Synthesis of Al2O3/carbon composites from wastewater as superior adsorbents for Pb(II) and Cd(II) removal

Abstract Al 2 O 3 /carbon (Al 2 O 3 /C) composites obtained from the alkaline wastewater of oil refinery and acid wastewater of aluminum anodizing factory have been studied with the principle of “using waste to treat waste”. The process includes these steps: (1) acid-alkali neutralization, (2) evaporation, (3) calcination, (4) washing and drying. The Al 2 O 3 /C composites prepared by calcinating the precursors under Ar atmosphere are used as high-capacity adsorbents for removal of Pb(II) and Cd(II) from aqueous solutions. For Pb(II), the adsorptive behavior satisfies the Langmuir assumptions and the maximum adsorption capacity reaches to 709.2 mg g −1 . For Cd (II), the adsorptive behavior satisfies the Freundlich assumptions and the equilibrium adsorption capacity is up to 1299.4 mg g −1 . For single adsorption of Pb(II) and Cd(II), the adsorption kinetics follows Pseudo-second-order model well. This route shows a possible way of reducing emissions to the environment, recovering resource as a valuable material, and providing a novel strategy for wastewater treatment.