Study On The Catalytic Ozonation Of Organic Pollutants In Wastewater By Carbon Nanometer Materials

The treatment of refractory organic pollutants produced in petroleum refining process which can not be completely removed by traditional wastewater treatment technology is always an important part of wastewater treatment,.Advanced oxidation processes（AOPs）have attracted intenstive attention because they can completely mineralize most of the organic pollutants with high efficiency.Among AOPs,catalytic ozonation process is a facile and efficiency treatment technique that relies on ozone molecules and the produced reactive oxygen species（ROS）obtaining high oxidation potentials.The commoly used catalysts in the heterogeneous catalytic ozonation process are metal or metal-supported catalysts.Even though they obtained high catalytic activities,metal leaching and secondary pollution could be resulted in the presence of highly active oxidants.Therefore,increasing research attention has been focused on the development of the environmental benigned metal-free catalysts.However,the preparation of the nanocarbons with high activities are usually cost-intensive,time consuming and complication.Herein,two kinds of low-cost,high-activity and high-stability nanocarbons i.e embedded carbon nanotubes and N-doped layered nanocarbons were prepared for catalytic ozonation to treatment of refractory organic pollutants.It was found that the synthesized embedded carbon nanotubes could completely remove 50 mg/L of oxalic acid within 20 minutes.The sp² carbon matrix within the nanotubes are responsible for O₃ activation.The direct electron transfer between the ozone molecule and the graphite layer could be accelerated by reducing the wall thickness of the nanotubes.Nonradical oxidation pathway was discovered for the degradation of the refractory organics in addition to the radical-based oxidaiton.To further increase the activity and the stability of the nanocarbons,N-doped layered nanocarbons were synthesized via a facile and cost-efficient strategy.It was found that pseudo-first order reaction rate constant of the N-doped nanocarbons was 30.3 times of that of undoped carbon nanomaterials.The characterization results showed that graphite N was the catalytic active sites for catalytic O₃ decomposition.With the help of in-situ Raman test results,it was confirmed that surface-adsrobed atomic oxygen was the dominant nonradical species for destruction of the organics.These studies provided a practical strategy for synthesizing nanocarbons with low-cost,high-activity and high-stability and unravel the mechanistic insights into the catalytic ozonation over the nanocarbons.