Efficiency and Mechanism of Sorption of Low Concentration Manganese in Water by Mercapto Attapulgite

In this study, (3-mercaptopropyl) trimethoxysilane as a modifier, the mercapto group (-SH) was grafted onto the surface of attapulgite (ATP) by ultrasonic stirring. Before and after modification, the surface feature and structure of attapulgite and mercapto attapulgite (ATP-SH) were characterized by using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD), the results indicated that the physicochemical changes of the materials and the mercapto groups were jointed on the surface of attapulgite. In this work, mercapto attapulgite was used as an adsorbent for manganese adsorption, adsorption experiments were implemented to investigate the effects of different influencing conditions, the results shown that the solution pH showed a slightly impact in the sorption process, because of the presence of manganese in the solution is Mn2+ and MnOH+. The Fourier transform infrared characterization results illustrated that the mercapto attapulgite had a number of active functional groups on the surface, which can combine with manganese. Moreover, the sorption process was more suitable for the pseudo-second-order model (R 2 = 0.9986), which was illustrated that the chemical sorption plays a major role, and also existed physisorption. The sorption experiments date were more suitable for fitted to Langmuir isotherm model (R 2 = 0.9961), illustrated that the adsorption process was dominated by monolayer adsorption. These results of the removal ratio, sorption capacity and adsorption mechanism of manganese suggest that the mercapto attapulgite could be applied as an adsorbent for extracting manganese from sewage.