Characterization of bentonite clays from Cubati, Paraíba (Northeast of Brazil)

Abstract

Clays of different composition have been used in the development of polymer nanocomposites. The utilization of bentonite clays of the State of Paraíba, Brazil, has been emphasized mainly due to their availability. However, these bentonite deposits are becoming exhausted after several years of exploitation. Thus, the aim of this work was to characterize bentonite clays recently discovered in the municipality of Cubati, Paraíba. The samples underwent a particle size classification step and were characterized by granulometric analysis by laser diffraction, X-ray fluorescence, X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and cation exchange capacity. The results of particle size distribution showed that the clay samples have similar physical characteristics to bentonite clays of Boa Vista, Paraíba. Results of X-ray diffraction indicated that the mineralogical composition of the samples consisted of montmorillonite, kaolinite and quartz. The characterization of the samples by FTIR confirmed these results. Results of chemical analysis showed that the samples are polycationic bentonite clays and have predominantly different exchangeable cations similar to those seen in South American bentonites.

Characterization of clays from the State of Paraíba, Brazil for aesthetic and medicinal use

“…The AC clay produced a value lower than the range required by the group of smectites (60 cmol/kg), due to the presence of accessory minerals in large quantities. The CEC results of the smectic clay of 88 cmol/kg of dry clay is a typical value for bentonite clays from the State of Paraíba, determined by the methylene blue methodology and compatible with data found in [41,44,50]. According to [51], a CEC so high, of more than 70.0 cmol/kg, indicates the presence of a greater amount of montmorillonite mineral.…”

“…According to literature, particles smaller than 63.00 μm may have anti-inflammatory effects and may assist in the skin hydration, retaining moisture due to the high skin adhesiveness [25]. Comparing the particle size distribution results of the samples under study with results obtained in [35][36][37][38][39][40][41][42][43][44][45][46][47][48], it was verified that the presented values were similar, showing that these samples had similar physical and granulometric characteristics. All samples had higher mean diameters than that of commercial clay (AC).…”

Cellulose acetate/AgNPs-organoclay and/or thymol nano-biocomposite films with combined antimicrobial/antioxidant properties for active food packaging use

“…From the wide angles region (Fig. 3b), The XRD patterns of all clay showed the presence of showed the presence of diffraction peaks of montmorillonite as main phase together with the presence of crystallites as impurities such as quartz (2θ = 19.8° and 26.6º) [40]. The compositional determination of clays by EDX analysis is given in Fig.…”

Organofilização de argila e sua aplicação como reforço em nanocompósitos com matriz de policarbonato/poli(acrilonitrila-butadieno-estireno)

“…Para o espectro da AN verificase as bandas características em 3626 cm-1 referente a vibração axial da ligação O-H, em 1635cm1 devido a vibração angular H-O-H, em 991 cm-1 e 1076 cm-1 devido a vibração axial da ligação Si-O, em 626 cm-1 e 916 cm-1 as bandas referentes a ligação Al-O e em 777 cm-1 894 cm-1 devido os modos de vibração (Al, Mg)-OH (GÜNISTER et al, 2007). Estas bandas são características da montmorilonita, o que confirma a predominância deste argilomineral na argila utilizada (OLIVEIRA et al, 2016). planos (001) e (020) respectivamente, o que confirma a presença predominante de montmorilonita na argila utilizada (LEITE;RAPOSO;SILVA, 2008;LUCIAN, 2016).…”