Maleic and phthalic anhydrides were chemically incorporated onto the banana pseudostem biopolymeric structure through reaction without solvent at the fusion temperatures of the reagents. The new biomaterials showed unequivocal success for these proposed reactions and demonstrated abilities to remove cations from aqueous solutions. Phthalic anhydride pendant chains bonded to biopolymeric structure showed high performance for cation sorption at short times, 60-180 min, to give the maximum sorption capacities of 0.52, 0.54, and 0.59 mmol g(-1) for copper, cobalt, and nickel, respectively. Identically, maleic anhydride chains gave 0.27, 0.32, and 0.20 mmol g(-1) for the same sequence of cations. The equilibrium data were best represented by the Langmuir model in a linear regression and by the Freundlich model in nonlinear regression procedures. These new biopolymers are promising for ecosystem remediation with advantages in using biopolymers based on a natural, cheap, and abundant raw biomaterial.