Removal of pollutants in banknote printing wastewater by mesoporous Fe/SiO2 prepared from rice husk pyrolytic residues.

Iron-incorporated silica (Fe/SiO2) with different Fe/Si molar ratio was successfully prepared from rice husk pyrolytic residues (RHR) through alkali pretreatment, co-precipitation, and calcination. Various characterization methods indicated that the Fe/SiO2 samples possessed mesoporous structure with Fe species incorporated into the framework of silica. The obtained materials were applied in the treatment of hazardous banknote printing wastewater, and under the optimal conditions, colored pollutants, humic acid-like and soluble microbial by-product-like organics were removed significantly. It was found that Fe/SiO2 acted as both flocculant and catalyst, and the framework iron species catalyzed the oxidative degradation of refractory organics in the presence of H2O2. A heterogeneous Fenton-like system was formed in the wastewater treatment process.