Multifunctional Slow-Release Fertilizer Prepared from Lignite Activated by a 3D-Molybdate-Sulfur Hierarchical Hollow Nanosphere Catalyst

To improve fertilizer use efficiency, reduce irrigation requirement, and minimize negative environmental impact, a novel large-grained-activated-lignite-slow-release fertilizer (LAF) with good water retention was developed by mechanical extrusion of activated lignite and conventional fertilizer. A 3D molybdate-sulfur hierarchical hollow nanosphere (3D-MoS₂–HN) catalyst was successfully fabricated via a simple route, and the lignite was activated by 3D-MoS₂–HN to increase its water-soluble humic acid content and nutrient adsorption ability. After activation, the amounts of small molecular active groups and water-soluble humic acid of activated lignite were significantly higher than those of raw lignite. The activation also increased adsorption ability of the activated lignite for nutrients. LAF prepared from the activated lignite had a preferable slow-release property and good water-holding capacity in soil. Moreover, a pot trial further demonstrated that LAF effectively improved the growth of an apple plant. With outstanding water-retention and slow-release capacities, this new fertilizer is economical and eco-friendly, and thus is promising in field applications.