Afshin Ebrahimi | Isfahan University of Medical Sciences (original) (raw)

Papers by Afshin Ebrahimi

International Journal of Environmental Health Engineering, 2012

ABSTRACT Aims: This study was conducted for degradation of 4-chlorophenol by microwave (MW) radia... more ABSTRACT Aims: This study was conducted for degradation of 4-chlorophenol by microwave (MW) radiations alone and in combination with hydrogen peroxide from aqueous solution. Materials and Methods: A modified domestic microwave oven was used alone and in combination with hydrogen peroxide for removing 4-chlorophenol. Furthermore, the influences of pH value, irradiation time, the power of MW radiations, and the initial concentration of 4-chlorophenol were studied. Results: It was shown that 4-chlorophenol removal efficiency extremely depend on the concentration of hydrogen peroxide, pH value, MW irradiation power and initial 4-chlorophenol concentration. The optimum conditions obtained for the best degradation rate were pH = 10.5, H 2 O 2 concentration of about 0.1 mol/l, and MW irradiation power of about 600 W. Other result shows that the best degradation rate of 4-chlorophenol was obtained when initial 4-chlorophenol concentration was 50 mg/l. Also the amount of the specific energy consumption in this method was 17460 kwh/kg of the removed organic compound. Conclusion: This result shows that MW irradiation in the presence of hydrogen peroxide can greatly enhance the degradation of 4-chlorophenol. However, the high consumption of energy for this method must be taken into consideration.

Journal of Water and Wastewater; Ab va Fazilab ( in persian ), 2010

Linear Alkyl Benzene Sulphonate Acids (LAS) are one of the anionic surfactants that are produced ... more Linear Alkyl Benzene Sulphonate Acids (LAS) are one of the anionic surfactants that are produced and used in large quantities in different countries and find their way into the natural environment through sewer systems. These compounds may potentially cause environmental hazards in such surface waters as rivers. It is, therefore, necessary to remove as much of these compounds as possible by biological processes in wastewater treatment plants. For this purpose, four parallel biological reactors were constructed that used the conventional activated sludge and aeration tanks with fixed bed on the bench scale in order to evaluate the removal efficiency of LAS. The reactors were operated under conditions similar to domestic wastewater treatment plants. Parameters of

Background: The use of alternative disinfectants and the control of natural organic material are ... more Background: The use of alternative disinfectants and the control of natural organic material are two approaches that are typically applied in water treatment utilities to reduce the formation of chlorinated disinfection by-products in recent years. Catalytic ozonation as a new technology is used to promote the efficiency of the single ozonation processes. The purpose of this study was to investigate the feasibility application of Pumice as a catalyst in ozonation process in removal of humic acids from aqueous solution. Methods: This study as an experimental study was carried out at the chemistry laboratory of water and wastewater in Hamadan University. The solid structure and chemical composition of activated carbon was determined by X-ray fluorescence (XRF) and X-ray diffraction (XRD). Ozonation and catalytic ozonation experiments were performed in semi-batch reactor and the mass of ozone produced was measured by iodo-metric titration methods. Concentration changes of humic Acid were determined using spectrophotometer at an absorbance wavelength of 254 nm. To evaluate the performance of catalytic ozonation in humic Acid removal, the effects of different parameters included pH, initial concentration of phenol contact, the amount pumice and Tert-butanol alcohol (TBA) were examined and the results were analyzed by Excel software. Findings: The results of the Catalytic ozonation indicated that using Pumice as a catalyst increased the humic acid's decomposition by 8 times and the removal efficiency was increased by increasing pH (4-12) and catalyst dosage (0.25-10 g). The experimental results showed that catalytic ozonation was the most effective in less time (10 min) with considerable efficiency (90%) compared to the sole ozonation process (SOP). The results indicated that the catalytic ozonation process, compared to SOP, was affected less by radical scavenger. Conclusion: Because of the low cost of Pumice, easy access to required raw materials and its remarkable performance as catalyst, it can be used as catalyst in sole ozonation processes to remove the organic material.

