BTXs removal with transition metals coated beds, considering the plausible reaction mechanisms

In this study, a natural zeolite (i.e., Clinoptilolite) was used as bed of a lab scale packed tower. The bed was coated with two transition metals nano-scale particles (i.e., Fe0 and Cu2O). Each coated metal to bed ratio was 4.6 wt. and the experiments were conducted in air flow of 1 L minG1 and temperature of 200°C. The results showed up to 83.83 of BTX (benzene, toluene and xylene) removal for Fe0 and respectively 32.0 and 56.98 for Cu2O and combined Fe0-Cu2O coated beds. However, the pollutants mineralization/elimination ratio on the combined metals coated bed, with up to 0.83, was greater than the remains which were 0.58 and 0.37 in order for Fe0 and Cu2O coated beds. © 2015 Asian Network for Scientific Information

Escherichia Coli Removal from Water Using Electrophotocatalytic Method

Electrochemical has the suitable method of drinking water disinfection. This method leads to production of hydroxyl radicals which are known powerfull oxidant agent. In recent years, water disinfection using electrophotocatalytic method is spreading. The aim of this experimental applied study is to evaluate the removal of Escherichia Coli, as the microbial contamination indicator of water, from drinking water using electrophotocatalytic method. The contaminated water in an electrophotocatalytic reactor were prepared by adding 102-103 cell of E. coli bacteria to drinking water. The studied variables were pH (6-8), the number of bacterial suspensions (102-103 cells / ml), the UV-A lamps (2-4 W), times (5-40 min), the distances between electrodes (2-3.5 cm), layering of zinc oxide nanoparticles (1-3), and voltages (10-40). The findings showed the correlation between removal of cells and UV-A lamps, voltage, and time of electrolysis. Optimal removal (MPN: 0) was obtained at pH 8, time of electrolysis: 5 minutes, 2 layer of nano ZnO, and voltage of 10 V. This result offers that this method is an efficient method for water disinfection. @JASEMKeywords: Escherichia Coli , Water disinfection, Electrophotocatalytic, UV- AJ. Appl. Sci. Environ. Manage. Sept, 2011, Vol. 15 (3) 439 - 44

Evaluation of photoionization detector performance for measuring the airborne toluene

Background and aims: In the field of chemical agents at workplaces, traditional measurement method for assessing the volatile organic compounds (VOCs) concentration is using a gas chromatograph generally equipped with a flame ionization detector (GC-FID). However, there are some limitations in working with this equipment including equipment accessibility, necessity of highly trained operators, and the high cost of sample analysis. The aim of this study was to evaluate the performance of photoionization detector (PID) as a substitution for GC-FID in the measurement of toluene as a representative of the VOCs in experimental studies. Methods: This study was carried out by an experimental set up for generating toluene known concentrations at 5, 20, 50, 100, 200, 500 and 1000 ppm with relative humidity 13 ±2. The concentration values were measured with PID as well as the National Institute of Occupational Safety and Health (NIOSH) 1501 reference method and results were compared. Results: The results showed a significant difference between the two methods at concentrations higher than 50 ppm while there was no significant difference at 5 ppm and 20 ppm. The correlation coefficient of the toluene concentrations at 5 to 1000 ppm was 0.999. The correction factor for the PID was 1.05 at the studied concentration range. Conclusion: Although the results presented by PID were different from those extracted from the NIOSH reference method, the response was linear. Thus, in studies of measuring airborne concentrations of toluene using this type of detector; the reading values must be corrected by the calculated correction factor

Mercury level in biological samples of dentists in Iran: a systematic review and meta-analysis

Exposure to mercury is an important risk to dentists health. The aim of the present study was to assess the pooled mean mercury level (MML) in the urine, blood, nail, and hair of Iranian dentists (IDs) through the meta-analysis technique. Comprehensive and systematic searches were performed in main local databases including SID, Magiran, Iran medex, and ISC as well as internationally available databases including Embase, PubMed and Scopus for all the relevant studies up to 2018. In order to prevent bias in this study and identify eligible studies, various steps of the study was performed independently by two researchers. Out of 13 studies in the meta-analysis process which included 1499 IDs, the mean of the mercury level in the urine, nail, and blood was estimated to be 6.29 (95 CI: 2.61�9.97, I-square: 62.7, P: 0.006), 3.54 (95 CI: 2.81�4.28, I-square: 0.0, P: 0.968), 11.20 (95 CI: 2.28�20.13, I-square: 59.9, P: 0.082), respectively. The mean mercury level (MML) in the biological samples of IDs was higher than the standard of World Health Organization (WHO). So, in accordance with Article 10 of the European Union Regulations (EUR), in the context of the Minamata Convention (MC) on Dental Amalgam (DA), in order to avoid the dangers of mercury exposure in dentists, it is necessary for Iran and other countries to approve laws and to implement a national plan to reduce mercury levels and replace the appropriate materials. © 2020, Springer Nature Switzerland AG

