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Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal

Cilt: 16 Sayı: 3 8 Eylül 2026
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Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal

Öz

Spent tea waste is generated in large quantities yet is commonly discarded despite its lignocellulosic structure, which can be valorized for water treatment. In this study, spent tea waste collected from a departmental kitchen was converted into three adsorbents: raw tea waste (RTW), hydrochar tea waste (HTW) produced via hydrothermal carbonization at 250 °C under different residence times, and alkali-modified tea waste (AMTW) obtained through KOH surface treatment. Congo Red (CR) was selected as a model anionic dye, and adsorption performance was evaluated under batch conditions by examining the effects of contact time, initial dye concentration, adsorbent dosage, and solution pH. HTW produced at 3 h showed the highest removal efficiency (≈79%) and was used for subsequent experiments. Characterization revealed carbon enrichment after hydrothermal treatment and a significant increase in surface area following alkali modification. Adsorption was rapid and reached equilibrium within 90–120 min, with HTW and AMTW outperforming RTW. Kinetic data followed the pseudo-second-order model, while equilibrium data fit the Freundlich isotherm, indicating heterogeneous adsorption. Desorption tests showed high preliminary desorption efficiencies, suggesting regeneration potential. Overall, hydrothermal carbonization and alkali modification effectively transformed spent tea waste into sustainable and low-cost adsorbents for dye removal from aqueous solutions.

Anahtar Kelimeler

Adsorption, Alkali modification, Congo Red, Hydrothermal carbonization, Kinetics and isotherms, Spent tea waste

Destekleyen Kurum

This study was supported by the Scientific Research Projects Coordination Unit of Ondokuz Mayıs University under the project titled “Evaluation of Biochars Obtained from Campus Tea Waste Using a Sustainability Approach” (Project No: PYO.MUH.1908.22.066).

Proje Numarası

PYO.MUH.1908.22.066

Etik Beyan

This study does not involve human participants or animals. Therefore, ethical approval and informed consent were not required. The authors declare that the study was conducted in accordance with the principles of research and publication ethics.

Teşekkür

The authors would like to thank the Scientific Research Projects Coordination Unit of Ondokuz Mayıs University for financial and institutional support during the study.

Kaynakça

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Kaynak Göster

APA
Darama, S. E., & Çoruh, S. (2026). Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal. Karadeniz Fen Bilimleri Dergisi, 16(3), 1362-1382. https://doi.org/10.31466/kfbd.1886593
AMA
1.Darama SE, Çoruh S. Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal. KFBD. 2026;16(3):1362-1382. doi:10.31466/kfbd.1886593
Chicago
Darama, Sevda Esma, ve Semra Çoruh. 2026. “Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal”. Karadeniz Fen Bilimleri Dergisi 16 (3): 1362-82. https://doi.org/10.31466/kfbd.1886593.
EndNote
Darama SE, Çoruh S (01 Eylül 2026) Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal. Karadeniz Fen Bilimleri Dergisi 16 3 1362–1382.
IEEE
[1]S. E. Darama ve S. Çoruh, “Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal”, KFBD, c. 16, sy 3, ss. 1362–1382, Eyl. 2026, doi: 10.31466/kfbd.1886593.
ISNAD
Darama, Sevda Esma - Çoruh, Semra. “Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal”. Karadeniz Fen Bilimleri Dergisi 16/3 (01 Eylül 2026): 1362-1382. https://doi.org/10.31466/kfbd.1886593.
JAMA
1.Darama SE, Çoruh S. Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal. KFBD. 2026;16:1362–1382.
MLA
Darama, Sevda Esma, ve Semra Çoruh. “Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal”. Karadeniz Fen Bilimleri Dergisi, c. 16, sy 3, Eylül 2026, ss. 1362-8, doi:10.31466/kfbd.1886593.
Vancouver
1.Sevda Esma Darama, Semra Çoruh. Valorization of Spent Tea Waste into Hydrochar and Alkali-Modified Biosorbents for Congo Red Removal. KFBD. 01 Eylül 2026;16(3):1362-8. doi:10.31466/kfbd.1886593