Abstract
Iron-immobilized nanoporous carbon is a well-known adsorbent used in treating arsenic-contaminated waters. In this contribution, we present findings on the adsorptive interactions and dynamics of arsenate-goethite cluster ([FeO(OH)](6)) with carbon nanotubes (CNTs) using hybridized quantum mechanics/molecular mechanics (QMMM) calculations. The CNTs adsorption mechanism is of interest since a better understanding of the fundamental interactions between arsenate, goethite, and carbon surfaces would translate to advances in CNT-based adsorbent production and utilization. Novel applications of general amber force field (GAFF) and isobaric-isothermal Gibbs ensemble Monte Carlo (NpT-GEMC) methods are described. By the above-mentioned methods, we postulate that the [FeO(OH)](6)/CNT-2.3 (diameter 2.3 nm - mesoporous) system enhances the qualitative (i.e., improved chemisorption) rather than the quantitative adsorptive aspect (i.e., total HAsO42- ions adsorbed) in comparison to the [FeO(OH)](5)/CNT-1.6 (diameter 1.6 nm - microporous) system.