Sorbents for CO2 capture from biogenesis calcium wastes

Egg shells, shellfish shells and cuttlefish bones, high calcium content alimentary wastes, were used to prepare CaO sorbents for CO2 capture. The materials were prepared by a simple procedure including two steps: crushing and calcination at 900 degrees C. Fine powders displaying chalky-white to pale grey-green shades were obtained depending on the starting material. All the prepared sorbents were microcrystalline limes containing various trace elements. The CO2 sorption ability of the obtained lime materials was assessed using cycle carbonation/calcination tests by thermogravimetry. The CO2 sorption profiles showed two regions: an initial region controlled by chemical reaction and a second region with diffusional control. The rate of chemical reaction of carbonation was almost invariant with the nature of the biomaterial used to produces the sorbent. The decarbonation (calcination step) was much faster than the carbonation for all the examined sorbents and also almost invariant with the sample. The diffusion rate depends on the calcite film thickness formed during chemical reaction controlled region. Results showed that alimentary wastes with high calcium content can be used to produces CO2 sorbents thus contributing to mitigate the anthropogenic carbon and the environment contamination with alimentary wastes. (C) 2013 Elsevier B.V. All rights reserved.