Adsorbent from Rice Husk for CO_2 Capture: Synthesis, Characterization, and Optimization of Parameters

摘要

In the present work, adsorbents were prepared from rice husk in order to capture CO2 from a flue gas stream. Various pretreatment processes such as desilicalization, chemical activation, and K2CO3 impregnation were followed to prepare the adsorbents. The physico-chemical characterization of the adsorbents was performed in detail in an elaborated way. A fixed-bed reactor was used to measure the CO2 capture capacity of the in-house developed adsorbents. The effect of various process parameters such as adsorption temperature, moisture content, and loading of active component on CO2 adsorption capacity was studied, and results were compared with a commercially available activated carbon. The maximum adsorption capacity observed for 20K-ARH adsorbent was as high as 67 g of CO2/kg sorbent. The effect of water on CO2 adsorption was critically examined, and formation of KHCO3 was observed in the presence of water during the adsorption process. The optimum operating conditions for the maximum removal of CO2 from a simulated flue gas include a temperature range of 30-40 degrees C, relative humidity range of 80-90%, and K2CO3 loading of about 20 wt %. It was observed that around 94% of the adsorbed CO2 can be desorbed at 180 degrees C, and the adsorbent can be reused for multiple cycles without compromising the capture capacity significantly.