Modified Activated Carbons from Tea Waste for the Removal of Cu(II) and Pb(II) Ions

COLLOIDAL carbon was prepared from tea waste and then modified with H2O2. The physical and chemical properties were studied using N2 adsorption at 77K, FTIR, SEM, effect of pH and base neutralization capacities. The adsorption of Cu(II) and pb(II) ions on the investigated sorbents was determined by kinetic and equilibrium measurements carried out at 303, 313 and 323K, respectively. Treatment of colloidal carbon with concentrated hydrogen peroxide, the surface area and micropore volume decreased but the total pore volume and mean pore radii increased. The adsorption capacity for both heavy metals ions was the highest at solution pH 5-6 for modified and unmodified sorbents, respectively. The kinetic data fits to pseudosecond order model and the adsorption is more controlled by intraparticle diffusion. The Langmuir adsorption isotherm model gave the better fit to the equilibrium adsorption data for both Cu(II) and pb(II) ions. The maximum adsorption capacities of Cu(II) and pb(II) ions per gram oxidized tea waste carbon were calculated as 1.385 and 1.750 mmol/g, respectively. The triangle G degrees, triangle H degrees and triangle S degrees were calculated. It was found that the adsorption was spontaneous and endothermic, with favourable adsorption capacities being observed at higher temperatures. The sorption energy values obtained suggesting that the sorption mechanism may be a combination of electrostatic and physical sorption.