An investigation was conducted using both biochar and magnetic biochar. Have been utilized as an effective, affordable, secure, and ecologically friendly way to get rid of heavy metals like cadmium. Microalgae from Spirulina platensis were used to make biochar by burning it. We mix biochar with hydrogen peroxide to create functional groups on the surface by using ice bath sonication which is biochar activate (BC). Also, magnetic biochar (MBC) has been prepared by mixing biochar activated with Fe₃O₄ (2:1 mole ratio) respectively.  Two concentrations of aqueous solutions (5 ppm and 10 ppm) were mixed with two weights of biochar and magnetic biochar (0.1 and 0.5 g) for 10, 20, and 40 minutes. The concentration of cadmium (5 ppm) with 0.5 g of biochar (BC) after 40 minutes removed 97.58% of cadmium ion from the aqueous solution. On the other hand, magnetic biochar (MBC) (0.5 g) with 5 ppm of cadmium solution after 40 minutes could remove 100% of cadmium ions. We character BC, MBC, and biochar treated with cadmium ions by using FTIR, FESEM, EDX, and XRD studies. These analytical results indicate that the effective groups in biochar and magnetic biochar can adsorb heavy metals by carboxyl, hydroxyl, and carbonyl groups. The findings of the investigation on magnetic biochar revealed that, in addition to carbonyl, hydroxyl, and carboxylic groups, the substance also included magnetite. The findings made it very clear that removing cadmium with biochar reduced their risk and did it in a quick, inexpensive, and environmentally beneficial manner.