The effect of additives on migration and transformation of gaseous pollutants in the vacuum pyrolysis process of waste printed circuit boards

Abstract

The effect of six additives (CaCO₃, HZSM-5, CaO, Al₂O₃, FeOOH and Ca(OH)₂) on the generation, migration, transformation and escaping behaviours of typical gaseous pollutants in the pyrolysis process were studied by vacuum pyrolysis experiments on epoxy resin powder from waste printed circuit boards with tube furnace. The results show that the additives Al₂O₃, CaO, Ca(OH) ₂ and FeOOH could reduce the yield of the gas phase. The removal rates of pollutants, such as benzene, toluene, ethyl benzene, phenol, p-xylene, HBr, NO₂ and SO₂ in the gaseous products, has changed variously with the increasing percentage of the above additives. Judging from the control of gas-phase pollutant discharge, the calcium-base additives are superior to the others. Ca(OH)₂ has the best inhibition effect among them. The increase of the pyrolysis temperature and vacuum degree enhanced the volatility of organic pollutants and weakened the Ca(OH)₂ inhibition effect on organic pollutants, while it improved the removal rate of SO₂. Under the condition of 500 °C pyrolysis temperature and 0.09 MPa vacuum degree, when the additive proportion of Ca(OH)₂ was one-fifth, the average removal rate of pollutants in gas phase is up to 66.4%.

Keywords

Vacuum pyrolysis brominated epoxy resin additives gas-phase pollutants waste printed circuit boards

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References

Long

L-s

Sun

S-y

Zhong

. (2009) Innocuous management and resource recovery techniques for scrap printed circuit boards. Chemical Industry and Engineering Progress 28: 1059–1064.

Liu

J-y

Sun

S-y

Zeng

X-h

. (2014) Case research on the green recovery technologies and centralized treatment of waste electronic and electric equipments. Recyclable Resources and Circular Economy 3: 34–39.

Xiao

H-x

(2012) Combustion characteristics and bromine conversion characteristics of waste printed circuit boards in high temperature. Doctoral Dissertation, Zhejiang University, Hangzhou.

S-y

(2014) Research on pyrolysis and debromination of waste printed circuit boards and recycling of the pyrolysis products. Doctoral Dissertation, Guangdong University of Technology, Guangzhou.

Tan

Wang

Tan

. (2007) Products from microwave heating of waste printed circuit boards. Environmental Pollution & Control 29: 599–601.

Qian

A-m

Gao

N-b

. The catalytic pyrolysis characteristics of waste printed circuit boards and dynamics research. In: Proceedings of the Chinese society of engineering thermophysics, conference papers, combustion science, number: 114316, pp. 1154–1158.

Wang

S-j

Chen

X-f

. (2009) Catalytic pyrolysis of waste printed circuit boards. Journal of Wuhan University of Science and Technology 32: 90–94.

Bockhorn

Hornung

. (1997) Dehydrochlorination of plastic mixtures. Journal of Analytical and Applied Pyrolysis 49: 97–106.

Peng

S-h

Chen

L-q

Y-l

. (2009) Study on compositions of pyrolystic tar from waste printed circuit boards mixed with calcium carbonate. Modern Chemical Industry 11: 44–47.

10.

Yang

Sun

S-y

. (2013) Characterization of products from waste printed circuit boards (WPCB) pyrolysis catalyzed by HZSM-5. China Sciencepaper 8: 225–229.

11.

J-q

Sun

S-y

. (2014) Effects of oxides on WPCB epoxy resin powder debromination under vacuum pyrolysis. Journal of Chemical Engineering of Chinese Universities 28: 888–894.

12.

Cornelia

Mihai

Tamer

. (2007) Feedstock recycling from plastics and thermosets fractions of used computers. II. Pyrolysis oil upgrading. Fuel 86: 477–485.

13.

Blazsó

Czéqény

Csoma

(2002) Pyrolysis and debrominated of flame retarded polymers of electronic scrap studied by analytical pyrolysis. Journal of Analytical and Applied Pyrolysis 64: 249–261.

14.

Mihai

Thallada

Kazuya

. (2005) Removal of nitrogen, bromine, and chlorine from PP/PE/PS/PVC/ABS-Br pyrolysis liquid products using Fe- and Ca-based catalysts. Polymer Degradation and Stability 87: 225–230.

15.

Zhang

Z-h

Qiu

K-q

(2011) Effect of additives on product of vacuum pyrolysis of waste epoxy printed circuit boards. Journal of Central South University (Science and Technology) 8: 2233–2238.

16.

Peng

S-h

Chen

L-q

Cai

M-z

(2006) Forming and scavenging of hydrogen bromide during pyrolysis of waste printed circuit boards. Journal of South China University of Technology (Natural Science Edition) 34: 15–24.

17.

Wang

Sun

S-y

Yang

. (2014) Influence of different catalysts on light of pyrolytic oil from WPCB pyrolysis. Journal of Central South University (Science and Technology) 45: 979–988.

18.

Y-j

Armor

J-n

(1994) Selective catalytic reduction of NO with methane on gallium catalysts. Journal of Catalysis 45: 1–9.

19.

Chen

(2008) Experimental study on debromination of waste printed circuit board. Master dissertation, Tsinghua University, Beijing.

20.

Mao

Y-y

Z-y

. (2009) Conversion of bromine during the pyrolysis of waste printed circuit board. Journal of Zhejiang University (Engineering Science) 43: 937–941.

21.

Zheng

S-l

(1995) Surface Modification of Powder. Beijing: China Building Materials Press.