海藻酸钠对改性黏土絮凝特征的影响

The effect of sodium alginate on the coagulation rate and flocs formation of modified clay

以海藻酸钠为藻源有机质的模式化合物,考察了赤潮水体中藻源有机化合物对改性黏土絮凝速率及絮凝体特征的影响;并利用图像分析法,测定了絮凝体的分形维数Df,借助分形维数对改性黏土的絮凝形态学特征进行了半定量化分析.结果表明:当海藻酸钠浓度在10～100mg/L范围内时,可以提高改性黏土絮凝的速率,絮凝体的分形维数Df、絮凝体强度呈现出先增大后减小的规律;其中,最佳浓度为50mg/L,其最大絮凝速率达到44.13、Df为1.6823.低浓度(<10mg/L)组的最大絮凝效率和Df均小于对照组,说明低浓度的海藻酸钠不利于改性黏土颗粒间的絮凝.高浓度的(>100mg/L)海藻酸钠能促进改性黏土的絮凝效率,但促进作用呈现减小的趋势,表现为最大絮凝效率减小,Df降低、絮凝体的空隙率增大.

In present study, we used sodium alginate as a model compound to investigate the effect of algal organic matters （AOMs） occurred during algal blooms on the coagulation rate and floes formation of modified clay. The flocculation kinetics of modified clay particles at various concentrations of sodium alginate solutions were studied. And the floes fractal dimension was calculated by image analysis software to assess the morphologic features of the floes semi-quantitatively. Our results indicate that the coagulation rate of modified clay and the fractal dimension of floes are lower than that of control when the concentration of sodium alginate is below 10mg/L. In the range of 10-100mg/L, sodium alginate can improve the coagulation rate of modified clay; the floes fractal dimension and floes strength increase steadily to a peak and then decrease. The optimum concentration of sodium alginate is 50mg/L, along with the maximum cogulation rate of 44.13 and the floes dimension of 1.6823 respectively. While, the floes fractal dimension and coagulation rate decreased when the concentration of sodium alginate is higher than 100mg/L,resulting in Subsequent increase of the floes voidage.