In this study, a blast furnace slag (BFS) and fly ash (FA) based adsorbent geopolymer to be used for removing Pb²⁺ from aqueous solutions were synthesized using the hydrothermal method at 60 °C for 24 h, and then cured at 25 °C for another six days. The alkali activator applied in this work was a combination of sodium hydroxide and sodium silicate solutions at a mass ratio of 2. The geopolymer slurry was adjusted to a Si/Al molar ratio of 3. A BFS-based geopolymer (GS) having a specific area of 23.56 m²/g and pore size and volume of 7.8 nm and 73 cm³/kg, respectively, surpassed the raw material surface by approximately 13-fold. An FA-based geopolymer (GA) having a specific area of 35.97 m²/g and a size and porous volume of 9 nm and 124 nm, respectively, surpassed the raw material surface by approximately 23-fold. In addition, GS and GA showed a cation exchange capacity (CEC) of 241.30 and 286.96 Meq/100 g, respectively. X-ray diffraction (XRD) determined sample crystallinity and it was proven by scanning electron microscopy (SEM), showing that both geopolymers were constituted of unreacted particles surrounded by amorphous and semi-amorphous products. Through Fourier transform infrared spectroscopy (FTIR), a band that was assigned to the asymmetric stretching vibration of Si-O-M (M = Na⁺ and/or Ca²⁺) non-bridging oxygen type was observed, which suggested that Na and Ca could serve as exchangeable ions in the ionic exchange process. Adsorption test data indicated that good adsorption was obtained when a neutral pH was used at room temperature, and the adsorption isotherm showed that GA had more adsorption sites than GS, which meant greater maximum adsorption capacity.

Different carbon materials, such as activated carbon and carbon aerogel, are used widely as adsorbents due to their high surface area. Carbon nanospheres (CNS), a nanometric form of carbon, are commonly used in drug delivery, heterogeneous catalysis, and encapsulation of catalysts. However, these properties sill can be improved by N doping. On the other hand, heavy metal ions are considered one of the most toxic aquatic pollutants, and their removal is a current line of research. Thus, the objective of the present study was to reduce the diameters of CNS, augment nitrogen content using different strategies, and assess the adsorption capacities of the newly synthesized CNS. In this work, 3 nitrogen-dopped CNS materials were synthesized via one-pot sol-gel synthesis their morphology and chemical composition were evaluated, and adsorption capacities were investigated with the batch adsorption method. The obtained results show that the particles´ size of the spheres can be reduced by producing steric impediment for nucleation or by cross-linking agent addition. Additionally, newly synthesized materials showed increased capacity for Pb adsorption, which may present an advantage for their industrial application.

This chapter describes the synthesis, characterization, and application of chitosan-montmorillonite microsphere composites for the removal of fluoride and chromium from aqueous solution. The basic structure of clays and composite clays is described and reviewed, with emphasis on their adsorption properties for anions present in water, such as fluoride and chromate. A practical case study is presented for the synthesis of low-molecular-weight chitosan and a montmorillonite-type clay for adsorption. using pH-variation gelation to obtain microspheres. The results of the physicochemical characterization of the clay show the interaction of chitosan between the nanoclay sheets, due to the electrostatic attraction between the hydroxyl groups of the clay and the protonated amine of the chitosan. The zero charge point for the composite clay was 7.3, indicating a neutral surface at that pH value. The adsorption equilibrium results at pH 5, 7 and 9 at T = 25 °C demonstrated the positive adsorption of fluoride and chromate ions on nanoclay-chitosan compounds by decreasing the pH of the solution. The maximum adsorption capacity obtained for an equilibrium concentration of 40 mg/L was 10 mg/g and 90 mg/g for fluoride and chromate, respectively. These results demonstrate a novel, simple, and easily applicable adsorbent. The results regarding the effect of temperature (15, 25, and 35 °C) on the adsorption equilibrium and adsorption capacity of the composite clay microspheres suggest a high chromate adsorption energy, achieved through surface complexation, creating ideal conditions for the removal of this element from aqueous solution.

Objectives. Contamination with heavy metals has augmented in last decades due to several factors. So, scientific community has a challenge to develop new and more efficient methods for contaminants removal. Electroadsorption is one of investigated techniques with promising results. The main challenge with this technique is determination of optimal parameters, such as electrode material, time and conditions of adsorption. Material for electrode for electroadsorption must fulfil some criteria: high electroactive area, low electrical resistance and environmental compatibility. For that reason, our research group decided to synthetize a set of new carbon materials with high surface area and features than make them interesting to test them as an electrode material. Methodology. 3 carbon materials were synthetized by sol-gel method using different time and temperature conditions. All materials were characterized by scanning electron microscopy and other techniques. FTO glasses were modified with synthetized materials separately. Electroadsorption of Cu (II) was conducted at room temperature. Contribution. In this work we demonstrate an easy synthesis of 3 carbonaceous materials with high surface area capable to remove Cu (II) from water solution by electroadsorption.

En este trabajo se realizó la síntesis de un composito poroso a partir de ceniza volcánica proveniente de laexhalación del volcán Popocatépetl en el mes de mayo del 2023. La síntesis de los compositos se realizómediante una reacción de geopolimerización en medio alcalino. Los datos de equilibrio y cinética de adsorciónse obtuvieron en un adsorbedor de lote y en una columna de adsorción, respectivamente. Los experimentosse realizaron a pH =5 y T = 25 °C y se usaron concentraciones entre 20 y 200 ppm de cada uno de loscontaminantes. Los datos experimentales se interpretaron con el modelo de la isoterma de Langmuir y seobservó que el equilibrio de adsorción de los metales la adsorción sobre los compositos se favorece deacuerdo con la siguiente relación Cu > Pb > Cd, para los iones de carga negativa la capacidad de adsorciónfue de 5 mg/g para el Flúor y de 1.8 mg/g para el Cromo VI. Para el caso de los colorantes azul de metilenoy naranja de metilo, el porcentaje de remoción fue del 95 %.

En este proyecto analizó la capacidad de adsorción de bioadsorbentes naturales como la cáscara de naranja y cáscara de huevo para su uso de la remoción de contaminantes tóxicos en agua, enfocándose específicamente en iones metálicos como plomo, cobre y algunos colorantes industriales. Estos contaminantes son comúnmente vertidos por industrias como la textil, representando una amenaza significativa para los ecosistemas acuáticos y la salud humana. Los datos de equilibrio de adsorción se obtuvieron utilizando un adsorbedor de lote a condiciones de T = 25 °C y pH = 4, en donde se puso en contacto una masa conocida del bioadsorbente con un volumen de plomo o cobre, para posteriormente analizar la concentración en equilibrio por Espectrometría de Absorción Atómica. Los bioadsorbentes se caracterizaron con la técnica de espectroscopía infrarroja (FTIR) para determinar los grupos funcionales presentes en el material adsorbente. Los resultados experimentales del equilibrio de adsorción se interpretaron con el modelo de la isoterma de Langmuir. Para la remoción de plomo, se observó una máxima capacidad de adsorción de 30 mg/g y de 12 mg/g para la cáscara de huevo y la cáscara de naranja, respectivamente. En el caso del cobre, se observó una máxima capacidad de adsorción de 15 mg/g para ambos bioadsorbentes. Este estudio contribuye al desarrollo de tecnologías limpias dentro del marco de la economía circular y el aprovechamiento de residuos orgánicos.