Green regeneration of spent activated carbon from antibiotics purification as remarkable absorbent for aqueous Cd2+ removal

Abstract

Spent activated carbon (SAC) from antibiotics purification was categorized into hazardous waste in China and forced to incineration, which cause heavily economic and environmental burden over medical industries. This work attempted the regeneration of SAC via a green tandem pyrolysis and steam activation process. The variation of morphology, porosity and surface chemistry state of regenerated activated carbon (RAC) as function of thermal processing parameters was systematically studied. Beside, the potential of RAC as absorbent for aqueous Cd2+ removal was explored by observing the influence of pH, initial concentration, metal ion interference over its adsorption behavior. The results showed that the pore structure of regenerated activated carbon recovered to the best state at 800 ℃ and 1 h. In addition, when the pH is 6 and the dosage of activated carbon is 0.3 g/L, the adsorption capacity of Cd2+ is 1759.02 mg/g and 550 mg/g, respectively, when the initial concentration of cadmium ion is 1 g/L and 0.3 g/L, which outperformed most of previous biomass- and coal-based counterparts. Further dynamic adsorption and isothermal adsorption experiment results implying that the Cd2+ adsorption behavior of RAC-800-1 was coexistence of physical and chemical adsorption. Moreover, RAC-800–1 also has strong adsorption selectivity and reusability. This work promise the great potential of thermally regenerated SAC as competent commercial adsorbent.