Efficient Phosphate Sequestration in Waters by the Unique Hierarchical 3D <i>Artemia</i> Egg Shell Supported Nano-Mg(OH)₂ Composite and Sequenced Potential Application in Slow Release Fertilizer

<i>Artemia</i> nauplii are important bait or food sources in aquaculture, but the egg shells after incubation are always subjected to discarding as natural wastes; therefore, application and utilization of the <i>Artemia</i> egg-shell wastes will be an important issue. Herein, we reported a new hybrid biomaterial by encapsulating nano-Mg­(OH)₂ onto discarded <i>Artemia</i> egg shells for phosphate sequestration enhancement. The unique hierarchically 3D-layered structure of <i>Artemia</i> egg shells can endow well-defined nano-Mg­(OH)₂ morphology and efficient phosphate adsorption performances. The results of the final hybrid biomaterial exhibit a wide pH dependent sorption process, strong affinity toward phosphate removal, and large sorption capacity. Moreover, the exhausted adsorbent shell–Mg-P can be further utilized as slow-release fertilizer without regular chemical regeneration. The efficient slow-release behaviors of phosphorus onto Shell–Mg–P for 30 days indicated the potential applicability as fertilizers. Additionally, the actual seedling tests further confirm that the shell–Mg–P can be readily used as a slow-release fertilizer for the soil improvement and crop productivity