Paper Title
The Investigation of Adsorption of Lead Ions Using Pirina as a Potential Biosorbent

Abstract
Heavy metal pollution, even at trace level has become one of the most serious environmental problems for environmental engineers.Thus, how to effectively and deeply remove undesirable metals from water systems is still a very important. Adsorption is the most used operation when metal ions are in low concentrations in the effluent. The use of agriculture solid waste as low-cost adsorbents is considered as an ecofriendly adsorbent due to their contribution in the reduction of costs for waste disposal. Pirina, by-product of olive oil industry, has been addressed in the present study as adsorbent for lead ions. Batch adsorption experiments were conducted under varying conditions of particle size, contact time (1-120 min), initial lead concentration (5-50 mg/L), biosorbentamount (5-40g/L) and pH (2-9). The experimental equilibrium data were examined using Langmuir, Freundlich, Temkin and Dubinin Radushkevich isotherm models. Kinetic data were modeled using the pseudo-second-order model, intra-particle diffusion model, Elovich mass transfer model and Modified Freundlich. The adsorption capacity of pirina for the removal of lead ions was determined with the Langmuir and found to be 3.44 mg/g. Adsorption data of the lead ions was fitted well by the pseudo second-order model. The results indicate that pirina is good low cost biosorbent for lead ions in aqueous solutions. Keywords- Lead, low cost biosorbent, adsorption, pirina, isotherm