Carbon dioxide minimization using sodium and potassium impregnated calcium oxide sorbent derived from waste eggshell

In this study, we have investigated the effects of sodium (Na + ) and potassium (K + ) impregnated calcium oxide (CaO) on CO 2 absorption from biogas. Na + and K + were impregnated on eggshell derived CaO by the incipient wetness impregnation method. A modified batch type reactor was used to conduct the absorption of CO 2 to the sorbent. The sorbents were characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and Thermogravimetric analysis (TGA) after absorption. Around 99.4% CO 2 removal efficiency was obtained using 5% KCl with 4% CaO suspension at 8 min contact time which is the best absorption condition. The XRD pattern for 5% K + impregnated CaO sorbent revealed the formation of crystalline CaCO 3 with the highest intensity, indicating the highest absorption of CO 2 . The more intensity of the FTIR spectra at 1795 and 1403 cm −1 for the K + impregnated CaO indicates CO 2 absorption. From the TGA analysis it can be seen that the three step weight loss was occurred and the calcium carbonate formed during the CO 2 absorption is completely decomposed at around 1000 °C. From the cost analysis of the sorbent preparation, it is observed that the net expense of the prepared sorbent in this study was about three times lesser than the commercially purchased one. Graphical abstract