Study On Silanization Of Alkalitreated Halloysite Nanotubes

Silicate minerals have wide variety and distribution,with unique structure and character,enjoying the reputation of“universal soil”.It is an important way to prepare new materials by modifying and processing natural clay minerals and change their crystal structure and surface chemistry further producing modified materials with novel structure and properties.Halloysite nanotubes?HNTs?are natural 1:1 type silicate clay mineral with the natural advantage of low cost,high strength and corrosion resistance.After modification and treatment,the composite materials with low-cost and high-performance can be prepared,and its development and application have become hotspots in current research.In this paper,the HNTs were modified by alkali to change the crystal structure of HNTs,increase the specific surface area,pore volume and hydroxyl active sites of nanotubes,organic modification will change the surface of halloysite from hydrophilic to hydrophobic and by X-ray diffraction?XRD?,inductively coupled plasma mass spectrometry?ICP?,transmission electron microscopy?TEM?,scanning electron microscopy?SEM?,in situ fourier transform infrared spectroscopy?FTIR?,heat weight loss analysis,nitrogen isotherm adsorption desorption test,nuclear magnetic resonance?MAS NMR?and other techniques were used to investigate the material composition,phase transformation,structural characteristics of the modified sample.the material composition,phase transformation,structural characteristics of the modified sample,the dissolution behavior of aluminum and silicon in alkaline solution after mineral activation and the corresponding research about the grafting effect and influence mechanism of HNTs in different solvents systems and the same solvent system different solvent ratios were discussed.The main research results of this paper are as follows:?1?During the activation of HNTs,the inner diameter gradually increased and the tube wall became thinner.Under the premise of retaining a more complete tubular morphology and obtaining more hydroxyl active sites,4 days is the best activation time,and halloysite forms a new phase,zeolite,after alkali activation.?2?Under the toluene grafting system,APTES was grafted on the halloysite,and the signal of APTES was found in the FTIR spectra,indicating that the APTES was grafted into halloysite successfully.According to the weight loss analysis,it was found that the 4-day alkali-activated grafting sample had the largest weight loss between 250 and 475°C,and the weight loss rate reached 8.88%.By TG,nitrogen isothermal adsorption and desorption,nuclear magnetic resonance and other analyses,the results further showed that the activation of the hallucination of the halloysite for4 days was the most.?3?The halloysite samples of activation for 2 days,4 days,6 days,8 days,10days,and 13 days were carried out in ethanol/water?concentration?V/V??of 10/0,9/1,8/2,7/3,6/4,5/5 system grafted APTES experiments,found that 4 days of activation and in the case of 9/1 ratio,the sample grafted the most,after grafting SBET by grafting The 40.8 m²/g was reduced to 36.18 m²/g,and the V_Pore was reduced from 0.124 cm³/g before grafting to 0.096 cm³/g.It indicates that the presence of proper amount of water in the system can accelerate the hydrolysis of APTES,which is more conducive to the grafting reaction.?4?Compared with the ethanol/water system,the anhydrous toluene system has a higher grafting amount of the anhydrous toluene system.It shows that in non-polar solvents,it is more helpful for the grafting of organosilanes.