One-Pot synthesis, characterization and adsorption studies of amine-functionalized magnetite nanoparticles for removal of Cr (VI) and Ni (II) ions from aqueous solution: Kinetic, isotherm and thermodynamic studies

Background: Discharge of heavy metals such as hexavalent chromium (Cr (VI)) and nickel (Ni (II)) into aquatic ecosystems is a matter of concern in wastewater treatment due to their harmful effects on humans. In this paper, removal of Cr (VI) and Ni (II) ions from aqueous solution was investigated using an amino-functionalized magnetic Nano-adsorbent (Fe3O4-NH2). Methods: An amino-functionalized magnetic Nano-adsorbent (Fe3O4-NH2) was synthesized by compositing Fe3O4 with 1, 6-hexanediamine for removal of Cr (VI) and Ni (II) ions from aqueous solution. The adsorbent was characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), powder X-Ray Diffraction (XRD), and Vibrating Sample Magnetometry (VSM). Also, the effects of various operational parameters were studied. Results: According to our finding, Fe3O4-NH2 could be simply separated from aqueous solution with an external magnetic field at 30 s. The experimental data for the adsorption of Cr (VI) and Ni (II) ions revealed that the process followed the Langmuir isotherm and the maximum adsorption capacity was 232.51 mg g-1 for Cr (VI) at pH = 3 and 222.12 mg g-1 and for Ni(II) at pH = 6 at 298 °K. Besides, the kinetic data indicated that the results fitted with the pseudo-second-order model (R2: 0.9871 and 0.9947 for Cr (VI) and Ni (II), respectively. The results of thermodynamic study indicated that: standard free energy changes (�G�), standard enthalpy change (�H�), and standard entropy change (�S�) were respectively -3.28, 137.1, and 26.91 kJ mol-1 for Cr (VI) and -6.8433, 116.7, and 31.02 kJ mol-1 for Ni (II). The adsorption/desorption cycles of Fe3O4-NH2 indicated that it could be used for five times. Conclusions: The selected metals' sorption was achieved mainly via electrostatic attraction and coordination interactions. In fact, Fe3O4-NH2 could be removed more than 96 for both Cr (VI) and Ni (II) ions from aqueous solution and actual wastewater. © 2016 The Author(s)

Economic aspects of dry solid waste recycling in Shiraz, Iran

Background and purpose: Nowadays, in developed countries, the economic profits of recycling and its role in waste reduction and disposal costs is well recognized. In this study, the economic aspects of dry solid waste recycling were evaluated in Shiraz, Iran. Materials and methods: A descriptive cross-sectional study was conducted in Shiraz in which data was collected through field observations, interviews with officials of municipal utilities and investigating the documents in the organization. Then, the economic benefits of different recycling rates including 15 (current), 50 and 80 were evaluated. Results: The recycling rate of waste paper, cardboard, glass, nylon and plastic carrier bags, disposable plastic containers, PET, other types of plastic, disposable metallic containers, and other types of metals were 23, 12, 8, 2.5, 8, 13, 13, 11, and 12, respectively. The total economic benefits of recycling in terms of current recycling (15), desirable recycling (50) and ideal recycling (80) rates were calculated as 11527, 39869, and 63791 million Rials per year, respectively. Conclusion: Only 15 of dry solid waste is recycled in Shiraz. The economic benefits from recycling could increase to 8-18 times of the current benefit with a 10 to 20 year proper planning and upgrading the current recycling program. © 2016, AMazandaran University of Medical Sciences. All rights reserved

Multi-walled carbon nanotubes modified with iron oxide and silver nanoparticles (MWCNT-Fe<inf>3</inf>O<inf>4</inf>/Ag) as a novel adsorbent for determining PAEs in carbonated soft drinks using magnetic SPE-GC/MS method

