Preparation of mesoporous Fe2O3·SiO2 composite from rice husk as an efficient heterogeneous Fenton-like catalyst for degradation of organic dyes

Mesoporous Fe2O3·SiO2 composite was prepared from rice husk for heterogeneous Fenton-like process and the performance was evaluated from oxidation of dyes in aqueous solution. Iron oxide particles with average 5 nm (8.1 wt.% of composite) were well dispersed on surface of silica particles and the Fe2O3·SiO2 composite was mesoporous with a high surface area (109.5 m2/g). The reaction rate and degradation efficiency of tartrazine by as-synthesized Fe2O3·SiO2 composite were compared with those of physically mixed Fe2O3-SiO2, as-synthesized (Fe2O3 and SiO2), and commercial Fe2O3. At optimal reaction conditions (tartrazine concentration of 50 mg/L, dosage catalyst of 0.5 g/L, H2O2 concentration of 12 mM, pH 3.0, and temperature of 30 °C), the Fe2O3·SiO2 composite showed much greater reaction rate and degradation efficiency of tartrazine than the others. In addition, the reusability of as-prepared composite was evaluated. The reaction rate and degradation efficiency of tratrazine were slightly decreased by the addition of NaCl and Na2SO4 in the solution where the addition of Na2HPO4 and EDTA led to drastic reduction of oxidation performance. The degradation profiles at temperature range of 30–60 °C were well fitted by the first-order kinetic model and the reaction mechanism of tartrazine was proposed.