Size of CO2 matters on the metal affinity in aqueous solution

Abstract

There is currently great interest in the utilisation of CO2, which has served as an essential tool for chemical conversion. Here, ultrafine bubblised form of CO2 (CUB) with an average size of 147 nm was doped onto activated carbon fibre (ACF) for the green heavy metal uptake in aqueous solution. As a counterpart, a non-bubblised size of CO2 sample (C-ACF) was also investigated. A CUB-treated sample (N-ACF) experienced a 22.53% decrease in the specific surface area, but a 26.81% increase in acidity as compared to ACF. This implies that CUBs could successfully introduce oxygen contents on the carbonaceous surface. Despite the different synthesis processes, the general adsorption trends of the samples were spontaneous and endothermic in nature. Under all circumstances, the maximum adsorption capacity was secured in the order of N-ACF > C-ACF > ACF. Further, special emphasis on the increased randomness via CUBs was discussed in detail. The use of CUBs also demonstrated a level of environmental feasibility by securing >75% of regeneration efficiency after three trials. Lastly, technical cost modelling revealed that CUBs could be a cost-viable option compared to traditional strong acids from a long-term macroeconomic viewpoint.