Solid-liquid separation of colloidal suspensions by use of gelation of natural polymers

利用天然聚合物的凝胶化反应，提出了一种难过滤胶体悬浮液的固液分离新技术。将胶体悬浮液与海藻酸钠溶液混合，然后将该混合物滴在氯化钙溶液中。从而形成包括胶体颗粒的海藻酸钙凝胶。凝胶悬浮液通过重力排出，然后进行凝胶的机械干燥。研究了海藻酸盐凝胶的制备条件。采用膨润土颗粒作为难过滤胶体的实验材料。使用海藻酸钠溶液和氯化钙溶液，两者都在1000ppm以上，可以得到球状的海藻酸钙凝胶，具有足够的重力排水强度。通过压缩渗透性试验估算出凝胶网络的网目尺寸为亚微米级：网目尺寸足够小，可以捕获胶体颗粒。当膨润土-海藻酸凝胶中含有约10-20wt%的海藻酸盐时，由于膨润土-海藻酸凝胶的比水动力阻力是原始膨润土泥的百分之一，因此Tate的表达最大。

A novel technique for solid-liqued separation of difficult-to-filter colloidal suspensions has been proposed by use of gelation reaction of natural polymers. Colloidal suspensions are mixed with a sodium alginate solution and this mixture are dropped on a calcium chloride solution. resulting in calcium-alginate gels including colloidal particles. Gel suspensions are then drained gravitationally, followed by mechanical expression of gels.Preparation conditions of colloid-inclusion alginate gels are studied. Bentonite particles are used as experimental materials of difficult-to-filter colloids. Using sodium alginate solutions and calcium chloride solutions of both above 1000 ppm, one can get spherical calcium-alginate gels with sufficient strength for gravitational drainage. The mesh size of gel network was estimated as a size of sub-micro meters from the compression-permeability test : the mesh size is small enough to trap colloidal particles. Bentonite-alginate gels which contain ca. 10 - 20wt% of alginate show the maximum expression tate, since the specific hydrodynamic resistance of the bentonite-alginate gels is one hundredth of original bentonite sludge.