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<p>The environmental persistence of plastic waste has driven development of pro-oxidant additives to accelerate degradation. This study evaluated iron stearate (FeSt) and cobalt stearate (CoSt) incorporated into polypropylene (PP) at 1–2 wt% concentrations, examining their effects on photo- and thermo-oxidation under accelerated weathering conditions. Pro-oxidant-modified PP experienced severe embrittlement and fragmentation within 318&#xa0;h (equivalent to ~ 2 months outdoor Florida exposure), with melting temperatures decreasing 4.7–13% and crystallinity declining from 47% to 34%. Cobalt stearate demonstrated superior degradation activity (CoSt 2 wt% &gt; FeSt 2 wt% &gt; CoSt 1 wt% &gt; FeSt 1 wt%), inducing &gt; 80% weight loss within two weeks. However, comprehensive environmental and economic analysis revealed critical sustainability concerns that challenge the viability of this technology. Rather than achieving complete mineralization, degradation produced persistent micro- and nanoplastics alongside water-soluble carbonyl compounds. Metal leaching analysis detected cobalt (0.62&#xa0;mg/L) and iron (0.95&#xa0;mg/L) in weathering chamber leachates, raising ecotoxicological concerns. Most critically, pro-oxidant additives severely undermine circular economy initiatives: current sorting technologies cannot distinguish treated plastics from conventional materials, and studies demonstrate that incorporating just 5% degraded pro-oxidant material reduces recycled product tensile strength by approximately 50%. While pro-oxidants accelerate visible macroplastic fragmentation, they generate persistent microplastic pollution and compromise recycling infrastructure, presenting an unacceptable trade-off. Sustainable plastic waste management requires balancing degradation enhancement with recyclability preservation and environmental safety.</p> Graphical abstract <p></p>

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Pro-oxidant additive to polypropylene degradation: impacts on environmental sustainability and recycling

  • 期刊论文

  • 发表日期：

    2026年4月7日

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  • Endalkachew Sahle-Demessie,
  • Ayenachew Tegenaw,
  • Raymond Smith

摘要

The environmental persistence of plastic waste has driven development of pro-oxidant additives to accelerate degradation. This study evaluated iron stearate (FeSt) and cobalt stearate (CoSt) incorporated into polypropylene (PP) at 1–2 wt% concentrations, examining their effects on photo- and thermo-oxidation under accelerated weathering conditions. Pro-oxidant-modified PP experienced severe embrittlement and fragmentation within 318 h (equivalent to ~ 2 months outdoor Florida exposure), with melting temperatures decreasing 4.7–13% and crystallinity declining from 47% to 34%. Cobalt stearate demonstrated superior degradation activity (CoSt 2 wt% > FeSt 2 wt% > CoSt 1 wt% > FeSt 1 wt%), inducing > 80% weight loss within two weeks. However, comprehensive environmental and economic analysis revealed critical sustainability concerns that challenge the viability of this technology. Rather than achieving complete mineralization, degradation produced persistent micro- and nanoplastics alongside water-soluble carbonyl compounds. Metal leaching analysis detected cobalt (0.62 mg/L) and iron (0.95 mg/L) in weathering chamber leachates, raising ecotoxicological concerns. Most critically, pro-oxidant additives severely undermine circular economy initiatives: current sorting technologies cannot distinguish treated plastics from conventional materials, and studies demonstrate that incorporating just 5% degraded pro-oxidant material reduces recycled product tensile strength by approximately 50%. While pro-oxidants accelerate visible macroplastic fragmentation, they generate persistent microplastic pollution and compromise recycling infrastructure, presenting an unacceptable trade-off. Sustainable plastic waste management requires balancing degradation enhancement with recyclability preservation and environmental safety.

Graphical abstract