Performance and mechanism of nitrophenol removal by nano zero-valent iron supported on granular activated carbon

Using granular activated carbon (GAC) as the carrier, a nano zero-valent iron composite (nZVI) was prepared by the liquid-phase reduction method. The surface morphology and element chemical morphology of nano zero-valent iron supported on granular activated carbon composite (nZVI/GAC) were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, specific surface area and aperture analyzer (Brunauer-Emmett-Teller). The effects of different materials, initial concentration, initial pH, temperature and dosage of nZVI/GAC on the removal of nitrophenol were studied. The results show that the nano zero-valent iron is successfully supported on the granular activated carbon and showed spherical morphology, but the specific surface area and pore diameter of the activated carbon is reduced; the removal rate of p-nitrophenol by nZVI/GAC under acidic conditions is better than that under alkaline condition, and the removal rate of p-nitrophenol by nZVI/GAC increases with the increase of the dosage of nZVI/GAC and the decrease of the initial concentration of nitrophenol. In the process of nitrophenol removal, there is a synergism between the adsorption of activated carbon and the reduction and degradation of nanometer zero-valent iron. The data fitted the pseudo-second-order kinetic model well (R-2 > 0.99). To investigate the degradation pathway degradation products was analyzed by high-performance liquid chromatography-mass spectrometry.

Automated summary

In this study, a nano zero-valent iron composite (nZVI) was prepared by liquid-phase reduction method using granular activated carbon (GAC) as the carrier. The nZVI/GAC composite showed successful support of nano zero-valent iron with spherical morphology. The removal efficiency of p-nitrophenol by nZVI/GAC was found to be better under acidic conditions, with removal rate increasing with higher nZVI/GAC dosage and lower nitrophenol concentration.