Removal of ciprofloxacin from aqueous solutions using pillared clays

Emerging contaminants in the environment have caused enormous concern in the last few decades, and among them, antibiotics have received special attention. On the other hand, adsorption has shown to be a useful, low-cost, and eco-friendly method for the removal of this type of contaminants from water. This work is focused on the study of ciprofloxacin (CPX) removal from water by adsorption on pillared clays (PILC) under basic pH conditions, where CPX is in its anionic form (CPX-). Four different materials were synthetized, characterized, and studied as adsorbents of CPX (Al-, Fe-, Si-, and Zr-PILC). The highest CPX adsorption capacities of 100.6 and 122.1 mg g-1 were obtained for the Si- and Fe-PILC (respectively), and can be related to the porous structure of the PILCs. The suggested adsorption mechanism involves inner-sphere complexes formation as well as van der Waals interactions between CPX- and the available adsorption sites on the PILC surfaces.Fil: Roca Jalil, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Baschini, Miria Teresita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentin

The role of different parameters of synthesis in the final structure of Ti-containing mesoporous materials

Ti-containing mesoporous materials have been prepared by hydrothermal synthesis at 373 K and compared to pure siliceous MCM-41 synthesized in the same conditions. A detailed and correlative study about the effect of different synthesis parameters on the physicochemical properties of the material has been carried out. All the samples showed typical XRD patterns of a kind MCM-41 structure. It seems that the synthesis time and the surfactant chain length are critical variables to obtain good structures. Mesoporous structure allowed the incorporation of different degrees of Ti loading, although a lower degree of ordering was observed with the increase of metal content above 1%. Moreover, a high incorporation of Ti into the structure seems responsible for the development of a secondary mesoporosity confirmed by TEM and associated with a pronounced hysteresis loop in the N2 isotherm. DRUVA-Vis and XPS studies revealed that the Ti species are mainly found isolated and tetrahedral coordinated into the framework. The superego-Ti(IV) species generated by the interaction of Ti-MCM-41 with aqueous H2O2 have been studied by EPR spectroscopy and correlated to DRUVA-Vis and XPS measurements.Fil: Eimer, Griselda Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; ArgentinaFil: Chanquia, Corina Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; ArgentinaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; ArgentinaFil: Herrero, Eduardo Renato. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; Argentin

Distribución de tamaño de poros de materiales mesoporos ordenados de sílice con poros de geometría cilíndrica utilizando el método macroscópico VBS

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Distribución de tamaño de poros de materiales mesoporos ordenados de sílice con poros de geometría cilíndrica utilizando el método macroscópico VBS

En este artículo se muestra el método VBS (Villarroel-Barrera-Sapag) para el cálculo de la PSD de materiales mesoporosos. Es un método macroscópico mejorado que modifica la ecuación de Kelvin utilizada en el método BJH, y considera los mecanismos de condensación y evaporación capilar más aceptados para materiales mesoporosos. En este método se adiciona un término de corrección (fc) a la ecuación de Kelvin original y adicionalmente toma en cuenta el volumen de microporos, en caso de existir, de los MMO. A diferencia de los métodos macroscópicos tradicionales, el método VBS es autoconsistente con los datos experimentales. Se muestran las bases para el desarrollo de este método con el fin de ser aplicado en la obtención de una PSD confiable a partir de datos de isotermas de adsorción-desorción de N2 a 77 K para MMO de sílice (MCM-41 y SBA-15) con geometría de poros cilíndrica.Fil: Villarroel Rocha, Jhonny. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; ArgentinaFil: Deicy Barrera. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; ArgentinaFil: Karim Sapag. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; Argentin

Adsorption of Methane in Porous Materials as the Basis for the Storage of Natural Gas