The synthesis of compounds with an excellent adsorption capability plays an essential role to remove contaminants such as phthalic acid esters (PAEs) with potential carcinogenic characteristics from different food products. In this context, for the first time, a novel adsorbent (MWCNT-Fe3O4/Ag) was synthesized by using iron (magnetic agent), and silver (catalytic and surface enhancer agent) to further approach in a magnetic SPE-GC/MS method for determining of PAEs in carbonated soft drink samples. The limit of detection (LOD) and limit of quantification (LOQ) values of MSPE-GC/MS were determined in six PAEs as a range of 10.8–22.5 and 36–75 ng/L, respectively. Also, the calibration curves of PAEs were linear (R2 = 0.9981–0.9995) over the concentration level of 10.000 ng/L and the recoveries of the six PAEs were ranging from 96.60% to 109.22% with the RSDs less than 8%. Moreover, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and transmission electron microscopy analyses (TEM) were utilized to characterize the produced MWCNT-Fe3O4/Ag. Based on the findings, the surface of MWCNT is relatively uniform, which became coarser after loading with Fe3O4/Ag particles. Also, EDX spectrum showed the carbon (C), iron (Fe), oxygen (O), Ag and copper (Cu) are the main components of synthesized MWCNTs-Fe3O4/Ag. The successful adhesion of Fe3O4/Ag on the texture of MWCNTs using a co-precipitation method was confirmed by XRD and FT-IR assays. Additionally, excellent crystallinity and clear lattice nanocrystals fringes of prepared MWCNT-Fe3O4/Ag was demonstrated by TEM analysis. Based on the obtained VSM images, the prepared sorbent (MWCNT-Fe3O4/Ag) has the good magnetic performance for magnetic separation and extraction processes. It was concluded that the synthesized MWCNT-Fe3O4/Ag could be used as an efficient adsorbent for determining contaminants such as PAEs in different beverage samples. © 201

On the nature and health impacts of BTEX in a populated middle eastern city: Tehran, Iran

This study describes a spatio-temporal characterization of concentrations of BTEX in ambient air of four hot spots (bus terminals) in the megacity of Tehran. Monte Carlo simulations were performed to evaluate cancer risk and non-cancer risk owing to BTEX exposure in three age groups (&lt;6, 6 to &lt;21 and 21 to &lt;81 years). The average toluene to benzene ratios for the four intercity bus terminals were 2.63 (summer) and 2.88 (winter). Furthermore, the mean xylenes to benzene and ethylbenzene to benzene ratios in the two seasons for all stations ranged from 3.33 to 4.40 (summer) and 2.13�2.80 (winter), respectively. There was insignificant difference in BTEX levels between working and non-working days owing to the lack of change in vehicular traffic during the full week. Factors promoting BTEX formation in the study region were fuel evaporation, gas stations, diesel bus emissions, and a lack of hydroxyl radicals (radOH) for reacting with the target compounds. Calculations suggested that cancer risk for benzene and ethylbenzene in three age groups at the four bus terminals exceeded values recommended by U. S. EPA. In addition, the hazard quotient for BTEX in both seasons for different age groups ranged between 1.23 � 10 �5 and 3.58 � 10 �1 , values of which were lower than reference levels. Carcinogenic emissions such as with benzene and ethylbenzene discharged by bus terminals impact the growing population in the study region, which requires additional action to reduce health effects. © 2019 Turkish National Committee for Air Pollution Research and Contro

Multi-walled carbon nanotubes modified with iron oxide and silver nanoparticles (MWCNT-Fe 3 O 4 /Ag) as a novel adsorbent for determining PAEs in carbonated soft drinks using magnetic SPE-GC/MS method

The synthesis of compounds with an excellent adsorption capability plays an essential role to remove contaminants such as phthalic acid esters (PAEs) with potential carcinogenic characteristics from different food products. In this context, for the first time, a novel adsorbent (MWCNT-Fe 3 O 4 /Ag) was synthesized by using iron (magnetic agent), and silver (catalytic and surface enhancer agent) to further approach in a magnetic SPE-GC/MS method for determining of PAEs in carbonated soft drink samples. The limit of detection (LOD) and limit of quantification (LOQ) values of MSPE-GC/MS were determined in six PAEs as a range of 10.8�22.5 and 36�75 ng/L, respectively. Also, the calibration curves of PAEs were linear (R 2 = 0.9981�0.9995) over the concentration level of 10.000 ng/L and the recoveries of the six PAEs were ranging from 96.60 to 109.22 with the RSDs less than 8. Moreover, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and transmission electron microscopy analyses (TEM) were utilized to characterize the produced MWCNT-Fe 3 O 4 /Ag. Based on the findings, the surface of MWCNT is relatively uniform, which became coarser after loading with Fe 3 O 4 /Ag particles. Also, EDX spectrum showed the carbon (C), iron (Fe), oxygen (O), Ag and copper (Cu) are the main components of synthesized MWCNTs-Fe 3 O 4 /Ag. The successful adhesion of Fe 3 O 4 /Ag on the texture of MWCNTs using a co-precipitation method was confirmed by XRD and FT-IR assays. Additionally, excellent crystallinity and clear lattice nanocrystals fringes of prepared MWCNT-Fe 3 O 4 /Ag was demonstrated by TEM analysis. Based on the obtained VSM images, the prepared sorbent (MWCNT-Fe 3 O 4 /Ag) has the good magnetic performance for magnetic separation and extraction processes. It was concluded that the synthesized MWCNT-Fe 3 O 4 /Ag could be used as an efficient adsorbent for determining contaminants such as PAEs in different beverage samples. © 2018 The Author

