Hydrothermal decomposition of liquid crystal in subcritical water

Xuning Zhuang; Wenzhi He; Guangming Li; Juwen Huang; Shangming Lu; Lianjiao Hou

doi:10.1016/j.jhazmat.2014.02.010

Hydrothermal decomposition of liquid crystal in subcritical water

J Hazard Mater. 2014 Apr 30:271:236-44. doi: 10.1016/j.jhazmat.2014.02.010. Epub 2014 Feb 18.

Authors

Xuning Zhuang¹, Wenzhi He², Guangming Li³, Juwen Huang³, Shangming Lu³, Lianjiao Hou³

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092, PR China; Shanghai Cooperative Centre for WEEE Recycling, Shanghai Second Polytechnic University, No. 2360 Jinhai Road, Shanghai 201209, PR China.
² State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092, PR China. Electronic address: hithwz@163.com.
³ State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092, PR China.

PMID: 24632487
DOI: 10.1016/j.jhazmat.2014.02.010

Abstract

Treatment of liquid crystal has important significance for the environment protection and human health. This study proposed a hydrothermal process to decompose the liquid crystal of 4-octoxy-4'-cyanobiphenyl. Experiments were conducted with a 5.7 mL stainless tube reactor and heated by a salt-bath. Factors affecting the decomposition rate of 4-octoxy-4'-cyanobiphenyl were evaluated with HPLC. The decomposed liquid products were characterized by GC-MS. Under optimized conditions i.e., 0.2 mL H2O2 supply, pH value 6, temperature 275°C and reaction time 5 min, 97.6% of 4-octoxy-4'-cyanobiphenyl was decomposed into simple and environment-friendly products. Based on the mechanism analysis and products characterization, a possible hydrothermal decomposition pathway was proposed. The results indicate that hydrothermal technology is a promising choice for liquid crystal treatment.

Keywords: 4-octoxy-4’-cyanobiphenyl; Decomposition; Hydrothermal technology; Liquid crystal; Waste LCDs.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biphenyl Compounds / chemistry*
Catalysis
Copper / chemistry
Hot Temperature
Hydrogen Peroxide / chemistry
Liquid Crystals / chemistry*
Manganese Compounds / chemistry
Nitriles / chemistry*
Oxides / chemistry
Water

Substances

Biphenyl Compounds
Manganese Compounds
Nitriles
Oxides
Water
Copper
Hydrogen Peroxide
manganese dioxide
cupric oxide