Utilization of barley straws as biosorbents for Cu2+ and Pb2+ ions

The potential to remove Cu2+ and Pb2+ ion from aqueous solutions through biosorption using barley straw (BS) was investigated in batch experiments. The main parameters influencing Cu2+ and Pb2+ ion sorption on BS were: initial metal ion concentration, amount of adsorbent, contact time and pH value of solution. The influences of initial Cu2+ and Pb2+ ion concentration (0.1-1 mM), pH (2-9), contact time (10-240 min) and adsorbent amount (0.1-1.0 g) have been reported. Equilibrium isotherms have been measured and modelled. The percent adsorption of Cu2+ and Pb2+ ions increased with an increase in pH and dosage of treated BS. The biosorptive capacity of the BS was dependent on the pH of Cu2+ and Pb2+ ion solution. Adsorption of Cu2+ and Pb2+ ion was in all cases pH dependent showing a maximum at equilibrium pH value at 6.0. The equilibrium sorption capacities of Cu2+ and Pb2+ after 2 h were 4.64 mg/g and 23.20 mg/g for BS, respectively. The adsorption data fit well with the Langmuir isotherm model and the experimental result inferred that complexation on surface, adsorption (chemisorption) and ion exchange is one of the major adsorption mechanisms for binding Cu2+ and Pb2+ ion to the sorbents.