Zr/Zn nanocomposites modified ceramsite enhances phosphorus removal from agricultural drainage water

Developing metal-based nanocomposites as adsorbent for phosphorus (P) removal is a simple and effective strategy, while the separation of nanoscale adsorbents from water after adsorption is a tedious job. In this work, a novel Zr/Zn nanocomposite (Zr/Zn NCs) modified ceramsite (ZZMC) was synthesized to enhance P removal from agricultural drainage water. Characterization results showed that Zr/Zn NCs with fusiform nanostructures were uniformly loaded on the ceramsite, hence depending on the high mechanical strength and large size of ceramsite, the Zr/Zn NCs can be conveniently handled and separated after adsorption with P. The common issues of weak adsorption capacity and short using life related to ceramsite for P removal in wastewater were also significantly improved in complementarity combination with Zr/Zn NCs. The ZZMC exhibited higher P removal efficiency (>90%) at 5 mg-P L-1 in a wide pH range (5-9) than bulk ceramsite (<10%) and performed well when other ions were co-existed. For two real agricultural drainage water samples with total phosphorus (TP) of 0.526 mg-P L-1 and 0.865 mg-P L-1, the ZZMC demonstrated desirable adsorption performance not only for truly dissolved P (<3 kDa; >85%), but also for fine colloidal P (3 kDa-220 nm; 76.1%-79.1%) and medium colloidal P (220-450 nm; 80.7%-82.2%) within 30 adsorption cycles that included two-time regeneration treatments towards this material. Moreover, the adsorption capacity of TP by ZZMC after two regenerated treatments was more than 90% of that of fresh ZZMC. The results revealed the feasibility to remove different-sized P at low concentration for agricultural drainage water by ZZMC.