In this study, magnetic nanoparticles were used to isolate cadmium from the environment. Biodegradable adsorbent was modified with Co-Depositional Fe3O4 magnetic nanoparticles; and the effect of different parameters and magnetic properties and absorption was investigated. Biological absorption of cadmium was carried out using a biological absorbent of Gundelia and modified Gundelia with magnetic nanoparticles, as a function of initial concentration of the metal ion(50 ppm), pH=7, absorbent dose(25-125 mg) and time(5-240 min) in a discontinuous system. Percentage of optimal removal of cadmium on activated gundelia and modified activated gundelia was obtained 100% and 98.26% at pH=7. Initial concentration for biological absorbent of gundelia and for modified gundelia earned 40 and 60 ppm at 200 and 100 minutes, respectively. With increase in absorbent dose, it decreased from 25 to 125 mg and the highest amount of cadmium ion removal in absorbance dose was 25 mg with a value of 94.48. The size of the Fe3O4 magnetic nanoparticles on the adsorbent was obtained by FESEM 49.30 and 43.09 nm. Correction of biological adsorbent with magnetic Fe3O4 nanoparticles can be used as a suitable method for the separation of cadmium from the environment.