Dissolution–Separation–Precipitation (D–S–P) method for removing carbon black from acrylonitrile–butadiene–styrene (ABS)

The growing accumulation of plastic waste in landfills necessitates improved recycling methods. This study addresses the challenge of recycling acrylonitrile–butadiene–styrene (ABS) plastic by focusing on the removal of carbon black (CB) pigments, which complicate solvent-based recycling processes by affecting dissolution, purification, and the quality of recovered polymers. We developed an innovative Dissolution–Separation–Precipitation (D–S–P) method that utilizes a collector solvent to attract and remove carbon black (CB) through hydrogen bonding. The process was evaluated using color measurements, Fourier-Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) to assess the efficiency of CB removal and the preservation of ABS properties. This research introduces a novel approach for targeted pigment removal in ABS recycling, addressing a specific gap in current solvent-based recycling techniques that generally do not focus on pigment contaminants. The D–S–P process effectively removed CB, with the recovery of transmittance related with carbonyl groups approaching that of virgin ABS. Additionally, the analyses confirmed that the molecular weight distribution and thermal properties of the recovered ABS were well-preserved. The D–S–P method enhances the recyclability of ABS by efficiently removing CB pigments while maintaining the polymer’s mechanical and chemical properties. This approach not only improves the quality of recycled materials but also offers a practical solution for advancing plastic recycling technologies.