Morphology and structure of gel-based water-absorbent slow release nitrogen fertilizers and the influence of salt

The water absorbing capacity of a gel is related to the basic characteristics of morphology,physical and chemical structure of the gel.The morphology and physical structure and chemical characteristics of a gel-based water-absorbent slow release nitrogen fertilizer(WASRNF) were investigated by environmental scanning electronic microscopy(ESEM) and infrared spectroscopy(IR).The results indicated that the phase structure of solid WASRNF was heterogeneous in macro-scale and homogeneous in micro-scale.The swelled gel of WASRNF is transparent hydrogel with network structure and pores to store water.The salts influenced and destructed physical and chemical structure of WASRNF,the effects of sodium chloride on WASRNF hydrogel were less than that of calcium chloride,and the destructive effect of calcium chloride on physical structure of WASRNF could hardly be inversed by distilled water.Thus,it is important to increase WASRNF's tolerance to salts to increase its water absorbency.