Adsorption Mechanism between Corn Stalk Fiber and Asphalt

Abstract

Corn stalk fibers are produced by physical and chemical means. To prove that corn stalk fibers can adsorb asphalt, the adsorption process of asphaltenes was studied. There are four main components in asphalt, and this study used asphaltenes as an adsorbate in an asphalt solution. The corn stalk fibers were characterized by scanning electron microscopy and Brunauer-Emmett-Teller (BET) analysis, which indicated that the corn stalk fibers were composed of macroporous and mesoporous structures, with uneven surfaces. The amount of asphaltenes adsorption was found to increase with the weight of the corn stalk fiber, the initial concentration of asphaltenes and the adsorption time. The asphaltene adsorption gradually slowed with time. The Redlich-Peterson model can describe the adsorption process better than the Freundlich and Langmuir models. The pseudo-second-order model presented better suitability for adsorption equilibrium data than the pseudo-first-order model. The adsorption process can be separated into three parts: film diffusion, both film diffusion and intraparticle diffusion, and intraparticle diffusion through the Weber and Morris model. The Boyd model found that film diffusion is the rate-limiting step. The high-temperature performance of corn stalk fiber asphalt increased with increasing mass ratio of fibers and increasing asphaltene adsorption rate. Finally, the corn stalk fibers were proven to adsorb the asphalt effectively.