Fenton-like oxidation of phenol with a Cu-chitosan/Al2O3 catalyst in a recirculating batch reactor

N. INCHAURRONDO; J. FONT; P. HAURE

Advanced Oxidation Technologies. Sustainable solutions for environmental treatments (Sustainable Energy Developments)

CRC Press/Balkema (Taylor & Francis Group)

Lugar: Leiden; Año: 2014;

Nowadays, Advanced Oxidation Processes (AOPs) are a promising alternative, with the common trend that they generate oxygen-based radicals in sufficient quantities to be able to oxidize the majority of the complex chemicals present in the aqueous effluent (Gogate and Pandit, 2004). Contaminants are oxidized through different reagents: ozone, hydrogen peroxide, oxygen and air or their combination. These procedures may also be combined with UV radiation (Liotta et al., 2009) and enhanced by catalytic materials. To choose the most appropriate technology, some aspects, such as the concentration and nature of the pollutants and the volume of wastewater, must be considered (Liotta et al., 2009). Among AOPs, Fenton processes (using reaction between Fe ions and hydrogen peroxide, i.e. Fenton´s reagent) have emerged as a viable alternative for the wastewater treatments of medium-high total organic carbon concentrations (Liotta et al., 2009). Hydrogen peroxide does not form any harmful by-products, and it is a non-toxic and ecological reactant. Moreover, although hydrogen peroxide is a relatively costly reactant, the peroxide oxidation compares very favorably to processes that use gaseous oxygen or ozone. The lack of a gas/liquid boundary removes mass-transfer limitations and the hydrogen peroxide acts as a free-radical initiator, providing hydroxyl (OH) radicals that promote the degradation of organics. This allows lowering residence times and enables conversion under milder conditions (Liotta et al., 2009). Furthermore, operating costs are compensated by the lower fixed capital cost with respect to ozonation and wet air oxidation (Centi et al., 2000). The objective of the present study is to synthesize and characterize a new Cu/chitosan composite catalyst obtained by immobilizing Cu-chitosan complexes onto alumina. The catalyst was used in the Catalytic Wet Peroxide Oxidation (CWPO) of phenol in a fixed bed recirculating reactor, at atmospheric pressure and moderate temperature of 50ºC. Phenolic compounds removal is a very active research field due to occurrence and the toxicity of phenolic pollutants in industrial wastewaters and therefore phenol is often used as a model compound for Fenton studies (Barrault et al., 2000, Crowther and Larachi, 2003, Inchaurrondo et al., 2012a, Inchaurrondo et al., 2012b, Liotta et al., 2009, Massa et al., 2011, Valkaj et al., 2007, Zazo et al., 2011).