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. Graphical Abstract

Model-Assisted Optimization of Cobalt Biosorption on Macroalgae Padina pavonica for Wastewater Treatment

“…Therefore, the Table S2 compares the maximum sorption capacity of different materials for Co(II) ions. It can be seen that the ability of P. pavonica biomass to remove Co(II) ions is higher than the Co(II) sorption capacity of some adsorbents reported in the literature [1,20,31,[59][60][61][62][63][64][65][66]. The variations in the adsorption capacity of Co ions among the adsorbents may be due to differences in the morphological and physico-chemical properties of the adsorbents, including the nature of the adsorbent, particle size, specific surface area, and adsorption conditions investigated [67].…”

“…Water contamination is one of the most serious environmental issues of the twenty-first century. It is thought to have an impact on food production and the notion of sustainable development [1]. Heavy metals have been a major source of water pollution, and their release into the environment is a severe problem since they are nonbiodegradable, toxic, and have a tendency to accumulate in the food chain [2].…”

Mesoporous Materials for Metal-Laden Wastewater Treatment

“…Mesoporous adsorbents, SBA-15-EDTA, and SBA-16-EDTA were regenerated using HCl solution for five cycles, maintaining their removal capacity on the level of 85% [95]. Mesoporous carbon applied for cobalt removal was efficiently regenerated using H 2 SO 4 , losing only 5% of its adsorption capacity [83]. Thus, mesoporous material can be reused for metal ion adsorption as long as its adsorption and desorption capacities differ only slightly from the first adsorption-desorption cycle.…”