International Journal of Preventive Medicine, 2015

Background: High concentrations of elements such as aluminum (Al) and silicon (Si) in drinking wa... more Background: High concentrations of elements such as aluminum (Al) and silicon (Si) in drinking water can affect human health. It is suggested that high daily intake of Al is associated with increased risk of neurodegenerative disorders. Si, as an antidote of Al, may decrease Al bioavailability. The study was conducted to estimate Al and Si concentration and correlation in water and evaluate their health risk. Methods: In this cross-sectional study, water samples were collected from 20 points of water distribution system and the water treatment plant of Isfahan in spring and summer. Samples were analyzed using DR-5000. The health risk was evaluated via calculating chronic daily intake (CDI) and hazard index (HI). Results: Significant negative correlation was documented between Al and Si (R = −0.482, P = 0.037 in spring, and R = −0.452, P = 0.049 in summer). These values were approximately similar in all types of Al and Si. The amounts of CDI for Al in spring and summer were 6.67E-04 and 0.002 mg/kg/day, respectively. The Al HI values were below 1 in both seasons. Conclusions: The significant correlation between Al and Si concentrations suggests that Si can eliminate Al in water, and probably it might do the same in the body. The health risk of Al intake from tap water was negligible, it was assessed in an acceptable range with an HI value of less than the standard levels. The health risk of Si remained unknown due to lack of information regarding its toxicity and adverse health effects.

International Journal of Environmental Analytical Chemistry, Sep 18, 2020

The applicability of heterogeneous photocatalytic degradation of low concentrations of the cyanob... more The applicability of heterogeneous photocatalytic degradation of low concentrations of the cyanobacterial toxin, microcystin-LR, in a natural organic-aqueous matrix is examined using titanium dioxide as the photocatalyst. The initial rate of toxin degradation is strongly pH dependent in a manner mirrored by the pH dependence of toxin adsorption to Ti02. Rapid degradation of toxin occurs in the acidic pH range in the presence of light and Ti02 with a maximum initial rate of degradation occurring at pH 3.5 while at higher concentrations and pH, a distinct lag is observed prior to commencement of toxin degradation. A proposed conceptual model for toxin degradation is developed and the veracity of the proposed model is tested by determining species concentrations for assumed kinetic constants. Very similar dependencies and trends to those observed in the laboratory studies were obtained suggesting that adsorption and sensitization effects are critical. In particular, under conditions where the contaminant adsorbs strongly to semiconductor surface sites, the primary degradation step appears to involve reaction between surface-located long-lived organic radicals and adsorbed trace contaminant. Significant presence of superoxide at low pH appears to enhance trace contaminant degradation via solution phase formation of highly oxidizing organic peroxy radicals from "bulk" background organic. Under conditions where the trace contaminant shows no observable adsorption, surface degradation adequately predicts removal due to surface concentration effects. Initial pilot scale studies using a solar fixed-bed photocatalytic reactor have been successful in achieving 96% removal of a 100 L microcystin-LR spiked drinking water solution. The model successfully predicts the much slower degradation achieved where a trace contaminant is a very small fraction of a natural organic-aqueous matrix and number of sites is significantly reduced.

International Journal of Environmental Health Engineering, 2013

In this study, the efficiency of several advanced oxidation processes such as ultrasonic oxidatio... more In this study, the efficiency of several advanced oxidation processes such as ultrasonic oxidation, heterogeneous Fenton-like oxidation, ultrasound or UV assisted heterogeneous Fenton-like oxidation, heterogeneous sonophotoFenton oxidation and oxidation with ultrasound+UV light combination was tested for COD reduction in effluents of purified terephthalic acid (PTA) production. The highest COD removal was achieved as 18% when UV light assisted heterogeneous Fenton-like oxidation was applied to PTA manufacturing wastewater in the presence of 5 wt% iron containing TiO2 catalyst. This combined advanced oxidation process seems to be a promising one to enhance the COD removal when it is used after biological treatment.

DESALINATION AND WATER TREATMENT, 2019

Humic acid is a major precursor of chlorinated byproducts that need to be removed from water, via... more Humic acid is a major precursor of chlorinated byproducts that need to be removed from water, via treatment, given their adverse effects on human health. The current study aimed at identifying the optimal conditions to remove humic acid from surface water, using coagulants such as polyaluminum chloride (PACl) and polyaluminum ferric chloride (PAFCl). The effects of independent variables such as total organic carbon (TOC) concentration (1.6-7 mg/L), pH level (5-9), and coagulant dosage (10-50 mg/L) on humic acid removal were studied using response surface methodology and central composite design. A coagulant dose of 15.72 mg/L (for PACl and PAFCl), TOC concentration of 2.66 mg/L, and pH of 7.84 comprised the optimal conditions, and the removal efficiencies of 97.55% and 98.18% were obtained with PACl and PAFCl, respectively. Zeta potential analysis showed that the leading mechanism for coagulation, with both coagulants, was charge neutralization. PACl and PAFCl had adequate potential to remove humic acid from surface water, but PAFCl had a better performance regarding the treatment of aluminum residuals.

