Synthesis and application of alginate immobilised banana peels nanocomposite in rare earth and radioactive minerals removal from mine water

This study describes the preparation, characterisation and application of pelletised immobilised alginate/montmorillonite/banana peels nanocomposite (BPNC) in a fixed-bed column for continuous adsorption of rare earth elements and radioactive minerals from water. The materials was characterised by Fourier transform infrared, X-ray diffraction and scanning electron microscopy analyses. Analyses indicated that the pellets are porous and spherical in shape. FT-IR analysis showed that the functional groups responsible for the coordination of metal ions were the carboxylic (-COO-) and siloxane (Si-O-Si and Si-O-Al) groups. XRD analysis showed two additional peaks which were attributed to alginate and montmorillonite. The influence of the initial concentration, bed depth and flow rate were investigated using synthetic and real mine water in order to determine the breakthrough behaviour of both minerals. The processed bed volume, adsorbent exhaustion rate and service time, were also explored as performance indices for the adsorbent material. Furthermore, the breakthrough data were fitted to both the Thomas and Bohart-Adams models. The BPNC exhibited high affinity for U, Th, Gd and La in the real mine water sample. However, studies may still be required using waters from different environments in order to determine the robustness of BPNC.