Self-assembled superhydrophobic bio-based controlled release fertilizer: Fabrication, membrane properties, release characteristics and mechanism

Controlled release fertilizers (CRF) have been developed rapidly because it can delay the release of nutrients. However, the traditional petroleum-based CRF is often harmful to the environment, which makes it difficult to large-scale directly apply for agricultural production. In this article, bio-based controlled-release fertilizers (BCF) was prepared using castor oils as coating materials. Fe3O4 nanoparticles were used to modify the surface of membrane to prepare super hydrophobic bio-based controlled-release fertilizers (SBCF). The micro-nano structure was self-assembly constructed with Fe3O4 spontaneously migrates to the outside under the action of an external magnetic field in the process of film formation. The results revealed that SBCF showed longer release period (∼70 d) than the BCF. The surface energy of SBCF was smaller (10.3 mJ/m2) because of the existence of micro-nano superhydrophobic structure. In addition, the roughness, microstructure, degree of cross-linking and other thermal properties of the membrane shells were measured. This self-assembly synthesis of SBCF through the magnetic interaction provides not only practical guidelines on development of sustainable and environmentally friendly controlled-release fertilizer but also other superhydrophobic materials for various applications.