Activated carbon as promoter of highly oxidant species in its interaction with gamma radiation

[EN] The objective of this study was to analyse the influence of the presence of activated carbon on the degradation of the triiodinated contrast medium diatrizoate (DTZ) by the simultaneous use of gamma radiation and activated carbon. Four commercial activated carbons (Ceca, Witco, Sorbo and Merck) with different textural and chemical characteristics were used for this purpose. The percentage DTZ removal obtained was considerably higher with the gamma radiation/activated carbon (GM/AC) system than with radiolysis in the absence of activated carbon, and it depended on the specific activated carbon employed. The amount of activated carbon required to maximize the amount of DTZ removed by the GM/AC system (0.06 g) was optimized. The degradation rate constants were higher with the GM/ AC system than with radiolysis alone, evidencing a synergic effect that favours pollutant removal. This synergic effect is independent of the textural but not the chemical characteristics of the activated carbon, observing a higher synergic activity for activated carbons with greater surface oxygen content, specifically quinone groups. It is also highlighted that the synergic effect of the activated carbon requires adsorbent–adsorbate electrostatic interactions, and this effect is absent when these interactions are hindered.[ES] El objetivo de este estudio fue analizar la influencia de la presencia de carbón activado en la degradación del medio de contraste triyodado diatrizoato (DTZ) mediante la utilización simultánea de radiación gamma y carbón activado. Cuatro carbones activados comerciales (Ceca, Witco, Sorbo y Merck) con diferentes características químicas y texturales fueron utilizados para este propósito. El porcentaje de degradación de DTZ obtenido fue considerablemente mayor con el sistema radiación gamma/carbón activado (GM/CA) que con la radiolisis en ausencia de carbón activado, y este sistema dependían de la cantidad específica de carbón activo empleado. En primer lugar, hemos optimizado la cantidad de carbón activado necesario para maximizar la cantidad de DTZ eliminado por el sistema GM/CA (0,06 g). Las constantes de velocidad de degradación fueron mayores con el sistema GM/AC que con sólo radiolisis, lo que evidencia un efecto sinérgico que favorece la eliminación de los contaminantes. Este efecto sinérgico es independiente de las características texturales del carbón activado, pero no de sus características químicas, observándose una mayor actividad sinérgica de los carbones con un contenido superficial más alto de oxígeno, concretamente de grupos quinona. Para que el efecto sinérgico tenga lugar se requiere la presencia de interacciones electrostáticas adsorbente-adsorbato.Peer reviewe

El carbón activado como promotor de especies altamente oxidantes en su interacción con la radiación gamma

The objective of this study was to analyse the influence of the presence of activated carbon on the degradation of the triiodinated contrast medium diatrizoate (DTZ) by the simultaneous use of gamma radiation and activated carbon. Four commercial activated carbons (Ceca, Witco, Sorbo and Merck) with different textural and chemical characteristics were used for this purpose. The percentage DTZ removal obtained was considerably higher with the gamma radiation/activated carbon (GM/AC) system than with radiolysis in the absence of activated carbon, and it depended on the specific activated carbon employed. The amount of activated carbon required to maximize the amount of DTZ removed by the GM/AC system (0.06 g) was optimized. The degradation rate constants were higher with the GM/ AC system than with radiolysis alone, evidencing a synergic effect that favours pollutant removal. This synergic effect is independent of the textural but not the chemical characteristics of the activated carbon, observing a higher synergic activity for activated carbons with greater surface oxygen content, specifically quinone groups. It is also highlighted that the synergic effect of the activated carbon requires adsorbent–adsorbate electrostatic interactions, and this effect is absent when these interactions are hinderedEl objetivo de este estudio fue analizar la influencia de la presencia de carbón activado en la degradación del medio de contraste triyodado diatrizoato (DTZ) mediante la utilización simultánea de radiación gamma y carbón activado. Cuatro carbones activados comerciales (Ceca, Witco, Sorbo y Merck) con diferentes características químicas y texturales fueron utilizados para este propósito. El porcentaje de degradación de DTZ obtenido fue considerablemente mayor con el sistema radiación gamma/carbón activado (GM/CA) que con la radiolisis en ausencia de carbón activado, y este sistema dependían de la cantidad específica de carbón activo empleado. En primer lugar, hemos optimizado la cantidad de carbón activado necesario para maximizar la cantidad de DTZ eliminado por el sistema GM/CA (0,06 g). Las constantes de velocidad de degradación fueron mayores con el sistema GM/AC que con sólo radiolisis, lo que evidencia un efecto sinérgico que favorece la eliminación de los contaminantes. Este efecto sinérgico es independiente de las características texturales del carbón activado, pero no de sus características químicas, observándose una mayor actividad sinérgica de los carbones con un contenido superficial más alto de oxígeno, concretamente de grupos quinona. Para que el efecto sinérgico tenga lugar se requiere la presencia de interacciones electrostáticas adsorbente-adsorbat

Optimizing microwave-assisted production of waste-based activated carbons for the removal of antibiotics from water

This work aimed at the microwave-assisted production of activated carbon (AC) from primary paper mill sludge (PS) for the adsorption of antibiotics from water. Production conditions, namely pyrolysis temperature, pyrolysis time and activating agent (KOH):PS ratio, were optimized as a function of product yield, specific surface area (SBET), total organic carbon (TOC) content and adsorptive removal percentage of two target antibiotics (amoxicillin (AMX) and sulfamethoxazole (SMX)). Under the optimized conditions (pyrolysis at 800 °C during 20 min and a KOH:PS ratio of 1:5), a microporous AC (MW800-20-1:5, with SBET = 1196 m2 g-1, TOC = 56.2% and removal of AMX and SMX = 85% and 72%, respectively) was produced and selected for further kinetic and equilibrium adsorption studies. The obtained results were properly described by the Elovich reaction-based kinetic model and the Langmuir equilibrium isotherm, with maximum adsorption capacities of 204 ± 5 mg g-1 and 217 ± 8 mg g-1 for AMX and SMX, respectively. Considering the satisfactory comparison of these results with the performance of commercial and alternative AC produced by conventional pyrolysis, this work demonstrated the feasibility of the microwave-assisted production of environmentally and energetically sustainable waste-based AC to be applied in the efficient removal of antibiotics from water.publishe