It is well known that the natural gas (NG) is a substance of fossil origin from the decomposition of organic matter. It is found trapped under the terrestrial surface in stratus that avoid the natural release to atmosphere. These underground deposits can be oceanic or terrestrial. The NG is a homogeneous mixture, having variable proportions of hydrocarbons, being the main constitute the methane (CH4), which content generally ranges from 55 to 98 % in volume. Also, it contains ethane (C2H6), propane (C3H8) and heavier constitutes. Although it can be found in gas phase or in solution with oil, under normal atmospheric conditions, remains in gas phase. It may have some impurities or substances that are not hydrocarbons, such as Hydrogen Sulfide, Nitrogen and Carbon Dioxide (Figure 1). According to its origin, natural gas is classified in associated and non-associated, being the first, the one which remains in contact and/or dissolved with the oil from the deposit. The non-associated gas can be found in deposits lacking oil crude at the initial conditions of pressure and temperature.Fil: Solar, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Garcia Blanco, Andres Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Vallone, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentin

Photothermal Desorption of Single-Walled Carbon Nanotubes and Coconut Shell-Activated Carbons Using a Continuous Light Source for Application in Air Sampling

Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02?<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sampleFil: Floyd, Evan L.. Oklahoma State University; Estados UnidosFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Oh, Jonghwa. University Of Alabama At Birmingahm; Estados UnidosFil: Lungu, Claudiu T.. University Of Alabama At Birmingahm; Estados Unido

O2 Adsorption on ZIF-8: Temperature Dependence of the Gate-Opening Transition

We present the results of an adsorption isotherm study of O2 on the metal–organic framework ZIF-8. This material undergoes a structural transition (“gate-opening”) as a function of increasing pressure and sorbent loading, which manifests itself in the isotherm data as a quasi-vertical substep. We used this feature to explore the temperature dependence of the structural transition; we have found that the transition occurs below the saturated vapor pressure only for temperatures below 95.39 K. The adsorption isotherm data measured at various temperatures were used also to determine the isosteric heat of adsorption of O2 on this sorbent for different sorbent loading values. We have studied the adsorption kinetics for this system, that is, how the equilibration times for adsorption change as a function of sorbent loading. The sorbent loading dependence of the equilibration time is nonmonotonic; this characteristic appears to be related to the structural transition in the sorbent.Fil: Russell, Brice Adam. Southern Illinois University. Department Of Physics; Estados UnidosFil: Villarroel Rocha, Jhonny. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Migone, Aldo D.. Southern Illinois University. Department Of Physics; Estados Unido

Produção e caracterização de carvões ativados a partir de residuos de Candeia (Eremanthus erythropappus) e testes de adsorção de compostos orgânicos

En este trabajo se prepararon dos carbones activados (CA), utilizando como agentes activantes ZnCl2 y K2CO3, denominados CA/ZnCl2, CA/K2CO3, respectivamente, a partir de residuos generados en el proceso de extracción del aceite esencial de candeia, árbol nativo de Brasil. Estos carbones se caracterizaron por microscopía electrónica de barrido, análisis termogravimétrico, análisis elemental, superficie específica por el método BET e índice de iodo. Estos materiales se probaron en la adsorción de dos moléculas modelos: el fenol y el azul de metileno, y se comparó su capacidad de adsorción con un carbón activado comercial (Merck), denominado CA/Com. Las isotermas de adsorción para CA/ZnCl2, CA/K2CO3 y CA/Com mostraron capacidades de adsorción máxima de 297, 228 y 271 mg g-1, para azul de metileno y de 109, 195 y 161 mg g-1, para el fenol, respectivamente. Los resultados evidenciaron que los carbones son eficientes en el proceso de adsorción de las moléculas modelo ensayadas. Las isotermas fueron ajustadas a las ecuaciones de Langmuir y de Freundlich. El modelo de Langmuir entregó un ajuste mejor, mostrando que los adsorbentes presentan superficies energéticamente más uniformes. Los carbones activados producidos se presentan como potenciales adsorbentes para compuestos orgánicos, agregando un valor adicional al residuo.In this work, two activated carbons were prepared, using as activating the ZnCl2 and K2CO3, denominated CA/ZnCl2, CA/K2CO3, respectively, from waste generated in the process of extraction of essential oil Candeia, tree native to Brazil. These carbons were characterized by scanning electron microscopy, thermal analysis, elemental analysis, BET surface area and iodine index. These materials were tested in the adsorption of model molecules: Phenol and Methylene Blue, and was used a commercial activated carbon (Merck) for comparison purposes. Adsorption isotherms for CA/ZnCl2, CA/K2CO3 and CA/Com showed maximum sorption capacities of 297, 228 and 271 mg g-1 for Methylene Blue and 109, 195 and 161 mg g-1 for phenol respectively. The results showed that the carbons are efficient in the adsorption process of molecules tested. The isotherms were fitted to equations of Langmuir and Freundlich, the Langmuir model provided better fit, showing that the adsorbents have energetically uniform surfaces. The materials produced were characterized as potential adsorbents for organic compounds can be used as an alternative for obtaining activated carbons, as well as adding value to the residue.Fil: Resende, Eliane C. de. Universidade Federal de Lavras; BrasilFil: Ramos, Paulize H.. Universidade Federal de Lavras; BrasilFil: Guerreiro, Mário C.. Universidade Federal de Lavras; BrasilFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina. Universidad Nacional de San Luis; Argentin

