Adsorption of Pb (II) from Aqueous Solution on Oxidized Activated Carbon Fibers

Activated carbon fiber (ACF) was oxidized by different concentrations of HNO3 solution and different contact time. Both the original and the oxidized ACFs were tested to adsorb Pb(II) from aqueous solution. Properties of ACFs were characterized by BET surface area, elemental analysis, Boehm titration and the pH of the point of zero charge (pH(pzc)). The results showed that the maximum adsorption ability of Pb(II) on the oxidized ACF was 0.34 mmol/g at pH 3.0, which was 3 times larger than that on the original ACF, and was enhanced to 0.96 mmol/g by increasing the solution pH from 3.0 to 5.9. The adsorption isotherm of all ACFs obeyed the Langmuir isotherm model. Moreover, the Pb(II) adsorption rate for the oxidized ACF was about 3-fold faster than that of the original ACF.