Optimization of photocatalytic persulfate activation by g-C3N4/carbon quantum dots composite for oxytetracycline removal: Mechanistic insights and Box–Behnken design
Inorganic Chemistry Communications, cilt.194, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 194
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.inoche.2026.117572
- Dergi Adı: Inorganic Chemistry Communications
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, DIALNET
- Anahtar Kelimeler: Antibiotics, Carbon materials, Peroxydisulfate, Photocatalytic, Response surface methodology, Water purification
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
Oxytetracycline (OTC), an antibiotic prevalent in aquatic environments, poses ecotoxicity and resistance risks. A mesoporous g-C3N4/carbon quantum dots (CN-CQDs) composite was synthesized and investigated for photocatalytic OTC removal under UV irradiation with peroxydisulfate (PDS) activation. The CN-CQDs heterojunction narrowed the bandgap from 2.9 eV (pristine CN) to 2.8 eV and reduced charge-transfer resistance from 1691 Ω to 975.8 Ω, indicating enhanced electron separation and transfer. Kinetic analysis revealed a rate constant of 0.042 min−1, corresponding to 1.16 and 1.21 times higher than those of UV/PDS/CN and UV/PDS/CQDs, respectively. Box–Behnken design (R2 = 0.9825, Adj-R2 = 0.9622) optimized the process, with Pareto analysis identifying reaction time (41.02%) and PDS concentration (31.09%) as the most influential parameters. Under optimized conditions ([catalyst] = 0.14 g/L, [PDS] = 0.11 g/L, pH = 3.4, and time = 57.8 min), the system achieved 98.7% OTC removal and 50% COD reduction. While OTC removal reflects the disappearance of the parent compound, the 50% COD reduction indicates partial mineralization, with the remaining organic matter likely consisting of breakdown products. The performance improvement is attributed to the electron-accepting characteristic of CQDs, which suppresses electron-hole recombination. Reactive species analysis identified singlet oxygen (1O2), photogenerated holes (h+), and superoxide anion radical ((Formula presented) ) as the dominant species. The composite maintained 92.9% of its initial activity after five consecutive cycles, demonstrating good reusability. These findings establish the UV/PDS/CN-CQDs system as a promising approach for antibiotic removal from water, though further studies with real wastewater are needed to assess practical viability.