Health Scope, Aug 3, 2016

Background: The control of microorganisms in industrial and residential environments is the main ... more Background: The control of microorganisms in industrial and residential environments is the main concern regarding the spread of infectious diseases.

Ecotoxicology and Environmental Safety, Mar 1, 2021

Journal of environmental health and sustainable development, Sep 15, 2016

Today, have been approved scientifically relationship between presence of asbestos fibers in the ... more Today, have been approved scientifically relationship between presence of asbestos fibers in the human respiratory area and malignant diseases such as lung advanced fibrosis (Asbestosis), gastrointestinal, lung and Laryngeal cancers. The aim of this study was the determination of asbestos fibers concentration in Yazd city's air in the summer of 2015. Materials and Methods: This is a descriptive cross sectional study in which 13 high-traffic points of Yazd city were selected for asbestos sampling. Sampling was conducted in the summer in two stages using SKC pump. In total were collected 26 samples from the high traffic points of Yazd city. Also for the counting of asbestos fibers was used scanning electron microscopy (SEM). Results: In the current research, the highest and the lowest concentration of asbestos fibers were related to Shohadayemehrab square (0.02131fiber/ml) and Azadshahr (0.00112 fiber/ml) respectively. Qualitative analysis of asbestos fibers by SEM showed that 75% of the samples were asbestos fibers and the other was non-asbestos fibers. Conclusion: The present study showed that the average of asbestos fibers concentration in total sampling stations (0.00848 fiber/ml) was higher than WHO guidelines (2.2 × 10-3 fiber/ml). The main reason for the presence of these fibers in the air of Yazd city can be attributed to brake pad, clutch and automobile gasket adhesive.

Environmental Research, Jun 1, 2023

Iranian journal of health, safety and environment, Jan 7, 2016

Trihalomethanes (THMs) formation in treated water is a consequence of a reaction between the chlo... more Trihalomethanes (THMs) formation in treated water is a consequence of a reaction between the chlorine used for water disinfection and some natural organic matters. The objectives of the present study were monitoring of THMs concentration in Isfahan (A metropolis city in center of Iran) water distribution network (IWDN), evaluation factors that affect the THMs formation potential and identification of critical points by using geographical information system (GIS). The study was performed in summer months of 2014. For sampling point's selection, city divided into 30 zones and water quality parameters such as pH, Electric Conductivity (EC), residual Chlorine, Total Organic Carbon (TOC) and THMs of IWDN measured. Multi regression analysis was used to estimate the correlation between THMs formation and these variables. While the statistical analysis with Spearman non-parametric correlation coefficients showed a positive correlation between distance from treatment plant and THMs concentration(r=0.45, P =0.01) and negative strong correlation(r=-0.95, p>0.001) between THMs and TOC concentrations, there was no strong significant relationship between THMs formation in IWDN and some variables including pH, temperature and residual Chlorine. The results reveal that the average value of the THMs at sampling points for summer attained 42.56 ppb which was lower than the EPA and WHO standards. It is recommended that the distance from the treatment plant was used as an effective parameter for estimation of THMs formation potential.

International Journal of Environmental Health Engineering, 2015

Aims: Feasibility of the anaerobic migrating blanket reactor (AMBR) was investigated for the trea... more Aims: Feasibility of the anaerobic migrating blanket reactor (AMBR) was investigated for the treatment of composting leachate. Materials and Methods: The AMBR consisted of a rectangular, plexiglas reactor (inside dimensions: length = 43 cm, height = 23.5 cm, width = 10 cm) with an active volume of 10 L. which divided reactor into four identical compartments (2.5 L). Composting leachate was used as a feed. Start-up of a reactor with diluted feed of approximately 10.43 g/L. Chemical oxygen demand (COD) was accomplished in about 44 weeks using seed sludge from the anaerobic digester of municipal wastewater treatment plant and operated continuously at mesophilic phase. The organic loading rates (OLRs) applied to the system was gradually increased from 1 to 19.65 g COD/L.d. Results: The reactor with hydraulic retention time of 10 day at 35΀C and initial OLR of 1 g COD/L.d showed 82.3% COD removal efficiency. The best performance of the reactor was observed with an OLR of 3.79 g COD/L.d. In influent of reactor, BOD 5 /COD ratio, TSS, VSS and TDS were ranged from 0.47 to 0.69, 1650 to 16,830, 990 to 12,622 and 2630 to 31,240 mg/L and in effluent of reactor were reached to 0.28 to 0.38, 660 to 7452, 346.5 to 4597 and 1860 to 19,490 mg/L, respectively. Conclusion: The AMBR could be an appealing option for pretreatment of organic load in composting leachate and improving the efficiency of the next biological reactors.

