Environmental-friendly nanocomposite attapulgite modified by β-cyclodextrin and ionic liquid for the adsorption of thiamethoxam

Abstract

Thiamethoxam (TH), extensively present in water environment, can adversely affect the ecological safety and human health. In this study, novel environmentally friendly β-Cyclodextrin/Attapulgite (β-CD/ATP) was synthesized by grafting method, followed by its further functionalization using 1-dodecyl-3-methylimidazolium-bis(trifluoromethanesulfonyl)imide([C12MIM][NTF2]) ionic liquid to prepare [C12MIM][NTF2]-β-CD/ATP nanocomposites for efficient TH adsorption. The results of β-CD/ATP and [C12MIM][NTF2]-β-CD/ATP adsorption TH aqueous solution showed that the initial pH and adsorbent dosage had significant effects on the TH load amount. The optimum pH, initial concentration and adsorbent dosage for β-CD/ATP were 9, 100 mg/L and 0.01 g, respectively. The adsorption process can be described by Pseudo-second-order model and Freundlich model. Furthermore, the maximum experimental adsorption amounts at an TH initial concentration 140 mg/L in 318 K displayed the following order: β-CD/ATP (73.45 mg/g) > [C12MIM][NTF2]-β-CD/ATP (55.42 mg/g) > ATP (24.58 mg/g). The Gibbs free energy (−ΔG0) and standard enthalpy change (+ΔH0) confirm that the adsorption process is essentially a spontaneous heat absorption process, the system randomness increases (+ΔS0). In addition, the removal rate of β-CD/ATP for TH was still above 91 % after six sequential cycles of adsorption-desorption. This work showed the high efficiency of β-CD/ATP in TH adsorption and highlighted its great potential in efficient removal of TH from real water samples.