Effect of Operating Parameters, Reaction Kinetics and Comparative Assessment of Fluidized-Bed Fenton Oxidation of 4-Nitrophenol

Abstract

The oxidation of 4-Nitrophenol (4-NP) has been studied using recirculating fluidized-bed Fenton process. The effect of various parameters such as pH, the concentration of hydrogen peroxide, the concentration of ferrous ions, various types of carriers, and dosage of the carrier were investigated on the oxidation of 4-NP. Al2O3 and SiO2 were used as two different carriers for the oxidation of 4-NP. The experimental results are reported in terms of degradation percentage of 4-NP, Chemical Oxygen Demand (COD), and Total Organic Carbon (TOC). The results showed that the degradation and COD removal of 4-NP in the presence of Al2O3 carrier was higher as compared to SiO2 carrier. The degradation of 96% was achieved under the optimal operating conditions of pH 3, 0.2 mM Fe2+, 4 mM H2O2, and 5g/L of Al2O3 as a carrier. The TOC and COD removals were 70% and 55%, respectively after 1 h of reaction time. The presence of Fe-O bond onto Al2O3 carrier after the reaction was confirmed by the FT-IR studies. The total iron remained in the solution after reaction using fluidized-bed Fenton process was lower (8.5%) than homogeneous Fenton process (17%). The fluidized bed Fenton process also showed higher TOC and COD removal as compared to the homogeneous Fenton process.