تحقیقات نظام سلامت, May 8, 2012

تحقیقات نظام سلامت, Jun 1, 2012

International Journal of Environmental Health Engineering, 2014

Aims: The purpose of this study was to investigate the composition of dental waste coming from si... more Aims: The purpose of this study was to investigate the composition of dental waste coming from six dental health services in Isfahan, Iran. Materials and Methods: From 45 public dental clinics in Isfahan, six public dental health services were selected (three dental clinics and three dental centers). Waste collection took place from October to December 2011. During this period, three samples were collected from each dental clinic and were divided to pre-determined groups manually. Results: In dental centers, the amount of infectious, non-infectious and domestic-type waste accounting for 45.07%, 12.15% and 42.78%, respectively. Whereas in dental clinics the production rates of infectious, non-infectious and domestic-type waste accounting for 52.2%, 8.58% and 39.22%, respectively. Conclusion: Overall, according to the results it can be said that integration of infectious and hazardous waste with general waste leads to the amount of infectious waste appears much greater than it actually is. The collection and disposal of amalgam and other hazardous dental solid waste should be regulated as soon as possible and to decrease the costs of dental waste management the uncontaminated recyclable items, which contained approximately 33% of total dental waste should be recycled or reused if possible.

Introduction: There are many varieties of compounds in chemical and petrochemical wastewater. One... more Introduction: There are many varieties of compounds in chemical and petrochemical wastewater. One of the important members of the Chlorophenols (CPs) family is ρ-chlorophenol. This pollutant is introduced into the environment through various human activities such as waste incineration, uncontrolled use of wood preservatives, pesticides, fungicides and herbicides, as well as via bleaching the pulp with chlorine, chlorination of drinking water and wastewater. Methods: Experiments with microwave irradiation were carried out in a modified domestic microwave oven with the cooling system (2450MHz, SAMSUNG Co.). The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, the irradiation time, the initial concentration of organic material and the microwave power. Findings: The result showed that the optimum conditions obtained for the best degradation rate was pH = 10.5, the H 2 O 2 concentration of about 0.1 mol/L and the microwave irradiation power of about 600W for the microwave/H 2 O 2 system at constant ρ-chlorophenol concentration. The degradation of ρ-chlorophenol by different types of oxidation processes were followed by the first order rate decay kinetics. Conclusion: The energy consumption for UV/H 2 O 2 in degradation of p-Chlorophenol (93%) and the reaction time of 180 min was 17460 KWh/kg p-Chlorophenol removing.

Journal of Environmental Management, 2021

In the present work, effect of coexisting anions on the degradation performance of UV/chlorine (U... more In the present work, effect of coexisting anions on the degradation performance of UV/chlorine (UV/Cl) processes as an advanced oxidation treatment for the dye containing wastewater was investigated. The results showed that by increasing pH of the solution from 3 to 11, degradation efficiency of UV/Cl process was reduced from 96.2 ± 1.4% to 62.9 ± 3.1%. In the case of 100 mg/L of DR83:1, the removal efficiency was improved from 30.2 ± 1.5% to 93.3 ± 4.7% when the chlorine dose was increased from 100 to 1000 μM. The HCO₃- and Br- ions were the main inhibitor and promotor anions responsible for the degradation of DR83:1. The relative contribution of Cl• was higher than that for HO• and UV, which was about three-times higher than that for HO•. The lowest and highest amounts of trihalomethanes were generated at acidic and alkaline conditions as well as low disinfection by products at low pH due to the generation of more HO• radicals at acidic pH in comparison to higher pH such that less intermediates were remained to react with chlorine.