g-C3N4/polyvinyl alcohol-sodium alginate aerogel for removal of typical heterocyclic drugs from water

Heterocyclic drugs (HCDs) detected at high frequencies in wastewater have raised great concerns and their advanced removal has been the hotspot for safe water reuse in recent years. Two-dimensional graphitic carbon nitride (g-C3N4) and its photocatalytic systems are increasingly emerging, however, there are inevitable drawbacks of stacking and difficulty in recycling, resulting in decreased pollutant removal and limited application. Herein, for the first time, this paper reported a three-dimensional g-C3N4/polyvinyl alcohol-sodium alginate aerogel (g-C3N4/PVA-SA aerogel) photocatalyst synthesized by ultrasonic exfoliation and in-situ polymerization for typical HCDs (sulfadiazine (SDZ), sulfamethoxazole (SMX), and carbamazepine (CBZ)) removal in water. The reduced stacking of g-C3N4 dispersed in PVA-SA aerogel was achieved as revealed by scanning electron microscopy (SEM) and X-ray diffractometer (XRD) analysis, and g-C3N4/PVA-SA aerogel was observed to possess encouraging degradation efficiencies and rates for SDZ (100%, 0.0249 min−1), SMX (100%, 0.1762 min−1) and CBZ (69.8%, 0.0056 min−1), which were improved by 50%–60% and 133%–216% compared to those of g-C3N4, respectively. Meanwhile, environmental impact factors such as pH and coexisting ions had less impact on the degradation of SDZ and SMX by g-C3N4/PVA-SA aerogel. The novel aerogel also had a good recyclability, with less than 5% reduction in degradation efficiency after five cycles observed. The photodegradation of SDZ, SMX and CBZ was confirmed to be driven by ⋅O2− and h+ through scavenger-quenching experiments. The new low carbon and recyclable g-C3N4/PVA-SA aerogel reported in this study indicated a good potential for efficient removal of HCDs from water, which provides an alternative strategy for advanced purification and safe reuse of wastewater.