Kinetic and equilibrium isotherms studies of adsorption of Pb(II) from water onto natural adsorbent

In this research dobera leaves (DL), an agricultural waste, available in large quantity in south re-gion of Saudi Arabia, were used as low-cost adsorbent for removal of metal ions such as Pb(II). Batch operation was used to study the equilibrium behavior of DL. The effects of initial concentra-tion of Pb(II), solution pH, contact time and adsorbent dose were evaluated. To study the kinetics of adsorption of Pb(II) onto DL, pseudo-first-order, pseudo-second-order and intra-particle diffu-sion were used. Adsorption process undergoes pseudo-second-order kinetic as proved by the high value of R2. Furthermore, to design the equilibrium data of adsorption of process, four adsorption isotherm models such as Langmuir, Freundlich Temkin and Dubinin-Radushkevich (D-R) were used. It is found that Langmuir equation has the highest value of R2 (0.999) compared with other models. In presences of a mixture of Pb(II)/Ni(II), DL were found to be selective for Pb(II) ions with a high adsorptive capacity of 83 mg/g and show favorable adsorption with RL < 1. In addition, preliminary results indicate that DL are very effective adsorbent for the removal of Pb(II) ion