Catalytic decomposition of hydrogen peroxide and 4-chlorophenol in the presence of modified activated carbons

Abstract

The objective of this research was to examine the heterogeneous catalytic decomposition of H 2 O 2 and 4-chlorophenol (4-CP) in the presence of activated carbons modified with chemical pretreatments. The decomposition of H 2 O 2 was suppressed significantly by the change of surface properties including the decreased pH pzc modified with oxidizing agent and the reduced active sites occupied by the adsorption of 4-CP. The apparent reaction rate of H 2 O 2 decomposition was dominated by the intrinsic reaction rates on the surface of activated carbon rather than the mass transfer rate of H 2 O 2 to the solid surface. By the detection of chloride ion in suspension, the reduction of 4-CP was not only attributed to the advanced adsorption but also the degradation of 4-CP. The catalytic activity toward 4-CP for the activated carbon followed the inverse sequence of the activity toward H 2 O 2 , suggesting that acidic surface functional group could retard the H 2 O 2 loss and reduce the effect of surface scavenging resulting in the increase of the 4-CP degradation efficiency. Few effective radicals were expected to react with 4-CP for the strong effect of surface scavenging, which could explain why the degradation rate of 4-CP observed in this study was so slow and the dechlorination efficiency was independent of the 4-CP concentration in aqueous phase. Results show that the combination of H 2 O 2 and granular activated carbon (GAC) did increase the total removal of 4-CP than that by single GAC adsorption.

Prussian Blue onto Activated Carbon as a Catalyst for Heterogeneous Fenton-Like Processes

“…The consumption rate of H 2 O 2 slightly decreases in the presence of Orange G, probably due to a partial blockage of active sites by the adsorbed dye, and by the competition of the organic species for the generated radicals' propagation. This is in line with outcomes reported with GAC for 4-chlorophenol and phenol by [2] and [12], respectively.…”

“…Thus, heterogeneous Fenton or Fenton-like degradation processes appear as a practical way to overcome these limitations. Activated carbons (ACs) have emerged as a good choice for oxidation processes working as catalysts themselves [2], [3] or as catalyst supports [4], [5]. Adsorption and reaction co-exist in heterogeneous AC supports, largely determining the performance of the oxidation process.…”

Carbon materials and catalytic wet air oxidation of organic pollutants in wastewater

“…30 years later, the use of carbon as catalyst for environmental oxidation processes is starting to develop. Excluding the patent and scientific literature on AC regeneration via WAO, about 25 papers were published during the last 10 years on catalytic wet oxidation using carbons as direct catalyst [26][27][28][29]35,61,[79][80][81][82][160][161][162][163][164][165][166][167][168][169][170][171][172][173]. Strictly, half of these studies was devoted either to low temperature oxidation employing AC and H 2 O 2 or O 3 oxidants [166][167][168][169][170][171][172][173] or partial oxidation for fine chemical synthesis [80][81][82] rather than to CWAO.…”

“…Further exposure of oxidised carbons to CO 2 , N 2 or H 2 during temperature rating up to 1177°C can progressively eliminate specific (acid) surface oxide groups to obtain carbons with basic properties [82,100,167,174,177,178]. High temperature N 2 -reduction produced basic but reoxidisable surfaces at room temperature, whereas a reducing H 2 -atmosphere provided stable basic carbon surfaces [177].…”

Estudio cinético de la descomposición catalizada de peróxido de hidrógeno sobre carbón activado

“…Lin y Gurol en 1998 estudiaron la DCPH catalizada por oxido de hierro, 7 y Huang et al en 2003 estudiaron la descomposición catalizada por carbones activados modificados, 8 encontrando que la tendencia de los datos experimentales se ajustan a una ley ciné-tica de tipo Langmuir-Hinshelwood, como la que se muestra en la Ecuación 2, (2) donde k vel y k h se interpretan como la constante cinética de reacción y la de formación de reactivos a partir de intermediarios, respectivamente; CAT es la relación masa/volumen de carbón activado y [H 2 O 2 ] 0 es la concentración inicial de peróxido de hidrógeno. Sin embargo estos estudios no se realizaron de manera sistemática, esto es, se llevaron a cabo a una sola temperatura y una sola relación masa-volumen de catalizador y además se realizaron pocos experimentos en un pequeño intervalo de concentraciones iniciales de peróxido de hidrógeno (1,8x10 -3 a 4,0x10 -2 mol L -1 ).…”