双层包覆型缓释材料中过硫酸盐释放性能研究

为了使修复材料在地下水原位修复技术中更持久、稳定的发挥作用，制备双层包覆型缓释材料并研究其释放性能.采用水泥、砂和水作为包覆材料制备不同规格的材料，通过周期性浸出试验方法研究外包覆层组分配比及厚度对其释放性能的影响，建立各影响因素与其释放性能的响应关系.结果表明:①双层包覆型缓释材料释放规律符合零级动力学特征，与单一包覆型缓释材料相比，稳定释放速率由初期释放速率的10%~15%升至60%~80%.②外包覆层厚度相同时，稳定释放速率随包覆材料渗透性的增加而逐渐增加，最小值为10 mg/d，最大值约为380 mg/d.③外包覆层组分配比相同时，材料稳定释放速率随其厚度的增加呈幂函数降低，使用寿命随外包覆层厚度的增加呈指数上升，采用自然临近点插值法预测材料最短使用寿命约为100 d，最长的可达10~15 a.外包覆层厚度导致渗透性能的改变是造成其释放特性发生变化的主要原因.④相同外包覆层厚度下，双层包覆型缓释材料稳定释放速率随包覆层渗透性的增加均呈现增加的趋势，并且外包覆层厚度越大，其稳定释放速率随渗透性能变幅越小.研究显示，双层包覆型缓释材料能够在长时间保持稳定的释放速率，构建的外包覆层组分配比与其释放特性之间的定量关系可指导实际地下水修复工程中修复材料的制备. 

Release Characteristics of Persulfate from Double Layer Slow-Release Materials

In order to make the remediation materials play a more durable and stable role in the in-situ groundwater remediation technology, double-layer slow-release persulfate materials were developed, and the release characteristics were studied. Cement, sand and water were used as outer layers materials to develop materials with different composition and thickness. The release characteristics were studied by periodic water leaching experiment. The effects of different composition ratio and thickness of outer layers on the release characteristics of double-layer slow-release materials as well as the response relationships among them were studied. The result showed that:(1) The release pattern of the double-layer slow-release materials is fit with zero-order kinetic. Compared with the single layer slow-release material, the stable release rate increased from 10%-15% to 60%-80%. (2) Under the same thickness of out layer, the stable release rate increases in accordance with the increasing permeability coefficient of the out layer, ranging from 10 mg/d to around 380 mg/d. (3) With the same composition of the outer layer, the stable release rate of the double-layer slow-release material decreases in power function with the increase of the out layer thickness while life span increases exponentially with it. The naturally proximal point interpolation method predicts that the life span of the material could reach at least 100 d to 10-15 a. The variation of release characteristics of the slow-release material is attributed by the permeability influenced by the thickness of out layer. (4) Under the same out layer thickness, the stable release rate of the slow-release material increases with the improve of the permeability of out layer. Meanwhile the larger the thickness of the out layer is, the smaller variation of the stable release rate affected by the out layer permeability. This study shows that relatively stable release rate of the double-layer slow-release material is feasible even in the long run. The quantitative relationship set up between the out layer composition ratio and the corresponding release characteristics of the double-layer slow-release material offers a reference for the development of slow-release materials in groundwater remediation project.