Journal of Materials Science Research and Reviews

Seashells and other waste shells are gaining attention as a cost—effective, sustainable, renewable alternative source of CaCO₃ for CO₂ adsorption. Consequently, this study evaluated the performance of periwinkle shell as a potential adsorbent for CO₂ capture. The periwinkle shells were washed, dried, then calcined at 800⁰C for 2 hrs, crushed, and sieved with 0.25 -1.44 mm sieves. Some portion of the calcined sample were activated with KOH in a 2:1 ratio i.e 240g of KOH to 120g of calcined periwinkle shell. A portion of the activated periwinkle shell was modified with deep eutectic solvent (DES) prepared with 15 ml of choline chloride and 30 ml of glycerol. 20 ml of the deep eutectic solvent was added to 10g of KOH-activated periwinkle shell and later dried in a furnace at 800^oC for 2 hrs to form a DES-modified activated periwinkle shell. Likewise, 60 ml of polyethylene glycol (PEG) was added to 30 g of another portion of the KOH-activated periwinkle shell to form the modified PEG-activated periwinkle shell sample. The result of the SEM and FTIR analysis of the samples showed that the DES and PEG modified samples had similar structure and functional groups. However, the unmodified calcined sample contained more functional groups than the modified samples. The results showed that the unmodified calcined periwinkle shells performed better than the KOH-activated and the DES and PEG-modified APS samples, with a CO₂ adsorption capacity of 0.16 and 0.42 mmol/g after 1 and 3 hours, respectively. The adsorption process of the CPS sample followed the Langmuir monolayer model of adsorption. The relatively low adsorption capacity of the developed adsorbents suggested that they were unsuitable for CO₂ capture. Recommendations for future studies were also highlighted.