This study aimed at preparing three types of biochar derived from rice husk via pyrolysis, including unactivated biochar, biochar chemically activated after with H₃PO₄, and biochar impregnated with γ-Fe₂O₃ nanoparticles. These materials were subsequently characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis, which revealed favorable textural properties, such as an increased surface area and porosity, as well as the presence of functional groups that facilitate the adsorption of methylene blue and malachite green in aqueous solutions. Several factors that affect the adsorption capacity, including the type of material, pH effect, and adsorbent dosage, were evaluated and optimized. The adsorption behavior was analyzed using isotherm and kinetic models to better understand the mechanisms involved. Under optimal conditions, biochar@γ-Fe₂O₃ NPs emerged as the most effective material due to its high surface area, functionalized surface, and magnetic properties, allowing easy water recovery without the need for complex instrumentation. Among the kinetic models evaluated, the pseudo-second-order model exhibited the highest linear regression coefficient (R² = 0.99), supporting a chemisorption process driven by strong interactions and stable chemical bond formation between the adsorbate and the adsorbent, while equilibrium data fit well with the Sips isotherm model, indicating a combination of monolayer and multilayer adsorption mechanisms. This magnetic biochar achieved removal efficiencies of 97% for methylene blue and 95% for malachite green, demonstrating a high performance and reusability over four cycles. Moreover, a possible adsorption mechanism of MB on the magnetic biochar was proposed to explain the interaction between the dye and the adsorbent surface. Thus, this work demonstrates that magnetic biochar is a sustainable and cost-effective adsorbent for wastewater treatment, integrating circular economy principles by transforming rice husk into a high-value material. The incorporation of γ-Fe₂O₃ nanoparticles enhances adsorption while enabling magnetic recovery, providing an eco-friendly and scalable solution for dye removal.

The Cabuya Negra (Agave americana L.) is widely distributed in South America and is considered a perennial plant due to its adaptability to dry and arid climates. It grows and develops extensively, mainly being used to delineate land boundaries. This study aimed to repurpose this biomass through the production of activated carbon as an adsorbent material for the removal of Diuron from aqueous solutions. The activated carbon was found to contain functional groups such as methyl, carbonyl, and hydroxyl, and the presence of phosphorus bonds was also observed, confirming the effectiveness of the chemical activation process using phosphoric acid. EDS analysis revealed that the activated carbon was primarily composed of carbon (85.68%), with a low ash content (11.8%), indicating that a significant portion of the organic material was consumed during the pyrolysis process. Two Diuron solutions (100 mL and 50 mL) were prepared, to which 0.25 g and 0.5 g of activated carbon were added. The adsorbent demonstrated high efficiency in Diuron removal, with the best treatment achieving 63.39% removal using 0.25 g of activated carbon with 100 mL of Diuron solution. These findings demonstrate that the activated carbon obtained is a viable alternative for the removal of this herbicide from aqueous solutions.

Soil contamination from oil spills in the canton of Francisco de Orellana in Ecuador is the biggest contamination problem in the region. It affects the quality of resources and poses health risks to the surrounding communities. To find an economical and efficient alternative for the remediation of soils contaminated with total petroleum hydrocarbons (TPHs), the application of oil palm bagasse was proposed. This is a locally available industrial waste. The methodology of the study was based on the application of six treatments (G-A, G-B, O-A, O-B, M-A, M-B) belonging to the bagasse of Elaeis guineensis and Elaeis oleifera, in two percentages of concentration, 98:2 and 96:4, during a period of 20 days. To determine the efficacy of the treatments, the bagasse of the two palms was characterized. In addition, the initial physicochemical characterization of the soil and the final characterization after the treatments were carried out. Soil characterization included analyses of macronutrients, micronutrients, metals, pH, EC and TPH. The results of the initial characterization revealed that the concentrations of electrical conductivity and TPH were more than 70 and 50 times the values established in the 97-A ministerial agreement, respectively. However, after the final characterization, the effectiveness of the treatments in reducing metal concentrations was observed. Likewise, conductivity levels were reduced by more than 10 times. As for TPH, the G-B treatment stood out by achieving a 56% removal of this pollutant.

La presente investigación se fundamentó en el empleo de la cáscara de limones de varias clases para producir licor artesanal a través del procedimiento de maceración. Con la asistencia de un diseño totalmente aleatorio 3x3x2 factores, se llevaron a cabo 18 formulaciones distintas del licor, fusionando los siguientes componentes de fabricación: Aguardiente de caña con una graduación de alcohol 50, 30 y 15% V/V, diferentes tipos de limón: Limón sutil (Citrus aurantifolia Swingle), Lima limón (Citrus aurantifolia) y Limón mandarina (Citrus taitensis Risso), y dos proporciones de azúcar 70 y 35g. Se determinaron las propiedades físico-químicas para cada formulación tales como: Porcentaje de alcohol, ºBrix, Densidad Relativa, Turbidez, Acidez, pH, Color; las cuales fueron comparadas con las propiedades físico-químicos de un licor comercial del mismo tipo el cual fue tomado como estándar. El programa Infostat fue el que se empleó para realizar el análisis estadístico. La formulación de licor base 50% de alcohol*Limón Mandarina*70 gramos de azúcar fue la combinación que más se aproximó a satisfacer las propiedades del estándar, lo cual constituyó el resultado más importante. Asimismo, se establecieron sus propiedades organolépticas (sabor, aroma y color) a través de encuestas y degustaciones realizadas por alumnos de la Facultad de Ciencias de la ESPOCH. La fórmula que fue más aceptada fue la del licor base 15% de alcohol*Lima limón*70 gramos de azúcar, lo que las convierte en las más adecuadas para ser replicadas en futuros proyectos comerciales. Para concluir la investigación, se elaboró el licor que logró las propiedades físico-químicas y organolépticas más óptimas según el estándar.

Allophane, halloysite, and imogolite are aluminosilicate clays, whose structures mainly contain silicon and aluminum. However, their morphologies differ markedly: allophane occurs as hollow/porous nanospheres, imogolite as single-walled aluminosilicate nanotubes, and halloysite as multi-walled rolled nanotubes. These structural contrasts control surface hydroxyl chemistry, pH-dependent (variable) charge, porosity, and the accessibility of inner/outer surfaces, which in turn govern the performance of adsorption, catalysis/photocatalysis, enzyme immobilization, biomedical delivery, hydrogel, and membrane technologies. Here, we critically synthesize recent advances with an emphasis on structure–property–function relationships and on the transition from natural/synthesized extracts to engineered/functionalized nanohybrids. At the end of the review, we show that targeted control of morphology, surface charge, and surface functionalization consistently shifts selectivity and stability, enabling application-specific optimization. We also highlight priorities for future research and explain how they contribute to Sustainable Development Goals.