Abstract
Photocatalytic degradation of organic pollutants in water using graphitic carbon nitride and persulfate under visible light (g-C(3)N(4)/PS system) has been studied. Here, we demonstrate augmentation of photocatalytic degradation of Acetaminophen (AAP) using hydrothermally treated g-C(3)N(4) and PS under 400 nm LED irradiation (HT-g-C(3)N(4)/PS system). A pseudo-first-order rate constant (k(obs,) 0.328 min(-1)) for degradation of AAP using HT-g-C(3)N(4)/PS system was determined to be 15 times higher compared to g-C(3)N(4)/PS system (k(obs,) 0.022 min(-1)). HT-g-C(3)N(4) showed a higher surface area (81 m(2)/g) than g-C(3)N(4) (21 m(2)/g). Photocurrent response for HT-g-C(3)N(4) was higher (1.5 times) than g-C(3)N(4). Moreover, Nyquist plot semicircle for HT-g-C(3)N(4) was smaller compared to g-C(3)N(4). These results confirm effective photoelectron-hole separation and charge-transfer in HT-g-C(3)N(4) compared to g-C(3)N(4). AAP degradation using HT-g-C(3)N(4)/PS system was significantly inhibited with O2.- and h(+) scavengers compared to (1)O(2,)SO4.- and HO. scavengers. ESR results revealed O2.- formation in HT-g-C(3)N(4)/PS system. Moreover, photocurrent measurements reveal AAP oxidation by h(+) of HT-g-C(3)N(4) was effective than g-C(3)N(4). HT-g-C(3)N(4) was reused for five cycles in HT-g-C(3)N(4)/PS system. Augmented photocatalytic degradation of AAP by HT-g-C(3)N(4)/PS system compared to g-C(3)N(4)/PS is attributed to effective photoelectron hole separation of HT-g-C(3)N(4) that generates O2.- and h(+) for oxidation of pollutant. Importantly, electrical energy per order (E(EO)) was 7.2 kWh m(-3) order(-1). k(obs) 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-C(3)N(4)/PS system.