Coupled adsorption-photocatalysis process for the removal of diclofenac using magnetite/reduced graphene oxide nanocomposite

Jooyoung Lee; Seong-Jun Jo; Soyeong Yoon; Mingi Ko; Taesoon Jang; Hyun-Kyung Kim; Jeong-Ann Park

doi:10.1016/j.chemosphere.2023.140788

Coupled adsorption-photocatalysis process for the removal of diclofenac using magnetite/reduced graphene oxide nanocomposite

Chemosphere. 2024 Feb:349:140788. doi: 10.1016/j.chemosphere.2023.140788. Epub 2023 Nov 30.

Authors

Jooyoung Lee¹, Seong-Jun Jo², Soyeong Yoon¹, Mingi Ko¹, Taesoon Jang¹, Hyun-Kyung Kim³, Jeong-Ann Park⁴

Affiliations

¹ Department of Environmental Engineering, Kangwon National University, Chuncheon, 24341, Republic of Korea.
² Department of Battery Convergence Engineering, Kangwon National University, Chuncheon, 24341, Republic of Korea.
³ Department of Battery Convergence Engineering, Kangwon National University, Chuncheon, 24341, Republic of Korea; Interdisciplinary Program in Advanced Functional Materials and Devices Development, Kangwon National University, Chuncheon, 24341, Republic of Korea. Electronic address: hkk@kangwon.ac.kr.
⁴ Department of Environmental Engineering, Kangwon National University, Chuncheon, 24341, Republic of Korea; Department of Integrated Energy and Infra System, Kangwon National University, Chuncheon, 24341, Republic of Korea. Electronic address: pjaan@kangwon.ac.kr.

PMID: 38042428
DOI: 10.1016/j.chemosphere.2023.140788

Abstract

Diclofenac (DCF) is frequently detected in water bodies (ng/L to g/L) as it is not completely removed by conventional wastewater treatment plants. Adsorption and photocatalysis have been studied as promising methods for treating DCF; however, both processes have limitations. Thus, in this study, the removal efficiency of DCF is evaluated using a magnetite/reduced graphene oxide (Fe₃O₄/RGO) nanocomposite via a coupled adsorption-catalysis process. The Fe₃O₄/RGO nanocomposite was successfully synthesized using a microwave-assisted solvothermal method and exhibited a bandgap of 2.60 eV. The kinetic data best fitted the Elovich model (R² = 0.994, χ² = 0.29), indicating rapid adsorption. The maximum DCF adsorption capacity calculated using the Langmuir model was 80.33 mg/g. An ultraviolet C (UVC) light source and 0.1 g/L of Fe₃O₄/RGO nanocomposite were the optimum conditions for the removal of DCF (C₀ = 30 mM) by a coupled adsorption-photocatalysis process (first-order rate constant (k) = 0.088/min), which was greater than the single adsorption (k = 0.029/min) and pre-adsorption and post-photocatalysis (k = 0.053/min) processes. This indicates that the adsorbed DCF did not hamper the photocatalytic reaction of the Fe₃O₄/RGO nanocomposite, but rather enhanced the coupled adsorption-photocatalytic reaction. DCF removal efficiency was higher at acidic conditions (pH 4.3-5.0), because high H⁺ promotes the generation of certain reactive oxygen species (ROS) and increases of electrostatic interaction. The presence of NaCl and CaCl₂ (10 mM) did not notably affect the total DCF removal efficiency; however, Ca²⁺ affected the initial DCF adsorption affinity. Scavenger experiments demonstrated O₂^∙- and h⁺ play a key ROS than ·OH to degrade DCF. The acute toxicity of DCF towards Aliivibrio fischeri gradually decreased with increasing treatment time.

Keywords: Acute toxicity; Adsorption; Coupled adsorption-photocatalysis; Diclofenac; Magnetite/reduced graphene oxide; Photocatalyst.

MeSH terms

Adsorption
Diclofenac
Ferrosoferric Oxide*
Nanocomposites*
Reactive Oxygen Species

Substances

Ferrosoferric Oxide
Diclofenac
graphene oxide
Reactive Oxygen Species