Application of quantum descriptors for predicting adsorption performance of starch and cyclodextrin adsorbents

Adsorption trend of aromatic compounds on epichlorohydrin (EPI), 1,6-hexamethylene diisocyanate (HDI), and 4,4-methylene diphenyl diisocyanate (MDI) cross-linked starch and cyclodextrin adsorbents were comparatively studied by density functional theorem (DFT) based interaction descriptors and batch adsorption studies. The DFT quantum chemical descriptors predicted adsorption trend of MDI adsorbents > HDI adsorbents > EPI adsorbents. The values of the fractional number of electrons transferred (ΔN) for all the studied adsorbent–adsorbate pair were negative, indicating that the adsorbents were electron donors in the studied adsorption interaction. The batch adsorption performance for the studied cross-linked adsorbents was in agreement with the DFT predictions. Energy gap, chemical hardness, and softness showed good linear correlation (R2 = 0.8073 ± 0.2259) to the batch adsorption performance for most of the studied adsorbent–adsorbate pairs. The present study demonstrated that DFT quantum chemical parameters are suitable adsorption descriptors for predicting adsorption performance of cross-linked adsorbents.