Turning waste into environmental remediation: Green synthesis of lemon peel-derived carbon quantum dots for photocatalytic dye removal

In this study, lemon peel waste was valorized as a sustainable carbon source for the green synthesis of carbon quantum dots (CQDs) via a hydrothermal method. The synthesized CQDs, characterized by FT-IR, Raman, XRD, zeta potential, TEM, TGA/DSC and BET analysis, exhibited mesoporous structures with a moderate surface area ۶.۹۰ m²/g, an average pore diameter of ۳.۵۱ nm, and excitation-dependent photoluminescence in the visible range. Structural characterization revealed the presence of oxygen-containing functional groups and disordered graphitic carbon domains. The CQDs demonstrated excellent thermal stability and a nearly neutral zeta potential, indicating colloidal stability in aqueous environments. Photocatalytic degradation studies were conducted using four model textile dyes (Basic Blue ۷, Acid Blue ۵۶, Acid Blue ۱۱۳, and Acid Blue ۱۲۸) under UV-Vis irradiation. The results showed that dye removal efficiency was significantly influenced by solution pH, CQD dosage, initial dye concentration, and contact time. Optimal removal occurred at low pH ۲, CQD loading ۰.۰۳ g, dye concentrations ۵ ppm, and contact times ۱۲۰ minutes, with Acid Blue ۱۱۳ achieving up to ۹۶% removal. These findings confirm the efficacy of lemon peel-derived CQDs as eco-friendly and efficient photocatalysts for the remediation of dye-contaminated wastewater, aligning with principles of green chemistry and circular economy.

کلیدواژه ها:

Lemon peel ، Carbon quantum dots ، Photocatalytic dye removal ، Basic Blue ۷ ، Acid Blue ۵۶ ، Acid Blue ۱۱۳ ، Acid Blue ۱۲۸