不同钠吸附比含水介质中胶体迁移-沉积动力学

摘要

Column experiment was conducted to elucidate dynamics of colloid transport-deposition in the coastal porous media of Tianjin with different sodium absorption ratios ( SAR). Kinetics curves of colloid deposition were measured, and deposition ratio and deposition rate constants of colloid were calculated. Moreover, the mechanism of colloid transport-deposition was discussed. Results show that the breakthrough curve of colloid had the critical pore volumes ( CPV) compared with the tracer ion, and the transport of colloidal particles was faster than that of the tracer before the critical CPV, and contrary to it after the CPV. Colloid was not completely breakthrough, and the maximums relative concentration of colloid in effluent was 0.65, 0. 16 and 0.70, respectively, for the sodium absorption ratio (SAR) of 0, 2.85 and ∞ . Deposition played a main role when colloid transported in the porous media, and the deposition capacity of colloid increased with increasing pore volumes. The total deposition ratio of colloids was 50. 96 % , 87. 95 % and 54. 24 % , respectively, for the SAR of 0, 2. 85 and ∞ . Furthermore, the kinetics curve of colloid deposition was linear, and the colloid deposition rate coefficient was 0. 151 h-1 for the SAR of 2. 85. Kinetics curves of colloid deposition were piecewise linear for the SAR of 0 and oo , and the first-order colloid deposition rate coefficients at pre-and post the demarcation point of colloid deposition dynamic curves were 0.072 h-1 0. 048h-1, respectively, for the SAR of 0, and were 0. 211 h-1,0. 194 h-1 for SAR of ∞ . All the results can be explained using the double ionization layer theory.%以滨海含水介质中天然胶体为研究对象,采用自行设计的室内土柱装置,研究不同钠吸附比胶体在滨海含水介质中迁移动态特征,测定了胶体沉积动力学曲线,计算了胶体总沉积率和沉积速率常数,最后对胶体迁移沉积机理进行了探讨.研究结果表明,胶体的穿透曲线与示踪离子相比,存在一个临界孔隙体积数(临界点),在临界点之前胶体的迁移速度大于示踪离子,之后则相反；胶体未发生完全穿透,钠吸附比SAR为0,2.85和∞；出水胶体最大相对浓度为0.65,0.16和0.70;胶体在含水介质迁移过程中发生了沉积,沉积量随孔隙体积数的增加而增加.胶体在含水介质中迁移的总沉积率分别为50.96％、87.95％和54.24％.钠吸附比SAR=2.85时沉积动态曲线为直线,沉积速率常数为0.151h-1,而钠吸附比SAR为0和∞时胶体沉积动态曲线为分段直线,拐点前后胶体沉积速率常数分别为0.072 h-1、0.048h-1和0.211 h-1、0.194 h-1.研究结果用双电子层理论可以很好地解释.