水保所知识产出(1956---)知识库

Bentonite possesses multiple physicochemical properties because of a large number of charges on the surface.
Understanding charges-related surface characteristics at various aqueous solution conditions is critical for
bentonite application in various fields, including material modification and environmental restoration. In this
study, the evolution of surface properties (surface potential, surface electric field strength, specific surface area,
and surface charge numbers) for bentonite samples was investigated using simple ion-exchange experiments and
extended combined determination method at different pH conditions. Zeta potential, X-ray diffraction (XRD),
and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) techniques were used to
examine changes in bentonite structure and surface functional groups. The results demonstrated that surface
potential was considerably negative (larger in absolute value) and more sensitive to pH variation than the zeta
potential of bentonite under identical conditions. At multiple pH settings, the surface electric field strength and
the numbers of bentonite’s surface charges were inversely proportional to hydrogen ion concentrations. Cations
covalently bonded to clay’s surface might reduce negative surface charges and diminish surface electric field
strength, particularly as ionic strength increased. Although moderate pH variation has no discernible effect on
bentonite interlayer structural alterations, moderate clay dissolution and changes in mineralogical properties
may increase the specific surface area of bentonite, particularly when the solvent chemical conditions are acidic.
This study comprehensively sheds light on the evolution of surface properties of bentonite clay under acidic,
neutral and alkaline conditions, which is helpful in understanding and optimizing its surface performance for
material and environmental applications.