In order to explore the influence of rainfall on the release of heavy metal Cadmium(Cd)in soil in a coal-mining area,soil column leaching experiments were carried out by simulating 3 types of rainfall(acid rain,normal...In order to explore the influence of rainfall on the release of heavy metal Cadmium(Cd)in soil in a coal-mining area,soil column leaching experiments were carried out by simulating 3 types of rainfall(acid rain,normal rainfall,and actual rainfall)with 5 different pH values(4,5,6,6.7,7),and 65 groups of data about leachate pH value and Cd concentration were obtained respectively.The results indicate the general change rule of Cd concentration in leachate:(1)the easiness of Cd release is negatively correlated to the pH value of leaching solution and positively correlated the leaching amount;(2)leaching solution with lower pH values shows more obvious release stages.Leached by solution with different pH values,the release of Cd in soil ranks as follows:Acid rain group>normal rainfall group>actual rainfall group.In the first stage,the acidity of rainfall has a significant impact on the release of Cd in soil,but in the second stage,the release of Cd is alleviated due to the soil buffering.Among the four dynamic equations to simulate the release of Cd in soil,the modified Elovich equation can describe the process most accurately,with the highest coefficient of determination R2 of 0.9975.These results can serve as a reference for further study on the migration,transformation and enrichment of Cd in soil.展开更多
混合过程是中药口服固体制剂成型共性关键环节之一。该文以桂枝茯苓胶囊浸膏粉和丹皮酚细粉为研究对象,分别测量了2种粉体的休止角、松密度和粒径,用于混合过程离散元仿真参数标定。在Hertz-Mindlin with JKR V2接触模型和颗粒缩放的基...混合过程是中药口服固体制剂成型共性关键环节之一。该文以桂枝茯苓胶囊浸膏粉和丹皮酚细粉为研究对象,分别测量了2种粉体的休止角、松密度和粒径,用于混合过程离散元仿真参数标定。在Hertz-Mindlin with JKR V2接触模型和颗粒缩放的基础上,采用离散元法首先标定了丹皮酚细粉和桂枝茯苓胶囊浸膏粉的仿真固体密度,然后通过Plackett-Burman试验设计筛选出对休止角模拟测定影响显著的关键接触参数,通过Box-Behnken试验设计建立了关键接触参数与模拟休止角之间的回归模型,基于回归模型对每种粉末的关键接触参数进行了优化。结果桂枝茯苓胶囊浸膏粉关键接触参数最佳组合为颗粒-颗粒静摩擦系数为0.51,颗粒-颗粒滚动摩擦系数为0.31,以及颗粒-不锈钢静摩擦系数为0.64,丹皮酚细粉关键接触参数最佳组合为颗粒-颗粒静摩擦系数为0.4,颗粒-颗粒滚动摩擦系数为0.19,丹皮酚细粉和桂枝茯苓胶囊浸膏粉颗粒间接触参数的最佳组合为碰撞恢复系数为0.27、静摩擦系数0.49和滚动摩擦系数0.38。验证结果表明,2种单一粉体休止角模拟值和实测值的相对误差小于1%,而两粉末质量比1∶1的混合粉体休止角模拟值和实测值的相对误差小于4%,研究结果为桂枝茯苓胶囊浸膏粉和丹皮酚细粉混合仿真实验提供了可靠的仿真物性数据。展开更多
基金This work was supported by the Major Scienceand Technology Projects (No. 80303-AZP005)Key R & D Project (No. 2018SZ0290)AppliedBasic Research Project (No. 2018JY0425) of theScience and Technology Planning Project of SichuanProvince, China.
文摘In order to explore the influence of rainfall on the release of heavy metal Cadmium(Cd)in soil in a coal-mining area,soil column leaching experiments were carried out by simulating 3 types of rainfall(acid rain,normal rainfall,and actual rainfall)with 5 different pH values(4,5,6,6.7,7),and 65 groups of data about leachate pH value and Cd concentration were obtained respectively.The results indicate the general change rule of Cd concentration in leachate:(1)the easiness of Cd release is negatively correlated to the pH value of leaching solution and positively correlated the leaching amount;(2)leaching solution with lower pH values shows more obvious release stages.Leached by solution with different pH values,the release of Cd in soil ranks as follows:Acid rain group>normal rainfall group>actual rainfall group.In the first stage,the acidity of rainfall has a significant impact on the release of Cd in soil,but in the second stage,the release of Cd is alleviated due to the soil buffering.Among the four dynamic equations to simulate the release of Cd in soil,the modified Elovich equation can describe the process most accurately,with the highest coefficient of determination R2 of 0.9975.These results can serve as a reference for further study on the migration,transformation and enrichment of Cd in soil.
文摘混合过程是中药口服固体制剂成型共性关键环节之一。该文以桂枝茯苓胶囊浸膏粉和丹皮酚细粉为研究对象,分别测量了2种粉体的休止角、松密度和粒径,用于混合过程离散元仿真参数标定。在Hertz-Mindlin with JKR V2接触模型和颗粒缩放的基础上,采用离散元法首先标定了丹皮酚细粉和桂枝茯苓胶囊浸膏粉的仿真固体密度,然后通过Plackett-Burman试验设计筛选出对休止角模拟测定影响显著的关键接触参数,通过Box-Behnken试验设计建立了关键接触参数与模拟休止角之间的回归模型,基于回归模型对每种粉末的关键接触参数进行了优化。结果桂枝茯苓胶囊浸膏粉关键接触参数最佳组合为颗粒-颗粒静摩擦系数为0.51,颗粒-颗粒滚动摩擦系数为0.31,以及颗粒-不锈钢静摩擦系数为0.64,丹皮酚细粉关键接触参数最佳组合为颗粒-颗粒静摩擦系数为0.4,颗粒-颗粒滚动摩擦系数为0.19,丹皮酚细粉和桂枝茯苓胶囊浸膏粉颗粒间接触参数的最佳组合为碰撞恢复系数为0.27、静摩擦系数0.49和滚动摩擦系数0.38。验证结果表明,2种单一粉体休止角模拟值和实测值的相对误差小于1%,而两粉末质量比1∶1的混合粉体休止角模拟值和实测值的相对误差小于4%,研究结果为桂枝茯苓胶囊浸膏粉和丹皮酚细粉混合仿真实验提供了可靠的仿真物性数据。