“…At present, various adsorbent materials have been employed to adsorb REEs from aqueous solutions including red clay (Gładysz-Płaska et al, 2014), hydrogel porous materials (Zhu et al, 2016a), carbon materials (Babu et al, 2018), silica gels (Ogata et al, 2015), marine sediments (Liatsou et al, 2015), and biopolymer microcapsules (Delrish et al, 2014). Among various adsorbents used, hydrogel porous materials are one of the most efficient types of adsorbents due to their superhydrophilic features and the metal-binding functional groups of the crosslinked polymeric networks (Ren et al, 2016).…”