排序方式: 共有110条查询结果,搜索用时 797 毫秒
81.
Sunflower stalk, an agricultural waste, as an adsorbent for the removal of lead and cadmium from aqueous solutions 总被引:2,自引:0,他引:2
Mohsen Jalali Fathemeh Aboulghazi 《Journal of Material Cycles and Waste Management》2013,15(4):548-555
Sunflower residue, an agricultural waste material for the removal of lead (Pb) and cadmium (Cd) from aqueous solutions were investigated using a batch method. Adsorbent was prepared by washing sunflower residue with deionized water until the effluent was colorless. Batch mode experiments were carried out as a function of solution pH, adsorbent dosage, initial concentration and contact time. The results indicated that the adsorbent showed good sorption potential and maximum metal removal was observed at pH 5. Within 150 min of operation about 97 and 87 % of Pb and Cd ions were removed from the solutions, respectively. Lead and Cd sorption curves were well fitted to the modified two-site Langmuir model. The adsorption capacities for Pb and Cd at optimum conditions were 182 and 70 mg g?1, respectively. The kinetics of Pb and Cd adsorption from aqueous solutions were analyzed by fitting the experimental data to a pseudo-second-order kinetic model and the rate constant was found to be 8.42 × 10?2 and 8.95 × 10?2 g mg?1 min?1 for Cd and Pb, respectively. The results revealed that sunflower can adsorb considerable amount of Pb and Cd ions and thus could be an economical method for the removal of Pb and Cd from aqueous systems. 相似文献
82.
Community structure of arbuscular mycorrhizal fungi associated to Veronica rechingeri at the Anguran zinc and lead mining region 总被引:1,自引:0,他引:1
Zarei M König S Hempel S Nekouei MK Savaghebi G Buscot F 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):1277-1283
Root colonization and diversity of arbuscular mycorrhizal fungi (AMF) were analyzed in Veronica rechingeri growing in heavy metal (HM) and non-polluted soils of the Anguran Zn and Pb mining region (Iran). Three species could be separated morphologically, while phylogenetic analyses after PCR amplification of the ITS region followed by RFLP and sequencing revealed seven different AMF sequence types all within the genus Glomus. Rarefaction analysis confirmed exhaustive molecular characterization of the AMF diversity present within root samples. Increasing heavy metal contamination between the sites studied was accompanied by a decrease in AMF spore numbers, mycorrhizal colonization parameters and the number of AMF sequence types colonizing the roots. Some AMF sequence types were only found at sites with the highest and lowest soil HM contents, respectively. 相似文献
83.
Y Kooch SM Hosseini C Zaccone H Jalilvand SM Hojjati 《Journal of environmental monitoring : JEM》2012,14(9):2438-2446
Following the ratification of the Kyoto Protocol, afforestation of formerly arable lands and/or degraded areas has been acknowledged as a land-use change contributing to the mitigation of increasing atmospheric CO(2) concentration in the atmosphere. In the present work, we study the soil organic carbon sequestration (SOCS) in 21 year old stands of maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C.A. Mey.), and red pine (Pinus brutia Ten.) in the Darab Kola region, north of Iran. Soil samples were collected at four different depths (0-10, 10-20, 20-30, and 30-40 cm), and characterized with respect to bulk density, water content, electrical conductivity, pH, texture, lime content, total organic C, total N, and earthworm density and biomass. Data showed that afforested stands significantly affected soil characteristics, also raising SOCS phenomena, with values of 163.3, 120.6, and 102.1 Mg C ha(-1) for red pine, oak and maple stands, respectively, vs. 83.0 Mg C ha(-1) for the control region. Even if the dynamics of organic matter (OM) in soil is very complex and affected by several pedo-climatic factors, a stepwise regression method indicates that SOCS values in the studied area could be predicted using the following parameters, i.e., sand, clay, lime, and total N contents, and C/N ratio. In particular, although the chemical and physical stabilization capacity of organic C by soil is believed to be mainly governed by clay content, regression analysis showed a positive correlation between SOCS and sand (R = 0.86(**)), whereas a negative correlation with clay (R = -0.77(**)) was observed, thus suggesting that most of this organic C occurs as particulate OM instead of mineral-associated OM. Although the proposed models do not take into account possible changes due to natural and anthropogenic processes, they represent a simple way that could be used to evaluate and/or monitor the potential of each forest plantation in immobilizing organic C in soil (thus reducing atmospheric C concentration), as well as to select more appropriate species during forestation plan management at least in the north of Iran. 相似文献
84.
85.
