Showing 16 results for Rastkari
K Naddafi, M.r Zare, M Younesian, M Alimohammadi, N Rastkari, N Mousavi,
Volume 4, Issue 2 (9 2011)
Abstract
Background and Objectives: This study was conducted to investigate the toxicity of Titanium Oxide (TiO2) and Zinc Oxide (ZnO) nanoparticles as two of most widely used nanoparticles. The result of this study can help to designing environmental standard and legislations for nanoparticles.
Materials and Methods: Different concentrations of nano ZnO and TiO2 nanoparticles were added to nutrient Agar culture media. Then, definite numbers of Escherichia coli and Staphylococcus aureus bacteria were added to culture media and inhibition of these bacteria growth was measured in comparison to controls. Obtained data were analyzed to determine nanoparticles' EC50 and NOEC (No Observed Effect Concentration) using SPSS ver.16 and Probit standard test.
Results: 24-hours EC50 of nano ZnO using E. coli and S. aureus determined to be 5.47 mg/L and 2.38 mg/L respectively. In addition, 24-hours EC50 of nano TiO2 using E. coli and S. aureus determined to be 5366 mg/L and 3471 mg/L respectively. In the case of ZnO nanoparticles, no observed effect concentration determined to be 1.15 and 3.28 mg/L for E. coli and S. aureus respectively and in the case of TiO2 nanoparticles no observed effect level determined to be 1937 and 1184 mg/L for E. coli and S. aureus respectively.
Conclusion: This study showed that acute toxicity of nano ZnO is by far more than that of nano TiO2. Regarding the EPA acute toxicity criteria, nano ZnO is categorized as moderately toxic and nano TiO2 is categorized as practically non toxic. Hence, regarding the acute toxicity, in recommending exposure criteria and environmental disposal standards, compared to nano TiO2, nano ZnO requires more attention.
Elnaz Iravani, Mohammadhadi Dehghani, Amirhossein Mahvi, Noushin Rastkari,
Volume 6, Issue 2 (9-2013)
Abstract
Background and objectives: Bisphenol A (BPA) is an endocrine disrupting chemical that releases to the environment through effluents of its producing factory, pulp and paper mill factories, and plastics industry. The purpose of this study was to investigate adsorption isotherms of removing BPA from aqueous solutions using single walled carbon nanotubes (SWCNTs).
Materials and methods: This study was an empirical investigation. Our experiments were conducted discontinuously using 50 mL of sample in each test. The variables of this study were the contact time (5, 15, 30, 60, 90, 120 min), the initial concentration of BPA (2, 5 , 20, 50 mg/L), and pH (3, 5, 6, 9, 11). The concentrations of BPA were measured using UV-Vis spectrophotometer.
Results: The maximum adsorption capacity was found to be 71.42 mg/g. The results of our experiments showed that maximum adsorption capacity at equilibrium was achieved at t = 60 min and pH = 9. Moreover, increasing the initial concentration is associated with an increase in adsorption capacity until it becomes constant.
Conclusion: The BPA adsorption on SWCNT follows Freundlich-Langmuir isotherm.
Amir Hossein Mahvi, Noushin Rastkari, Ramin Nabizadeh Nodehi, Shahrokh Nazmara, Simin Nasseri, Mahboobeh Ghoochani,
Volume 6, Issue 3 (12-2013)
Abstract
Background and Objectives:Chlorination is the most common method of water disinfection. Chlorine reaction with natural organic compounds nor removed completely during treatment process would result in forming disinfection byproducts. Followed by trihalomethanes, Haloaceticacides are the second main byproducts of chlorination in water. The research works conducted in Iran have assessed trihalomethanes. Hence, this is the first time we are reporting haloacetic acids in Iran.
Materials and Methodology: We collected samples from surface water resources and treated water in Tehran for six consecutive months (first half, 2010). We measured temperature, pH, UV adsorption at 254 nm and TOC in each surface water sample and analyzed pH, residual chlorine, and haloacetic acids in the treated water samples.
Results: We found that TOC in surface water resources is 3.6-4.42 and 1.78-2.71 mg/l in spring and summer respectively. Moreover, haloacetic acids concentration was found to be 41.7-55.56 and 34.83-43.73 μg/l in spring and summer respectively.
