Upcycling factory potato peel into a hierarchically porous carbon for dye removal, phytotoxicity mitigation, and wastewater remediation.

Potato peel from chip factories, a centralized, continuously generated agro-industrial waste stream, is valorized here into a nitrogen-enriched, hierarchically porous activated carbon (PMC) through melamine-assisted N-doping and KOH activation. Unlike laboratory-scale biomass studies relying on inconsistent feedstocks, this work leverages factory-scale peel sourcing to improve feedstock consistency and industrial relevance. The engineered carbon exhibits a micro-mesoporous architecture (BET surface area = 284.3 m2 g-1) facilitates molecular accessibility, together with a highly super-hydrophilic surface (contact angle = 3.7°) and a strongly negative surface charge (ζ = -35.6 mV; pHpzc = 6.8). XPS, FTIR, Raman, and surface analyses show abundant nitrogen and oxygen containing functionalities and a defect-rich carbon matrix that facilitates adsorption through pore filling, hydrogen bonding, π-π interactions, and electrostatic attractions. PMC rapidly removes 98.9% of crystal violet in 60 min (Langmuir q m = 110.18 mg g-1, R 2 = 0.99) and follows pseudo-second-order kinetics (R 2 = 0.99). The adsorbent exhibits clear selectivity for cationic over anionic dyes, achieving 96.9% and 87% decolourization of two real textile effluents within 1 h, and retains >89% of its capacity after five ethanol regeneration cycles, demonstrating structural stability and practical reusability. Treated effluent restores germination and seedling growth in Vigna radiata, demonstrating an adsorption-based ecological remediation pathway. These results highlight the potential of PMC as an efficient and reusable adsorbent for practical dye removal from industrial wastewater. By coupling factory-scale feedstock consistency with targeted heteroatom tuning and pore design, PMC offers a low-cost, potentially scalable route for selective dye remediation aligned with circular-economy goals.