It has been demonstrated that natural RS exhibitedpoor performance for removal of heavy metal ions(Demirbas 2008). The saturated adsorption capacitiesof RS-g-APSAN towards Pb2?, Cu2?, Zn2?, and Ni2?were evaluated to be 662.9, 248.8, 110.1, and 94.9 mg/g at the optimal pH 6, which were much higher thanthat of pure RS (Table 3). Compared with the similarmaterial AO Cellulose-g-PAN (El-Khouly et al.2011), the greatly enhanced adsorption capacities ofRS-g-APSAN were contributed to the abundant aminoTEPA chelating groups of tethered APSAN brushes,which provided effectively active contact with Pb2?and Cu2?. The grafted APSAN polymer of RS-gAPSAN contained more active sites for Pb2?, Cu2?,and Ni2? than aminated PAN nanofiber mats (Saeedet al. 2008), which were merely surface modified andthus provided limited amine chelating groups on fibersurface. Compared with functional cellulose adsorbents reported by other authors, such as Cellulose-gGMA (O’Connell et al. 2008) and Cellulose-g-PAN-bPMAA (Singha and Guleria 2014), RS-g-APSANexhibited much higher adsorption capacity becausethe abundant pendent groups of amidoxime wereeasily accessible and thus available to capture metalions efficiently via the interactions between metal ionsand the lone-pair electrons of nitrogen (Fig. 17).ConclusionsIn the present study, RS composites of C18-RS-g-PSand RS-g-APSAN were prepared successfully by SIATRP for continuous purification of heavy metal ionscontaminated oil/water mixture. The chemically modified RS composites demonstrated comprehensiveperformance for efficient oil/water separation andremoval of heavy metal ions in simulated wastewatertreatment. C18-RS-g-PS possessed high superhydrophobicity with the WCA of 154 and the absorptioncapacities of toluene, ethyl acetate, n-hexadecane,dichloromethane, and chloroform were 3.33, 5.63,4.15, 8.35, and 4.77 g/g. C18-RS-g-PS demonstratedhigh separation efficiency of above 98% towards aseries of oil/water mixture with stable superhydrophobicity and recyclability. The optimal adsorption performance of RS-g-APSAN was obtained in solution atpH 6.0 with the saturated adsorption capacities of662.9, 248.8, 110.1, and 94.9 mg/g for Pb2?, Cu2?,Zn2?, and Ni2?, which were higher than previouslyreported natural adsorbents. The obtained biomassadsorbent possessed a tremendous potential for use as