Performance and mechanism of pyrite for nitrobenzene removal in aqueous solution

Based on the concept of waste trading, the natural Fe(II) compound pyrite, which is waste caused by acid mine drainage, was here used to remove nitrobenzene. The morphology, crystal structure, and elemental composition of pyrite were analyzed by scanning electron microscopy. X-ray diffraction, and X-ray photoelectron spectroscopy (XPS), respectively. The effects of pyrite concentration, nitrobenzene concentration, initial pH and humic acid were investigated, and the reaction products and removal mechanism were also studied. The results revealed that pyrite can efficiently remove nitrobenzene, where 20 mg/L nitrobenzene could nearly be 100% removed by reacting with 30 g/L of pyrite for 5 h. The removal capacity of nitrobenzene by pyrite was approximately 2.3 mg/g. The acid-producing property of pyrite naturally guaranteed the desired acidic pH condition, which is required for the reaction, no matter what the initial pH was The effect did not significantly change with the presence of humic acid in our system. The products detected by HPLC-UV and GC/MS/MS included nitrosobenzene and phenylhydroxylamine as intermediate products and aniline as the final product, indicating nitrobenzene was reduced by pyrite. Our study provides a promising insight into the application of pyrite to remove nitrobenzene contaminants and provides an example of waste trading. (C) 2014 Elsevier Ltd. All rights reservecl.