Open AccessCrystal chemistry characteristics and dispersion performance of Ca-montmorillonite with different layer charge density
Author(s) -
Jun Qiu,
Shan Jiang,
Yueting Wang,
Guowei Chen,
Dongliang Li,
Xiaodong Liu,
Guifang Wang,
Peng Wu,
Xin Lyu
Publication year - 2020
Publication title -
materials research express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 35
ISSN - 2053-1591
DOI - 10.1088/2053-1591/aba803
Subject(s) - montmorillonite , exfoliation joint , charge density , surface charge , crystal (programming language) , analytical chemistry (journal) , dispersion (optics) , materials science , bet theory , zeta potential , fourier transform infrared spectroscopy , crystal structure , layer (electronics) , chemistry , crystallography , graphene , chemical engineering , nanotechnology , adsorption , organic chemistry , composite material , physics , nanoparticle , optics , quantum mechanics , engineering , computer science , programming language
The correlation between crystal chemistry characteristics and dispersion performance of Ca-montmorillonite with different layer charge density was studied. The four kinds of purified montmorillonite were characterized by XRD, XRF, FTIR, SEM, TEM, BET, TG-DTG, Zeta potential, and Molecular dynamics simulation (MD). The XRD analysis results show that the d (001) value of the four kinds of Ca-montmorillonite are 1.51 nm, 1.51 nm, 1.53 nm, and 1.50 nm, respectively, and the calculation results of layer charge density show that the semi-unit cell charge density are 0.38, 0.53, 0.61, and 0.69, respectively. The charge density is positively correlated with the mass content of MgO. The FTIR analysis results show that with the increase of layer charge density, the couple vibration wave number of Si–O–Mg and Mg–O move towards the high frequency region, from 464.70 cm −1 to 466.36 cm −1 and from 517.12 cm −1 to 520.41 cm −1 . The SEM analysis results show that the higher layer charge density of montmorillonite, the worse exfoliation between layers and the thicker layer thickness, The images of TEM show that montmorillonites are mainly composed of a clearly layered structure. The results of BET show that with the increase of charge density, the BET surface area, micropore area and total pore volume gradually increase from 32.69 m 2 g −1 to 64.50 m 2 g −1 , from 4.87 m 2 g −1 to 18.24 m 2 g −1 , and from 0.06 cm 3 g −1 to 0.12 cm 3 g −1 , respectively, while PSDs and pore diameter decrease from 7.88 nm to 1.74 nm, and from 7.65 nm to 5.47 nm. The results of TG and DTG show that with the increase of charge density, the removal temperature of free water and inter-layer water increase from 80 °C to 100 °C and 139 °C to 155 °C, respectively. The simulation results of MD show that with the increase of layer charge density, the number of hydrogen bonds increase from 186 to 271 and the adsorption energy increases from −1467.11 to −1874.32 kcal mol −1 . The particle size increases from 701 nm(Mt1) to 1576 nm(Mt4) with the layer charge density, and the absolute value of Zeta potential, colloidal value and expansion capacity of montmorillonites suspension decrease with the increase of the layer charge density, which further indicates that the dispersion of montmorillonites decrease with the increase of layer charge density.