefore, it can be used for decision making and assurance of monitoring results and optimizing the monitoring costs.


Efficiency of the fungus Aspergillus niger biomass in Pentachlorophenol (PCP) absorption from aqueous solutions
Reza Shokoohi, Salah Azizi, Said Amir Ghiasian, Javad Fredmal,
Volume 7, Issue 2 (10-2014)
Abstract

Background and Objectives: Pentachlorophenol (PCP) is an organic compound and phenolic derivatives categorized as priority pollutants that have harmful effects on humans, animals, and plants in low concentrations. Therefore, PCP removal from water and wastewater is very important. The aim of this study was to assess the efficiency of A. niger fungus biomass in PCP absorption. Materials and Methods: This was an experimental study in which different steps of the experiments were performed. A. niger strain was prepared from Persian Type Culture Collection of Iranian Research Organization for Science and Technology (IROST). After activation in potato dextrose agar (PDA) culture plates, fungi were incubated for 7 to 10 days at 25 °C. The prepared A. niger biomass was modified by NaOH and then it was used for PCP absorption assay. The concentration of PCP was measured using high-performance liquid chromatography. Results: The findings of present study showed that contact time is an important and effective factor in the PCP absorption rate. Two hours was selected as the optimum retention time in this experiment and after that the removal percentage did not raise significantly. The results of PCP absorption in different pH demonstrated that the adsorption efficiency decreases by rising pH and initial PCP concentration. The effects of contact time, pH and initial PCP concentration on the absorption process was significant (P-value <0.001). Conclusion: The results show that absorption efficiency increases by rising retention time under constant conditions. In addition, at low pH the modified A. niger biomass could be a good absorber for PCP.


Investigating the Amount of Heavy Metals in Different Parts of Some Consumable Vegetables in Karaj City
N Rouniasi , H Parvizi Mosaed,
Volume 9, Issue 2 (9-2016)
Abstract

Background and Objectives: Heavy metals are seriously dangerous for the human body and their accumulation in the body can cause pathological changes in the organs and this can result in cardiovascular, liver and bone diseases, and even cancer. Human is exposed daily to these pollutants via consumption of food and water.

Materials and Methods: Considering the cumulative properties of these metals in plant organs, the amount of Cr, Mn, and Fe in soil and leaf, stem, and root tissues of cabbage, lettuce, spinach, and onions in Karaj City were investigated. For this purpose, 15 samples were randomly collected from each part of the plants, and then, the density of heavy metals was measured via atomic absorption spectrometer after cleansing, grinding, drying, and acid digestion. The data were then analyzed using SPSS software.

Results: It was found that leaves of spinach, cabbage, lettuce, and onion have higher concentrations of Cr, Mn, and Fe rather than their stems and roots. The roots of plants contain the least densities of metals. Moreover, concentrations of Fe, Cr, and Mn in soil were 11.87, 3.99 and 17.78 mg/kg, respectively. This was due to the high transportation of these metals to air-related parts of the plant like leaves. This research also showed that the densities of Cr, Mn, and Fe in leaves of studied spinach, onion, cabbage, and lettuce exceeded the FAO/WHO standard limitations (0.15, 0.3, and 0.3 mg/kg for Cr, Fe and Mn, respectively).

Conclusion: Due to the high concentrations of Cr, Mn, and Fe in studied vegetables in Karaj City, the consumption of these kinds of vegetables by citizens must be taken into consideration by regulatory agencies.


Removal of heavy metals of cadmium and lead from aqueous solutions using graphene oxide nanosheets process optimization by response surface methodology
N Rouniasi, Sm Monavari, Ma Abdoli, M Baghdadi, A Karbasi,
Volume 11, Issue 2 (9-2018)
Abstract
Background and Objective: Water pollution due to heavy metals is a critical and increasing problem worldwide. In this study, removal of cadmium and lead heavy metals using a graphene oxide (GO) adsorbent was examined.
Materials and Methods: GO nanosheets were synthesized through Hummer’s method, and its characterizations were examined using FTIR, XRD, and SEM. The effect of independent variables pH, contact time and initial concentration of the solution on removal efficiency of Cd2+and Pb2+ using response surface methodology was evaluated according to Box-Behnken experimental design. Applying quadratic model, adsorption rate of Cd2+ and Pb2+ achieved 99%. ANOVA was applied for statistical analysis of responses.
Results: According to SEM images, the average size of graphene oxide sheets was 1 to 3 µm. After optimization through RSM, the adsorption capacity for Pb2+ and Cd2+ was 136 mg/g and 68 mg/g, respectively. Examination of the isotherms suggested that Cd2+ and Pb2+ adsorption follows Langmuir and Freundlich isotherm, respectively.
Conclusion: the results show that the graphene oxide performed well in removing both Cd2+ and Pb2+ ions from aqueous solutions. The most influential parameters on the above-mentioned heavy metals adsorption were pH of the solution and the initial concentration.
 

