Zeolite-mediated advanced oxidation of model chlorinated phenolic aqueous waste. Part 1: Aqueous phase Fenton catalysis

Advanced (hydroxyl radical) oxidation has been used in combination with zeolitic materials in the destruction of chlorinated phenols in a model aqueous waste stream. The generation of the hydroxyl radicals is expensive, and their lack of selectivity leads to their loss by parallel reaction with other species ('scavengers'). This work attempts to achieve more efficient use of the radicals by the selective adsorption of the target micropollutant onto a zeolite, leaving the dissolved scavengers to be removed by through-flow. The zeolite can then be regenerated, by advanced oxidation of the adsorbed organics using Fenton's reagent. This paper describes the adsorption of 2,4-dichlorophenol (2-4-DCP) in aqueous solution onto zeolites Beta and Y at 20degreesC. The Fenton oxidation of 2,4-DCP without zeolite was investigated at pH 3.5. A breakthrough curve for the adsorption of 2,4-DCP (10(-3) m) from aqueous solution onto zeolite Beta in a 5 mm diameter x 50 mm adsorption column at flow rate of 1.5 ml/min 20degreesC is presented. Regeneration of the column using Fenton's reagent is described. The effect of model inorganic and organic 'scavengers' on the adsorption process was investigated using 0.1 m sodium sulphate and 1 and 10% acetone as the 'scavengers'. The inorganic 'scavenger' increased the adsorption capacity of the column, believed to be due to the 'salting-out' effect. The organic 'scavenger' decreased the adsorption capacity of the column, believed to be due to a 'co-solvent' effect. An outline economic evaluation indicates that the approach is potentially viable.