The potential of rice straw, agricultural waste, to remove copper (II) from aqueous solution was evaluated in a batch process.Experiments were carried out as function of contact time, initial concentration, pH and temperature.Adsorption isotherms were modeled with the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms.The data fitted well with the Freundlich isotherm.The equilibrium biosorption isotherms showed that biosorbent possess high affinity and sorption capacity for Cu(II) ions, with sorption capacities of 74.70 mg Cu 2+ per 1 g biomass.Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated on the basis of Langmuir constants.The results indicated that the rice straw could be an alternative for more costly adsorbents used for heavy metal removal.
In this study, biosorption of Cu(II) and Zn(II) ions from aqueous solutions by water hyacinth fiber was investigated as a function of initial solution concentration, initial biomass concentration and temperature. Solutions containing copper and zinc ions were prepared synthetically in single component and the time required for attaining adsorption equilibrium was studied. The optimum sorption conditions were studied for each metal separately. The adsorption equilibrium data were adequately characterized by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich equations. The equilibrium biosorption isotherms showed that water hyacinth possess high affinity and sorption capacity for Cu(II) and Zn(II) ions, with sorption capacities of 99.42 mg Cu 2+ and 83.01 mg Zn 2+ per 1 g biomass, respectively. All results showed that water hyacinth fiber is an alternative low cost biosorbent for removal of heavy metal ions from aqueous media. Keywords: biosorption, low cost biosorbent, wastewater treatment, heavy metal
