RESUMEN
The land application of sewage sludge can cause different environmental problems due to the high content of potentially toxic elements (PTEs). The objective of this study was to compare the effect of urban biological sewage sludge (i.e. the waste of activated sludge process) and its derived biochar as the soil amendments on the bioavailability of PTEs and their bioaccumulation by corn (Zea mays L.) under two months of greenhouse conditions. The soil was treated by adding biochar samples at 0 (control), 1, 3, 5% w/w. The diethylenetriamine pentaacetic acid (DTPA)-extractable concentrations of PTEs including Zn, Pb, Cd, Cr, Ni, Fe, and Cu in soil and their accumulation by plant shoot and root were measured. Conversion of the biological sewage sludge into the biochar led to decrease the PTEs bioavailability and consequently decreased their contents in plant tissues. The DTPA extractable metal concentrations of produced biochar in comparison to the biological sewage sludge reduced 75% (Cd), 65% (Cr), 79% (Ni and Pb), 76% (Zn), 91% (Cu) and 88% (Fe). Therefore, the content of Ni, Fe, Zn and Cd in corn shoot was decreased 61, 32, 18 and 17% respectively in application of 5% biochar than of raw sewage sludge. Furthermore, the application of 5% biochar enhanced the physiological parameters of the plants including shoot dry weight (twice) and wet weight (2.25 times), stem diameter (1.70 times), chlorophyll content (1.03 times) in comparison to using 5% raw sewage sludge. The results of the study highlight that application of the biochar derived from urban biological sewage sludge in soil could decrease the risk of PTEs to the plant.
Asunto(s)
Carbón Orgánico , Metales Pesados , Contaminantes del Suelo , Metales Pesados/análisis , Aguas del Alcantarillado , Zea mays , Cadmio , Plomo , Suelo , Contaminantes del Suelo/análisis , Ácido PentéticoRESUMEN
The efficiency of a novel synthetic zeolite (Ze) prepared from stone cutting sludge and a natural zeolite (clinoptilolite, Cp) as the support of TiO2 photocatalyst was examined for the CO2 removal under solar irradiation using a designed parabolic trough collector (PTC). The used samples were characterized using XRF, BET, SEM/EDS, and XPS analyses. The enhanced sunlight irradiation obtained by PTC increased the performance of CO2 photocatalytic removal. The maximum CO2 adsorption by TiO2-Ze and TiO2-Cp composites was 21.1% and 28.4% which increased to 61.8% and 78.9% under sunlight irradiation, respectively. The efficiency of zeolite-TiO2 composites for CO2 removal was approximately two times higher than zeolites and TiO2 alone. The performance of TiO2-Ze-coated composite with lower use of photocatalyst for CO2 adsorption and photocatalytic removal was better than that of powder one. Regeneration of TiO2-Ze using NaOH solution improved its removal efficiency. The adsorption behavior of CO2 on TiO2-Ze composite was well described by the Langmuir isotherm and the pseudo-first-order kinetic model. This work promises CO2 reduction using natural and synthetic zeolite as an efficient photocatalyst support under solar irradiation.
Asunto(s)
Luz Solar , Zeolitas , Dióxido de Carbono , Polvos , Catálisis , Titanio/efectos de la radiaciónRESUMEN
The aim of this study was to identify potentially toxic elements (PTEs) associated with airborne particulate matters (PMs) and their source identification and environmental risk in Isfahan Province, central Iran. Dust samples were collected from various locations included three urban and four rural locations. Results revealed the eastern part of the region as the main source of dust and showed that the highest monthly atmospheric dust deposition was in July (5.53 g m-2). The mean concentrations of Zn, Pb, Cu and Cd were respectively 279, 63, 49 and 0.5 mg kg-1 in dust samples, whereas Cd showed the highest ecological risk index. Dust samples of urban areas showed considerable and very high levels of pollution indices for Pb and Zn, respectively. Among the metals, Zn showed the highest enrichment factor (>5), mainly due to anthropogenic sources. The comprehensive ecological risk index of PTEs revealed the moderate and considerable risk of Isfahan and Najafabad cities, respectively.
