Preparation of Lotus Root-Type Monolithic-Activated Carbons with an Hierarchical Pore Structure from Rice Husks and Their Adsorption of Vitamin B12.

Activated carbon is widely used in many fields because of its well-developed pore structure. Especially in hemoperfusion, activated carbon beads derived from macroporous resin spheres are the predominant adsorbents in hemoditoxifiers. In comparison, biomass-activated carbon attracts more extensive attention on account of its renewability and environmental protection. In this study, a lotus root-type monolithic-activated carbon with a hierarchical pore structure was made from rice husks by the injection molding process followed by carbonization and activation. The straight square channels with the side length of about 1.3 mm were designable, and these channels with adjustable lengths were favorable for the fluid flow during blood purification compared with the tightly packed carbon beads in commercialized hemoditoxifiers. Complementally, the hierarchical nano-sized pores in the walls of the big channels would contribute much to the adsorption capacity for the monolith. Specifically, the adsorption of vitamin B12, a representative of middle molecular toxins in human blood, was about 3.7 mg g, which was acquired by simulated in vitro hemoperfusion tests and this demonstrated the promising application of the lotus root-type biomass-activated carbon in hemoperfusion.