Source apportionment and transport of pollutants within the South African paper recycling chain

Nondumiso N. Mofokeng; Lawrence M. Madikizela; Luke Chimuka

doi:10.17159/sajs.2025/17228

Authors

Nondumiso N. Mofokeng 1.Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa; 2.Mpact Operations Pty (Ltd), Innovation, Research & Development Division, Stellenbosch, South Africa https://orcid.org/0000-0002-8565-3267
Lawrence M. Madikizela Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Johannesburg, South Africa https://orcid.org/0000-0001-6096-2701
Luke Chimuka Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa https://orcid.org/0000-0002-8552-2478

DOI:

https://doi.org/10.17159/sajs.2025/17228

Keywords:

paper recycling, accelerated solvent extraction, gas chromatography, pollutants, emerging contaminants

Abstract

Recycled paper is a valuable commodity that forms an intrinsic part of promoting sustainable resource utilisation. In this study, we aimed to investigate the possible sources and transport of semi-volatile organic pollutants in paper grades used in the recycled paperboard value chain. Accelerated solvent extraction followed by gas chromatography-mass spectrometry were employed for the analyses. The results show that diethylhexyl phthalate and dibutyl phthalate were the most prominent pollutants, whilst tris (2,4-di-tert-butylphenyl) phosphite and butylated hydroxytoluene were the least significant pollutants. Tris (2,4-di-tert-butylphenyl) phosphate was predominantly detected at the recycling sites, with a maximum concentration of 3.054 mg/kg, whereas N-butylbenzene sulfonamide was found in retail and post-consumer samples but not at pre-consumer sites. Manufacturing additives and retail activities were identified as possible exposure sources. Post-consumer usage, collection, sorting and mingling of various waste materials were also identified as factors that influence the prevalence of pollutants. The presence of pollutants in pre-consumer samples indicates that certain compounds may potentially accumulate or circulate within the paper recycling chain and that other pollutants may be removed during the reprocessing of recycled fibre.

Significance:

To the best of our knowledge, this study is the first performed in South Africa on the identification of chemical constituents of different recycling paper grades, that considers the unique South African paper recycling chain. The pollutants identified indicate that the South African paper recycling chain has pollutants in common with those reported in Global North studies as well as unique pollutants. These included butylated hydroxytoluene, N-butylbenzene sulfonamide, tris (2,4-di-tert-butylphenyl) phosphite and its degradation product tris (2,4-di-tert-butylphenyl) phosphate.