Asunto(s)
Polvo , Metales Pesados , Cadmio , China , Ciudades , Polvo/análisis , Monitoreo del Ambiente/métodos , Irán , Plomo , Metales Pesados/análisis , Medición de RiesgoRESUMEN
Particulate matters (PMs) and their associated chemical compounds such as polycyclic aromatic hydrocarbons (PAHs) are important factors to evaluate air pollution and its health impacts particularly in developing countries. Source identification of these compounds can be used for air quality management. The aim of this study was to identify the sources of PM2.5-bound PAHs in Isfahan city, a metropolitan and industrialized area in central Iran. The PM2.5 samples were collected at 50 sites during 1 year. Source identification and apportionment of particle-bound PAHs were carried out using diagnostic ratios (DRs) of PAHs and positive matrix factorization (PMF) model. The results showed that the concentrations of PM2.5 ranged from 8 to 291 µg/m3 with an average of 60.2 ± 53.9 µg/m3, whereas the sum of concentrations of the 19 PAH compounds (Æ©PAHs) ranged from 0.3 to 61.4 ng/m3 with an average of 4.65 ± 8.54 ng/m3. The PAH compounds showed their highest and lowest concentrations occurred in cold and warm seasons, respectively. The mean concentration of benzo[a]pyrene (1.357 ng m-3) in December-January, when inversion occured, was higher than the Iranian national standard value showing the risk of exposure to PM2.5-bound PAHs. Applying DRs suggested that the sources of the PAHs were mainly from fuel combustion. The main sources identified by the PMF model were gasoline combustion (23.8 to 33.1%) followed by diesel combustion (20.6 to 24.8%), natural gas combustion (9.5 to 28.4%), evaporative-uncombusted (9.5 to 23.0%), industrial activities (8.4 to 13.5%), and unknown sources (2.8 to 15.7%). It is concluded that transportation, industrial activities, and combustion of natural gas (both in residential-commercial and industrial sectors) as the main sources of PAHs in PM2.5 should be managed in the metropolitan area, particularly in cold seasons.
Asunto(s)
Contaminantes Atmosféricos , Hidrocarburos Policíclicos Aromáticos , Contaminantes Atmosféricos/análisis , China , Monitoreo del Ambiente/métodos , Irán , Gas Natural , Material Particulado/análisis , Hidrocarburos Policíclicos Aromáticos/análisis , Medición de Riesgo , Estaciones del AñoRESUMEN
Effects of Elm tree sawdust pretreatments using alkali and alkaline earth metals (NaCl, KCl, CaCl2, MgCl2 and Elm tree ash) and deashing solutions (water, HCl, HNO3 and aqua regia) before the carbonization process on the porosity of produced activated carbons and Pb (II) and Cr (VI) adsorption were studied. The activated carbons were characterized by pore size distribution, surface area, FTIR, and SEM-EDX analysies. Based on the results, HCl leaching pretreatment of the biomass increased the activated carbon adsorption capacity of Cr (VI) from 114 to 190 mg g-1. The treatment of biomass with alkali and alkali earth metal salts, especially MgCl2, remarkably increased the activated carbon adsorption capacity of Pb (II) from 233 to 1430 mg g-1. The results indicated that Pb (II) adsorption was attributed to both the mesoporous structure of activated carbon and the abundance of Mg on the activated carbon's surface. On the other hand, the micropores played a major role in Cr (VI) adsorption capacity. The development of the micro- or mesoporous structure of activated carbons through pretreatment of lignocellulosic precursor could be an approach for providing high performance activated carbons for Pb (II) and Cr (VI) removal from aqueous solutions.