Batch and Column Studies for the Removal of Lead from Aqueous Solutions Using Activated Carbons from Viticultural Industry Wastes

Adsorption studies (kinetic, batch and dynamic assays) were carried out for lead removal from aqueous solutions using wastes from the wine industry. The adsorbents used were obtained from grape stalk and pomace.These materials were carbonized, briquetted and activated with steam. Addition of a leaching step before activation lowered the high ash content of the materials.The products were characterized by elemental and proximate analysis, point of zero charge pH, specific surface area, pore-size distribution, Fourier transform infrared spectroscopy and surface acidic and basic groups. Considering the physicochemical and textural properties of the adsorbents, a comparative analysis of the results was made. These solids showed a marked basic character; therefore, the pH was a very important variable in adsorption tests, and thus it was necessary to maintain the pH in a favourable range. Batch equilibrium assays showed that the tested adsorbents had good adsorption capacities, better than the ones reported previously for similar materials. In dynamic tests, the removal of lead by both activated carbon briquettes was good and attributed to the coupling of adsorption and precipitation as a result of the increase in the pH values, which could not be controlled.Fil: Deiana, A. C.. Universidad Nacional de San Juan. Facultad de Ingenieria. Instituto de Ingenieria Quimica; ArgentinaFil: Gimenez Guerrero, Marianela Gema. Universidad Nacional de San Juan. Facultad de Ingenieria. Instituto de Ingenieria Quimica; ArgentinaFil: Rómoli, Santiago. Universidad Nacional de San Juan. Facultad de Ingenieria. Instituto de Ingenieria Quimica; ArgentinaFil: Sardella, Maria Fabiana. Universidad Nacional de San Juan. Facultad de Ingenieria. Instituto de Ingenieria Quimica; ArgentinaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentin

Materiales nanoporosos a partir de residuos para captura de CO2 y almacenamiento de H2

En este trabajo se obtuvieron dos materiales nanoporosos (Metal Organic Framework y Carbón activado) los cuales se obtuvieron a partir de residuos: envases de bebidas (PET) y carozos de duraznos. Estos materiales se caracterizaron mediante difracción de rayos X en polvo, técnicas espectroscópicas, análisis termogravimétrico, adsorción-desorción de N2 a 77 K, adsorción de CO2 a 273 K y se evaluó su capacidad de captura de CO2 a 308 K y almacenamiento de H2 a 77 K. Se encontró que estos materiales poseen interesantes valores de capacidades de adsorción de CO2 y H2, las cuales están relacionadas directamente con sus propiedades fisicoquímicas, siendo la más importante la textura de dichos materialesFil: Villarroel Rocha, Dimar. Universidad Nacional de San Luis.Fil: Arroyo Gómez, Jose. Universidad Nacional de San Luis.Fil: Sapag, Karim. Universidad Nacional de San Luis