In the present study, the removal of lead (II) ions from aqueous solutions was investigated by powdered Henna. Henna is a herbal material that can dramatically adsorb metal ions. Adsorption experiments were carried out in a batch system at room temperature. Then, the equilibrium concentration of each sample was analyzed by atomic adsorption device. The effects of various parameters such as time, initial concentration, adsorbent amount, and pH were investigated. pH, initial concentration, and adsorbent amount showed sharp effects on the adsorption rate. The effect of time on the process was not considerable, as well. The optimum operating conditions were found at pH of 4.78, time of 49.47 min, lead (II) initial concentration of 93.5 mg/L, and adsorbent amount of 1 g led to 97.8% removal of lead (II). Furthermore, Langmuir and Freundlich adsorption isotherms were investigated for the lead (II) adsorption process on Henna. The results showed that Langmuir's isotherm model is more suitable for this process (R2=0.947).
