Cefalexin adsorption on the surface of pristine and Al-doped boron nitride nanocages (B12N12 and AlB11N12): A theoretical study

Abstract

In this study, the capability of pristine and Al-doped BN nanocages (B12N12 and AlB11N12) as sensor and adsorbent for the detection and removal of cefalexin antibiotic as an emerging environmental contaminant was investigated by infra-red (IR), frontier molecular orbital (FMO) and natural bond orbital (NBO) computations. The obtained negative values of adsorption energies, adsorption enthalpy changes and Gibbs free energy changes showed cefalexin interaction with both nanostructures is experimentally possible, exothermic, and spontaneous. The NBO results showed cefalexin adsorption on the B12N12 surface is a chemisorption but its interaction with AlB11N12 is a physisorption and the calculated values of thermodynamic constants also confirmed this subject. The influence of temperature on the adsorption processes was also scrutinized and the obtained results demonstrated cefalexin interaction with both adsorbents is more favorable at lower temperatures. The computed density of states (DOS) spectrums showed when cefalexin adsorbs on the surface of B12N12, the bandgap of nanostructure declined -39.052 % from 14.908 (eV) to 9.130 (eV). But in the case of Al-doped nanocage, the bandgap decreased -63.718 % from 12.830 (eV) to 4.655 (eV). The strong and chemisorption nature of cefalexin interaction with B12N12 and relatively subtle decline of nanostructure bandgap suggested that B12N12 can be a potential adsorbent for the removal of cefalexin but it cannot be a suitable sensing material for its detection. However, the semi-chemisorption nature of cefalexin interaction with AlB11N12 and tangible decreasing of adsorbent bandgap showed AlB11N12 is an ideal sensing material for the development of new disposable electrochemical sensors for detection of cefalexin.