Sorptive removal of lead (Ⅱ) from water using chemically modified mulch of Madhuca longifolia and Polyalthia longifolia as novel biosorbents

摘要

In this study, dried leaves (mulch) of Madhuca longifolia and Polyalthia longifolia have been used for removing Pb(Ⅱ) from aqueous media. Their biosorption capacities were enhanced by chemical treatment using dipping methodology. It is found that formalin modified M. longifolia leaves and acetone modified P. longifolia leaves have greater biosorption capacity as compared to non-modified leaves. After optimizing operational parameters, Langmuir, Freundlich, and Temkin isotherms were applied to equilibrium data for determining maximum biosorption capacities, heat of biosorption, and biosorption intensities. The maximum biosorption capacity "q_m" values were 17.18, 25.77, 14.11, 4.50, 8.99, and 6.99 mg/g using simple M. longifolia leaves, base modified M. longifolia leaves, formalin modified M. longifolia leaves, simple P. longifolia leaves, base modified P. longifolia leaves, and acetone modified P. longifolia leaves correspondingly. Thermodynamic revealed that biosorption using these biosorbents occur spontaneously due to larger negative values of △G° and kinetic investigations suggested that pseudo-second order of reaction could be applied for explaining the mechanism of biosorption. Nitric acid was found as suitable desorbent for recycling of biosorbents.