Conclusion: Our results revealed that concentration of NOM, TOC, and HAAs was more in spring than summer. In addition, concentration of HAAs was depended up on NOM and TOC. Considering maximum permeable concentration of HAAs (60 μg/l) by EPA, it can be claimed that concentration of HAAs was less than the maximum permissible level in all of the samples. However, the immanency of the monitored values to the standard values can be a warning for concerned authorities in water industry.
Mohamad Hadi Dehghani , Mamood Alimohammadi , Amir Hossein Mahvi, Noushin Rastkari, Masoome Mostofi, Maryam Gholami ,
Volume 6, Issue 4 (3-2014)
Abstract
Background and Objective: Various industries such as petrochemical, oil refinery, pharmaceutical, plastics, paper, steel and, resin produce a substantial of phenol and its derivatives. Wastewaters containing phenol need careful treatment before discharging into the environment due to their poor biodegradability and high toxicity. The objective of this study was to remove phenol by multiwall carbon nanotubes from aqueous solution. Materials and Methods: Adsorption process was implemented in a laboratory-scale batch with emphasis on the effect of various parameters such as contact time (5 to 120 minutes), pH (3- 11), initial concentration of phenol (5 - 50 mg/l) and the sulfate and chloride ions (20 - 200 mg/l) on adsorption process. To achieve a better realization of adsorption process, sorption kinetics and equilibrium isotherms were also determined. Results: The results indicated that maximum adsorption capacity occurred at concentration 50 mg/L and t =30 minutes. The uptake fluctuated very little in the pH range of 3–9, and at greater than 9 the absorption decreased suddenly. Moreover, the presence of sulfate and chloride ions had no effect on the process. It was found that adsorption kinetics and equilibrium data follow a pseudo-second-order kinetics model and a Freundlich isotherm model respectively. Conclusion: It is concluded that carbon nanotubes being effective in a wide range of pH, short time to reach equilibrium and the absence of competing ions on the absorption process can be used effectively in removing phenol from aqueous solution.
B. Kakavandi, M. Mokhtari, R. Rezaee Kalantari, E. Ahmadi, N. Rastkari, M. Fatehi, A. Azari,
Volume 7, Issue 3 (5-2014)
Abstract
Background and Objectives: Phenol is one of priority pollutants produced through leather, paint, resin, and pharmaceutical industries and it can contaminate groundwater after entering to the environment. Hence, it is necessary to use a suitable method for its removal. The aim of this study was synthesize and efficiency evaluation of magnetic nanocomposite of activated carbon powder-zero valent iron/silver (PAC-Feo/Ag) in the removal of phenol from aqueous solution. Material & Methods: Reduction method was used for converting bivalent iron to zero valent iron and co-precipitation method for depositing of iron on activated carbon. For coating silver on nano zero valent iron, rapid mixing at high temperature was used. The adsorbent was characterized using SEM, TEM, and XRD techniques. Then, the impact of pH, contact time, agitation speed, temperature, adsorbent, and initial phenol concentration were evaluated and optimized by one factor at the time method. Reaction kinetics and isotherms were also determined. Results: It was found that PAC-Feo/Ag has cubic and intertwined structure and has a diameter in the range from 40 to 100 nm. The optimum conditions for phenol removal by PAC-Feo/Ag were as pH=3, 90 min contact time, 200 rpm agitating speed and adsorbent concentration equal to 1 g/l. Isotherm and kinetic equations showed that the experimental data of phenol adsorption onto PAC-Feo/Ag are correlated to the Langmuir (R2>0.969) and pseudo-second order (R2<0.965) models, respectively. Conclusion: Under optimum conditions, modified adsorbent by zero valent iron and silver with maximum efficiency of 97% has quickly and effectively ability in removal of phenol and it can be easily separated from the solution sample by magnet because of its magnetic properties.
