Effect of pyrolusite loading on sewage sludge-based activated carbon in Cu(II), Pb(II), and Cd(II) adsorption



Activated carbons were prepared from sewage sludge by chemical activation with pyrolusite addition to develop effective adsorbents for the removal of Cu(II), Pb(II), and Cd(II) metal ions from aqueous solution. The transition metal compositions in pyrolusite were demonstrated to exhibit catalytic alike effects on the formation of pore structures, the carbon with pyrolusite addition showed 11.30% higher BET surface area than the one without pyrolusite addition. The XRD pattern showed the presence of MnO2 on the carbon surface by pyrolusite addition, and the accumulation of metal ions can also be seen on the carbon surface after adsorbing metal ions. The analyses of Boehm titration data, FTIR and XPS suggested that the surface chemistry of the activated carbons were modified by pyrolusite addition. Some acid functional groups (hydroxyl and carboxylate) were introduced to the carbon surface, which were responsible for the enhanced removal of Cu(II), Pb(II), and Cd(II). Adsorption experiments showed that the removal rate toward Cu(II), Pb(II), and Cd(II) were increased 30.2, 15.7, and 2.95% with pyrolusite modification, respectively. The adsorption selectivity in multi-ions solution was also studied for further understanding the adsorption affinities of pyrolusite modified adsorbents. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1066–1073, 2013