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Background & Aims of the Study: Heavy metals discharge to environment is a worldwide problem growing in scale. When they accumulate in the environment and in food chains, they can profoundly disrupt biological processes. Peganum Harmala Seeds (PHS) was used as a bio-sorbent, using a continuous system for removing Pb²⁺, Co²⁺, Ni²⁺ and Cu²⁺ ions from aqueous solutions.

Results: The adsorption efficiency was found to be pH dependent and enhanced by increasing the solution pH. Maximum removal of ions were obtained at pH=4-8. The equilibrium time was attained after 30 min and desorption studies were performed, using diluted HNO₃, H₂SO₄ and HCl solution (1M) on adsorbed metal ions from PHS. Results illustrated that adsorbed metal ions could be recovered under acidic conditions. Investigation of the process kinetic was best fitted with pseudo second-order model. Langmuir, Freundlich and Temkin models were tested for describing the equilibrium data. The Langmuir isotherm illustrated the best description of the cobalt and copper adsorption mechanism and Freundlich model describes lead and nickel ions adsorption on PHS.

Conclusion: It was found that PHS would be a good adsorbent for removal of heavy metals.