Abstract
Halloysite (HNT) is treated with sulfuric acid and the physico-chemical properties of its morphology, surface activity, physical and chemical properties have been investigated when HNT is exposed to sulfuric acid with treatment periods of 1 h (H1), 3 h (H3), 8 h (H8), and 21 h (H21). The significance of this and similar work lies in the importance of using HNT as a functional material in nanocomposites. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). The spectrum demonstrates that the hydroxyl groups were active for grafting modification using sulfuric acid, promoting a promising potential use for halloysite in ceramic applications as filler for novel clay-polymer nanocomposites. From the X-ray diffraction (XRD) spectrum, it can be seen that the sulfuric acid breaks down the HNT crystal structure and alters it into amorphous silica. In addition, the FESEM images reveal that the sulfuric acid treatment dissolves the AlO6 octahedral layers and induces the disintegration of SiO4 tetrahedral layers, resulting in porous nanorods. The Bruncher-Emmett-Teller (BET) surface area and total pore volume of HNTs showed an increase. The reaction of the acid with both the outer and inner surfaces of the nanotubes causes the AlO6 octahedral layers to dissolve, which leads to the breakdown and collapse of the tetrahedral layers of SiO4. The multi-fold results presented in this paper serve as a guide for further HNT functional treatment for producing new and advanced nanocomposites.
Highlights
Aluminosilicate (Al2 Si2 O5 (OH)4 ̈ nH2 O), commercially known as halloysite nanotubes (HNTs), is quarried naturally from many countries around the world such as Japan, China, America, South Korea, Brazil, France, and Turkey [1]
Despite the fact that the two studies agreed on the destruction of HNT crystal structure due to sulfuric acid treatment, there are some conflicting results about the BET surface area and the number of the X-ray diffraction (XRD) peaks attained
The effects of sulfuric acid-time treatment on the morphology, surface activity, and physio-chemical properties of HNTs have been investigated at four acid-time treatments of 1 h (H1), 3 h (H3), 8 h (H8), and 21 h (H21) and compared to a neat HNT (H0) sample
Summary
Aluminosilicate (Al2 Si2 O5 (OH)4 ̈ nH2 O), commercially known as halloysite nanotubes (HNTs), is quarried naturally from many countries around the world such as Japan, China, America, South Korea, Brazil, France, and Turkey [1]. Despite all the two surfaces have separate modifications [18] Despite all of these preparations, there are of these preparations, there are deficiencies in HNTs such as mismatching of the tetrahedral layer deficiencies in HNTs such as mismatching of the tetrahedral layer and octahedral layer due to the and octahedral layer due to the interlayer water. Kaolinite, which shares the same chemical family as HNT, along with HNT, has almost the same benefits due to attaining the adsorption equilibrium much faster with that does not react with acid due to its plate structure [19]. Despite the fact that the two studies agreed on the destruction of HNT crystal structure due to sulfuric acid treatment, there are some conflicting results about the BET surface area and the number of the XRD peaks attained
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