Investigation of calcium carbonate porogen on methylene blue adsorption in alginate cellulose xanthate beads from corn stalks

Abstract

Corn stalk can be used as a potential adsorbent because of its abundance, cost-effectiveness, and accessible functional groups that allow chemical modifications. This study aims to synthesize cellulose xanthate alginate beads (ACX beads) from corn stalks to remove methylene blue from aqueous solutions. ACX beads with various doses of porogen CaCO3 were printed using the ionic gelation method, and then characterized using FTIR, optical microscopy, and SEM-EDX. The results of the FTIR analysis reported changes in the C-S, C=S, and S-C-S vibrations that indicated the xanthate formation. Furthermore, as the porogen dose increased, the OH intensity decreased. The high intensity of the OH group results in a high swelling process. The results of the optical microscopy analysis showed that the porogen made the ACX beads spherical. SEM-EDX analysis showed that the higher the porogen dose, the rougher the surface morphology of the ACX beads and the larger the pore diameter. The maximum adsorption capacity was obtained on ACX beads without porogen with a contact time of 360 hours. The study reveals that the kinetic adsorption followed a pseudo-second-order kinetic model proposed chemical adsorption. The larger the porogen, the more crosslinks between the divalent cations and alginate or cellulose that are formed, inhibiting the bond between the ACX beads and water and methylene blue, thereby reducing the swelling process and the adsorption capacity of the ACX beads. In addition, the pore size that is too large does not match the size of the methylene blue molecule.