Synthesis and Characterization of Slow-Release Nitrogen Fertilizer with Water Absorbency: Based on Poly(acrylic acid-acrylic amide)/Na-Bentonite

摘要

A novel slow-release nitrogen fertilizer with high-water absorbency (SRNFWA) was prepared by cross-linking poly (acrylic acid-acrylic amide)/bentonite and urea. The synthesis conditions were studied systematically and optimized by using the response surface methodology (RSM). Meanwhile, the effects of the concentration of cross-linker, initiator, bentonite, and degree of neutralization of acrylic acid on WA were investigated. The SRNFWA was characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and scanning electron microscopy (SEM). The results of SEM showed the undulant and coarse surface, facilitated the permeation of nutrition into the polymeric network. We also investigated the slow release property and release mechanism of the nitrogen from the network structure, and the WA in different external solutions. The released characteristic of nitrogen was less than 15% by the third day and reached up to almost 75% after 30 days in distilled water. The WA was 700 g g~(-1) and 150 g g~(-1) in distilled water and 0.9 wt % NaCl solutions, respectively. These studies exhibited the excellent slow-release property and WA capacity of this polymer in 0.9 wt % NaCl solution and could be quite effective in improving the utilization of fertilizer and its water retention capacity simultaneously.