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

The potential to remove Cu(2+) and Pb(2+) ion from aqueous solutions through biosorption using barley straw (BS) was investigated in batch experiments. The main parameters influencing Cu(2+) and Pb(2+) ion sorption on BS were: initial metal ion concentration, amount of adsorbent, contact time and pH value of solution. The influences of initial Cu(2+) and Pb(2+) ion concentration (0.1-1mM), 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 Cu(2+) and Pb(2+) ions increased with an increase in pH and dosage of treated BS. The biosorptive capacity of the BS was dependent on the pH of Cu(2+) and Pb(2+) ion solution. Adsorption of Cu(2+) and Pb(2+) ion was in all cases pH dependent showing a maximum at equilibrium pH value at 6.0. The equilibrium sorption capacities of Cu(2+) and Pb(2+) after 2h were 4.64 mg/g and 23.20mg/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 Cu(2+) and Pb(2+) ion to the sorbents.