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Carbón Orgánico/química , Carbón Orgánico/síntesis química , Cromo/química , Plomo/química , Lignina/química , Contaminantes Químicos del Agua/química , Agua/química , Adsorción , Biomasa , Ácido Clorhídrico/química , Concentración de Iones de Hidrógeno , Cinética , Cloruro de Magnesio/química , Modelos Químicos , Porosidad , Soluciones , Ulmus/química , Purificación del Agua/métodosRESUMEN
Pharmaceutical compounds are considered as emerging contaminants in the aquatic environments that are not easily eliminated by conventional treatment processes. In the present study, the photocatalytic oxidation of acetaminophen and codeine medicines under UV and solar irradiation was investigated in the aqueous solutions using a novel synthesized zeolite from stone cutting sludge as a support for TiO2 and ZnO. The effect of photocatalyst synthesis conditions including catalyst dose, mixing time, calcination time, and temperature on the efficiency of the pharmaceutical removal were optimized using Taguchi process optimization method. The prepared photocatalysts were characterized using X-ray diffractometer, field emission scanning electron microscopy, energy-dispersive X-ray, the BET surface area, and the Fourier transformation infrared. The results indicated that the performance of ZnO-zeolite for the removal of acetaminophen-codeine under UV and solar radiation with 58.7% and 45.7% was better than that of TiO2-zeolite with 44.3% and 39.2% efficiency, respectively. Removal efficiency under UV and solar radiation was comparable, suggesting that sunlight could be a promising source for treatment of contaminated water by acetaminophen and codeine using photocatalytic degradation. Regeneration of the prepared photocatalysts after 4 cycles revealed a slight decrease in their efficiency. Overall, photocatalytic degradation of the medicines in the water and wastewater using the ZnO-zeolite and TiO2-zeolite could be developed as an efficient treatment process.
Asunto(s)
Zeolitas , Óxido de Zinc , Acetaminofén , Catálisis , Codeína , Luz Solar , TitanioRESUMEN
In this study, surface sediments along the Zayandehrud River (14 samples), and two dated core sediments (46 samples) from small artificial urban lakes at the middle section of the Zayandehrud River in the Gavkhooni basin in the central arid regions of Iran were analyzed for residual levels of 20 organochlorine pesticide (OCP) compounds. Total OCP concentrations ranged from 0.1 to 50.1 ng g-1 dry weight and from 1.9 to 51.5 ng g-1 dry weight in surface and core sediments, respectively. Dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) were found to be the predominant OCPs in these sediments. The calculated metabolic and isomeric ratios confirmed the aged nature of residual dichlorodiphenyltrichloroethane (DDT) in sediments. Moreover, the isomeric ratios indicated the aged nature of technical HCH (hexachlorocyclohexane), while the contribution of γ- HCH (lindane) as a main source has increased, especially in the last two decades. Past usage, as well as current usage of endosulfan technical mixture in the Gavkhooni basin, has been found in the last four decades. Analyses of sedimentary cores, as natural archives, have shown the successful ban on the use of organochlorine pesticides (especially DDT) in the Gavkhooni basin, and to some extent, in the central plateau of Iran. In general, it can be concluded that natural factors (i.e., floods and wet years) lead to soil leachate and play an essential role in remobilization and transfer of residual OCPs from soil to inland aquatic ecosystems in the Gavkhooni basin, which is an arid region.
