Waste-derived activated carbons from phenol-formaldehyde and polystyrene: The role of PAN and alkali treatment

This study investigates the conversion of phenol-formaldehyde resin (PFR) and polystyrene (PS) waste into activated carbon materials with controlled porous structures. Each polymer was modified with ۰–۱۰ wt.% polyacrylonitrile (PAN), followed by carbonization at ۷۰۰–۸۰۰ °C in combination with chemical activation using sodium hydroxide (NaOH) at a carbon-to-NaOH ratio of ۱:۰.۴–۱:۱.۵. Thermogravimetric analysis revealed that PAN increases the total mass loss: for PS, from ۴۲% to ۵۱% at ۱۰۰۰ °C, and for PFR, from ۳۶.۷% to approximately ۳۹%. X-ray diffraction analysis indicated the formation of short-range graphitic domains: in PFR-derived carbon at ۸۰۰ °C, the (۰۰۲) peak narrows and a weak (۱۰۰) reflection appears, whereas ordering in PS-derived carbon was observed only upon PAN addition. Optimal activation with NaOH at a ratio of ۱:۰.۸ produced an ultramicroporous structure, with specific surface areas reaching ۸۷۳ m²/g for PFR-based carbon and ۷۵۰ m²/g for PS-based carbon, micropore volumes of ۰.۹–۱.۰ cm³/g, and average pore radii of ۳.۵–۳.۸ Å. Electron microscopy confirmed uniform microporosity in PFR-derived matrices and a hierarchical, “cellular” morphology in PS-derived matrices. The combination of ۱۰% PAN and NaOH activation at ۸۰۰ °C yielded the most favorable textural properties, demonstrating that separate processing of PFR and PS waste with PAN modification and alkaline activation is an effective strategy for producing highly porous carbon sorbents at moderate temperatures.

کلیدواژه ها:

Activated carbon ، Microporosity ، Specific surface area ، IR spectroscopy ، X-ray analysis ، polymer pyrolysis ، Plastic Waste