Nitrogen and phosphorous-doped porous carbon xerogels as metal-free catalysts for environmental catalytic peroxide oxidation of 4-nitrophenol

This work reports an environmental benign porous carbon catalyst for the catalytic peroxide oxidation of 4-nitrophenol (4-NP) pollutant. Nitrogen and phosphorous-doped carbon xerogels as metal-free catalysts, which are namely as CX30, CX50 and CX75 with corresponding to initial concentrations of H3PO4 acid (30, 50 and 75 v/v %) were synthesized. Nitrogen gas adsorption measurements of the prepared carbon catalysts were performed at -196 degrees C, while Fourier transform infrared spectroscopy (FTIR) and high resolution scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analyses were examined for the sample of CX75 which appeared high catalytic performance. The effect of various factors such as temperature, catalyst loading, H2O2 dose and initial concentration of 4-NP on the catalytic oxidation performance of the metal-free catalysts was studied at pH = 4. Results revealed that the phosphoric acid activation of nitrogen-doped resorcinol-formaldehyde xerogel developed significant influence on the porosity and surface chemistry characteristics of the hereby catalysts. Increasing the concentration of H3PO4 enhances the microporosity at expense of mesoporosity yielding micro-mesoporous carbons with surface area as high as 442m(2)/g. EDS and FTIR analyses confirmed the presence of phosphorous-and nitrogen-containing functional groups with high content of carbon and oxygen groups. During catalytic wet peroxide oxidation experiments, the CX75 catalyst exhibits complete decomposition 4-NP (100%) within 60 min. Moreover, reusability experiments with this catalyst were run through three cycles and revealed high stability where up to 52.6% conversion of 4-NP in the third recycle was occurred at 120 min. (C) 2016 Curtin University of Technology and John Wiley & Sons, Ltd.