Catalytic potential of CuFe2O4/GO for activation of peroxymonosulfate in metronidazole degradation: study of mechanisms

Application of magnetite nanoparticles (CuFe2O4/GO) were anchored on graphene oxide (GO), as a Heterogeneous nanocomposite for activating of peroxymonosulfate (PMS) into Metronidazole (MNZ) destruction. The effect of solution pH, reaction time, effectiveness of water matrix components and trapping factors, different catalyst concentrations, PMS and contaminants were evaluated as operating factors on the efficiency of MNZ degradation. Also, mineralization, stability, reactivity and Recycling tests of the catalyst, and the degradation kinetics were performed. MNZ degradation and mineralization were obtained under optimal conditions (0.2 g/L catalyst, pH = 5, 30 mg/L MNZ and 2 mM PMS), 100 and 41.02, respectively over 120 min. Leaching of Fe and Cu was found <0.2 mg/L for CuFe2O4/GO showed a high stability of catalyst, and a significant recyclability was achieved CuFe2O4/GO within 5 times consecutive use. MNZ degradation affected by anions was reduced as follows: HCO3� > NO3� > Cl� > SO42�. The experimental data were very good agreement with pseudo-first-order kinetic model, and during quenching tests SO4�- radicals played a dominant role in the degradation process of MNZ. As a result, the CuFe2O4/GO/PMS system can be described as a promising activation of PMS in MNZ degradation, due to its high stability, reusability and good catalyst reactivity, and the production of reactive species simultaneously. © 2020, Springer Nature Switzerland AG

Characterization, possible sources and health risk assessment of PM2.5-bound Heavy Metals in the most industrial city of Iran

Air pollution associated with particulate matters results in different types of disease including allergy, lung destruction, heart failure, and related problems. This study has been designed and performed to examine the concentration of PM2.5-bound heavy metals, risk assessment, possible sources and effect of meteorological parameters on 17 sites of the air of the most industrial city of Iran (Karaj) in 2018-19. For this purpose, four samples were taken from every point of Karaj air over one year using a pump (Leland Legacy (SKC)) with flow rate of 3 L/min on PTFE filter for 24 h. Overall, 68 samples of PM2.5-bound heavy metals were collected. Note that during the sampling, atmospheric parameters including temperature, pressure, humidity, and wind speed were regularly recorded using PHB318 portable device. In examining the chemical composition of these particles, the concentration of metals (Al-Zn- Ar-Cd-Cr-Cu-Fe-Hg-Mn-Ni-Pb) was determined after digestion of the collected samples and through injection into ICP-OEC device. The results indicated that the mean annual concentration of PM2.5 particles range from 21.84 to 72.75 µg/m3. The mean concentration of heavy metals lied within the range of 25.63 to 336.27 ng/m3. Among heavy metals, the maximum concentration belonged to aluminum (277.95 ng/m3) and iron (336.27 ng/m3), which are known as elements with a ground source (sources such as car fuels, exhaust gases, decorative materials, batteries, indoor smoking, the paint used for painting walls, erosion and corrosion of rubber of cars). Meanwhile, there was a positive relationship between heavy metals and temperature(r: 0.418, p < 0.019), pressure (r: 0.184, p < 0.0.402), as well as wind speed (r: 0.38, p < 0.017), while an inverse relationship was observed with relative humidity (r: -0.219, p < 0.018). The ecological risk of the metals calculated was very notable, with the maximum environmental risk being related to cadmium in children (6.61) and manganese in adults (0.82). The largest HQ in children and adults was associated with Cr. Finally, ILCR values for cadmium in both children (1.19 E-04) and adult (4.81 E-04) groups indicated high risk of developing cancer in humans

Enhanced electro kinetic- pseudo-Fenton degradation of pyrene-contaminated soil using Fe 3 O 4 magnetic nanoparticles: A data set

