13 research outputs found
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
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
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