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11.
Sorption-desorption of cadmium in aqueous palygorskite, sepiolite, and calcite suspensions: isotherm hysteresis 总被引:2,自引:0,他引:2
Sorption isotherms have been widely used to assess the heavy metal retention characteristics of soil particles. Desorption behavior of the retained metals, however, usually differ from that of sorption, leading to a lack of coincidence in the experimentally obtained sorption and desorption isotherms. In this study, we examine the nonsingularity of cadmium (Cd) sorption–desorption isotherms, to check the possible hysteresis and reversibility phenomena, in aqueous palygorskite, sepiolite and calcite systems. Sorption of Cd was carried out using a 24-h batch equilibration experiment with eight different Cd solution concentrations, equivalent to 20–100% of maximum sorption capacity of each mineral. Immediately after sorption, desorption took place using successive dilution method with five consecutive desorption steps. Both Cd sorption and desorption data were adequately described by Freundlich equation (0.81 < r2 < 0.99). The sorption and desorption reactions, however, did not provide the same isotherms, indicating that hysteresis occurred in Cd sorption–desorption processes. The extent of hysteresis was quantified based on the differences obtained from sorption and desorption isotherms regarding the amount of Cd sorbed, the Freundlich exponent, and the Cd distribution coefficient. The results revealed that, sepiolite possessed the most hysteretic behavior among the minerals studied. Calcite showed much smaller hysteresis compared to the other two silicate clays at low Cd surface load, but its hysteresis indices significantly increased, and exceeded that of palygorskite, as the amount of Cd in the systems increased. The average amount of Cd released after five desorption steps, was 13.8%, 2.2% and 3.6% for the palygorskite, sepiolite and calcite, respectively, indicating that a large portion of Cd was irreversibly retained by the minerals. 相似文献
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Afsaneh Somy Mohammad Reza Mehrnia Hosein Delavari Amrei Amin Ghanizadeh Mohammadhosein Safari 《International Journal of Greenhouse Gas Control》2009,3(3):249-254
The effect of impregnation of activated carbon with Cr2O and Fe2O3 and promotion by Zn2+ on its adsorptive properties of carbon dioxide was studied using a volumetric adsorption apparatus at ambient temperature and low pressures. Slurry and solution impregnation methods were used to compare CO2 capture capacity of the impregnated activated carbon promoted by Zinc. The obtained adsorption isotherms showed that amount of CO2 adsorbed on the samples impregnated by Cr2O was increased about 20% in compare to raw activated carbon. The results also showed that Fe2O3 was not an effective impregnating species for activated carbon modification. Moreover slurry impregnation method showed higher CO2 adsorption capacity in comparison with solution impregnation method. Samples prepared by co-impregnation of two metal species showed more adsorption capacity than samples impregnated by just one metal species individually. Washing the impregnated samples by metal oxide resulted in 15% increase in CO2 adsorption capacities of activated carbons which can be attributed to the metal oxides removal covering the adsorption surface. Decreasing impregnation temperature from 95 to 25 °C in solution method showed a significant increase in CO2 adsorption capacity. Sips equation was found a suitable model fitting to the adsorption data in the range studied. 相似文献
13.
Soleimani Mozhgan Akbari Nematollah Saffari Babak Haghshenas Hosein 《Environmental science and pollution research international》2021,28(47):66535-66555
Environmental Science and Pollution Research - Since mobile sources are one of the most important sources of air pollution, this paper tries to estimate the health effects and economic burden due... 相似文献
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Air pollution has been associated with an increased incidence of respiratory disease. However, significant differences may exist between air pollution levels measured at conventional fixed monitoring stations and actual levels inhaled by a subject. Furthermore, studies of effects of air pollution might best be done using asthmatics as study subjects, since they have irritable airways. This is a preliminary report of a study using a control and asthmatic group in which effects of air pollution are assessed by sympton and medication diaries and simple pulmonary function tests. Air pollution exposure is measured using a small portable sampler for particulates, SO2 and NO2; these samplers are carried by the subject (“personal”) and are situated inside and outside the home. Levels obtained are compared to data obtained from the same type of sampler located at a fixed monitoring station. Preliminary analysis of the data shows that the levels of pollutants are low and there are significant differences between the four air pollution measurements, with weak correlations among the various measurements. In this preliminary report, change in pulmonary function during the day correlates only with personal NO2 measurements. This suggests the need for estimating air pollution exposure using “personal” samplers, when investigating health effects. 相似文献
