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41.
Violeta Neagu Carmen Paduraru Ion Bunia Lavinia Tofan 《Journal of environmental management》2009,91(1):270-276
Two acrylic adsorbents with different morphological structures and bearing amidoethylenamine and thiol groups were obtained and used for platinum sorption from chloride solution by the batch method. Physico-chemical parameters that influence adsorption such as initial Pt(IV) concentration, stirring time, pH, and adsorbent amount were investigated. The thermodynamic parameters of Pt(IV) sorption on the synthesized adsorbent were also evaluated based on Langmuir and Freundlich isotherms. Thermodynamic parameters estimated from Langmuir constants indicated that the adsorption is spontaneous, exothermic and there is a disordered state at the molecular level. The models used to analyze the sorption rate led to the conclusion that the most important step in the sorption of Pt(IV) could be both particle diffusion and chemical reaction of [PtCl6]− with amine functional groups. Thus, both the ion exchange and complex formation mechanisms can occur via nitrogen atoms in the recovery of Pt(IV) on the studied adsorbent. 相似文献
42.
Soil structure critically affects the hydrological behaviour of soils. In this paper, we examined the impact of areal heterogeneity of hydraulic properties of a structured soil on soil ensemble behaviour for various soil water flow processes with different top boundary conditions (redistribution and drainage plus evaporation and infiltration). Using a numerical solution of the Richards' equation in a stochastic framework, the ensemble characteristics and flow dynamics were studied for drying and wetting processes observed during a time interval of ten days when a series of relatively intense rainfall events occurred. The effects of using unimodal and bimodal interpretative models of hydraulic properties on the ensemble hydrological behaviour of the soil were illustrated by comparing predictions to mean water contents measured over time in several sites at field scale. Although the differences between unimodal and bimodal fitting are not significant in terms of goodness of fit, the differences in process predictions are considerable with the bimodal soil simulating water content measurements much better than unimodal soil. We also investigated the relative contribution of the soil variability of each parameter on the variance of the water contents obtained as the main output of the stochastic simulations. The variability of the structural parameter, weighting the two pore space fractions in the bimodal interpretative model, has the largest contribution to water content variance. The contribution of each parameter depends only partly on the coefficient of variation, much more on the sensitivity of the model to the parameters and on the flow process being observed. We observed that the contribution of the retention parameters to uncertainty increases during drainage processes; the opposite occurs with the hydraulic conductivity parameters. 相似文献
43.
The effects of turbulence intensity (velocity gradient, G (s−1)), Henry's law constant (H), and molecular weight (M) on the volatilization rates of organic compounds are examined using changes in the mass transfer coefficients (KOL (cm/min)) under specific liquid-mixing intensities. The selected compounds were divided into three groups according to their H values (mole in gas/mole in liquid, dimensionless), which ranged from 102 to 10−5. The relationship of the KOL relative to G, H and M was obtained via multiple regression. The obtained values of these parameters indicate that the primary factor affecting the KOL values of the high H compounds is their M values. The effects of the H values on the KOL values of the high H compounds can be neglected. On the other hand, the H value is the major factor determining the KOL values of the low H compounds. The changes in the KOL values of the different H compounds exhibit different profiles as the liquid-mixing intensity increases. The M and H values of middle H compounds possibly affect their KOL values. The effects of the liquid-mixing intensity on the KOL values of the organic compounds increase with increasing H values. The variation in the KOL values might be a result of the concentration of the organic compounds at the interface between the liquid and gas films. The empirical relationship between KOL and some selected parameters, G, H and M, is examined in this study. The obtained results can help to estimate volatilization loss of organic solutes in wastewater treatment facilities. 相似文献
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基于ASM2d模型建立了稳定运行的MUCT工艺营养物质去除过程的动力学反应模型,比较各种COD、TN、NH 4+-N、TP的实测值和模拟值,以确定系统在低C/N条件下运行时的动力学和化学计量学参数.模拟结果表明,稳态模型中的动力学参数qPHA、KA、KPP、YPO3-4、μAUT和ηNO-3分别取值2.90 g.(g.d)-1、3.85 g.m-3、1.35 g.(g.d)-1、0.35、1.6和0.8.其他的动力学和化学计量学参数可采用IWA给出的默认值. 相似文献
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49.
Ganesh Raj Ghimire Witold F. Krajewski Ricardo Mantilla 《Journal of the American Water Resources Association》2018,54(5):1055-1067
This study explores power law relationships to estimate water flow velocity as a function of discharge and drainage area across river networks. We test the model using empirical data from 214 United States (U.S.) Geological Survey gauging stations distributed over the state of Iowa in the U.S. The empirical data are the measurements of the mean cross‐sectional velocity and concurrent discharge. The data are used to estimate parameters for a state‐wide model and to test for spatial variability for 15 large river basins contained within the state. Spatial differences among the basins are small but some parameters significantly differ from the state‐wide model. Using individual station data, the authors also explore a simpler power law model that disregards dependence on the drainage area. Overall, the study shows that including drainage area improves the model. Our study provides parameter values that can be directly incorporated into a regional scale routing model, and provides a framework for developing flow velocity models for hydraulically similar rivers in the U.S. and the world. 相似文献
50.
全球气候变化对森林生态系统产生广泛影响,特别是对气候响应敏感的农牧交错带。辽西丘陵位于我国农牧交错带东北部,为探究辽西丘陵人工林油松径向生长与气候要素的关系,基于树木年代学方法,利用树轮宽度年表,对温度、降水、scPDSI及生长期要素进行相关分析,探究气象因子对树木径向生长的影响情况。结果表明:油松标准化年表与上年7月、9月及当年5月的气温呈负相关,相关系数分别为?0.457、?0.426、?0.471(p<0.05),与当年5月的降水量呈正相关,相关系数为0.52(p<0.05);年表与逐月scPDSI显著正相关,并表现出相近的周期变化,表明水分胁迫是研究区油松生长的关键限制因子;在不同阈值温度下,辽西人工林油松径向生长与生长期活动积温和持续天数呈负相关,由高温引起的水分蒸发是影响其径向生长的关键因子。最低温11℃阈值下对树木生长期影响大,年表与其初日位序、积温、持续天数的相关系数分别达到0.663、?0.619、?0.732(p<0.01);通过V-S模型模拟出辽西油松的生长对春季的9.0℃和秋季的9.5℃较敏感,生长期为4—10月,生长速率的变化受温度和土壤湿度变化的影响。因此,在进行人工油松林区经营抚育时,可适当考虑造林树种对不同气候因子响应的敏感期,注意水热合理配置,以提高林区生态林的营林质量。 相似文献