Improving the photodegradation efficiency of POPs in oily sewage: Design and synthesis of G-C3N4-based photocatalysts incorporating a pickering emulsion catalytic strategy

Graphitic carbon nitride (g-C3N4) has been intriguing researchers for the preeminent role in water treatment and organic pollutant degradation applications. However, bulk g-C3N4 has bottlenecks such as small specific surface area and insufficient light absorption, reducing the photocatalytic degradation activity. Herein, g-C3N4 photocatalytic nanosheets with high specific surface area were prepared by a morphology control strategy, meanwhile amphiphilic groups were introduced through surface modification to endow the photocatalysts with Pickering particle function, so that they can be stably adsorbed at the micron-scale oil-water emulsion interface to enhance the mass transfer efficiency of oil-water biphasic media. The results showed that the degradation rate of n-hexane model oily sewage was as high as 97.2% by this simple Pickering emulsion (PE) photocatalytic system. Simultaneously, the photocatalytic degradation study was also carried out on an oily sewage sample from the oil production plant in Changqing oilfield, and the degradation rate of the actual oily sewage was 72.3%, which was much higher than that of the bulk-C3N4 photocatalyst (42.9%). This study integrates the photocatalytic technology and PE catalysis and applies them to the treatment of oily sewage, which is an innovative application of emulsion interface photocatalysis and opens up a new perspective for enhancing the photocatalytic activity of g-C3N4.