Study on Decolorization of Methylene Blue by H2O2 Catalyzed with Iron-loaded Hydrated Cement Particles

In this study, a new type of heterogeneous catalyst based on cement matrix composite was developed. Hydrated cement particles (HCP) were used as the carrier material to immobilize the ferric iron produced by Fe2+/H2O2 system. Iron load bearing by new catalyst was calculated to be about 130.5mg/g. The formation of iron compounds were verified by scan electron microscopy and energy dispersive spectroscopy. Due to there was no thermal treatment, the main constituents of iron phases were estimated to be the amorphous ferric hydroxide or hydrated ferric oxide. On this basis, the catalytic performances of new catalyst on methylene blue were investigated. Results showed that, for 50mg/L methylene blue solution, when the adding dosage of the catalyst and peroxide were of 100g/L and 100mM, the catalytic decolorization rate at room temperature on 9h reached 90.4%. The decolorization rate increased with the increase of the dosage of hydrogen peroxide. When the dosage of hydrogen peroxide was 250mM, the highest decolorization rate on 9h reached 98.7%. This result was about 74% higher than the catalytic efficiency of only peroxide. In addition, the new catalyst showed strong adaptability to pH value. On the whole, the decolorization efficiencies of MB at the acid conditions were superior to at the alkaline conditions. Circulating decolorization results demonstrated that the catalytic performance of iron-loaded HCP could keep relatively stable at original pH conditon of MB mixture solution.