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Masumeh?Taheri Jalil?MehrzadEmail author Mohamad?Hosein?Mahmudy Gharaie Reza?Afshari Ahmad?Dadsetan Shakiba?Hami 《Environmental geochemistry and health》2016,38(2):469-482
Arsenic bioavailability in rock, soil and water resources is notoriously hazardous. Geogenic arsenic enters the body and adversely affects many biochemical processes in animals and humans, posing risk to public health. Chelpu is located in NE Iran, where realgar, orpiment and pyrite mineralization is the source of arsenic in the macroenvironment. Using cluster random sampling strategy eight rocks, 23 soils, 12 drinking water resources, 36 human urine and hair samples and 15 adult sheep urine and wool samples in several large-scale herds in the area were randomly taken for quantification of arsenic in rock/soil/water, wool/hair/urine. Arsenic levels in rock/soil/water and wool/hair/urine were measured using inductively coupled plasma spectroscopy and atomic absorption spectrophotometry, respectively. While arsenic levels in rocks, soils and water resources hazardously ranged 9.40–25,873.3 mg kg?1, 7.10–1448.80 mg kg?1 and 12–606 μg L?1, respectively, arsenic concentrations in humans’ hair and urine and sheep’s wool and urine varied from 0.37–1.37 μg g?1 and 9–271.4 μg L?1 and 0.3–3.11 μg g?1 and 29.1–1015 μg L?1, respectively. Local sheep and human were widely sick and slightly anemic. Hematological examination of the inhabitants revealed that geogenic arsenic could harm blood cells, potentially resulting in many other hematoimmunological disorders including cancer. The findings warn widespread exposure of animals and human in this agroecologically and geopolitically important region (i.e., its proximity with Afghanistan, Pakistan and Turkmenistan) and give a clue on how arsenic could induce infectious and non-infectious diseases in highly exposed human/animals. 相似文献
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Sonocatalytic degradation of tetracycline antibiotic in aqueous solution by sonocatalysis 总被引:1,自引:0,他引:1
Mohammad Hoseini Gholam Hossein Safari Hossein Kamani Jalil Jaafari Marjan Ghanbarain 《毒物与环境化学》2013,95(10):1680-1689
Tetracycline (TC), one of the most common antibiotics, is often poorly bio-degraded in conventional wastewater treatment plants. In this study, the sonocatalytic degradation of TC was investigated using TiO2 nano-particles as catalyst. The effect of pH, initial TC concentrations, reaction times, and H2O2 concentrations were evaluated. The efficacy of ultrasonic irradiation alone in the removal of this pollutant was negligible but removal efficiency increased upon addition of TiO2 up to 250 mg L?1; increase of pH and initial TC concentration attenuated TC degradation. Addition of H2O2 raised the removal efficiency so that complete removal of TC was achieved within 75 min. 相似文献
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Masoud Yazdanpanah Dariush Hayati Gholam Hosein Zamani Fereshteh Karbalaee Stefan Hochrainer-Stigler 《Environment, Development and Sustainability》2013,15(6):1605-1621
This article reflects on the fundamentals of first and second modernity and its usefulness and practicability for problem formulation and solving in the context of water management practices in Iran. It is argued that the current water crisis in Iran resulted from modernization based on first modernity paradigms, and second modernity concepts are used to present a framework for new water management approaches. Based on the concept of sub-political arrangements, we suggest that water management issues can be treated best in process-based ways under a reflexive modernity point of view. 相似文献
19.
Monireh Sadat Mousavi Khosro Ashrafi Majid Shafie Pour Motlagh Mohhamad Hosein Niksokhan Hamid Reza Vosoughifar 《Environmental Modeling and Assessment》2017,22(5):431-444
Numerical and experimental analyses were applied to carbon monoxide (CO) concentration dispersion to monitor air quality in an enclosed residential complex parking area in Tehran. Firstly, the parking area was preliminary assessed through verifying the characteristics of the problem including the geometry and boundary conditions. Then, proportion of vehicular exhaust emissions was estimated and eventually experimental and numerical analyses were performed. In order to perform numerical calculation, a three-dimensional model was created to numerically simulate the enclosed residential complex parking area by FLUENT software that solves flow governing equations with finite volume method. In FLUENT, species model was selected to assess the dispersion of CO in flow domain. In experimental analysis, CO concentration was measured using sampling bags with a volume of 10 l in 4 min at 6 different points. The sample air was drawn into sampling bags by electric pumps. The findings show that the maximum amount of CO concentration is above the permissible standard recommended by the World Health Organization. Pollutant accumulation was significant in confined areas. In the place where openings exist, the level of accumulation was lower than other areas. The findings obtained from numerical simulation are in complete accord with experimental results. 相似文献