M Abtahi, K Naddafi, A.r Mesdaghinia, K Yaghmaeian, R Nabizadeh, N Jaafarzadeh, N Rastkari, R Saeedi, Sh Nazmara,
Volume 7, Issue 4 (1-2015)
Abstract
Background and objectives: Dichloromethane (DCM) is one of the hazardous contaminants of the environment, especially ambient air that threatens human health at both acute and chronic exposures. In this study, the performance of a pilot-scale hybrid bubble column/biofilter (HBCB) bioreactor was studied for the removal of DCM from waste gas streams at steady state. Materials and methods: The experiments were conducted in four stages with relatively constant concentrations of DCM (approximately 240 ppm) and variable empty bed residence time (EBRT) of 50, 100, 150 and 200 s. In addition to determining DCM removal rate and efficiency, quality parameters of mixed liquor of the bubble column bioreactor were studied and kinetic of biofiltration was analyzed. Results: The average DCM removal efficiency of the HBCB bioreactor at EBRT of 200 and 150 s were 79 and 71% respectively. However, further reduction of EBRT resulted in significantly decreased DCM removal efficiency, so that at EBRT of 50 s, the DCM removal efficiency decreased to 32%. In addition, the EBRT reduction from 200 s to 50 s through increasing DCM loading rate resulted in increasing DCM removal rate from 12.1 to 19.6 g/m3.h. The results of kinetic analysis showed that the kinetic data of biofiltration were in the best fitness with the first order rate equation (R2>0.99 and &epsilon%<2.2) and the DCM removal rate constant was determined 0.0114 s-1. The mixed liquor characterization indicated that the daily adjustment of pH and EC was sufficient to prevent any limitation in the performance of the HBCB bioreactor. Conclusion: This study indicated that the DCM removal rate and efficiency of the HBCB bioreactor were relatively high and the HBCB bioreactor had reliable performance during the variable operational conditions.
M Zare Jeddi, N Rastkari, R Ahmadkhaniha, M Alimohammadi, M Yunesian,
Volume 8, Issue 1 (8-2015)
Abstract
Background and Objectives: Bottles for packaging drinking water represent one of the most popular uses of plastic and polymer additives. Recently, public concerns related to possibility of exposure to chemicals through the consumption of polyethylene terephthalate bottled water has caused great concern to consumers. Phthalate esters, as a class of these compounds, are often classified as endocrine disruptors and one of them is a possible carcinogen for human. The aim of this study was to determine the concentrations of phthalates in bottled water and to calculate the health risk of phthalates intake via consumption of bottled waters. Materials and Method: After purchasing, samples were immediately stored according to the recommended conditions (25 ºC, dark place) given on the bottle label. Migration of phthalates was investigated in PET-bottled water at different time intervals using gas chromatography–mass spectroscopy. Therefore, a phthalate exposure assessment was performed to characterize their risk to the consumer’s health via a calculated hazard quotient (HQ). Results: It seems that the duration of storage affects phthalate migration. Total increases of DEHP (811.8%), DBP (2545.2%), and BBP (832%) were observed at 12 months over the initial level before storage (bottled water immediately after production) but the level of phthalates in bottled water was always very low (<EPA:6 μg/L). Non-carcinogenic risk assessment from exposure to phthalate via consumption of bottled water was negligible in all of the subject groups (HQ<1). Furthermore, a little excess cancer risk of 9.9×10-7 for bis (2-ethylhexyl) phthalate (DEHP) was observed.Conclusion: The research showed that the concentration of phthalates in PET-bottled water was extremely low. Consequently, based on the risk assessment results, bottled waters regarding existence of safe for consumers and they phthalates are not considered as public health issue for consumers as phthalates does not have any risk exposure for the consumers.
N Rastkari, F Izadpanah, M Yunesian,
Volume 8, Issue 2 (8-2015)
Abstract
Background and objective: Benzene is one of the main pollutants in air and one of the most extensive chemical compound used in both natural and industrial processes. Benzene exposure leads to the most dangerous adverse health effects, particularly blood cancer. The aim of this study was to evaluate the gas station workers’ exposure to benzene by measuring benzene in breathing air and urinary trans, trans-muconic acid. Materials and Methods: This cross-sectional study conducted in summer 2014 investigated 40 gas station workers and 40 occupationally non-exposed persons. Spot urine samples were obtained prior to and at the end of the work shift from each subject. The urinary levels of trans, trans-muconic acid was determined by liquid chromatography (HPLC) with diode array detector. At the end of the work shift, the benzene collected on sorbing cartridges was desorbed using carbon disulfide and was analyzed using gas chromatography and mass spectrometry detection. Results: The mean value for exposure to benzene in breathing zone of gas station workers was 5.90 ±1.93 ppm, which was significantly greater than the occupationally non exposed group (1.15±0.744 ppm). The mean urinary concentrations of trans, trans-muconic acid differed significantly between samples of gas station workers (64.75±19.47 µg/L) and occupationally non-exposed persons (47.10±13.67 µg/L). Conclusion: A good correlation (r = 0.581) between the mean values of benzene in breathing zone and the urinary concentration trans, trans-muconic acid was observed. Gas station workers were found to be probably the most exposed groups in this study. Inhalation is presumably the main route of exposure in gas station workers.
