Emerging pollutants such as butylparaben (BP) are often difficult to remove via conventional wastewater treatment. Therefore, this study aimed to produce and characterize graphene oxide (GO) and evaluate the adsorption of BP on this adsorbent. The GO was made using the Hummers method and characterized by TGA/DTA, XRD, XRF, BET, point of zero charge (pHpzc), SEM, and the Boehman method. Adsorption experiments were performed in a batch system. The removal efficiency from a Box–Behnken experimental design was 84.3% at a BP concentration 600 µg∙L⁻¹, adsorbent five g∙L^−1, and pH 7 in solution. The first-order (PFO) kinetics obtained the best fit to the experimental data compared to the other models tested in this study: pseudo-second-order (PSO), Elovich (ELC), and intra-particle diffusion (IPD). The Langmuir isotherm provided the best fit compared to the Freundlich isotherm. The temperature effect showed that the system has a spontaneous adsorption process, with a Gibbs energy lower than zero, and that increasing the temperature increases the adsorption capacity. The ionic effect showed that increasing the salt concentration of 1 M increased the repulsive forces but did not decrease the adsorption capacity. The regeneration cycle showed a rate of 85% up to the second cycle. The toxicity analysis confirmed the efficiency of the adsorption process using GO before and after BP adsorption on GO.

Phenyl urea herbicides such as diuron and linuron are commonly used in agriculture to eliminate weeds. Their uncontrolled use can cause environmental problems. In this study, the adsorption of these herbicides was evaluated using activated carbon from coffee grounds, activated with zinc chloride (AC-ZnCl₂, 100% purity), nitric acid (AC-HNO₃, 65% purity), and commercially activated (AC-C) carbon for comparison purposes. The spent coffee grounds were transformed into activated carbon through the calcination process. The highest removal efficiency for diuron 40 mg∙L⁻¹ and linuron 31 mg∙L⁻¹ was obtained using the ZnCl₂-activated adsorbent, being 100% and 45%, respectively. The best pH range was between 4 and 6. Adsorption kinetic studies showed that pseudo-first and second-order models fit the experimental data, with the adsorption rate increasing rapidly within 60 min for the concentrations tested. Adsorption isotherms indicated that the Langmuir model provided the best fit for diuron, while the Freundlich model was more appropriate for linuron. The efficiency of the adsorption process using activated carbon (AC) was confirmed by the toxicity analysis of diuron and linuron solutions before and after adsorption with AC.

Ethylparaben (EtP) is an emerging pollutant that is widely found in the environment, particularly in agricultural landscapes. With the extensive contamination of agricultural soils and irrigation waters, there is a rising concern about their potential impact on crop yields. To provide some of the first evidence that EtP may be more than just an agricultural contaminant, but a potential pollutant, we evaluated the systemic toxicities and cellular responses triggered by EtP in seed roots of Daucus carota, Lycopersicum esculentum, and Cucumis sativus, and in bulb roots of Allium cepa, at environmentally relevant concentrations of 1, 10, 100, and 1000 ng·L⁻¹. The seeds and bulbs remained in contact with the concentrations for 7 days. Distilled water and Tween 80 at 1000 ng·L⁻¹ were used as negative controls. The results were subjected to Kruskal–Wallis analysis of variance followed by Dunn’s test (p ≤ 0.05). In all plants, all concentrations significantly altered the activity of catalase, ascorbate peroxidase, guaiacol peroxidase, and superoxide dismutase. In carrot (10, 100, and 1000 ng·L⁻¹), tomato (1000 ng·L⁻¹), and cucumber (all concentrations), such concentrations caused lipid peroxidation, leading to the accumulation of hydrogen peroxide, as well as hydroxyl and superoxide radicals in the cells. These oxidants caused a delay in the progression of the cell cycle and alterations to the mitotic spindle in the root meristems, significantly inhibiting root growth in the plants evaluated. Recurrent contamination with EtP can potentially harm soil quality, posing a risk to both agricultural productivity and the environment.