Heavy metal ions are nowadays among the most important pollutants in surface and ground water. They are often discharged by a number of industries, and they are extremely toxic and harmful for plants and animals even at low concentrations [1] therefore, the elimination of these ions from waste waters is important to protect public health. Traditional technologies for removal of heavy metals from waste waters include chemical precipitation ion -exchange, membrane separation, reverse osmosis, evaporation and electrolysis [2], most of these methods generated toxic sludge [3]. Therefore, need to find alternative methods which are environmentally friendly, effective and economic is necessary. Using a variety of biological materials including micro-algae and seaweed, bacteria and ect. [4] had been reported before. Lead has been used in many industries and the removal of lead ions from wastewaters is significant. Pb2+ is a heavy metal poison which can forms complexes with oxo-groups in enzymes to affect virtually all steps in the process of hemoglobin synthesis and porphyria metabolism. Toxic levels of Pb2+ in man have been associated with encephalopathy, seizures and mental retardation. The objective of this study is:” to investigate the biosorption potential of Syringa Vulgaris tree leaves to trea Waste waters contaminated with pb2+ ion”. Ulmus Syringa Vulgaris tree leaves, which are in great supply in Iran, were evaluated for removal of Pb2+ from aqueous solution. Maximum bio sorption capacities for Syringa Vulgaris were measured as 290.98 mg/g for Pb2+ ion, respectively. For sorbent the most effective pH range was found to be 6–5 for Pb2+ ion. Metal ion biosorption increased as the ratio of metal solution to the biomass quantity decreased. Conversely, Biosorption/g biosorbent decreased as the quantity of biomass increased. The biosorption of metal ion increased as the initial metal concentration increased. The equilibrium data for Pb2+ ion best fit the Langmuir adsorpt
