Three adsorption rate rnodels are derived for multicomponent adsorption systems under either pore diffusion or surface diffusion control. The linear driving force (LDF) model is obtained by assuming a parabolic intrap...Three adsorption rate rnodels are derived for multicomponent adsorption systems under either pore diffusion or surface diffusion control. The linear driving force (LDF) model is obtained by assuming a parabolic intraparticle concentration profile. Models Ⅰ and Ⅱ are obtained from the parabolic concentration layer approximation. Examples are presented to demonstrate the usage and accuracy of these models. It is shown that Model Ⅰ is suitable for batch adsorption calculations and Model Ⅱ provides a good approximation in fixed-bed adsorption pro-cesses while the LDF model should not be used in batch adsorption and may be considered acceptable in fixed-bed adsorption where the parameter Ti is relatively large.展开更多
Leaching of boron （B） and zinc （Zn） can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied us...Leaching of boron （B） and zinc （Zn） can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied using 8.4 cm diameter × 28 cm long intact columns from two calcareous soil series with differing clay contents and vadose zone structures： Lyallpur soil series, clay loam （fine-silty, mixed, hyperthermic Ustalfic Haplargid）, and Sultanpur soil series, sandy loam （coarse-silty, mixed, hyperthermic Ustollic Camborthid）. The adsorption isotherms were developed by equilibrating soil with 0.01 tool L^-1 CaCl2 aqueous solution containing varying amounts of B and Zn and were fitted to the Langmuir equation. The B and Zn breakthrough curves were fitted to the two-domain convective-dispersive equation. At the end of the leaching experiment, 0.11 L 10 g L^-1 blue dye solution was also applied to each column to mark the flow paths. The Lyallpur soil columns had a slightly greater adsorption partition coefficient both for B and Zn than the Sultanpur soil columns. In the Lyallpur soil columns, B arrival was immediate but the peak concentration ratio （the concentration in solution at equilibrium/concentration applied） was lower than that in the Sultanpur soil columns. The breakthrough of B in the Sultanpur soil columns occurred after about 10 cm of cumulative drainage in both the columns; the rise in effluent concentration was fast and the peak concentration ratio was almost 1. Zinc leaching through the soil columns was very limited as only one column from the Lyallpur soil series showed Zn breakthrough in the effluent where the peak concentration ratio was only 0.05. This study demonstrates the effect of soil structure on B transport and has implications for the nutrient management in field soils.展开更多
Some interrelated parameters of heat and mass transfer in two phases of pressure rise and constant pressure are obtained by studying the desorption processes of two kinds of cylindrical adsorbent beds,with fins and wi...Some interrelated parameters of heat and mass transfer in two phases of pressure rise and constant pressure are obtained by studying the desorption processes of two kinds of cylindrical adsorbent beds,with fins and without fins. Moreover, the effects of equiValent thermal conductivity of adsorbent beds,contact thermal transfer coefficient, heat transfer of fins, condensation temperature, uncondensable gas in the adsorber are analyzed, finally, enhancement of heat and mass transfer has been attained展开更多
基金Supported by the National Natural Science Foundation of China (No. 30070636).
文摘Three adsorption rate rnodels are derived for multicomponent adsorption systems under either pore diffusion or surface diffusion control. The linear driving force (LDF) model is obtained by assuming a parabolic intraparticle concentration profile. Models Ⅰ and Ⅱ are obtained from the parabolic concentration layer approximation. Examples are presented to demonstrate the usage and accuracy of these models. It is shown that Model Ⅰ is suitable for batch adsorption calculations and Model Ⅱ provides a good approximation in fixed-bed adsorption pro-cesses while the LDF model should not be used in batch adsorption and may be considered acceptable in fixed-bed adsorption where the parameter Ti is relatively large.
文摘Leaching of boron （B） and zinc （Zn） can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied using 8.4 cm diameter × 28 cm long intact columns from two calcareous soil series with differing clay contents and vadose zone structures： Lyallpur soil series, clay loam （fine-silty, mixed, hyperthermic Ustalfic Haplargid）, and Sultanpur soil series, sandy loam （coarse-silty, mixed, hyperthermic Ustollic Camborthid）. The adsorption isotherms were developed by equilibrating soil with 0.01 tool L^-1 CaCl2 aqueous solution containing varying amounts of B and Zn and were fitted to the Langmuir equation. The B and Zn breakthrough curves were fitted to the two-domain convective-dispersive equation. At the end of the leaching experiment, 0.11 L 10 g L^-1 blue dye solution was also applied to each column to mark the flow paths. The Lyallpur soil columns had a slightly greater adsorption partition coefficient both for B and Zn than the Sultanpur soil columns. In the Lyallpur soil columns, B arrival was immediate but the peak concentration ratio （the concentration in solution at equilibrium/concentration applied） was lower than that in the Sultanpur soil columns. The breakthrough of B in the Sultanpur soil columns occurred after about 10 cm of cumulative drainage in both the columns; the rise in effluent concentration was fast and the peak concentration ratio was almost 1. Zinc leaching through the soil columns was very limited as only one column from the Lyallpur soil series showed Zn breakthrough in the effluent where the peak concentration ratio was only 0.05. This study demonstrates the effect of soil structure on B transport and has implications for the nutrient management in field soils.
文摘Some interrelated parameters of heat and mass transfer in two phases of pressure rise and constant pressure are obtained by studying the desorption processes of two kinds of cylindrical adsorbent beds,with fins and without fins. Moreover, the effects of equiValent thermal conductivity of adsorbent beds,contact thermal transfer coefficient, heat transfer of fins, condensation temperature, uncondensable gas in the adsorber are analyzed, finally, enhancement of heat and mass transfer has been attained
