The biosorption potential of Opuntia fragalis for detoxification of Zn (II) ions from human blood plasma was investigated. The influence of biosorbent dose, concentration of Zn (II) ions, pH and rate of biosorption was examined at constant physiological temperature(370C). FTIR results of the biosorbent revealed that –C-Br, -C-N, -N-O, -N-H, -C?C- and –OH functional groups were responsible for the biosorption of Zn (II) ions from human blood plasma. SEM micrograph revealed the active availablepore sites responsible for the binding of Zn (II) ion unto Opuntia fragalis. The optimum detoxification of Zn (II) ionswere attained at biosorbent dose of 1.5 g, concentration of Zn (II) ion at 40 mg/L, pH of 6 and rate of biosorption of Zn (II) ions at 70 min. The experimental data were subjected to four adsorption isotherm models; Langmuir, Freundlich, Tempkin and Dubinin-RadushkevichIsotherms. The adsorption process fits into Tempkin isotherm with correlation coefficient R2 value of 0.9376, the maximum monolayer coverage capacity, Qmis -1.2522 mgg-1, Langmuir isotherm constant KLis -1.029 Lmg-1, separation factor RLis -1.029 which revealed a favorable biosorption process. The biosorption experimental data was modelled with Pseudo-first order, Pseudo-second order, Elovichand Intra particle diffusion kinetic models. Pseudo first order model explained the biosorption process best with R2 = 0.9998. The interaction between Zn (II) ions and Opuntia fragalis defined a chemisorption reaction which involved chemical bonds formation.

Keywords: Opuntia fragalis, biosorption, blood plasma, zinc, isotherm and kinetic