158 Cerâmica 67 (2021) 158-163 http://dx.doi.org/10.1590/0366-69132021673822994 INTRODUCTION Clays are very versatile and abundant materials and used as raw material for various applications, such as building materials, ceramics, paper, petroleum drilling, pharmaceutical industry, as well as adsorbents, catalysts or catalyst carriers, ion exchangers, and others, depending on the specifc property that it presents [1, 2]. Many materials developed in the most diverse felds of science become applicable through the improvement of technologies and the acquisition of new materials. From this point of view, clay materials present a great promise in the optimization of new materials due mainly to their low cost and availability. Some studies have shown the application of adsorption systems to phenolic compounds in which alginate inserted nanocomposites using calcium chloride solution for the removal of phenolic compounds in aqueous systems were developed [3]. In this study, it was shown that the organophilic clay modifed with the cationic surfactant hexadecyltrimethylammonium bromide resulted in a good organophilization effciency. In addition, adsorption results were obtained in agitation systems with different times, obtaining the maximum adsorption capacity of 0.334 and 0.118 mg/g for phenolic compounds 4-chlorophenol (4CF) and phenol, respectively. Another application for organophilic clays was studied by Iannuccelli et al. [4], with the aim of modifying and improving the biological activity of gentamicin (GM) on the evaluation of crude bentonite (Bt) for the development of new gentamicin, a clay hybrid material for topical use. For this, the bentonite was treated with sodium chloride and subsequently, dispersions of bentonite and gentamicin were prepared. Controlled X-ray powder diffraction, thermogravimetry coupled to mass spectrometry, and molecular dynamics simulations indicated monolayer arrangement of gentamicin within the montmorillonite structure without producing substantial effects on the layer periodicity. Concerning skin biomedical application, unlike the pure antibiotic permeating along the transfollicular pathway across stratum corneum, the organo- modifed Bt/GM would favor the trans-epidermal route along inter-cluster corneocyte region, as in vivo skin penetration studies by means of tape stripping test indicated. The GM intercalation could represent a potential advantageous approach in the contribution to a new antibiotic material [4]. Pandey and Ramontja [5] presented a review on the application of modifed bentonites as adsorbents in the remediation of wastewater, given the importance of these materials in the organic and inorganic removal of several pollutants, evaluating different parameters of physical processes such as the impact of pH, the adsorption mechanism and the applicability of several kinetic and thermodynamic models of adsorption. It was verifed that the great majority of the results showed that the adsorption for several pollutants followed a pseudo-second-order and the isotherms conformed to the Langmuir model. In addition, the great potential of bentonite in relation to other existing materials was highlighted, however with a disadvantage of the small pore size, suggesting that the diameters for the Organophilic clays and their application in atrazine adsorption E. A. Silva Filho 1 *, F. S. D’Agostini Vazzoler 1 , H. Vazzoler 2 , F. Uliana 1 , F. R. Valenzuela Diaz 2 1 Universidade Federal do Espírito Santo, Departamento de Química, Laboratório de Físico-Química, Vitória, ES, Brazil 2 Universidade de São Paulo, Departamento de Engenharia Metalúrgica e de Materiais, Laboratório de Sólidos Não metálicos, São Paulo, SP, Brazil *eloisilv@gmail.com https://orcid.org/0000-0002-9306-7882 Abstract Atrazine’s adsorptive capabilities make the use of clays practical and effective. Three types of organophilic clays modifed by cationic surfactants with the ability of one of these clays to adsorb atrazine in an aqueous medium are discussed in this work. The modifcation in clays was done with the surfactants cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, and dodecyltrimethylammonium chloride. The X-ray diffraction data indicated different lamellar expansions for the three organophilic clays obtained when compared to in natura clay, proving the presence of quaternary ammonium salts in the interlamellar space. There was also a decrease in the specifc surface area showing less accessibility to the lamellar spaces due to the presence of surfactants. The thermogravimetric analysis showed a negative variation profle in all the clays. The adsorption test showed a better capacity for atrazine adsorption in the organophilic clay of 64% when compared with 36% of in natura clay, and it followed the Freundlich isotherm model. Keywords: adsorption, atrazine, organophilic clays, surfactants, wastewater.