PREPARATION, REGENERATION AND CYCLIC CO₂ CAPTURE PERFORMANCE OF CUTTLEBONEDERIVED CaO IN A SLURRY BUBBLE COLUMN REACTOR

The work described in this paper evaluated the ability of calcium oxide (CaO) produced from cuttlebone waste to be prepared, regenerated, and used for cyclic CO₂ capture in a slurry bubble column reactor. The waste cuttlebone material was thermally calcined into a porous form and subsequently tested for its ability to be cycled through carbonation. The results show that the porous biomorphic structure of the cuttlebone-derived CaO played an important role in increasing the interaction between gas and solid, resulting in greater stability during carbonation tests. The main conclusions from the study are ·       As slurry concentration was increased, the CO₂ removal efficiency increased, resulting in more available reaction sites for carbonation ·       The highest CO₂ removal efficiency of 70%, corresponding to an approximately 0.70 g CO₂/g sorbent maximum uptake, occurred at the optimal CaO slurry concentration of 8 wt% ·       When slurry concentrations exceeded the optimal concentration, carbonation efficiency decreased slightly because of increased viscosity of the slurries, bubble coalescence, and limitations on gas dispersion ·       The slurry bubble column reactor provided good interaction between gas, liquid, and solid as well as stable hydrodynamics, and as a result, was a good candidate for use in carbonation applications under ambient conditions. ·       Cuttlebone-derived CaO derived from regeneration has shown significant carbonation activity after many carbonation and calcinations, demonstrating that it can be reused and cycled with good stability. ·       After 3 cycles of batch regeneration CaO from cuttlebone retained roughly 75 % of its originally retained weight, which shows less deactivation behaviour compared to other CaO sorbents from dense chemicals owned. ·       Cuttlebone has a naturally porous, interconnecting pore network and was preserved through multiple cycles of being regenerated, resulting in increased gas diffusion from and reduced pure structural failure of cuttlebone CaO through multiple cycles of regeneration. The results indicate that CaO is a viable, environmentally-friendly and low-cost waste product for successive capture; therefore, this also serves as a foundation for further studies of CO₂ capture techniques such as the use of marine biowastes as an environmentally sustainable way of developing calcium looping systems for carbon capture after combustion, and provides a basis for future studies related to mechanical flue gas disposal from an engineering perspective, large-scale batch slurry reactors and long-term carbon sequestration studies for greenhouse gas reduction technologies.

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