Sustainable Recovery of Cobalt from Aqueous Solutions Using an Optimized Mesoporous Carbon

Abstract

The aim of this paper is to employ a factorial design to optimize the activation step in the synthesis process of a mesoporous-activated carbon to be used as adsorbent for removing and recovering cobalt ions from aqueous solutions. This activation has been carried out in a tubular furnace in the presence of an air stream, following a 23 factorial design. According to the obtained results, the best activation conditions to reach a maximum cobalt removal are mild conditions, low activation temperatures and large times, while the air flow seems to be positive influence working in a low level. This is due to the enhancement of superficial oxygenated groups formation in these conditions, responsible of the adsorption process. The kinetic curve obtained for the adsorbent prepared at the most favorable conditions showed that the adsorption process was very fast and efficient, reaching equilibrium in 15 min, and was properly described by a pseudo-second-order kinetic, typical of the processes in which there are no diffusion limitations. Additionally, with the aim of studying the potential of metal recovery, desorption studies were performed. Sulfuric acid as stripping agent led to twofold Co preconcentration ratio, by reducing the desorption volume to the quarter.