Synthesis of ultralight phosphorylated carbon aerogel for efficient removal of U(VI): Batch and fixed-bed column studies

A novel ultra-flyweight phosphorylated carbon aerogel (CA-PO4) was successfully synthesized with phosphate functionalized graphene as skeletons and CNTs as reinforcing ribs, and was applied to adsorb uranyl ions from radioactive wastewater. The characterization results confirmed abundant phosphate groups on CA-PO4 surfaces, which could bind uranyl ions selectively by electrostatic interaction and surface complexation. The maximum adsorption capacity was improved from 102.7 mg.g(-1) (CA) to 150.3(-1) mg.g (CA-PO4) at 298 K and pH 5.5. U(VI) selectivity remained over 50% in the wide pH range of 1.0-5.5 and reached maximum of 66.8% at pH 5.5. The fixed bed column experiments revealed that higher adsorption was found at higher bed height and lower flow rate. Furthermore, CA-PO4 exhibited excellent structural stability, satisfied regeneration and reusability. This paper highlighted a simple synthesis of CA-PO4 as an efficient adsorbent for effective adsorption/recovery of uranyl ions from radioactive wastewater.