Adsorptive Removal of Pb(II) Ions from Aqueous Solution by (NH4)(2)S2O8 Oxidized Activated Carbons

摘要

A commercially available activated carbon (AC) was oxidized using 1M H2SO4 solution containing 2 M (NH4)(2)S2O8 oxidant with the solution to carbon ratio of 50 cm(3) g(-1) by changing oxidation period ranging 1 to 10 days at ambient temperatures of 20 or 30 degrees C to introduce carboxy groups onto the carbon surface to capture Pb(II) ions. Adsorptive removal of Pb(II) ions from aqueous solution was also examined with the oxidized ACs. The Pb(II) ion adsorption progressed via ion exchange with protons of carboxy groups bound to graphite and 2.2 mmol g(-1) of Pb(II) could be accommodated at equilibrium pH above 4.0 for ACs oxidized for at least 10 days at 20 degrees C and 4 days at 30 degrees C. Decrease in specific surface area and yield and increase in oxygen and hydrogen content in ACs also observed during the (NH4)(2)S2O8 treatment implied that the oxidation could convert graphite sheets to smaller size by hydrolysis while many carboxy groups would be introduced to the peripherals of the graphite sheets to scavenge Pb(II) ions.