Performance Evaluation of Modified Periwinkle Shell–derived Adsorbent for CO2 Post-combustion Capture

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 800oC 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.