No abstract

The primary source of the discharge of phenols into the environment is industrial activity, such as the production of pharmaceuticals, plastics, and pesticides, being the majority discharged into surface water sources, reaching concentrations around 0.001 to 0.400 mg/L. These compounds are considered a priority contaminant due to their toxicity to aquatic life and effects on human health. The presence of phenols even at low concentrations generates flavour and odour in drinking water. Due to the molecular stability and solubility of phenols in water, their removal by conventional water treatment methods is inefficient. However, adsorption with granular activated carbon (GAC), after conventional filtration with sand and anthracite, is an efficient technique for the reduction of organic compounds such as phenols. This paper studied the effect of applying double filtration to the reduction of phenols present in the filtered water of a conventional drinking water treatment plant, using two types of GAC (vegetable and mineral) and three GAC:Sand configurations (100:00; 00:100; 50:50). The configurations with GAC showed an efficient reduction of turbidity, organic matter indicator variables (UV254 absorbance and total organic carbon) and phenols, the mineral GAC being the most efficient GAC.

La Atrazina es uno de los herbicidas de mayor aplicación en el mundo, ingresa a los cuerpos de agua superficial por escorrentía, aplicación directa o dispersión aérea. Los métodos de tratamiento convencional de agua no remueven eficientemente este tipo de contaminantes, mientras que la adsorción con Carbón Activado Granular (CAG), es una técnica apropiada para la remoción de compuestos orgánicos del agua. En este trabajo, se evaluó la reducción de Atrazina de un agua dopada con dos concentraciones Atrazina, durante el proceso de tratamiento convencional (coagulación, floculación, sedimentación y filtración con arena y antracita) seguido de una doble filtración con dos medios adsorbentes granulares (CAG de origen Vegetal y Mineral), la cual permitió obtener una eficiente reducción de UV254 (86%) y Atrazina (99%).

La reducción de la calidad fisicoquímica y microbiológica de las fuentes superficiales de suministro para consumo humano, requiere utilizar tratamientos complementarios para garantizar el suministro de agua segura. En este estudio se evaluó la doble filtración con carbón activado granular (CAG: vegetal- cáscara de coco y mineral-bituminoso), para evaluar la reducción de turbiedad y materia orgánica disuelta (UV254). Se empleó agua filtrada de una Planta de Tratamiento Convencional–PTAP; la segunda filtración se realizó en columnas de laboratorio de flujo continuo a gravedad, con porcentajes CAG:arena 100:0, 80:20, 50:50, 30:70, 0:100. Mientras el filtro de arena fue más eficiente en remoción de turbiedad, las configuraciones con CAG lo fueron en la remoción de UV254, siendo más eficientes los filtros con mayor porcentaje de CAG. Los resultados demuestran que la doble filtración empleando CAG, puede ser una alternativa eficiente para la remoción de materia orgánica y la producción de un agua potable segura.

Nanoporous carbons were prepared via chemical and physical activation from mangosteen-peel-derived chars. The removal of atrazine was studied due to the bifunctionality of the N groups. Pseudo-first-order, pseudo-second-order, and intraparticle pore diffusion kinetic models were analyzed. Adsorption isotherms were also analyzed according to the Langmuir and Freundlich models. The obtained results were compared against two commercially activated carbons with comparable surface chemistry and porosimetry. The highest uptake was found for carbons with higher content of basic surface groups. The role of the oxygen-containing groups in the removal of atrazine was estimated experimentally using the surface density. The results were compared with the adsorption energy of atrazine theoretically estimated on pristine and functionalized graphene with different oxygen groups using periodic DFT methods. The energy of adsorption followed the same trend observed experimentally, namely the more basic the pH, the more favored the adsorption of atrazine. Micropores played an important role in the uptake of atrazine at low concentrations, but the presence of mesoporous was also required to inhibit the pore mass diffusion limitations. The present work contributes to the understanding of the interactions between triazine-based pollutants and the surface functional groups on nanoporous carbons in the liquid–solid interface.