Nguyen, Lan Huong
[Author];
Nguyen, Xuan Hoan
[Author];
Nguyen, Van Long
[Author];
Pham, Van Thinh
[Author];
Thai, Nam Van
[Author];
Luu, Tran Le
[Author];
Van, Huu Tap
[Author];
Le, Hoang Nghiem
[Author]
Enhanced Degradation of Cefalexin Using Co2sno4Rgo as an Effective Peroxymonosulfate Activator in Hybrid Ozonation System
Description:
This study successfully developed a nanocomposite catalyst (Co2SnO4rGO) at optimal composite ratio of 2:1 between Co2SnO4 and GO for effectively activation of peroxymonosulfate (PMS) to degrade cefalexin (CFX) from aqueous solution by hybrid ozonation system (O3/Co2SnO4@rGO/PMS). The CFX removal efficiency was compared in three oxidation systems, including O3, Co2SnO4@rGO/PMS and O3/Co2SnO4@rGO/PMS under various operational conditions of initial CFX concentration, PMS dosage, Co2SnO4@rGO catalyst dosage and solution pH over certain time period. The effect of co-existing anions and scavengers was studied to determine the CFX removal mechanisms. The characteristics of catalyst were analyzed using SBET, SEM, EDS and mapping, XRD and pHPZC. The results illustrated that supplementation of O3 into Co2SnO4@rGO/PMS system exhibited the highest degradation and mineralization efficiencies of CFX, reaching 99.93% and 67.03%, respectively, under optimal operational condition of 100 mg/L of initial CFX, 300 mg/L of PMS dosage, 0.3 g/L of catalyst dosage at pH of 7.0 over certain time period. At this condition, the CFX degradation and mineralization rates in O3/ Co2SnO4@rGO/PMS system were higher than those in Co2SnO4@rGO/PMS system by 2.8 and 1.32 times, respectively, thanks to synergistic effect of O3 and Co2SnO4@rGO/PMS in the same reactor. The CFX removal mechanisms were proposed through both pathways: non-radical and radical pathway. The non-radical mechanism was through singlet oxygen (1O2) formed due to activation of PMS by the rGO, Sn and Co in catalyst’s constituent and a neutral environment benefited for production of 1O2. Meanwhile, the free radicals of *OH, *SO4- and *O2 were produced by the Sn and Co in catalyst’s composition which activated PMS and enhanced decomposition of O3. Besides, the O3 effectively activated PMS to form more free radicals. Then, all these formed free radicals were responsible for the promoted degradation and mineralization of CFX via radical mechanism. The scavenging experiments further confirmed the CFX removal mechanism through both non-radical and radical pathways by 1O2, *OH, *SO4- and *O2. Among them, the 1O2 was predominately species in removal of CFX. Besides, the Co2SnO4@rGO catalyst exhibited a high reusability over four consecutive catalytic cycles. These findings demonstrated the occurrence of O3 and Co2SnO4@rGO nanocatalyst in the hybrid ozonation system effectively activated PMS to enhance CFX removal from wastewater