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Monitoreo del Ambiente , Hidrocarburos Clorados/análisis , Plaguicidas/análisis , Contaminantes Químicos del Agua/análisis , China , DDT/análisis , Diclorodifenil Dicloroetileno/análisis , Ecosistema , Endosulfano/análisis , Sedimentos Geológicos/análisis , Hexaclorociclohexano , Irán , Lagos/análisis , Ríos , SueloRESUMEN
Preparation and characterization of activated carbons (ACs) from oily sludge by physical and chemical activation using steam, ZnCl2 and FeCl3 were investigated. The characteristics of produced adsorbents were determined by iodine number, Brunauer-Emmett-Teller (BET) equation, Fourier transform infrared spectrometry and scanning electron microscopy analyses. Batch adsorption experiments for phenol and phosphate were performed to evaluate the efficiency of adsorbents. The optimum porous structure of adsorbents with a BET surface area of 1,259 m2 g-1, total pore volume of 1.22 cm3 g-1 and iodine number of 994 mg g-1 was achieved by ZnCl2 activation at 500 °C and impregnation ratio of 1:1. The adsorption data were well fitted to the pseudo-second-order kinetic model (R2>0.99) and Freundlich isotherm (R2>0.99). The maximum adsorption capacity of phenol (238 mg g-1) and phosphate (102 mg g-1) based on the Langmuir model was achieved at pH of 6.0 and adsorbent dose of 1 g L-1. Thermodynamic parameters were negative and showed that adsorption of phenol and phosphate onto the AC was feasible, spontaneous and exothermic. The results suggested that prepared AC was an effective adsorbent for removal of phenol and phosphate ions from the polluted water.
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Carbón Orgánico , Fenol/análisis , Fosfatos/análisis , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Cinética , Aguas del Alcantarillado , SolucionesRESUMEN
Air pollution due to emission of various hazardous gases such as SO2 into the atmosphere and its control is an important environmental issue. Application of photocatalysts is considered as a suitable process to control the gaseous pollutants. In this study, the efficiency of clinoptilolite as a natural zeolite (Ze) modified by TiO2 (Ze-Ti) and a polymeric surfactant polyoxypropylene (Ze-Ti-POP) for removal of SO2 was investigated. The nanocomposites were characterized by SEM, EDX, and BET analyses. The photocatalytic oxidation experiments of SO2 by the nanocomposites and natural zeolite were done under UV irradiation with initial SO2 concentration of 500 ppm in a photoreactor. The effects of different factors including reaction time, catalyst dose, UV irradiation intensity, humidity content, and calcination temperature and dose of TiO2 were studied. The modification of clinoptilolite by TiO2 and POP increased considerably the BET specific surface area of the nanocomposites. The results showed that maximum removal efficiencies of SO2 by Ze-Ti and Ze-Ti-POP under the optimum experimental conditions were 82.1 and 87.4%, respectively. Adsorption kinetics data well fitted with the Langmuir-Hinshelwood model. Moreover, reusing of nanocomposites after three regeneration cycles indicated that application of Ze-Ti and Ze-Ti-POP nanocomposites could be a promising approach for SO2 removal. Graphical abstract á .
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Contaminantes Atmosféricos/química , Polímeros/química , Glicoles de Propileno/química , Dióxido de Azufre/química , Tensoactivos/química , Titanio/química , Contaminantes Atmosféricos/análisis , Catálisis , Gases , Humedad , Nanocompuestos/efectos de la radiación , Oxidación-Reducción , Procesos Fotoquímicos , Dióxido de Azufre/análisis , Temperatura , Titanio/efectos de la radiación , Rayos Ultravioleta , ZeolitasRESUMEN
The Fenton process is a useful and inexpensive type of advanced oxidation process for industrial wastewater treatment. This study was performed with the aim of using the steel slag as a catalyst in the heterogeneous Fenton process in order to reduce the chemical oxygen demand (COD) of oil refinery wastewater. The effects of various parameters including the reaction time (0.5, 1.0, 2.0, 3.0 and 4.0 h), pH (2.0, 3.0, 4.0, 5.0, 6.0 and 7.0), the concentration of steel slag (12.5, 25.0 and 37.5 g/L), and H2O2 concentration (100, 250, 400 and 500 mg/L) on the Fenton process were investigated. Furthermore, the effect of microwave irradiation on the process efficiency was studied by considering the optimum conditions of the mentioned parameters. The results showed that using 25.0 g/L of steel slag and 250 mg/L H2O2, at pH = 3.0, could reduce COD by up to 64% after 2.0 h. Also, microwave irradiation decreased the time of the process from 120 min to 25 min in the optimum conditions, but it consumed a high amount of energy. It could be concluded that steel slags had a high potential in the treatment of oil refinery wastewater through the Fenton process.
