5-7 OCTOBER

ISFR

2011

133

TOLEDO (SPAIN)

DEHYDROCHLORINATION OF POLYVINYL CHLORIDE IN GREEN SOLVENT
Q.Zhou 1, X.L.He 1 and Y.Z.Wang 1
1 Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MoE), College of Chemistry, State Key
Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064, China; Tel: +86-28-85410755; Fax: +8628-85410755;
e-mail: qzhou@scu.edu.cn

Abstract
Highly efficient dechlorination contributes to successful chemical recycling of PVC-containing waste plastics. We utilize green
solvents such as poly (ethylene glycol) (PEG) and ionic liquids for highly efficient dehydrochlorination of PVC at atmosphericpressure. The significant advantages of this method are: operational simplicity, high dechlorination efficiency, greenness ofprocedure by avoiding hazardous organic solvent, additional catalysts, and toxic waste byproducts, and satisfactory
recyclable properties. It holds great promise for application in other dehalogenation processes.

Keywords: Dehydrochlorination; Polyvinyl chloride; PEG; Ionic liquids; Recycling

Recycling of waste plastics is of great interest due to theserious environmental problems caused by waste
plastics. Highly efficient dechlorination contributes tosuccessful chemical recycling of PVC-containing waste
plastics [1]. Dehydrochlorination in an alkaline solution isefficient for the dechlorination [2]. However, volatile andoften toxic solvents were adopted using this method,moreover, by-product such as KCl could be produced
that caused the problem of secondary pollution. Although
the methods of hydrothermal and supercriticaldechlorination have been developed to increase thedechlorination efficiency, they have high requirements forthe equipments [3]. Therefore, the development ofenvironment-friendly methods for highly efficientdehydrochlorination of PVC is an area of considerable
importance.
In this paper, we utilize green solvents such as poly
(ethylene glycol) (PEG) and ionic liquids for highly
efficient dechlorination of PVC at atmospheric pressure.
These green solvents possess environmentally benign
characteristics. In addition, they showed satisfactory
recyclable properties in this reaction system.

2. Materials and Methods
PVC (SG-1) was obtained from Xian Chemical Co.,
China. Its chlorine content of the PVC is 51.5 %.1-butyl3-methylimidazoliumchloride([Bmim]Cl),
1-Allyl-3methylimidazolium Chloride ([Amim]Cl), 1-butyl-3methylimidazolium hydroxide ([Bmim]OH), 1-butyl-3methylimidazolium tetrafluoroborate ([Bmim]BF 4) and 1butyl-3-methyl-imidazolium
hexafluorophosphate
1-(2-hydroxylethyl)-3([Bmim]PF6),
methylimidazoliumchloride ([C2OHmim]Cl ) and PEGs
were of analytical grade and dried under vacuum at 60ºC for 24 h.

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PVC and solvent were added into a 100 mL three-neckflask equipped with a thermometer and a nitrogen gas
bubbler to react under set temperatures. After reaction,
the dechlorinated PVC (DPVC) was filtered and dried
under vacuum at 60 °C for 24 h, then characterized using
oxygen–combustion–chlorine selective electrode method.

3. Results and Discussion
Effects of solvents on dehydrochlorination of PVC areshown in Fig.1. The dechlorination degree of PVC is asfollows: BmimOH ˚ BmimCl ˚ PEG600>AmimCl ˚
BmimBF4˚C2OHmimCl˚BmimPF6,suggesting that thestructureofthesolvents
influencethedehydrochlorination of PVC.

100

Dechlorination degree(%)

1. Introduction

80
60
40
20
0
PVC

PEG600 BmimOH BmimCl [Amim]Cl BmimBF4 BmimPF6C2OHmimCl

Fig. 1. Effects of solvents on the dechlorination degree of
PVC
Moreover, it can be seen from Fig.2 that thedehydrochlorination is almost constant for 6 cycles for

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6th International Symposium on Feedstock Recycling of Polymeric Materials

Dechlorination Degree(%) Dechlorination Degree(%)

both PEG600 and [Bmim]Cl, proving that the reuse of
theses green solvents is feasible for thedehydrochlorination of PVC.

100

(a)

80
60
40
20
0
100

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Run2

Run3

Run4

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(b)

80
60
40
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0
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Fig.2 Recyclability of (a) PEG (180 0C, 1 h) (b) BmimCl(200 0C, 1 h) in dechlorination of PVC

4. Conclusions
Highly efficient dehydrochlorination of PVC has beenrealized using green solvents such as PEG and ionicliquids at atmospheric pressure. The process does not
require any organic solvent or additional catalysts, andthe solvents can be recycled (6 cycles) without any
appreciable loss of its catalytic efficiency. It is found thestructure of the solvents influence upon thedehydrochlorination process.

References[1] Q.Zhou, W.W. Lan, A.K.Du, Y.Z.Wang, J.W.Yang,
Y.H.Wu, K.K.Yang and X.L.Wang. Highly efficientpyrolysis of Polypropylene/Polyvinyl chloride overLanthanum promoted MgO: simutaneous catalytic
cracking and dechlorination. Appl. Cata. B-Eniron, 80(2008), 141-146.
[2] S.M. Shin, T. Yoshioka, A. Okuwaki,
Dehydrochlorination behavior of rigid PVC pellet in NaOH
solutions at elevated temperature, Polym. Degrad. Stabil.
61 (1998) 349-353.
[3] Y. Takeshita, K. Kato, K. Takahashi, Y. Sato, S. Nishi,
Basic study on treatment of waste polyvinyl chloride
plastics by hydrothermal decomposition in subcritical andsupercritical regions, J. Supercritic. Fluid. 31 (2004) 185193.

Acknowledgments
The authors thank the financial support of the 863
program (Contract No: 2007AA06Z325) and the Program
for New Century Excellent Talents in University (NCET08-0366).

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