Multi-walled carbon nanotubes modified with iron oxide and silver nanoparticles (MWCNT-Fe3O4/Ag) as a novel adsorbent for determining PAEs in carbonated soft drinks using magnetic SPE-GC/MS method

The synthesis of compounds with an excellent adsorption capability plays an essential role to remove contaminants such as phthalic acid esters (PAEs) with potential carcinogenic characteristics from different food products. In this context, for the first time, a novel adsorbent (MWCNT-Fe3O4/Ag) was synthesized by using iron (magnetic agent), and silver (catalytic and surface enhancer agent) to further approach in a magnetic SPE-GC/MS method for determining of PAEs in carbonated soft drink samples. The limit of detection (LOD) and limit of quantification (LOQ) values of MSPE-GC/MS were determined in six PAEs as a range of 10.8�22.5 and 36�75 ng/L, respectively. Also, the calibration curves of PAEs were linear (R2 = 0.9981�0.9995) over the concentration level of 10.000 ng/L and the recoveries of the six PAEs were ranging from 96.60 to 109.22 with the RSDs less than 8. Moreover, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and transmission electron microscopy analyses (TEM) were utilized to characterize the produced MWCNT-Fe3O4/Ag. Based on the findings, the surface of MWCNT is relatively uniform, which became coarser after loading with Fe3O4/Ag particles. Also, EDX spectrum showed the carbon (C), iron (Fe), oxygen (O), Ag and copper (Cu) are the main components of synthesized MWCNTs-Fe3O4/Ag. The successful adhesion of Fe3O4/Ag on the texture of MWCNTs using a co-precipitation method was confirmed by XRD and FT-IR assays. Additionally, excellent crystallinity and clear lattice nanocrystals fringes of prepared MWCNT-Fe3O4/Ag was demonstrated by TEM analysis. Based on the obtained VSM images, the prepared sorbent (MWCNT-Fe3O4/Ag) has the good magnetic performance for magnetic separation and extraction processes. It was concluded that the synthesized MWCNT-Fe3O4/Ag could be used as an efficient adsorbent for determining contaminants such as PAEs in different beverage samples. © 201

BTEX in indoor air of beauty salons: Risk assessment, levels and factors influencing their concentrations

Concentrations of benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated in indoor air quality of 50 beauty salons in Ardabil, Iran (2017). Ten liters of air samples were collected from each salons regarding the recommended method and analyzed by GC-FID for BTEX concentration. Also, structural and operational conditions of the salons were studied with a self-designed questioner. The results of this study show that the mean concentration of benzene (32.40 ± 26.38) higher than the recommended levels by Health Canada, ANSES and HKSAR. Among the BTEX, ethylbenzene (62.38 ± 32.37) has the most concentrations in the salons. Subsequently, the cancer risk values in different age groups of birth to &lt;6, 6 to &lt;21, and 21 to &lt;81 for benzene (1.83 × 10−3, 2.76 × 10−4 and 1.50 × 10−4, respectively) and ethylbenzene (4.9 × 10−4, 7.30 × 10−5 and 3.52 × 10−5, respectively) for long time exposure were drastically higher than the recommended levels. The results showed that the benzene concentration is significantly influenced by the structural and operational conditions of type of ventilation system, area of the salons, the number of people in the salon, number of services in the salons, and while doing of bridal makeup. © 2018 Elsevier Inc

On the nature and health impacts of BTEX in a populated middle eastern city: Tehran, Iran

