Factorial design applied to sodium activation of a Brazilian bentonite

Abstract

Sodium bentonites are extensively used in industry because they have specific properties that are wanted for several purposes, such as high swelling, thixotropy, and cation exchange capacity. Otherwise, calcium and polycationic bentonites, which are predominant in Brazil, need to be chemically treated by sodium activation to expand their content of interlayer exchangeable sodium cations, which increases these properties. The present study shows the factorial design of the sodium activation for a polycationic bentonite from Quatro Barras, Paraná. The factors considered in the study were: reagent (NaOH and Na2CO3), concentration (1% and 5%) and contact time (24 and 72 h). The response variables were swelling and cation exchange capacity. Statistical analysis indicated significant effects of all factors over swelling and response surface methodology indicated optimal activation with sodium carbonate at 5% for 24 h.

Formulation of Novel Composite (Activated Nanoclay/Hydrocolloid of Nostoc sphaericum) and Its Application in the Removal of Heavy Metals from Wastewater

“…It was observed that natural clay presented CEC 4.95 ± 0.17 cmol/kg and that after activation it increased significantly ( p -value < 0.05) up to 42.64 ± 108 cmol/kg. That is, the treatment with NaCl allows the activation of the adsorption sites [ 36 ] due to the exchange of the divalent cation Ca 2+ and Al 3+ by the monovalent cation Na 1+ present in clays, thus improving the thixotropic behavior of clay in suspension and dispersion. This exchange can be represented using Equation (9) [ 37 ].…”

Characterization of bentonite, vermiculite and soil as potential materials to compose the natural barriers in a near-surface repository

“…The bentonite used was an activated sodium bentonite, named Brasgel™ Bentonite, produced and supplied by Bentonit União Nordeste Ltd., sited in Boa Vista, PB. The term "activated" means that this material was processed to substitute the calcium, predominantly present in the natural Brazilian bentonite, for sodium [8]. The vermiculite used was an expanded vermiculite produced and supplied by Vermiculita Isolantes Termo-Acústicos Ltd., sited in Belo Horizonte, MG.…”