Molecular dynamic simulation study on interaction mechanism between biopolymer and kaolinite

¹ Civil & Environmental Engineering (CEE), Syracuse University, 0006 Link Hall, Syracuse, NY 13244, United States.
² Laura J. and L. Douglas Meredith Professor for Teaching Excellence, Civil & Environmental Engineering (CEE), Syracuse University, 151 Link Hall, Syracuse NY, 13244, United States.
³ Associate Professor, Civil and Environmental Engineering (CEE), University of Tennessee, 423 John D. Tickle Engineering Building, Knoxville, TN 37996, United States.

^* Corresponding author: saraluma@syr.edu

Abstract

The mining industry produces enormous amounts of waste annually. These wastes – mine tailings – predominantly consist of clay size particles with the major clay mineral being kaolinite. Due to its colloidal nature, kaolinite is generally separated using polymeric flocculants. Recently, biopolymers have been explored in place of synthetic polymers as a flocculant. Researchers have previously investigated kaolinite-biopolymer surface interaction mechanisms by inferring using bench scale physical tests. However, there is a lack of clear understanding of exact interactions between kaolinite and biopolymers at the atomistic scale. In this study, molecular dynamic simulation is used to investigate the interaction mechanism(s) at the atomistic scale between sodium carboxymethyl cellulose (anionic) and a kaolinite surface at neutral pH (7). Molecular dynamic simulation was also performed with a kaolinite surface with deprotonated edges to identify interaction mechanisms. Hydrogen bonding and cation bridging interaction mechanisms were identified from the visualization of interacting atoms. Simulation results have been supplemented with sedimentation test results and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy results.