Ball milling synthesis of covalent organic framework as a highly active photocatalyst for degradation of organic contaminants

Hongzhou Lv; Xiaoli Zhao; Hongyun Niu; Sijing He; Zhi Tang; Fengchang Wu; John P Giesy

doi:10.1016/j.jhazmat.2019.02.046

Ball milling synthesis of covalent organic framework as a highly active photocatalyst for degradation of organic contaminants

J Hazard Mater. 2019 May 5:369:494-502. doi: 10.1016/j.jhazmat.2019.02.046. Epub 2019 Feb 13.

Authors

Hongzhou Lv¹, Xiaoli Zhao², Hongyun Niu³, Sijing He³, Zhi Tang⁴, Fengchang Wu⁴, John P Giesy⁵

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085,China; College of Environment, Hohai University, Nanjing 210098, China.
² State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address: zhaoxiaoli_zxl@126.com.
³ State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085,China.
⁴ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
⁵ Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

PMID: 30807989
DOI: 10.1016/j.jhazmat.2019.02.046

Abstract

Facile, environmentally-friendly fabrication of high-yield and stable covalent organic framework (COF) materials has been a limitation to their large-scale production and application. In this work, ball milling was used to synthesize COF by mechanochemical reaction between 1,3,5-triformylphloroglucinol (Tp) and melamine (MA) at ambient temperature. Different routes (liquid-free, solvent-assisted and catalyst-assisted) and proportions of liquids (solvents or catalyst) were investigated. Two morphologies were obtained when various amounts of liquid were added during grinding. The two forms were interwoven thread-shaped and exfoliative thin ribbon-like structures. Further, visible-light photocatalytic (λ > 400 nm) performance and mechanism of the two structures of COFs were investigated. The exfoliative ribbon-like structures exhibited greater rates of photodegradation of phenol and retained 87.6% of initial photodegradation after being used four times. Addition of liquid catalyst not only improved crystallinity of the COF materials, but also enhanced rates of photocatalytic reactions. Photocatalytic activity of the exfoliative structure of TpMA synthesized by ball milling was comparable with that of the photocatalyst prepared by use of the solvothermal method, while time to prepare the catalyst was shortened by 36-fold and the amount of solvent used was reduced by 8-fold at room temperature. Mechanochemical synthesis is a promising potential tool for large-scale production of COFs, which will make greater use of COFs for degradation of pollutants.

Keywords: Ball milling; Covalent organic framework; Mechanochemical fabrication; Photocatalysis; TpMA.