Adsorption characteristics and influencing factors of cucurbit6 uril for dye eosin Y from printing and dying wastewater

The adsorption characteristics of cucurbit6uril (CB6) for the typical dye eosin in printing and dyeing wastewater were investigated. The effects of initial pH, adsorbent dosage and co-existing ions on the adsorption effect were studied, and the adsorption mechanism was discussed. The results showed that the adsorption removal efficiency was 79.5% after 2 hours when the initial concentration of eosin Y (EY) was 20 mg/L at 25 ℃ and the dosage of CB6 was 0.5 g/L, and the adsorption kinetics characteristics was consistent with the pseudo-second-order kinetic equation. The Langmuir isotherm model had higher correlation coefficient than Freundlich model. The maximum adsorption capacity calculated using Langmuir model was 413.05 mg/g, and with the increase of the temperature, the maximum adsorption capacity of CB6 decreased, indicating that the adsorption process of CB6 was exothermic. As the initial pH of the solution increased from 3 to 11, the adsorption capacity decreased from 33.28 mg/g to 9.14 mg/g. The adverse effects of coexisting anions on adsorption were in the order of PO3-4>CO2-3>NO-2>NO-3. CB6 was recyclable and retained 84.9% adsorption capacity of the original material after 3 times of regeneration using Fenton reagent. The samples were characterized by BET,¹H NMR, IR and SEM. The electrostatic potential distribution map of CB6 was analyzed by the density functional theory (DFT), which revealed that the possible adsorption principle of CB6 was that the “waist” of CB6 and the hydrolysate of EY in the form of anions generated electrostatic attraction, thus forming a supramolecular outsourcing package.