Biosorption of Congo red from aqueous Solution using Syzygium cumini .L

Biosorption is potentially an attractive technology for treatment of waste water for retaining dyes from dilute solutions. Studies carried through environmental biotechnology have shown that many biosorbents present in the nature have great capacity for removal of dyes. Biosorption of Congo red on Syzygium cumini .L had been studied and compared by using batch techniques. The Congo red dye was biosorbed on a biosorbent prepared from matured leaves of the java plum tree (Syzygium cumini .L). A batch biosorption study was carried out using variable dye concentration, pH, biosorbent dosage, biosorbent average particle size and different temperatures. 91.37% of Congo red dye was removed by 0.1 g of java plum leaf powder from 30 ml of aqueous dye solution containing 20 mg of dye at 303 K and at equilibrium time 120 min. The biosorption followed by pseudo second order kinetics with a rate constant of 0.0371 mg^-1 min^-1. The experimental data yielded excellent fit with Langmuir, Freundlich and Temkin isotherm models. The biosorption of the dye was exothermic in nature with enthalpy (∆H⁰) change of -18.712 KJ mol^-1,   an entropy (∆S⁰) change of - 0.078 KJ mol^-1 and Gibbs free energy (∆G⁰) was found to vary from 4.926 to 7.266 KJ mol^-1 for temperatures varying from 303 to 333 K.