Powdered activated carbon (PAC)-assisted peroxymonosulfate activation for efficient urea elimination in ultrapure water production from reclaimed water

Chaelin Kim; Heeji Yoo; Gyubin Lee; Hye-Jin Hong

doi:10.1038/s41598-024-55414-w

Powdered activated carbon (PAC)-assisted peroxymonosulfate activation for efficient urea elimination in ultrapure water production from reclaimed water

Sci Rep. 2024 Feb 26;14(1):4597. doi: 10.1038/s41598-024-55414-w.

Authors

Chaelin Kim¹, Heeji Yoo¹, Gyubin Lee¹, Hye-Jin Hong²

Affiliations

¹ Department of Environmental Engineering, Chungbuk National University, Chungdaero 1, Chungbuk, SeowonGu, Cheongju, 28644, Republic of Korea.
² Department of Environmental Engineering, Chungbuk National University, Chungdaero 1, Chungbuk, SeowonGu, Cheongju, 28644, Republic of Korea. hyejiny@chungbuk.ac.kr.

Abstract

Urea is a problematic pollutant in reclaimed water for ultrapure water (UPW) production. The sulfate radical-based advanced oxidation process (SR-AOP) has been recognized as an effective method for urea degradation. However, conventional metal-based catalysts for peroxymonosulfate (PMS) activation are unsuitable for UPW production due to issues related to metal ion leaching. In this study, the use of powdered activated carbon (PAC) was investigated for the removal of urea from reclaimed water. The PAC exhibited a high degree of defects (I_D/I_G = 1.709) and various surface oxygen functional groups (C-OH, C=O, and C-O), which greatly enhanced its catalytic capability. The PAC significantly facilitated PMS activation in the PMS + PAC system, leading to the complete urea decomposition. The PMS + PAC system demonstrated excellent urea removal efficiency within a wide pH range, except for pH < 3. Among the various anions present, the CO₃^2- and PO₄^3- inhibited urea degradation, while the coexistence of Cl^- promoted urea removal. Furthermore, the feasibility test was evaluated using actual reclaimed water. The quenching test revealed that SO₄^-·, ·OH, and O₂^-· played crucial roles in the degradation of urea in the PAC-assisted SR-AOP. The oxygen functional groups (C-OH and O-C=O) and defect sites of PAC clearly contributed to PMS activation.