Preparation of 1 T/2H MoS2@MMT with sphere structure: Study on selective adsorption of Pb2+

Abstract

In this paper, MoS2/MMT composites (S-Mt) with 1 T/2H mixed crystalline phase were successfully prepared via NaF impregnation method, for selectively adsorbing Pb2+. S-Mt was etched via introducing sodium fluoride (NaF), where the inserted Na+ played a role in inducing MoS2 to change from 2H phase to 1 T phase. As a result, it provided more S vacancies and exposed more numbers of Mo4+. Meanwhile, part of [Si4O10]4- in MMT was corroded by F-, which promoted forming Si-O-Mo bonds, thus it improved the chemical stability of the resulted material. And a selective removal rate of 92.31 % for Pb2+ was achieved in the polymetallic ion system, which was higher than that of similar adsorbent materials in the past. In addition, it suggested that S-Mt exhibited an obvious spherical structure from SEM, and the presence of plenty of S vacancy defects in S-Mt was proved via Raman. Meanwhile, the analysis on experimental mechanism indicated that the excellent adsorption capacity to Pb2+ on S-Mt may be related to electrostatic interactions and complexation. Furthermore, density functional theory (DFT) also confirmed the formation of Si-O-Mo, and verified the adsorption of Pb2+ on S-Mt. Therefore, the application of S-Mt for selective removal of Pb2+ in complex wastewater systems is promising.