M Zare Jeddi, M Yunesian, R Ahmadkhaniha, H Kashani, N Rastkari,
Volume 8, Issue 3 (12-2015)
Abstract
Background and Objective: One of the air pollutants is volatile organic compounds (VOCs). Benzene, as a part of petrol, is a VOC, known to be carcinogenic to human beings (Group 1) and it has widespread application in various industries and professions. Hence, the aim of the present study was semi-quantitative and quantitative health risk assessment of petrol bank workers exposure to benzene via inhalation in the Tehran, Iran.
Material and method: For these purpose, this descriptive cross-sectional study was conducted in three stages. First stage consisted of measurement of benzene in two groups of participants: (1) petrol bank workers and (2) non-exposed people as control group. The second stage included the evaluation of worker's exposure to benzene and semi-quantitative risk assessment, and the third stage was estimating the lifetime cancer risk caused by exposure to benzene.
Results: Benzene mean concentration was near the threshold limit value (1600 µg/m3) and the mean benzene personal air level was 1527±246.4 µg/m3 in the petrol bank areas. With regard to semi-quantitative risk assessment method, benzene introduced as the most hazardous chemical with risk ratio of 4.5 has 5th rank in risk levels (Extremely dangerous). Lifetime cancer risk estimation showed that in petrol bank workers the excess lifetime cancer risk was 27.5 times higher than unexposed group and the chance of cancer was one in a 1000 petrol bank workers.
Conclusion: This study indicates that petrol bank workers in Tehran have a potentially high cancer risk through inhalation exposure. Thus, preventative actions regarding to this hazardous and carcinogenic chemical must be started as soon as possible.
N Rastkari, F Izadpanah ,
Volume 9, Issue 1 (6-2016)
Abstract
Background and Objective: Formaldehyde is a toxic volatile organic compound, which its removal from polluted air is essential. One of the techniques available for removing such compounds is photocatalytic degradation. The aim of this study was to investigate the photocatalytic degradation of gaseous formaldehyde on TiO2 nanoparticles coated on reduced graphene oxide
Materials and Methods: The synthesized reduced graphene oxide- TiO2 nanocomposite was characterized using SEM, EDS, and FTIR spectra. The photocatalytic activity of prepared reduced graphene oxide- TiO2 nanocomposite was investigated for degradation of gaseous toluene under different operational conditions such as different initial concentration, flow rate, and time.
Results: The photocatalytic degradation efficiency of the RGO-TiO2 nanocomposite was much higher than P25 TiO2. The photocatalytic degradation efficiency of the RGO-TiO2 nanocomposite decreased by increasing the flow rate so the flow rate is a key factor for the use of RGO-TiO2 nanocomposite as a photocatalyst. The results showed that the photocatalytic degradation rates decreased from 89 to 30% with increasing formaldehyde initial concentration from 0.1 to 1 ppm.
Conclusion: This research indicated that RGO-TiO2 nanocomposite can be effectively used as suitable photocatalyst to remove gaseous pollutants. One of the advantages of the as-prepared composite was using visible light instead of UV to activate the oxidation process.
Ar Khajeamiri, M Zare Jeddi, R Ahmadkhaniha, N Rastkari,
Volume 9, Issue 3 (12-2016)
Abstract
Background and Objective: Organochlorine pesticides are among the endocrine disrupting chemicals believed to produce a wide variety of adverse health outcomes such as cancers. Generally, fatty foods of animal origin are the major sources of human exposure to lipophilic contaminants such as DDTs and their metabolites. The objectives of the present study were to evaluate exposure of general population to DDTs via dietary milk consumption in Iran, and to assess the respective potential risks to health of people in terms of carcinogenic and none-carcinogenic effects.
Materials and Methods: The DDT residue levels were determined by GC/MS analysis in 60 milk samples of full fat pasteurized commercial types (3% fat). The assessment of carcinogenic and non-carcinogenic risks was calculated through international standard methods.
