Sorption of organic contaminants by biochars with multiple porous structures: Experiments and molecular dynamics simulations mediated by three-dimensional models

Abstract

Interactions between organic pollutants and carbon-based particles are critical for understanding and predicting the fate of organic contaminants in the environment. However, traditional modeling concepts did not consider three-dimensional (3-D) structures of carbon-based materials. This prevents a deep understanding of the sequestration of organic pollutants. Therefore, this study revealed interactions between organics and biochars by combining experimental measurements and molecular dynamics simulations. Biochars displayed the best and worst sorption performances for naphthalene (NAP) and benzoic acid (BA), respectively, among the five adsorbates. The kinetic model fitting suggested that biochar pores played a vital role during sorption and led to the fast and slow sorption of organics on the biochar surface and in pores, respectively. Active sites on the biochar surface predominantly sorbed organics. Organics were only sorbed in pores when the surface's active sites were fully occupied. These results can guide the development of efficient organic pollution control strategies to protect human health and improve ecological security.

Keywords: Porous sorption; Preferential site; Sorption process; Surface sorption; Three-dimensional structural model.