Stabilization of Palygorskite Aqueous Suspensions Using Bio-Based and Synthetic Polyelectrolytes

Abstract

Palygorskite is a natural fibrous clay mineral that can be used in several applications, for which colloidal stability in aqueous suspensions is a key point to improve its performance. In this study, methods of magnetic stirring, high-speed shearing, and ultrasonication, as well as different chemical dispersants, combined with these methods, namely carboxymethylcellulose, alginate, polyphosphate, and polyacrylate, were used to improve the dispersibility and the formation of stable suspensions of palygorskite in different conditions of pH. The stability and particle size of suspensions with a low concentration of palygorskite were evaluated by visual inspection, optical and electron microscopy, dynamic light scattering, and zeta potential measurements. Moreover, the palygorskite used in this work was initially characterized for its mineralogical, chemical, physical, and morphological properties. It was found that more stable suspensions were produced with ultrasonication compared to the other two physical treatments, with magnetic stirring being inefficient in all tested cases, and for higher pH values (pH of 12 and pH of 8, the natural pH of the clay) when compared to lower pH values (pH of 3). Remarkably, combined with ultrasonication, carboxymethylcellulose or in a lesser extent polyphosphate at near neutral pH allowed for the disaggregation of crystal bundles of palygorskite into individualized crystals. These results may be helpful to optimize the performance of palygorskite in several domains where it is applied.

Sepiolite-Hydrogels: Synthesis by Ultrasound Irradiation and Their Use for the Preparation of Functional Clay-Based Nanoarchitectured Materials

“…Unlike sepiolite, which results in highly viscous stable hydrogels, attempts to generate clay hydrogels by applying similar ultrasound treatments using palygorskite lead to inhomogeneous dispersions with very low viscosity. Recently, Ferraz and co-workers (Ferraz et al, 2021) have reported on the production of relatively stable palygorskite dispersions by ultrasound irradiation, although these authors point out the requirement to incorporate dispersants such as polyphosphates to obtain better dispersions of this silicate. The different behavior observed between sepiolite and palygorskite to give viscous and stable gels is not clear.…”

Comparison of Surface Properties of Sepiolite and Palygorskite: Surface Energy and Nanoroughness

“…The specific surface area was also determined, and the values of 288, 337, and 129 m 2 g −1 were found for Sep. 1, Sep. 2, and Pal, respectively. A detailed and exhaustive characterization of the studied samples is reported by Alves et al (2020) and Ferraz et al (2021) [ 14 , 15 ].…”

“…The general characterization of these fibrous clay samples was reported in detail elsewhere [ 14 , 15 ].…”

Effect of the dispersion state of minerals on the properties of cellulose nanofiber-based composite films

“…For some applications, such as bionanocomposites, a good dispersion of the clay mineral in a selected medium, preferentially water-based, is essential to achieve superior properties in the final materials (Alves et al, 2019). To improve the dispersibility of fibrous minerals, several strategies have been evaluated mainly based on mechanical treatments, the addition of chemical dispersants to the suspension and the chemical modification of the mineral surface (Alves et al, 2020b;Ferraz et al, 2021;García et al, 2011).…”