Results: In all of the milk samples, DDT and its metabolites were detected in the range of 0.0015 to 0.28 µg/L with the mean of 0.05±0.03, 0.15±0.08, 0.09±0.05, 0.05±0.02 µg/L for o, p-DDE, p,p-DDE, p,p-DDT, p,p-DDD, respectively. The calculated estimated daily intake (0.00006-0.0002 mg/kg/day) for all categories and all compounds were lower than the Reference doses (RfDs). Consequently, the hazard quotients calculated in these groups for DDTs were less than 1. Hazard index obtained for all compounds in full fat pasteurized milk based on maximum DDT residue concentrations was higher than unity confirming health risk. From the carcinogenic point of view, there is no risk and it was within the acceptable threshold of EPA.
Conclusion: The results of the present study showed that the general population are exposing to DDT and its metabolites constantly. Therefore, it is recommended to biomonitoring and measuring these chemicals in all age groups especially in children.
M Seifi, N Rastkari, Ms Hassanvand, H Arfaeinia, M Younesian,
Volume 10, Issue 1 (6-2017)
Abstract
Background and Objective: The collection of exhaled breath condensate (EBC) is a noninvasive, safe and simple technique to obtain direct samples from lung and use for estimation of the effects of air pollution on human subjects. EBC contains several compounds including simple ions, hydrogen peroxide, proteins, cytokines, deoxyribonucleic acid (DNA), creatine, Electrolytes, trace elements and toxic metals that are diluted by water vapor. The objective of this study was to determine biomarker IL-6 in exhaled breath condensate using an exhaled breath condensate collector.
Materials and Methods: The collector was designed and built and was used for collection and condensation of exhaled breath. EBC was taken from 36 young participants. Each person was asked to breathe for 10-15 min and the condensate was kept in a vial. The samples of exhaled breath were cooled down to -20 °C using the collector. The exhaled breath was converted to the solid/liquid mixture and then, the biomarker IL-6 was measured with ELISA (Enzyme -linked immunosorbent assay) method using HS600B R&D Kit.
Results: The mean concentration of IL-6 was 1.08 pg/mL in collected samples. The standard deviation of IL-6 concentration was 0.47. Moreover, the average volume of collected EBC was 2.3 mL, ranged between 0.3 and 3.5 mL.
Conclusion: The results of this study showed that the volume of the exhaled breath condensate was comparable with similar commercial devices. The average concentration of interlukin-6 was similar to the concentrations reported by other studies. Based on the findings, this equipment can be used by researchers as a suitable device for measurement of IL-6 in exhaled breath condensate.
K Naddafi, M Yunesian, S Faridi, A Rafiee, S Parmy, Gh Safari, R Nabizadeh Nodehi , K Yaghmaeian, N Rastkari, R Ahmadkhaniha, S Niazi, M Hoseini,
Volume 10, Issue 1 (6-2017)
Abstract
Background and Objective: Polycyclic aromatic hydrocarbons (PAHs) are a group of organic pollutants that are mostly generated during the incomplete combustion. The main objective of this study was to characterize potential sources of PAHs in Tehran.
Materials and Methods:, Samples of PM10 were collected at 10 monitoring stations belonging to Tehran Air Quality Control Company (AQCC) and transferred to laboratory for analysis. Besides, a SKC Flite 2 Air Sampling Pump (SKC, USA) equipped with a sampling head and PM10 size-selective inlet was used at four stations to compare the results obtained by collecting AQCC monitors (AQCCMs) tapes with the standard sampling procedures for assessing the interchangeability of two field sampling methods. The principal component analysis (PCA) and diagnostic ratios were applied to identify emission sources and source contribution.
Results: The average diagnostic ratios of phenanthrene (Phe)/ (Phe+anthracene (Ant)), benzo(a)anthracene (BaA)/ (BaA+chrysene (Chry)), fluorantene(Flu)/ (Flu+pyrene (Py)), and indeno(1,2,3cd) pyrene (IcP)/(IcP+benzo(ghi)perylene (BghiP)) in samples were 0.79, 0.52, 0.43 and 0.38, respectively. These ratios showed that the combustion, especially fossil fuels and motor vehicles, was the main sources of PAHs emission in Tehran. The results of PCA analysis also indicated that 49, 29 and 22% of PAHs sources in Tehran atmosphere were attributed to gasoline-driven vehicles, diesel vehicles and other sources, respectively.