The aim of the data were to increase the treatment efficiency of pyrene from soil using Nano catalysts magnetite iron oxide (Fe 3 O 4 )and combined with electro kinetic. Soil provided with 100 mg/kg concentration and removal of pyrene done with EK-Fenton process. Nano catalyst was synthesized via a facile co-precipitation method and characterized by FTIR, XRD, SEM, EDX, VSM techniques. The effects of some operational parameters include catalyst dosage, pH, hydrogen peroxide concentration and the voltage were studied on the removal efficiency of pyrene. Results indicated the removal efficiency was obtained 87 under optimal conditions (pH = 3, Nano catalyst dosage= 1 g/l, H 2 O 2 =10 mM and voltage 30 V). Electrokinetic Fenton process can be as efficient and effective method for the removal of pyrene from contaminated soil using Nano Catalyst Fe 3 O 4 introduced in optimal conditions. © 201

Municipal solid waste management during COVID-19 pandemic: a comparison between the current activities and guidelines

The COVID-19 pandemic has affected everyone�s lifestyle and this has resulted in a change in the quantity and composition of municipal solid wastes. Moreover, the post-pandemic waste management is very important as a bad management may lead to the more spread of the disease. The objective of this study was to evaluate the application of guidelines presented for the era of the COVID-19 pandemic in proper solid waste management. To this end, the data were collected by using interviews and field researches and then the obtained data were compared with the international guidelines presented by international organizations. By investigating the municipal waste management during this pandemic and its changes compared to pre-COVID-19, coordination of the plans with the guidelines was investigated. The activities of storage, collection, transportation, recycling, final landfill, as well as the observation of the health instructions by staff and informal sections were assessed in the current research. Although the results showed that the situation was satisfactory in the sections like health and safety of waste management operators due to the existence of protocols and general educations, the waste management plans have not been changed much from before the epidemic of the Coronavirus. The absence of a national policy and plan for waste management in the era of a pandemic and ignoring the guidelines developed by other countries and organizations were observable. Therefore, the codification of new policies for municipal waste management during an epidemic is necessary. © 2021, Springer Nature Switzerland AG

Concentrations, spatial distribution, and human health risk assessment of asbestos fibers in ambient air of Tehran, Iran

The aim of current research was to determine airborne asbestos fiber concentrations in the ambient air of Tehran, and to investigate their spatial distribution, seasonal variation, and human health risk assessment. For this, the sampling of the study was carried out during August 2017 and June 2018, and totally, 64 samples were taken from 8 stations along the different areas of Tehran. The concentrations of airborne asbestos fibers were determined by phase contrast microscope (PCM) and scanning electron microscopy (SEM) analyses. Spatial mapping was conducted using the inverse distance weighting (IDW) technique. The health risk assessment was done based on the detected levels of airborne asbestosis fibers. The mean concentrations of the airborne asbestos fiber were 1.9 × 10−3 f/ml and 595 × 10−3 f/ml based on PCM and SEM analyses, respectively. One of the effective factors on ambient level of asbestos fibers is meteorological parameters, where the maximum and minimum concentrations of asbestos fibers are related to cold and warm seasons, respectively. These differences could be due to the presence of inversions phenomenon in cold seasons in Tehran. It was observed that the excess lifetime cancer risk (ELCR) calculated for all the sampling areas are between 5.26 × 10−5 and 5.37 × 10−4. Based on the EPA-suggested standards (10−4–10−6), these values are categorized rather to moderate levels. The obtained data indicated no threat of asbestos fibers to Tehran’s citizens’ health

Study of littered wastes in different urban land-uses: An 6 environmental status assessment

Littered waste is a severe environmental problem. Although there have been many studies on wastes littered in the environments like beaches and seas, there is insufficient information on littered wastes in the urban settings. In this research, employing visual survey by the field litter counts method, littered wastes in six urban land uses in Qazvin, Iran were studied. The results showed that administrative and recreational land uses, by an average of 5.22 and 9.59 items per 100 m, respectively, had the lowest pollution, while low-density commercial land use had the maximum pollution by 185.96 items per 100 m. Urban littered waste ratios were not the same in various land uses: cigarette waste and paper and cardboard accounted for higher than 80 of the whole littered wastes in most studied land uses. The cigarette butt was also the most frequently litter in the city. In terms of environmental status, administrative and recreational areas can be defined as places with good conditions, while low-density commercial land use had bad conditions. Consequently, urban land use was acknowledged as a significant factor in the density of littered waste. More attention to cleaning the commercial land use to reduce the density of littered waste, and also finding methods to decrease littering waste by citizens, is a need in urban environment. © 2020, Springer Nature Switzerland AG