Amine–functionalized kenaf as carbon dioxide adsorbent in pressure swing adsorption system

Abstract

Kenaf (Hibiscus Cannabinus L.) that belongs to the family of Malvaceae is abundantly grown in Malaysia since 2006 to replace tobacco plantation as it is inexpensive, easy to grow, and biodegradable. The use of kenaf as adsorbent is seen as an attractive and innovative method, and it has been used for various adsorptions. Adsorption is a promising technology that has the ability to capture carbon dioxide (CO2), the predominant contributor of global climate change. Inspired by the established and well–known amine–based absorption process of carbon capture and storage technology, the development towards new adsorbent by introducing amine functional group has been studied. Therefore, this study explores the potential of modified kenaf as adsorbent by incorporating amine functional group on the surface and investigates the CO2 adsorptive characteristics of amine–modified kenaf adsorbent using pressure swing adsorption system (PSA). The preparation of amine–modified kenaf was conducted via the incipient wetness impregnation technique. The physical and structural characteristics of amine–modified kenaf were determined via micromeritics 3 flex, field emission scanning electrons microscopy, energy dispersive x–ray, Fourier transform infrared spectroscopy, and thermogravimetric analyzer. The results show that the types of amine, amine loading concentration, and impregnation time affect the physical and structural properties of kenaf and thus affecting the capability for capturing CO2. Screening of various types of amines via PSA revealed that tetraethylenepentamine (TEPA) has recorded the highest CO2 adsorption (0.914 mmol/g). Further examination on amine loading divulged that kenaf to TEPA ratio of 1:2 presents the highest CO2 adsorption (2.086 mmol/g) with 5 hour impregnation time. To examine the utilization of amine–modified kenaf adsorbent in PSA system, pressure bed, adsorption time, and feed flowing rate were evaluated. The result revealed that these parameters affect the gas adsorption of amine–modified kenaf adsorbent. The regeneration study had shown that kenaf adsorbent could sustain the repeated adsorption/desorption cyclic operations. This study also found that physical and chemical adsorption occurred during the adsorption of CO2 on raw kenaf and amine–modified kenaf. Thus, amine–modified kenaf adsorbent has high potential to be used as low–cost CO2 agro–based adsorbent hence inducing towards innovative material in the field of gas adsorption.