Conclusion: According to the results, the combustion, especially fossil fuel and motor vehicle, was the main sources of PAHs emission in Tehran.
F Ahmadi, N Rastkari, P Sadighara, Gh Jahed Khaniki,
Volume 10, Issue 3 (12-2017)
Abstract
Background and Objective: Aluminum (Al) is a neurotoxic agent and this element is being associated with Alzheimer disease. The use of semi-rigid packaging has been increased in recent years. In these packages, the main layer is aluminum. The purpose of this study was to determine the Al concentration in foods packaged in semi-rigid packaging in during storage time.
Materials and Methods: Al concentration of the samples (Joje kabab, khorake morgh, khoresh gheymeh, n=36) was determined at different storage times (0, 60, 120, and 180 days after packaging). Aluminum was determined by ICP-OES after wet digestion method of the samples. A two-way analysis of variance was used to analyze the results with respect to time and food factors.
Results: The effect of storage time on Al concentration was significant p˂0.001. The samples that were stored longer had significantly higher aluminum concentrations. The highest concentration was determined in Joje kabab (3.27 ±0.93 ppm( and lowest Al content was determined in khoresh gheymeh (1.04 ± 0.16 ppm). The results showed that Al concentration of the foods packaged in semi-rigid packaging increased significantly during storage.
Conclusion: Considering the present state of knowledge and the suggested provisional tolerable daily intake of 1 mg/kg body weight per day of according to World Health Organization, Al leaching from semi-rigid packages may add low doses of Al into the diet.
N Golchinpour, N Rastkari, R Nabizadeh Nodehi, M Abtahi, A Azari, E Iravani, K Yaghmaeian,
Volume 10, Issue 4 (3-2018)
Abstract
Background and Objective: Triclosan is one of the substances as anti-microbial that is used in many of these pharmaceutical products. This compound can affect human such as reduction of thyroid hormone levels, antibiotic resistant, and increasing skin cancer. This study evaluated the performance nanophotocatalysis process UV/Xe/TiO2-GO on triclosan removal from aqueous solutions.
Materials and Methods: Synthesis of TiO2@GO and its structure was analyzed by SEM, EDX and FTIR. The effects of pollutant concentration, catalyst dosage, and contact time on the removal of Triclosan were studied by DOE software according to response surface methodology. Analysis of variance test was considered for the influence of parameters. Optimum process condition was determined by desirability factor.
Results: Optimum conditions regarding concentration of pollutant, contact time, and catalyst dosage were determined as 0.205 g/L, 14.898 min, and 0.487 mg/L, respectively. Maximum removal efficiency in optimum condition was 97.542 percent. The catalyst dosage was the most effective parameter in removal of Triclosan.
Conclusion: Using of TiO2@GO and xenon lamp had acceptable efficiency for the removal of Triclosan. The use of Xenon lamps alone was economically affordable.
F Sarlak, R Nabizadeh, M Yunesian, N Rastkari,
Volume 11, Issue 4 (3-2019)
Abstract
Background and Objective: Iodized salt is one of the most important sources iodine in Iran. Former studies show that the iodine levels were insufficient both in distribution and consumption levels. The aim of this descriptive-analytical sectional study was to investigate the iodine content in table salts used by families covered by health services of Tehran University of Medical Sciences during 2017.
Materials and Methods: 315 families from SIB (Integrated Health System) with random sampling method were studied. A questionnaire was filled out through interviews and salt samples were taken for analysis. The iodine in all samples was measured by iodine-meter kits and one third of the samples were also measured by titration.
Results: The average iodized salt consumed by the families was 18.53 µg/g iodine, which is less than the national standard. Iodine amount in %12 of the samples was not in compliance with WHO standards. In %59 of the samples, there was less iodine amount than the previous standard level set by the Iranian Ministry of Health (20-55 µg/g iodine). None of the samples were compatible with the new standards set by the Iranian Ministry of Health (30-60 µg/g iodine).
Conclusion: it was found that there is no meaningful relation between the variables such as Material, type of salt container and the amounts of iodine (p>0.05). Families are not aware of the effects of iodine deficiency.
