An upgraded electro-Fenton treatment of wastewater using nanoclay-embedded graphene composite prepared via exfoliation of pencil rods by submerged liquid plasma

Jaganathan Senthilnathan; Ambika Selvaraj; Sherif A Younis; Ki-Hyun Kim; Masahiro Yoshimura

doi:10.1016/j.jhazmat.2020.122788

An upgraded electro-Fenton treatment of wastewater using nanoclay-embedded graphene composite prepared via exfoliation of pencil rods by submerged liquid plasma

J Hazard Mater. 2020 Oct 5:397:122788. doi: 10.1016/j.jhazmat.2020.122788. Epub 2020 Apr 24.

Authors

Jaganathan Senthilnathan¹, Ambika Selvaraj², Sherif A Younis³, Ki-Hyun Kim⁴, Masahiro Yoshimura⁵

Affiliations

¹ Environmental and Water Resources Division, Department of Civil Engineering, Indian Institute of Technology Madras, 600036, India.
² Dept of civil engineering, Indian institute of technology hyderabad,India.
³ Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul, 04763, Republic of Korea; Analysis and Evaluation Department, Egyptian Petroleum Research Institute (EPRI), Nasr City 11727, Cairo, Egypt.
⁴ Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul, 04763, Republic of Korea. Electronic address: kkim61@hanyang.ac.kr.
⁵ Promotion Centre for Global Materials Research, Department of Material Science and Engineering, National Cheng Kung University, Tainan, Taiwan.

PMID: 32388098
DOI: 10.1016/j.jhazmat.2020.122788

Abstract

In this work, two types of electrochemical electrodes were synthesized using two types (i.e., 4 black (4B) and hard black (HB)) of pencil rods during submerged liquid plasma (SLP) process. At high potential (3 kV) electrons, the SLP process offered an effective exfoliation route for the disorientation of the graphite sp² domain to produce two nanoclay-graphene composite electrodes with a few graphene layers (thickness = 4-9 layers) and high dispersibility (< 19% settlement: 4 h) in polar/non-polar solution (52-53.1% settlement: 4 h). Their performance was then evaluated towards the electro-Fenton (EF) degradation of lindane using a coated Fe₃O₄ plate (as Fenton catalyst). Accordingly, both 4B- and HB-ENcGe electrodes showed high specific capacitance values (473 and 363 F g^-1) at 0.05 A g^-1 and excellent triangular charge-discharge patterns (< 9% and 35% reduction of capacitance, respectively after 1000 cycles (charging rate: 0.2 A g^-1)). At pH 3 and current density of 6.5 mA cm^-2, 4B-ENcGe exhibited superior EF degradation performance (99.4% after 60 min) against 2.5 mg L^-1 lindane (H₂O₂ generation capacity: 2.53 mmol. h^-1, current efficiency: 89.4%, and stability: up to 5th cycles). The complete EF-based mineralization of lindane suggests that these electrodes should offer one-step cost-effective treatment for wastewater contaminants.

Keywords: Electro-Fenton oxidation; Electrochemical electrodes; Nanoclay-graphene composite; Pencil rods; Submerged liquid plasma; Wastewater treatment.