Effective separation of U(VI) in acidic uranium-containing wastewater by potassium manganese ferrocyanide and carbon nanotube encapsulated calcium alginate beads

The separation and enrichment of uranium from uranium containing wastewater is important for the sustainable development of nuclear energy. Therefore, there is an urgent need to develop a low-cost, readily available, simple preparation process and environmentally friendly adsorbent. In this study, potassium manganese ferro-cyanide and carbon nanotube encapsulated calcium alginate beads (KMnFC/CNT@SA) for uranium adsorption was prepared by a simple method using the inexpensive natural polymer material sodium alginate and the ion exchange material potassium manganese ferricyanide as well as carbon nanotubes capable of enhancing the spatial structure. Static adsorption experiments show that the adsorption capacity of KMnFC/CNT@SA for uranium is significantly affected by pH, contact time, U(VI) concentration and temperature, but is not affected by sodium ion concentration in solution. Furthermore, desorption and cycling tests demonstrate that KMnFC/ CNT@SA has good reusability, with the adsorption capacity remaining above 89.83% of the maximum adsorption capacity after 10 adsorption-desorption cycles. It is worth noting that KMnFC/CNT@SA can adsorb uranium well under acidic conditions, and is easy to solid-liquid separation and recovery. This work provides an effective strategy for the development of high-quality, inexpensive, practical and durable adsorbents for uranium extraction from acidic uranium-containing wastewater.