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Peróxido de Hidrógeno , Residuos Industriales/análisis , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química , Contaminantes Químicos del Agua/química , Análisis de la Demanda Biológica de Oxígeno , Hierro , Microondas , Industria del Petróleo y Gas , Oxidación-Reducción , AceroRESUMEN
Efficiency of a biosorbent prepared from the green macroalga Enteromorpha intestinalis biomass for decontamination of seawater and freshwater polluted by crude oil and engine spent oil was compared. The effect of different experimental conditions including contact time, pH, particle size, initial oil concentration, and biosorbent dose on the oil biosorption was studied in the batch method. The biosorbent was characterized by CHNOS, FTIR, and SEM analysis. The experimental data were well fitted to the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. Based on the obtained results, the adsorption of spent oil with higher viscosity was better than crude oil. The biosorption of oil hydrocarbons from seawater was more efficient than freshwater. The algal biomasses which are abundantly available could be effectively used as a low-cost and environmentally friendly adsorbent for remediation of oil spill in the marine environments or in the water and wastewater treatment.
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Agua Dulce/química , Contaminación por Petróleo/análisis , Petróleo/análisis , Agua de Mar/química , Ulva/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Biomasa , Concentración de Iones de Hidrógeno , Cinética , Tamaño de la Partícula , Termodinámica , Contaminantes Químicos del Agua/químicaRESUMEN
The raw rice husk (RRH) was used as a low cost adsorbent to remove three oil compounds with different viscosities (crude oil, engine oil and spent engine oil) from an aqueous environment. Some of the sorbent specifications were characterized using a CHNSO analyzer, Fourier transform infrared, scanning electron microscope and inductively coupled plasma spectroscopy. With decreasing RRH particles size, the oil adsorption percentage was reduced for crude, spent and engine oils from 50 to 30%, 65 to 20% and 70 to 0.01%, respectively. This was probably due to damage of the microcavities. The removal percentage by sorbent at optimized conditions was 88, 80 and 55% for engine, spent and crude oils, respectively, corresponding to their descending viscosity. The adsorption of crude and spent oils on rice husk followed the Freundlich isotherm model, while the adsorption of engine oil was fitted by the Langmuir model. The maximum adsorption capacity (qmax), calculated from the Langmuir model for the adsorption of engine oil on RRH, was 1,250 mg/g.
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Oryza , Contaminación por Petróleo/prevención & control , Petróleo , Adsorción , Tamaño de la Partícula , TermodinámicaRESUMEN
BACKGROUND: Reaching a better understanding of the modifiable factors associated with inflammatory and oxidative biomarkers in children would be relevant to the design of further investigation and prevention strategies. OBJECTIVE: To determine the association of air pollution as well as dietary and physical activity habits with markers of inflammation, oxidative stress and insulin resistance for the first time in a population-based sample of children. METHODS: We conducted a population-based study of 374 children, aged 10-18 years, and assessed the exposure of participants to air pollutants as well as their dietary and physical activity habits. In addition to anthropometric and blood pressure measurements, we determined the fasting serum levels of lipid profile, insulin and markers of inflammation and oxidation. RESULTS: We found independent associations between improper air quality and plasma markers of inflammation, oxidative stress and insulin resistance. The Pollutant Standard Index (PSI) and the level of fine particulate matter were significantly associated to all biomarkers studied. The associations between different markers of air pollutants and markers of inflammation, oxidative stress and insulin resistance remained significant after adjustment for age, gender, body mass index, waist circumference, healthy eating index and physical activity level. The association of healthy eating score with CRP and insulin resistance was mediated through anthropometric indices, and physical activity had independent association with insulin resistance. CONCLUSION: The independent influence of inflammatory/oxidative mechanisms of air pollution effects on surrogate markers of atherosclerosis from early life should be highlighted.