Study on sewage sludge-based activated carbons with natural mineral modification for enhanced removal of heavy metal ions from aqueous solution

Activated carbons were prepared from sewage sludge by chemical activation with pyrolusite (PAC) and lithium-silicon powder addition (LSAC) to develop effective adsorbents for the removal of Cu(II), Pb(II), Cd(II) and Cr(III) metal ions from aqueous solution. Both modifiers with an optimum dosage of 1% (wt.) were demonstrated to exhibit important effects on the formation of the adsorbent’s pore structure. PAC and LSAC showed 17.06% and 8.38% higher BET surface area than the common one without modification (AC). The XPS result showed that after modification, the hydroxyl and carboxyl groups on modified activated carbons surface were remarkably improved compared with the ordinary carbon. The adsorption results in single ion solution showed that the metal ions’ removal rates were 13~29% and 20~43%, respectively, by LSAC and PAC compared with AC’s. Adsorption isotherm and kinetics studies showed that the adsorption of heavy metal ions onto the modified adsorbents was well-fitted by the Langmuir isotherm and could be described by the pseudo-second-order kinetic model. In a multi-ions solution system, the produced carbons showed high affinity and good selective adsorptive capacity on Cu (II), Pb (II) removal, while an improvement in adsorption of Cd(II) and Cr(III) was observed. It will help a lot in wastewater industries due to its efficiency and low-price. © 2021 Bentham Science Publishers.