Abstract
Background: Brazilian bentonites have a low sodium concentration in their interlayer
structure. This is a problem with most of the industrial applications that demand the
characteristics of sodium bentonites.
Objective: As a solution for this limitation, sodium carbonate is added to in natura clays,
promoting ion exchange between other interlayer cations with sodium.
Methods: A process was used based on the principle of Stokes’ Law (BR Patent 10 2013
016298). For this, we used four glass columns in series, in which a high water flow was
considered to obtain purified clays. It was proposed as a simple, fast and economical method
for sodium determination that was developed and applied in bentonites by flame photometry.
The equipment calibration was performed with a NaCl standard solution in concentrations
between 80 and 110 ppm. The bentonites in the suspension were separated by means of centrifugation,
being thus analyzed by a flame photometer.
Results: The samples were prepared according to the manufacturer’s specifications to contain
detectable amounts of sodium by means of flame photometry. A resulting linear relationship
between the average value readings versus sodium standard content solution (both
in ppm) was obtained by the logarithmic scale, as expected.
Conclusion: The procedure allowed to define a method that could be used in the sodification
control process, thus making it possible to differentiate the sodium cation content in terms of
the value of cation exchange capacity (CEC) from bentonite. X-ray analysis of in natura and
the sodified clays showed nanostructural differences related to interlayer distance.
Keywords:
Clay, bentonite, sodium procedure characterization, flame photometry, nanotechnology, cation
exchange capacity.
Graphical Abstract
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