Diethylaminoethyl cellulose and quaternary ammonium cellulose matrices as adsorbent materials for potentially toxic CrO42−, Cr2O72−, SeO32− and SeO42− anions: A theoretical study

Abstract

The present study theoretically analysis the adsorptive capacities of diethylaminoethyl cellulose (DMC) and quaternary ammonium cellulose (QC) biopolymer matrices toward CrO42−, Cr2O72−, SeO32−, and SeO42− at the B3LYP/6-31+G(d,p)/LANL2DZ level of theory. The locations of possible sites of interaction between structures were verified using molecular electrostatic potentials, which revealed that these matrices have quaternary nitrogen atoms that are partially positively charged and can interact with Se and Cr anions. The frontier molecular orbitals show that interactions between chemical species are possible, while structural data reveal that interactions occur through hydrogen bonds that are 1.574–3.263 Å long. The calculated energies associated with these processes, namely interaction (ΔEint) and Gibbs (ΔG) energies as well as the enthalpy (ΔH) are all negative, demonstrating that the anions interact spontaneously with the matrices and release heat. Topological analysis revealed that almost all interactions are weak (∇2(r) > 0 ua and H > 0 ua). Non-covalent-interaction and reduced-density-gradient plots show that the weak interactions are mostly van der Waals in nature with some hydrogen bonds. These theoretical results show that the QC and DMC matrices are good materials for adsorbing CrO42−, Cr2O72−, SeO32−, and SeO42− and can be used to remediate these contaminants.