空冷条件下钛渣颗粒的氧化路径及氧化动力学

The oxidation pathway and kinetics of titania slag powders in air were analyzed using differential scanning calorimetry (DSC) andthermogravimetry (TG). The oxidation pathway of titania slag powder in air was divided into three stages according to their three exothermic peaks and three corresponding mass gain stages indicated by the respective non-isothermal DSC and TG curves. The isothermal oxidation kin-etics of high titania slag powders of different sizes were analyzed using the ln-ln analysis method. The results revealed that the entire isotherm-al oxidation process comprises two stages. The kinetic mechanism of the first stage can be described as f (α)=1.77 (1?α) [?ln (1?α)](1.77?1)/1.77 , f (α)=1.97 (1?α) [?ln (1?α)](1.97?1)/1.97 , and f (α)=1.18 (1?α) [?ln (1?α)](1.18?1)/1.18 . The kinetic mechanism of the second stage for all samples can be described as f (α)=1.5(1?α)2/3[1?(1?α)1/3]?1 . The activation energies of titania slag powders with different sizes (d1 < 0.075 mm, 0.125 mm < d2 < 0.150 mm, and 0.425 mm < d3 < 0.600 mm) for different reaction degrees were calculated. For the given experimental conditions, the rate-controlling step in the first oxidation stage of all the samples is a chemical reaction. The rate-controlling steps of the second oxidation stage are a chemical reaction and internal diffusion (for powders d1 < 0.075 mm) and internal diffusion (for powders 0.125 mm < d2 <0.150 mm and 0.425 mm < d3 < 0.600 mm).     

壳聚糖基复合控释膜的制备及其渗透性能

以氢化可的松为模型药物,通过2-水平参数设计实验,定量探讨了壳聚糖复合膜中壳聚糖质量浓度、戊二醛质量浓度、甘油质量浓度及三者的交互作用对壳聚糖复合膜渗透性的影响。实验结果表明:壳聚糖质量浓度、戊二醛质量浓度及两者的交互作用对复合膜的渗透性具有显著性影响,而甘油质量浓度对膜渗透性的影响不显著;膜的渗透性随着壳聚糖及戊二醛质量浓度的增加而减弱,随甘油质量浓度的增加而有所改善;当壳聚糖、戊二醛及甘油的质量浓度分别为0.02~0.04 g/mL,0~2.5×10-4g/mL及0~2.5×10-3g/mL时,得到壳聚糖基复合膜的渗透系数(P)与壳聚糖质量浓度(A)、戊二醛质量浓度(B)及两者交互作用(AB)的定量数学模型为P=0.28-4.58A-399.66B+7807.00AB,对模型及参数的有效性进行评价和验证,结果表明模型及参数都是有效的。     

基于不同粒级硫化铜矿石生物浸出的动力学

西藏甲玛地区的硫化铜矿石中含铜矿物以次生硫化铜矿物为主,且含量较低.采用氧化亚铁硫杆菌柱浸的方法对该矿石进行了生物浸出并研究了浸出动力学.基于不同粒级矿石,考察了粒级对铜浸出速率和浸出率的影响,并对浸出率与收缩核模型中的控制方程进行了拟合,确定了浸出过程的控速环节.试验结果表明,铜的浸出速率和浸出率随粒级的减小而增加.矿石表面形貌的SEM表明,浸出过程中矿石表面形成了包含黄钾铁矾的产物层,阻碍了浸出反应的进行.浸出动力学表明,该矿石的浸出过程符合收缩核模型,且浸出应主要受固体产物层内扩散控制.