In this work, commercial organophilic clay was used in adsorption studies for the liquid phase of Atrazine, Ametryn, Diuron, and 2-(2,4-dichlorophenoxy)acetic acid (2,4-D) in a batch type system. The affinity study showed that clay is a promising material to remove contamination from agricultural activities. The adsorbent material showed a great removal capacity, especially for Diuron because that reached a higher value than 98%. The adsorption rate was evaluated by pseudo-first-order, pseudo-second order, Elovich, intraparticle diffusion, and external film mass transfer (EFMT) models. In these models, the pseudo-second order and EFMT models represented properly experimental data for Atrazine, Ametryn, and Diuron, whereas the Elovich model was the most predictive for 2,4-D. The maximum adsorption capacities in the monolayer for each contaminant were obtained by the equilibrium isotherms, and the values were 2.275, 25.253, 47.149, and 6.450 mg g⁻¹ for Atrazine, Ametryn, Diuron, and 2,4-D, respectively. In addition, the Langmuir model was the best adjustment to equilibrium data for Atrazine, Ametryn, and Diuron adsorption. For 2,4-D, the model that best represented the experimental data was Freundlich. Finally, characterization techniques indicated that herbicide adsorption contributed to textural, chemical, morphological, and thermal modifications in the clay mineral.

Due to their abundance in nature, clays have been frequently studied in the adsorption of different emergent contaminants, since they have good efficiency and low cost. Therefore, the present study aimed to evaluate the performance of commercial organoclays as an adsorbent in the environmental remediation of wastewater containing the herbicide Diuron. The clay was characterized by the techniques of N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and point of zero charge. In the batch adsorption experiments it was verified that the adsorption kinetics is ruled by the pseudo-second-order model (R² > 0.97), and the adsorption equilibrium study at different temperatures (298, 302 and 308 K) showed that the non-linear models of Langmuir (R² > 0.99) and Freundlich (R² > 0.98) were those that present better adjustments to the experimental data. In addition, the adsorption capacity in monolayer (q_max) was 44.24 mg g⁻¹, being higher or comparable to several works reported in the literature. As for the thermodynamic adsorption study, it was possible to infer that the process is spontaneous (ΔG°_ads < 0) and endothermic (ΔH°_ads = 71.58 kJ mol⁻¹) in the temperature range studied. As far as the regeneration study was concerned, the maximum desorption capacity, 26.59 mg g⁻¹, was obtained from the use of ethanol as eluent at 298 K.

Contamination of water resources by pathogenic microorganisms is a major concern worldwide. As an example, hospitals generate effluents with a wide range of chemical and microbiological contaminants. These effluents are generally not treated beforehand due to the high costs and are, therefore, mixed with domestic effluents in regional treatment systems. Thus, actions to maintain water quality include the development of appropriate materials for its sustainable treatment. In this context, this study aims to develop natural antibacterial materials by impregnating aqueous and alcoholic extracts of garlic in activated babassu charcoal to reduce the microbial load of effluents. This material has been tested in a standard saline solution, which simulates the composition of hospital wastewater and allows bacteria to develop. The biomaterials were characterized by Scanning Electron Microscopy, pH_PZC assays, Boehm’s method, and microbiological assays. Significant antibacterial activities were verified for the garlic extract-impregnated biomaterials; the activated carbon functionalized with HNO₃ and impregnated with aqueous garlic extract inhibited 100% of E. coli growth. This result pointed to garlic extract associated with babassu activated carbon as a green alternative for the pre-treatment of complex effluents, such as hospital effluents.