Continuous heterogeneous Fenton type degradation of a model dye

MAISTERRENA, AGUSTINA; CASSANELLO, MIRYAN; DOUMIC, LUCILA; AYUDE, MARIA ALEJANDRA; SALIERNO, GABRIEL

Qingdao

Simposio; 10th International Symposium on Catalysis in Multiphase Reactors (CAMURE-10); 2017

Chinese Academy of Science

Prussian Blue nanoparticles (PBNP) supported onto -Al2O3 beads of 2.5 mm mean diameter have proved to be a useful catalysts for batch removal, and significant mineralization, of the model azo dye Orange G (OG) via the heterogeneous Fenton type (HFT) process [1]. In this work, results of carrying out the process in a continuously operated packed bed reactor are presented to examine the influence of oxidant concentration and molar flow rate on the dye removal efficiency. Moreover, iron leaching and catalysts stability are particularly analyzed under continuous operation. Experiments were carried out in a thermostated packed bed reactor; the initial dye concentration (0.02 mM), the mass of catalyst (20 g), the temperature (343 K) and pH (3) were kept constant. The reactor was a 2.4 cm internal diameter glass column filled with catalyst for 8 cm length; glass beads of 2 mm diameter were packed in the entrance region to promote good dispersion. The liquid was circulated in upwards direction to ensure complete wetting of the catalyst. The reactor and a previous glass coil were immersed in a thermostatic bath regulated at the desired temperature. Inlet and outlet concentrations of dye, hydrogen peroxide and oxygen were regularly measured for each experiment for at least one hour to check that the steady state was attained. Figure 1 illustrates results of experiments carried out with different oxidant concentrations. The dye and oxidant conversions under steady state condition are represented as a function of the molar oxidant flow rate. These preliminary results point to a combined influence of the flow rate and concentration of the oxidant. When the liquid flow rate is too low, even if the oxidant conversion increases due to a longer residence time, the improvement in dye (OG) conversion is less marked indicating a diminished efficiency. As expected, iron leaching increases with flow rate; the hourly lost amount was between 0.05-0.2% of the total iron load. Further studies are ongoing to systematically analyze the dye conversion, leached iron and TOC conversion for assessing the influence of oxidant molar flow rate on mineralization efficieny and catalysts stability.