Fabrication of reusable temperature-controlled-released fertilizer using a palygorskite-based magnetic nanocomposite

In this work, a temperature-controlled-release and collectable iron fertilizer (TCIF) with a core-shell structure was developed using a nanocomposite consisting of palygorskite (Pal), ferroferric oxide (Fe3O4), ferrous ammonium sulfate hexahydrate (FASH), ethylene oxide/propylene oxide block copolymer (F-127), and amino silicon oil (ASO). Therein, the core was made up of Pal-Fe3O4-FASH mixture, and the shell was composed of ASO-F-127. Pal with a porous micro/nano networks structure could bind a great many of Fe2+ through electrostatic attraction. FASH, as the iron fertilizer and a foaming agent in this system, can produce NH3 at 100 degrees C to make a plenty of micro/nano pores in the ASO-F-127 shell, which facilitated the release of Fe2+. F-127, a thermally sensitive polymer, can open and close the pores through the liquid-gel transition under different temperature to adjust the release of Fe2+. The hydrophobic ASO endowed TCIF a high stability in aqueous solution for at least 100 days. Fe3O4 made TCIF own a relatively high magnetism so that TCIF could be conveniently collected from water and soil. Significantly, this technology could improve the utilization efficiency of iron fertilizer and promote the absorption of Fe2+ by maize. Besides, TCIF displayed a good reuse performance, which could favor to lower the cost and decrease the residual.