Research On Sodium Polyacrylate Water-retainingagent Modified By Bentonite And Fly Ash In Agriculture

Our country is one of 13 countries with water shortage in the world, so the development and utilization of new water-keep agent is one of the effective means to improve limited water resource utilization in China. In order to utilize mineral resources of fly ash and bentonite effectively, give full play to the advantages of fly ash and bentonite and reduce the cost of super absorbent polymers, the application of fly ash and bentonite in water-keep agent is discussed in this article.In this paper, the influence of factors on water absorptivity and salt resistance of five kinds of water-retaining materials was examined by using one-factor experimental design. Preparation processes of the five water-keep agents are optimized with orthogonal experiment, and the performances of the five kinds of water-keep agents prepared in optimal conditions were comparatively analysed. The results showed that under optimal conditions, water absorbency of starch/sodium acrylate composites is the highest, which is 258. But the salt tolerance rate is 30, which is the poor in all composites. Adding bentonite or fly ash composite, the water absorbency decreases, but the salt tolerance rate increases in certain degree. The water absorbency and the salt tolerance rate bentonite/starch/sodium acrylate composite are 175 and 24, respectively. The water absorbency and the salt tolerance rate of fly ash/starch/sodium acrylate composite are 151.2 and 39.6, respectively. The water absorbency of fly ash/bentonite/sodium acrylate composite is the worst, which is 102, and the the salt tolerance rate is 42.4. In view of soil environment to water-keep agent using and special physical and chemical characteristics of bentonite and fly ash, adding bentonite or fly ash to super absorbent polymers has bigger practical value.For further estimating water-keep agent properties, infrared spectrum analysis, X-ray diffraction and scanning electron microscopy (SEM) were used. The result reveals that: fly ash and bentonite are completely scattered in composite materials, which forms composite products with amorphous structure. Polymer matrix is density, where inorganic is well fixed and bond together. And composite material surface was full of irregular creases, which is meaningful for raising bibulous strength of water-retaining material and gel strength after absorption.