13 research outputs found

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

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    [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鈥揳dsorbate 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 carb贸n activado en la degradaci贸n del medio de contraste triyodado diatrizoato (DTZ) mediante la utilizaci贸n simult谩nea de radiaci贸n gamma y carb贸n activado. Cuatro carbones activados comerciales (Ceca, Witco, Sorbo y Merck) con diferentes caracter铆sticas qu铆micas y texturales fueron utilizados para este prop贸sito. El porcentaje de degradaci贸n de DTZ obtenido fue considerablemente mayor con el sistema radiaci贸n gamma/carb贸n activado (GM/CA) que con la radiolisis en ausencia de carb贸n activado, y este sistema depend铆an de la cantidad espec铆fica de carb贸n activo empleado. En primer lugar, hemos optimizado la cantidad de carb贸n activado necesario para maximizar la cantidad de DTZ eliminado por el sistema GM/CA (0,06 g). Las constantes de velocidad de degradaci贸n fueron mayores con el sistema GM/AC que con s贸lo radiolisis, lo que evidencia un efecto sin茅rgico que favorece la eliminaci贸n de los contaminantes. Este efecto sin茅rgico es independiente de las caracter铆sticas texturales del carb贸n activado, pero no de sus caracter铆sticas qu铆micas, observ谩ndose una mayor actividad sin茅rgica de los carbones con un contenido superficial m谩s alto de ox铆geno, concretamente de grupos quinona. Para que el efecto sin茅rgico tenga lugar se requiere la presencia de interacciones electrost谩ticas adsorbente-adsorbato.Peer reviewe

    El carb贸n activado como promotor de especies altamente oxidantes en su interacci贸n con la radiaci贸n gamma

    No full text
    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鈥揳dsorbate electrostatic interactions, and this effect is absent when these interactions are hinderedEl objetivo de este estudio fue analizar la influencia de la presencia de carb贸n activado en la degradaci贸n del medio de contraste triyodado diatrizoato (DTZ) mediante la utilizaci贸n simult谩nea de radiaci贸n gamma y carb贸n activado. Cuatro carbones activados comerciales (Ceca, Witco, Sorbo y Merck) con diferentes caracter铆sticas qu铆micas y texturales fueron utilizados para este prop贸sito. El porcentaje de degradaci贸n de DTZ obtenido fue considerablemente mayor con el sistema radiaci贸n gamma/carb贸n activado (GM/CA) que con la radiolisis en ausencia de carb贸n activado, y este sistema depend铆an de la cantidad espec铆fica de carb贸n activo empleado. En primer lugar, hemos optimizado la cantidad de carb贸n activado necesario para maximizar la cantidad de DTZ eliminado por el sistema GM/CA (0,06 g). Las constantes de velocidad de degradaci贸n fueron mayores con el sistema GM/AC que con s贸lo radiolisis, lo que evidencia un efecto sin茅rgico que favorece la eliminaci贸n de los contaminantes. Este efecto sin茅rgico es independiente de las caracter铆sticas texturales del carb贸n activado, pero no de sus caracter铆sticas qu铆micas, observ谩ndose una mayor actividad sin茅rgica de los carbones con un contenido superficial m谩s alto de ox铆geno, concretamente de grupos quinona. Para que el efecto sin茅rgico tenga lugar se requiere la presencia de interacciones electrost谩ticas adsorbente-adsorbat

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

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    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聽掳C during 20聽min and a KOH:PS ratio of 1:5), a microporous AC (MW800-20-1:5, with SBET聽=聽1196聽m2聽g-1, TOC聽=聽56.2% and removal of AMX and SMX聽=聽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聽卤聽5聽mg聽g-1 and 217聽卤聽8聽mg聽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
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