reza shokoohi; Hossain Farji; Seyed Amir Ghiasian; Javad Faradmal; Salah Azizi; mahdi salari
Abstract
Background & Objective: Cadmium is considered as one of the most hazardous heavy metals, a non-essential, non-beneficial and highly toxic element to people. In the current study, the ability of aspergillus terreus fungi biomass was surveyed in the removal of cadmium from aquatic solutions. Materials ...
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Background & Objective: Cadmium is considered as one of the most hazardous heavy metals, a non-essential, non-beneficial and highly toxic element to people. In the current study, the ability of aspergillus terreus fungi biomass was surveyed in the removal of cadmium from aquatic solutions. Materials & Methods: This cross-sectional study was carried out in 2015 using fungal biomass culture on a shake flask. The dead biomass of aspergillus terreus fungi was applied as an adsorbent for the treatment of aquatic solution under the conditions of cadmium concentrations: 20, 40, 60, 80, 100 and 120 mg/l, pH: 3, 5, 7 and 9, retention time: 15, 30, 45, 60, 90, and 120 min and adsorbent dose: 0.1, 0.2, 0.5, 1 and 2 g. The remained concentrations of cadmium after adsorption were determined by atomic absorption spectrophotometer. Results: Results indicated that under condition of retention time: 90 min, pH: 7, initial cadmium concentration: 20mg/l and adsorbent dose: 1g, the biomass had a removal efficiency of 94%. Moreover, Adsorption process fitted to Freundlich isotherm with R2=0.9463 and first order kinetic with R2=0.9935. Conclusion: In current study, it was observed that the factors of pH, retention time, dose of aspergillus terreus fungi and initial cadmium concentration had a noticeable effect on the adsorption amount. with regard to the high adsorption capacity of the biomass in comparison to other adsorbents in the removal of cadmium, this biomass can be used as a good adsorbent in wastewater treatment.
Shahrokh Nazmara; fatemeh eslami; mehdi salari; Alireza beheshti; Mohsen Yazdani avval
Abstract
Background & objective: People commonly spend, on average, 5-6% of their time in a day in enclosed vehicles. Smoking in vehicles with little volume can result in potential harmful effects on children and other passengers. This study aimed to evaluate the concentrations of suspended particles produced ...
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Background & objective: People commonly spend, on average, 5-6% of their time in a day in enclosed vehicles. Smoking in vehicles with little volume can result in potential harmful effects on children and other passengers. This study aimed to evaluate the concentrations of suspended particles produced from smoking and the exposer time of passengers to the produced smoke. Materials & Methods: This cross–sectional study was performed in Tehran, 2014. The exposure to cigarette smoke was measured using Grimm11-A device that had 16 entrances with different sizes from 0.3 to 20 µm. The studied vehicle was Pejo 405 , andwindows condition were as following: 1 back window open, 2 back windows open, 1 front window open, 2 front windows open, 2 front and 1 back windows open, 4 windows open and 4 windows close. SPSS 16 software was used to make statistical analysis ( one-way ANOVA (p<0/05)). Results: Numerical concentrations of particles in small size row (PM2.5) were several LOGs higher than larger sizes row. In addition, it was observed that exposure time to particles in small size row had significant difference with large size row. The maximum exposure concentrations with a p-value<0.05, and the maximum exposure time with a p-valueConclusion: According to the gained results, the largest portion of cigarette smoke particles in vehicles belonged to the PM2.5. Different conditions of windows in their opened and closed states can be effective on ventilation. So that the more numbers of windows are opened the greater ventilation will occure. Generally, because of the limit space of vehicles and high exposure concentrations, the enactment of cigarette smoking prohibition legislation seems to be necessary.
mahdi salari; Shahrokh Nazmara; Kazem Naddafi; Mohammad Hadi Dehghani
Abstract
Background & Objective:Formaldehyde is one of the most important aldehydes in ambient air which originates from vehicles and photochemical processes. Because of the importance of this pollutant in public health, in this study, we addressed the concentration level in coupled with daily and cross sectional ...
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Background & Objective:Formaldehyde is one of the most important aldehydes in ambient air which originates from vehicles and photochemical processes. Because of the importance of this pollutant in public health, in this study, we addressed the concentration level in coupled with daily and cross sectional variation of formaldehyde in the high traffic area of Enghelab Square in Tehran city and also the effect of meteorological parameters on variation of formaldehyde concentration were determined. Materials & Methods:This cross-sectional study was done in Enghelab Square placed in the district 6 of Tehran in December, January and February (period 1) and April, May and June (period 2) in 2014-2015. To measure the concentration of formaldehyde, the chromotropic acid method was used and samples were analyzed by Perkin Elmer LAMBDA spectrophotometer model of 25 UV/Vis at wavelength 580nm. Data analysing performed by SPSS (T-test and coefficient correlation) and excel ( graphical drawing). Results:The formaldehyde concentration on Fridays in comparison with other days during the week have a significant difference (Independent T-test, p<0.05). The average concentration of formaldehyde in the period 2 of sampling was higher than that in the period 1 by 6.5 ppb (Paired T-test p<0.05). A significant positive correlation was found between temperature and humidity parameters and formaldehyde’s concentration with correlation coefficients of 0.457 and 0.338 respectively, and also pressure parameter with correlation coefficient of 0.1 showed no significant correlation between formaldehyde concentration variations. Furthermore, formaldehyde concentrations were increased under inversion conditions. Conclusion:Formaldehyde concentration on Fridays in comparison with other days had lower level that can be resulted from low traffic volume on Fridays. Moreover, increasing formaldehyde concentration in the period 2 (April, May and June months) in comparison to period 1 (December, January and February months) is the result of intensifying photochemical processes in the warm months. Also the effect of temperature, humidity and inversion condition on increasing the concentration of formaldehyde show the importance of meteorological conditions in formaldehyde concentration variations.