Sustainable Conversion of Waste PET into Porous Activated Carbon for Efficient Cu²⁺ Elimination from Aqueous Solution

Heavy metal pollutants, such as Cu²⁺, pose significant environmental and health risks due to their toxicity and persistence in water systems. Simultaneously, the increasing accumulation of waste poly(ethylene terephthalate) (PET) bottles represents a growing environmental challenge, contributing to plastic pollution. This study addresses both issues by converting waste PET bottles into porous activated carbon (APC) via pyrolysis, creating an efficient and sustainable adsorbent for Cu²⁺ removal from aqueous solutions. The APC materials were thoroughly characterized by SEM, BET, and XPS analyses, revealing a highly porous structure and abundant oxygen-containing functional groups, which enhance Cu²⁺ adsorption. The adsorption process was determined to be spontaneous, with a low activation energy of 7.47 kJ/mol, indicating a favorable and energy-efficient adsorption mechanism. Among the APC samples, APC-800 exhibited the best performance, achieving a Cu²⁺ removal efficiency of 99.30% and a maximum adsorption capacity of 5.85 mg/g. Recyclability tests confirmed the material's durability, maintaining over 96% efficiency during the first three cycles, with a slight decline in later cycles. This study demonstrates a dual environmental benefit: mitigating plastic waste by repurposing PET bottles and providing an effective solution for heavy metal pollution, aligning with circular economy principles, and promoting sustainability in environmental management.