SUSTAINABILITY
Valorization of waste waxed corrugated cardboard via
pyrolysis for recovering wax
Farid Sotoudehnia | Endalkachew Mengistie | Abdulbaset Alayat |
Armando G. McDonald
Department of Forest, Rangeland and Fire
Sciences, University of Idaho, Moscow,
Idaho, USA
Correspondence
Armando G. McDonald, Department of Forest,
Rangeland and Fire Sciences, University of
Idaho, Moscow, ID 83844-1133, USA.
Email: armandm@uidaho.edu
Abstract
Corrugated cardboard (CCB) comprises a substantial portion of municipal solid waste,
of which ~5% is wax coated CCB (WCCB) to enhance its performance. WCCB cannot
be recycled, making it a suitable resource to recover wax and produce char. The
WCCB was characterized for its extractable wax, lignin, and carbohydrate contents
and by thermogravimetric analysis to study its thermal degradation behavior. WCCB
was preliminarily examined by pyrolysis-gas chromatography–mass spectrometry to
determine product composition. WCCB samples were then pyrolyzed in auger and
tube reactors at 450, 500, and 550
C, and their pyrolysis wax-oil and char products
characterized. WCCB and char were subjected to proximate, ultimate, surface area,
analyses. The highest char yield was 36% at 450
C, and the highest wax-oil yield was
53% at 550
C in the tube reactor. The wax-oil fraction contained mainly alkanes,
alkenes, and dienes (C
9
–C
36
), and chain length decreased with pyrolysis temperature.
This wax fraction could be recovered and used as bunker fuel (C
12
–C
40
) or further
converted to diesel (C
10
–C
20
).
KEYWORDS
char, kinetics, pyrolysis, waxed corrugated cardboard, wax-oil
1 | INTRODUCTION
Municipal solid waste (MSW) poses serious environmental,
health, and economic concerns globally.
1
It is estimated that the
MSW generation will double to 30 million tons by the year 2033
as the urban population grows.
2
According to the Environmental
Protection Agency, paper products and corrugated cardboard
(CCB) comprise a substantial portion (25%) of the generated
MSW.
3
About 5% of all CCB is coated with wax (WCCB) to
enhance its compression strength and durability under humid/
wet conditions for produce packaging.
4
While a significant por-
tion of paper and CCB are recyclable, waxed WCCB cannot be
recycled, and in fact, can adversely impact the environment and
ecosystems if comingled with non-coated cardboard.
4
Therefore,
there is a need for alternative solutions to recover value and
materials from WCCB.
Given that most WCCB is coated with paraffin wax,
5
and paraffin
has properties similar to polyolefins and other polymers,
6
energy
recovery technologies commonly explored for plastic waste recycling
such as thermal and catalytic pyrolysis, gasification, and plasma gasifi-
cation can be viable options for WCCB processing.
7
Furthermore, the
wax coating of WCCB has a high H/C ratio and convenient hydrocar-
bon structure that make it suitable for liquid fuel production.
8
Other
paper-based packaging products (cups and juice cartons) can be
coated with polyethylene to improve their in-service performance.
9
In
general, thermal degradation of plastics is expected to yield useful
products, fuels, and combustible gases.
8,10
Pyrolysis is an irreversible process of thermal decomposition of
organic materials at high temperatures in an inert atmosphere. The
process generally delivers gas, char, and oil products. Many factors,
such as temperature, residence time, and particle size, affect the ratio
and quality of the products.
11
It has been demonstrated that CCB
Received: 4 August 2020 Revised: 16 November 2020 Accepted: 22 November 2020
DOI: 10.1002/ep.13566
Environ Prog Sustainable Energy. 2020;e13566. wileyonlinelibrary.com/journal/ep © 2020 American Institute of Chemical Engineers 1 of 13
https://doi.org/10.1002/ep.13566