Abstract

In the present study, mycelial pellets of Rhizopus oryzae (MPRO) were investigated as a potential biosorbent for the removal of copper (II) from aqueous solution. The effects of the pellet diameter, solution pH, contact time, initial copper (II) concentration and temperature were studied. The optimum diameter and pH for biosorption of copper (II) was found to be 1.0 to 1.2 mm and 4.0. Evaluation of the experimental data in terms of biosorption dynamics showed that the biosorption of copper (II) ontoMPRO followed the pseudo-second-order kinetic model. The equilibrium data fitted very well to the Langmuir adsorption model in the concentration range of copper (II) and at all the temperatures studied. The calculated thermodynamic parameters (∆G°, ∆H° and ∆S°) showed that the biosorption of copper (II) were feasible, spontaneous and endothermic at the temperature ranges of 298 to 318K.

Key words: Biosorption, copper (II), mycelial pellet, Rhizopus oryzae.

Abbreviation

MPRO, mycelial pellets of Rhizopus oryzae; C_i, Initial copper (II) concentration in aqueous solution (mg/L); C_q, final copper (II) concentration in aqueous solution (mg/L); V, volume of the solution (L); W, dry weight of MPRO (g);q_e, the amounts of copper (II) adsorbed on MPRO at equilibrium (mg/g); q_t, the amounts of copper (II) adsorbed on MPRO at a given time t (mg/g); k₁, the rate constant of Lagergren-first-order kinetic model (min^-1); k₂, the rate constant of pseudo-second-order kinetic model (g/(mg·min)); t, time for biosorption (min); C_e, the copper (II) concentration at equilibrium in aqueous solution (mg/L); K_F, the Freundlich constant (mg^1-1/nL^1/n/g); n, the Freundlich constant; q_m, the Langmuir constant(mg/g); K_L, the Langmuir constant (L/mg); R, the universal gas constant (8.314J/(mol^.K)); T, the absolute temperature in Kelvin (K); âˆ†G°, change in Gibbs free energy (kJ/mol); âˆ†H°, change in enthalpy (kJ/mol); âˆ†S°, change in entropy(kJ/(mol^.K)).