Heavy metals discharged into the environment from various industries constitute one of the major causes of water and soil pollution. Conventional methods for the removal of heavy metals from waste waters are often cost prohibitive. These constraints have caused the search for alternative technologies for metal sequestering to cost-effective environmentally acceptable levels. One of the exploitations is the use of biomaterials. The results obtained after contacting for 120 min showed that sour sop seeds achieved the removal of 77.6, 68.5, 56.4and 40.6% for  Cu²⁺ , Ni²⁺,  Zn²⁺  and Pb²⁺ ions, respectively. The residual metallic ion concentrations were determined using an Atomic Absorption Spectrophotometer (AAS). The ability of sour sop seeds to absorb metal ions as shown from the results can be used for the development of an efficient, clean and cheap technology for effluent treatment.

Key words: Toxic, heavy metal, ions, synthetic, adsorption, biosorptio