This study describes a spatio-temporal characterization of concentrations of BTEX in ambient air of four hot spots (bus terminals) in the megacity of Tehran. Monte Carlo simulations were performed to evaluate cancer risk and non-cancer risk owing to BTEX exposure in three age groups (&lt;6, 6 to &lt;21 and 21 to &lt;81 years). The average toluene to benzene ratios for the four intercity bus terminals were 2.63 (summer) and 2.88 (winter). Furthermore, the mean xylenes to benzene and ethylbenzene to benzene ratios in the two seasons for all stations ranged from 3.33 to 4.40 (summer) and 2.13�2.80 (winter), respectively. There was insignificant difference in BTEX levels between working and non-working days owing to the lack of change in vehicular traffic during the full week. Factors promoting BTEX formation in the study region were fuel evaporation, gas stations, diesel bus emissions, and a lack of hydroxyl radicals (radOH) for reacting with the target compounds. Calculations suggested that cancer risk for benzene and ethylbenzene in three age groups at the four bus terminals exceeded values recommended by U. S. EPA. In addition, the hazard quotient for BTEX in both seasons for different age groups ranged between 1.23 � 10 �5 and 3.58 � 10 �1 , values of which were lower than reference levels. Carcinogenic emissions such as with benzene and ethylbenzene discharged by bus terminals impact the growing population in the study region, which requires additional action to reduce health effects. © 2019 Turkish National Committee for Air Pollution Research and Contro

Characteristics of gaseous and particulate air pollutants at four different urban hotspots in Tehran, Iran

This study reports a characterization of outdoor gaseous and particulate pollutants and their associated health effects in four different urban hotspots in Tehran, Iran during winter and summer. Buses, taxis, and cars are prominent sources of toxic pollutants in Tehran. There is a significant level of exposure to emissions from diesel buses in bus terminals, especially with boarding, disembarking, and waiting. Mean concentrations (μg/m3) in summer and winter, respectively, ranged from 10 to 20.67 and 17�21 for PM1, 52.50�79.19 and 58.33�85.33 for PM2.5, 64.50�102 and 78.83�125.83 for PM7, 130.17�204.67 and 157�231.67 for PM10, 261�409.50 and 305.83�458.83 for TSP, and 372.50�418.33 vs. 351.27�373.47 for CO2 (ppm). Particulate concentrations were higher in winter, especially the first three days of the week, assisted in part by the shallower mixing layer height as compared to summer. Mean hazard quotient (HQ) values for both PM2.5 and PM10 in both seasons for bus terminals in three scenarios ranged between 0.81 and 4.96, which exceeded reference levels (1 &lt; HQ). The results of this study have implications for public health, especially in dense traffic areas. © 2021 Elsevier Lt

A case study of BTEX characteristics and health effects by major point sources of pollution during winter in Iran

This is the first such study investigating BTEX in this understudied, yet largely populated, region in the Middle East with attention geared towards spatial and diurnal trends, health effects of BTEX, and amount of BTEX emissions in gas stations versus CNG stations. © 2019 Elsevier Ltd This study characterized spatio-temporal variations in the concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in the vicinity of gas and compressed natural gas (CNG) stations in Tehran, Iran. Health risk assessment (HRA) was computed using Monte Carlo simulations (MCS) for evaluating inhalation lifetime cancer risk (LTCR), the hazard quotient (HQ), and sensitivity analysis (SA) for BTEX exposure in different age groups (birth to &lt;81) and as a function of distance (0�250 m) from the center of the stations. For all monitoring stations, the average values of benzene, toluene, ethylbenzene, and xylene in winter were 466.09 ± 132.25, 873.13 ± 233.51, 493.05 ± 141.22, and 910.57 ± 145.40 μg m �3 , respectively. The mean wintertime ratios of T/B for the 12 stations ranged from 1.69 to 2.04. Furthermore, there was no significant relationship between the concentration of BTEX with either the specific month or distance from the center of stations (p &gt; 0.05). Factors promoting BTEX formation in the study region were fuel evaporation and gas/CNG station emissions. The LTCRs for the target compounds in the winter for different age groups and distances from the center of stations was limited to 2.11 � 10 �4 to 1.82 � 10 �3 and 2.30 � 10 �4 to 2.01 � 10 �3 , respectively, which exceeded proposed values by U.S. EPA. Moreover, the HQs for BTEX for three age groups and distances were limited to between 2.89 � 10 �5 and 9.33 � 10 �2 , which were lower than the acceptable limit (HQs &lt; 1). The results of this work are applicable to similar areas that are heavily populated with vehicular traffic. This study motivates a closer look at mitigation strategies to limit the health effects of carcinogenic emissions such as benzene and ethylbenzene from gas/CNG stations. © 2019 Elsevier Lt