The efficient removal of surface coatings from post-consumer polycarbonate (PC) plastics is a critical step in producing high-quality post-consumer recycled (PCR) materials, yet current industrial paint removal processes lack systematic optimization that balances both technical performance and economic viability. This study presents a cost-efficiency integrated approach to optimizing the chemical paint removal process for recycling baked-enamel-coated PC waste. Two novel quantitative evaluation metrics were developed: De-painting efficiency (δ), defined as the product yield per unit processing time, and cost-efficiency index (Δ), which integrates comprehensive production costs into the efficiency assessment. Through preliminary screening of solvents, co-solvents, and process parameters, a systematic L16(45) orthogonal experimental design was implemented to investigate five factors (NaOH concentration, reaction temperature, primary solvent dosage, surfactant dosage, and co-solvent addition) at four levels. Range analysis identified NaOH concentration and reaction temperature as the dominant factors influencing both de-painting efficiency and cost-effectiveness. The optimal cost-efficient process was determined as: NaOH 14.00% (w/w), reaction temperature 80 °C, Solvent A 3.50% (w/w), surfactant 3.50% (w/w), and no co-solvent addition. Triplicate validation experiments demonstrated that the optimized process achieved a 74.20% improvement in de-painting efficiency (δ: 14.089 vs. 8.087), a 43.8% reduction in the cost-efficiency index (Δ: 9.982 vs. 17.774), a 40.00% reduction in batch processing time, and a 4.49% increase in product yield compared to the current industrial process. The proposed dual-metric methodology provides a practical framework for bridging laboratory optimization with industrial-scale implementation in polymer recycling.
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Wei, Y. (2025) Optimization of Paint Removal Process for Recycling Post-Consumer Polycarbonate (PC) Plastics: A Cost-Efficiency Integrated Approach. Scientific Research Bulletin, 2(5), 59-69. https://doi.org/10.71052/srb2024/BQQE2951