In this research, montmorillonite nanoclay (MNC) and vermiculite were used to adsorb ammonium (NH4 +) from simulated wastewater. The effect of organic acids, cations, and anions on adsorption of NH4 + was also studied using batch experiments. The presence of organic acids significantly decreased the NH4 + adsorption using both adsorbents and the reduction followed the order of citric acid > malic acid > oxalic acid. The presence of cations in wastewater could decrease the adsorption of NH4 + and the ion exchange selectivity on the MNC and vermiculite followed the orders Mg > Ca ≥ K > Na and Mg > > Ca > Na > K, respectively. Adsorption of NH4 + by adsorbents in the presence of sulfate (SO4) was higher than those in the presence of phosphate (PO4) and chloride (Cl) anions. Results indicated that MNC and vermiculite had good potential for NH4 + removal depending on adsorbent dosage, pH, contact time, and initial NH4 + concentration. The effect of pH on removal of NH4 + indicated that MNC would be more appropriate as the adsorbent than vermiculite at low pH values. Kinetic analysis demonstrated that the rate-controlling step adsorption for NH4 + by MNC and vermiculite was heterogeneous chemisorption and followed the pseudo-second-order model. The desorption experiments indicated that the adsorption of NH4 + by adsorbents was not fully reversible, and the total recovery of adsorbed NH4 + for MNC and vermiculite varied in the range of 72 to 94.6% and 11.5 to 45.7%, respectively. Cation exchange model (CEM) in PHREEQC program was used to simulate NH4 + adsorption. Agreement between measured and simulated data suggested that CEM was favored in simulating adsorption of NH4 + by clay minerals. The results indicated that MNC and vermiculite have good performance as economic and nature-friendly adsorbents that can ameliorate the water and environment quality. 相似文献
86.
Mohammad Miri Elham Akbari Abdeltif Amrane Seyed Javad Jafari Hadi Eslami Edris Hoseinzadeh Mansur Zarrabi Javad Salimi Mohsen Sayyad-Arbabi Mahmoud Taghavi 《Environmental monitoring and assessment》2017,189(11):583
The heavy metal (Pb, Cd, Cr, and Ni) content of a fish species consumed by the Sistan population and its associated health risk factors were investigated. The mean concentrations of Pb, Cd, and Cr were slightly higher than the standard levels. The Ni content of fish was below the maximum guideline proposed by the US Food and Drug Administration (USFDA). The average estimated weekly intake was significantly below the provisional tolerable intake based on the FAO and WHO standards for all studied metals. The target hazard quotients (THQ) of all metals were below 1, showing an absence of health hazard for the population of Sistan. The combined target hazard quotient for the considered metals was 26.94 × 10?3. The cancer risk factor for Pb (1.57 × 10?7) was below the acceptable lifetime carcinogenic risk (10?5). The results of this study reveal an almost safe level of Pb, Cd, Cr, and Ni contents in the fish consumed by the Sistan population. 相似文献
87.
Phosphorus (P) leaching from a sandy soil was investigated in the presence of modified and unmodified clay minerals and nanoparticles (NPs). Compared with control soil, amended soil with NPs had the highest percentage of P retention than amended soil with clay minerals. Among the adsorbents used, the highest percentage of P retention was produced by Al2O3-chitosan while the lowest percentage of P retention was by zeolite. Data measured for P leaching after using adsorbents were used to predict P leaching using transport model. PHREEQC model was able to model P leaching from control and amended soil. After leaching, P values in control and amended soil were fractionated by a sequential extraction procedure. Concentration of P in Ca-bound fraction (HCl–P) after application of modified and unmodified clay minerals and NPs (except TiO2 and Al2O3) increased and decreased, respectively. Saturation indices (SIs) and P speciation were assessed using the Visual MINTEQ version 2.3 program. According to the SIs, leaching P from control and amended soil with different adsorbent was controlled by dissolution of hydroxyapatite. The results indicated that used adsorbents can reduce P leaching from the sandy soil. Thus, retention of P by amended soil reduced a risk in terms of groundwater contamination with P. 相似文献
88.
Rasoul Hemmatjo Mohsen Aliabadi Omid Kalatpour Maryam Farhadian 《International journal of occupational safety and ergonomics》2018,24(3):358-365
This study investigated the combined effect of firefighting operations and exposure to smoke on physiological responses, cognitive functions and physical performance among firefighters. Each firefighter was engaged in two experimental conditions: (a) without artificial smoke, control (NS); (b) with artificial smoke (WS). The results of data analysis revealed that heart rate and body temperature increased significantly after the firefighting activities in the two conditions relative to baseline. In addition, reaction time (RT) and correct response (CR) decreased after the activity relative to baseline and there was a significant difference in RT and CR between the NS and WS conditions. There was also a significant difference in performance time between the NS and WS conditions. These findings demonstrated that a smoke compound has an insignificant effect on physiological responses during firefighting activity. On the contrary, the smoke compound has a detrimental influence on cognitive and physical performance. 相似文献
89.
Hatami Manesh Masoud Haghshenas Arash Mirzaei Mohsen Azadi Hossein Marofi Safar 《Environmental geochemistry and health》2021,43(10):3897-3919
Environmental Geochemistry and Health - Polycyclic aromatic hydrocarbons (PAHs) are an important group of compounds of major environmental concern, which are in the class of persistent organic... 相似文献
90.
Atamaleki Ali Yazdanbakhsh Ahmadreza Fallah Sevda Hesami Arani Mohsen Neshat Aliasghar Fakhri Yadolah 《Environmental science and pollution research international》2021,28(11):13083-13083
Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-021-13115-1 相似文献