Augmented photocatalytic degradation of Acetaminophen using hydrothermally treated g-C3N4 and persulfate under LED irradiation

Abstract

Photocatalytic degradation of organic pollutants in water using graphitic carbon nitride and persulfate under visible light (g-C3N4/PS system) has been studied. Here, we demonstrate augmentation of photocatalytic degradation of Acetaminophen (AAP) using hydrothermally treated g-C3N4 and PS under 400 nm LED irradiation (HT-g-C3N4/PS system). A pseudo-first-order rate constant (kobs, 0.328 min−1) for degradation of AAP using HT-g-C3N4/PS system was determined to be 15 times higher compared to g-C3N4/PS system (kobs, 0.022 min−1). HT-g-C3N4 showed a higher surface area (81 m2/g) than g-C3N4 (21 m2/g). Photocurrent response for HT-g-C3N4 was higher (1.5 times) than g-C3N4. Moreover, Nyquist plot semicircle for HT-g-C3N4 was smaller compared to g-C3N4. These results confirm effective photoelectron-hole separation and charge-transfer in HT-g-C3N4 compared to g-C3N4. AAP degradation using HT-g-C3N4/PS system was significantly inhibited with O2.− and h+ scavengers compared to 1O2,SO4.− and HO. scavengers. ESR results revealed O2.− formation in HT-g-C3N4/PS system. Moreover, photocurrent measurements reveal AAP oxidation by h+ of HT-g-C3N4 was effective than g-C3N4. HT-g-C3N4 was reused for five cycles in HT-g-C3N4/PS system. Augmented photocatalytic degradation of AAP by HT-g-C3N4/PS system compared to g-C3N4/PS is attributed to effective photoelectron hole separation of HT-g-C3N4 that generates O2.− and h+ for oxidation of pollutant. Importantly, electrical energy per order (EEO) was 7.2 kWh m−3 order−1. kobs for degradation of AAP in simulated groundwater and tap water were determined as 0.029 and 0.035 min−1, respectively. Degradation intermediates of AAP were proposed. AAP ecotoxicity against marine bacteria Aliivibrio fischeri was completely removed after treatment by HT-g-C3N4/PS system.