Comparative study of efficiency between 2,4 dinitrophenol removal using dry sludge and modified calcium chloride
H Niknejad, M Farzadkia, A Esrafili, M Kermani,
Volume 12, Issue 4 (2-2020)
Abstract 
Background and Objective: 2,4 dinitrophenol is observed in sewage produced from chemical and petrochemical industries. Contamination of drinking water with these pollutants causes toxicity, health problems and change in taste and odor. The present study was developed to evaluate the efficiency of removal 2,4-DNP through dried sludge adsorbent and modified calcium chloride sludge adsorbent.
Materials and Methods: At first, sludge was dried at temperature of 60 °C. Next, CaCl2 was used to improve adsorption capacity. The removal efficiency of 2,4 dinitrophenol were determined by HPLC at wavelength of 360 nm. The effects of influencing factors including pH, initial pollutant concentration, contact time, and adsorbent dose were examined.                            
Results: The optimum pH of adsorption for both adsorbents was found to be 7. The optimum concentration of 2,4-DNP was 10 ppm. The results obtained from the present research showed that the removal of the contaminant using dried and modified sludge sorbent was increased from 72.6% to 86% at a dosage of 1.5 g. The adsorption kinetics were fitted with the pseudo second order kinetics model for both adsorbents. The isotherm data also showed that the adsorption of this pollutant on both adsorbents is fitted with the Freundlich model.
Conclusion: Results obtained from the present study indicated that the efficiency of the modified sludge ash is more than the non-modified sludge in 2,4 dinitrophenol removal. This can reduce adsorbent consumption in industrial treatment plants.

Feasibility study of silica aerogel nanocomposites application to enhance acoustic properties
Mansoureh Hamidi, Parvin Nassiri, Homayoon Ahmad Panahi, Lobat Taghavi, Saeed Bazgir,
Volume 13, Issue 3 (11-2020)
Abstract
Background and Objective: Noise pollution is one of the serious environmental issue. Sound control technologies based on sound absorption and sound insulation are considered as the two widely used methods. Therefore, the aim of this study was to modify silica aerogel nanocomposites to improve its acoustic properties.
Materials and Methods:  This applied experimental research involved in examining eight various types of nanocomposites to evaluate their performance of acoustic properties. In this study, nanocomposites were synthesized by sol-gel method. For this purpose, TEOS and ethanol were added to SiO2 which subsequently stirred and diluted with ethanol as a precursor of silica sol. A solution of 5.5 M ammonium hydroxide is added drop-wise to the silica sol and then was stirred. The activated silica sol was quickly poured into the mold in which the samples were placed and finally placed in an oven at 150 °C for 3 hours. The acoustic properties of the samples were measured by the impedance tube and the reduction sound pressure level using a sound level meter. Each sample morphology was characterized by scanning electron microscopy.
Results: The sound absorption properties of as prepared nanocomposite relatively increased at high frequencies. The results indicated > 0.6 sound absorption coefficient by the modified nanocopmosites at higher frequencies. The sound absorption coefficient and transmission loss of D1 nanocomposite were higher at medium and low frequencies as compared to other nanocomposites. 4.6 and 9.73 dB average reduction of sound pressure level were achieved by either with or without nanocomposite enclosure, respectively, at a distance of 1 meter.   
Conclusion: The results of the current study showed that the simultaneous addition of organic and mineral materials to silica aerogels (especially with the highest amounts of nanoclay) improves its acoustic properties, especially at medium and low frequencies. Among the samples, D1 nanocomposite shows better acoustic properties at medium and low frequencies. The sound absorption coefficient of D1 nanocomposite at frequencies of 315, 400, 500, 1000, 1250, 2000 Hz were obtained as 0.27, 0.38, 0.51, 0.78, 0.83 and 0.84, respectively. The findings also indicated 9.37 dB reduction of sound pressure level using D1 nanocomposite.

Equilibrium and kinetic investigation of solophenyl dye removal from aqueous solution using cellulose adsorbents
Hanieh Mirbolooki, Shahriar Mahdavi, Eisa Solgi, Babak Razdar, Mahboubeh Zarabi, Davoud Akhzari,
Volume 17, Issue 4 (3-2025)
Abstract
Background and Objective: Dyes are among the most widespread pollutants found in industrial wastewater. The aim of this study is to investigate the potential of vineyard wood waste as a green adsorbent for the removal of polyazo solophenyl dye from aquatic environments.
Materials and Methods: In this laboratory research, two forms of adsorbents modified with H₂SO₄ and NaOH were used. Data obtained from dye adsorption in synthetic solutions were fitted to isotherm, kinetic, and thermodynamic models, with all calculations performed using Excel software. Zeta potential analysis, along with FTIR, BET, and FESEM-EDS instrumental analyses, was conducted to determine the properties of the adsorbent. Additionally, the desorption rates of the adsorbents were analyzed.
Results: The results showed that the highest color removal efficiency for the adsorbent modified with H2SO4 was achieved at a contact time of 180 minutes and a reaction temperature of 50 °C, while for the adsorbent modified with NaOH, the highest efficiency was observed at a contact time of 105 minutes and a reaction temperature of 25 °C. For both adsorbents, the optimal pH was 4, and the optimal adsorbent dosage was 1 g. The adsorption data for both modified adsorbents followed the pseudo-second-order kinetic model, while the equilibrium data aligned with the Freundlich and Temkin isotherm models. The adsorption capacities were found to be 22.27 mg/g and 9.87 mg/g for the adsorbents modified with acid and base, respectively, under optimal conditions.
Conclusion: This study introduces a novel, low-cost adsorbent derived from natural waste for water pollution removal, transforming the current approach into a cost-effective and eco-friendly solution.
 

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