Aluminate treated Casuarina equisetifolia leaves as potential adsorbent for sequestering Cu(II), Pb(II) and Ni(II) from aqueous solution

In the present study, a novel biosrbent was prepared by treating Casuarina equisetifolia leaves with sodium aluminate (SATCEL) and utilized for the removal of heavy metals from single and multi-metal system. The biosorbent was characterized by various different techniques. Brunauer-Emmett-Teller (BET) analysis showed increase in surface area of biosorbent from 5.902 m(2) g(-1) (in its raw form) to 10.582 m(2) g(-1) (after chemical modification). Response surface methodology (RSM) using central composite design (CCD) was employed for Optimization of process variables and evaluating their interactive effect Isotherm data were fitted in Langmuir, Freundlich, Temkin and SIPS by non-linear curve fitting. Maximum biosorption capacity (qm) calculated from Langmuir isotherm in single metal system for Cu(II), Pb(II) and Ni(II) were 44.0, 28.0 and 39.0 mg g(-1), respectively. In multi-metal system competition among metal ions caused the q(m) values to decrease drastically. Thermodynamic parameters, standard Gibbs free energy change (Delta G(0)), enthalpy change (Delta H-0) and entropy change (Delta S-0) showed that the biosorption of metal ions onto SATCEL was spontaneous and endothermic in nature. Analysis of kinetic data showed that Pseudo-second order kinetic model was well obeyed. Regeneration study indicated that SATCEL could be reused successfully upto four consecutive cycles. (C) 2017 Elsevier Ltd. All rights reserved.