Textile wastewater (TWW) is one of the most hazardous wastewaters for ecosystems when it is discharged directly into water streams without adequate treatment. Some organic pollutants, such as dyes in TWW, are considered refractory compounds that are difficult to degrade using conventional chemical and biological methods. The bicarbonate-activated peroxide (BAP) system is an advanced oxidation process (AOP) based on applying H₂O₂, which has been demonstrated to be a clean and efficient technology for dye degradation, with the advantage of operating under slightly alkaline pH conditions. In this study, response surface methodology (RSM) based on a central composite design (CCD) was used to optimize the degradation of TWW contaminated with the azo dye Acid Black 194 using the BAP system catalyzed with cobalt ions in solution (Co²⁺). The analysis of variance (ANOVA) technique was applied to identify significant variables and their individual and interactive effects on the degradation of TWW. The optimum reagent concentrations for degrading TWW at 25 °C and with 45 μM Co²⁺ were 787.61 and 183.34 mM for H₂O₂ and NaHCO₃, respectively. Under these conditions, complete decolorization (≥99.40), 32.20 % mineralization, and 52.02 % chemical oxygen demand removal were achieved. Additionally, the acute toxicity of textile wastewater before and after oxidation was evaluated with guppy fish (Poecilia reticulata), showing a total reduction in mortality after treatment with the Co²⁺–BAP system. The Co²⁺–BAP oxidation system is a potential method for textile wastewater treatment, which, in addition to achieving complete decolorization and partial mineralization, improves biodegradability and reduces the toxicity of the treated water.

Emerging contaminants are chemical products that are found in low concentrations, are not regulated by environmental norms, and cause health effects. Among this group of contaminants are parabens, a family of p-hydroxybenzoic acid esters used as preservatives in cosmetics, pharmaceuticals, and food products. Recent research describes parabens as endocrine disruptors that can cause health alterations. Some of the best alternatives for pollutant removal include the adsorption process, which can use materials that are inexpensive, abundant, and susceptible to modifications. In this sense, cellulose can be an option for obtaining materials that can be used in the removal of contaminants. This research investigates the synthesis of benzoic cellulose (MCB) and magnetic cellulose (MCM) as well as its use as an adsorbent for the removal of methylparaben (MP) and butylparaben (BP) from water. Likewise, physicochemical characterization, including Fourier transform infrared (FTIR), scanning electronic microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), for both cellulose materials was carried out. Moreover, pseudo-first-order, pseudo-second-order, Elovich, Weber, Morris, and Boyd models were used to investigate the adsorption kinetics. As a result, the pseudo-second-order model was favorable for both modified cellulose and the two parabens assayed. Finally, Freundlich, Langmuir, and Sips adsorption isotherm models were investigated; the Langmuir model was the best for the adsorption isotherm data. The adsorption of methylparaben and butylparaben was in the following order: MCM > MCB. The maximum adsorption capacity of MP and BP for MCM was 9.58 and 12.03 mg g–1, respectively. For instance, the results showed that the modified cellulose adsorbed the parabens physically, which could involve electrostatic attraction, hydrogen bonding, π–π bonding, and hydrophobic interactions.

Phytohormones are molecules responsible for growth, development, and metabolism regulation in plants. Gibberellic acid (GA₃) and abscisic acid (ABA) are the main phytohormones involved in seed germination. Notably, it should be a highlight that GA₃ induces germination, whereas ABA inhibits it. For this reason, it is important to calculate the concentration of these two phytohormones during seeds germination.

The oxidation of aqueous solutions containing Allura Red AC (AR–AC) using bicarbonate-activated peroxide (BAP) and cobalt-impregnated pillared clay (Co/Al–PILC) as the catalyst was investigated. Using the CCD-RMS approach (central composite design–response surface methodology), the effects of dye, H₂O₂, and NaHCO₃ concentrations on AR–AC degradation were studied. The decolorization, total nitrogen (TN), and total carbon (TC) removals were the analyzed responses, and the experimental data were fitted to empirical quadratic equations for these responses, obtaining coefficients of determination R² and adjusted-R² higher than 0.9528. The multi-objective optimization conditions were [dye] = 21.25 mg/L, [H₂O₂] = 2.59 mM, [NaHCO₃] = 1.25 mM, and a catalyst loading of 2 g/L. Under these conditions, a decolorization greater than 99.43% was obtained, as well as TN and TC removals of 72.82 and 18.74%, respectively, with the added advantage of showing cobalt leaching below 0.01 mg/L. Chromatographic analyses (GC–MS and HPLC) were used to identify some reaction intermediates and by-products. This research showed that wastewater containing azo dyes may be treated using the cobalt-catalyzed BAP system in heterogeneous media.

Gibberellic acid is a phytohormone that triggers the germination of seeds in a state of dormancy. Through the quantification of this hormone, the physiological condition of seeds of economic importance can be studded. In this work we validated a High-Performance Liquid Chromatography method to quantify gibberellic acid in germinated maize (Zea mays L.) seeds. Chromatographic conditions included the use of a C-18 reversed-phase column, acetonitrile-formic acid (1 : 9 %) as the mobile phase, flow of 0.5 mL·min-1, and detection at 195 nm. We evaluated our method for seven analytical parameters. The method was linear for gibberellic acid concentrations from1.0 mg·kg-1 to 50.0 mg·kg-1. The method’s limits were 0.3 mg·kg-1 and1.0 mg·kg-1 for detection and quantification, respectively. The method was highly precise; we obtained variable but low relative standard deviations (2.62 % - 12.66 %) for the studied gibberellic acid concentrations. We assessed accuracy through recovery percentages, ranging from 52.85 % - 63.68 %, for three gibberellic acid concentrations. We conclude that our analytical method can be used to measure gibberellic acid during the early stages of maize germination. In addition, the method could be used for the analysis of other types of plant matrices.

Emerging pollutants, such as parabens, pose challenges to removal through conventional wastewater treatment and require innovative approaches to remove these contaminants from water. This research evaluated the adsorption of methylparaben onto six biochars derived from fique bagasse. Batch experiments were carried out to investigate adsorption kinetics, equilibrium adsorption, and the influence of solution pH. Results showed that the adsorption capacity decreased at pH values above 6.0 for all evaluated biochars. Kinetic studies revealed that approximately 90% of methylparaben was removed within 10 h, with the pseudo-first-order (PFO) model providing the best fit to the experimental data compared to other tested models. The adsorption process was governed by both internal and external diffusion mechanisms. Equilibrium adsorption data were best described by the Langmuir isotherm, with the adsorption capacity strongly correlated to the specific surface area of the biochars. Maximum adsorption capacities (Q _max) were 134.285 mg g^–1 (FB-3Na), 87.461 mg g^–1 (FB-3C), and 64.349 mg g^–1 (FB-3). Molecular dynamics simulations provided insights into the physisorption of methylparaben onto fique bagasse biochar, confirming that the interactions were exclusively of the π–π and π–alkyl types.