Modification of halloysite nanotubes for enhancement of gas adsorption capacity

Abstract

Gas adsorption capacity of surface modified halloysite nanotubes were measured. Natural halloysite nanotubes were modified by sulfuric acid in different concentration to selectively remove alumina composition of the tubes. X-ray diffraction and energy dispersive X-ray spectroscopy were used for verifying the compositional change of the inorganic tubes. The surface modification increased inner space volume of the tubes and decreased the mass of nanotubes because of alumina elimination. Transmission electron microscopy shows the internal structure and morphology of natural halloysites and modified halloysites. The transformations of the structure caused by sulfuric acid increase specific surface area, pore volumes, and gas adsorption capacity of reacted halloysite nanotubes. The gas adsorption capacity of natural halloysite nanotubes and modified ones was quantitatively analyzed by BET measurement. BJH plot and thickness plot were utilized for comparing the porosities after dealumination. The numerical data of gas adsorption shows the modification of halloysite nanotubes is immensely effective to increase gas adsorption efficiency of the materials. Halloysite nanotubes were separated by centrifugation to study property differences between each group in further research. The morphology and porosity characteristics were analyzed by BET measurement and TEM images.