Black bean pod-derived pyrochar for single and binary adsorption of Cu(ii) and direct red 79: adsorption performance, interfacial interactions and regeneration
- 1TNU-University of Sciences, Thai Nguyen University Phan Dinh Phung Ward Thai Nguyen 250000 Vietnam [email protected] [email protected].
- 2Faculty of Chemistry, University of Science, Vietnam National University Hanoi, 19 Le Thanh Tong, Cua Nam Hanoi 100000 Vietnam.
- 3Institute of Life Sciences, Thai Nguyen University Phan Dinh Phung Ward Thai Nguyen 250000 Vietnam.
Abstract
The interplay between interfacial interactions and pore accessibility during binary adsorption of co-existing metal ions and anionic dyes on biomass-derived pyrochars remains insufficiently understood. Here, a pyrochar derived from black bean pods was investigated for Cu(ii) and Direct Red 79 (DR79) adsorption in single-solute and binary systems. Controlled pyrolysis (300-700 °C, 1-5 h) progressively altered the carbon structure and pore characteristics of the resulting pyrochars. BP7003, prepared at 700 °C for 3 h, exhibited a specific surface area of 517 m² g⁻¹, a substantial microporous contribution accompanied by mesopore-range features, and oxygen-containing surface functionalities. Cu(ii) showed rapid uptake, reaching a maximum experimentally determined equilibrium adsorption capacity of 117.13 ± 0.95 mg g⁻¹ at pH 5 under the investigated conditions. Its adsorption behaviour was consistent with contributions from surface electrostatics and oxygen-containing surface functionalities. DR79 exhibited a lower experimental equilibrium adsorption capacity of 66.05 ± 1.15 mg g⁻¹, with its adsorption behaviour suggesting a stronger influence of pore accessibility within the heterogeneous carbon structure. Kinetic and equilibrium analyses were consistent with heterogeneous adsorption environments for both solutes. Binary adsorption exhibited concentration-dependent behaviour under the investigated binary conditions, with small deviations from the corresponding single-solute reference systems across the tested concentration combinations. These observations are compatible with changes in the interfacial environment and competition for accessible adsorption domains, although a specific Cu-associated interaction mechanism remains unconfirmed. BP7003 retained most of its adsorption performance after four regeneration cycles, although a greater decline was observed for DR79. Overall, the results highlight the combined roles of surface chemistry, interfacial electrostatics, and pore accessibility in shaping Cu(ii)-DR79 co-adsorption across different loading regimes.
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BibTeX
@article{hoang2026black,
title = {{Black bean pod-derived pyrochar for single and binary adsorption of Cu(ii) and direct red 79: adsorption performance, interfacial interactions and regeneration}},
author = {Ngoc Anh Hoang and Thi Thuy Ha Dinh and Truong Xuan Vuong and Tien Duc Pham and Thuong Tuan Nguyen and Thi Thao Truong},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra07689k},
url = {https://europepmc.org/article/PMC/PMC13717515},
note = {CC BY},
}
RIS
TY - JOUR
TI - Black bean pod-derived pyrochar for single and binary adsorption of Cu(ii) and direct red 79: adsorption performance, interfacial interactions and regeneration
AU - Ngoc Anh Hoang
AU - Thi Thuy Ha Dinh
AU - Truong Xuan Vuong
AU - Tien Duc Pham
AU - Thuong Tuan Nguyen
AU - Thi Thao Truong
PY - 2026
DA - 2026/10/29
JO - RSC advances
DO - 10.1039/d6ra07689k
UR - https://europepmc.org/article/PMC/PMC13717515
AB - The interplay between interfacial interactions and pore accessibility during binary adsorption of co-existing metal ions and anionic dyes on biomass-derived pyrochars remains insufficiently understood. Here, a pyrochar derived from black bean pods was investigated for Cu(ii) and Direct Red 79 (DR79) adsorption in single-solute and binary systems. Controlled pyrolysis (300-700 °C, 1-5 h) progressively altered the carbon structure and pore characteristics of the resulting pyrochars. BP7003, prepared at 700 °C for 3 h, exhibited a specific surface area of 517 m² g⁻¹, a substantial microporous contribution accompanied by mesopore-range features, and oxygen-containing surface functionalities. Cu(ii) showed rapid uptake, reaching a maximum experimentally determined equilibrium adsorption capacity of 117.13 ± 0.95 mg g⁻¹ at pH 5 under the investigated conditions. Its adsorption behaviour was consistent with contributions from surface electrostatics and oxygen-containing surface functionalities. DR79 exhibited a lower experimental equilibrium adsorption capacity of 66.05 ± 1.15 mg g⁻¹, with its adsorption behaviour suggesting a stronger influence of pore accessibility within the heterogeneous carbon structure. Kinetic and equilibrium analyses were consistent with heterogeneous adsorption environments for both solutes. Binary adsorption exhibited concentration-dependent behaviour under the investigated binary conditions, with small deviations from the corresponding single-solute reference systems across the tested concentration combinations. These observations are compatible with changes in the interfacial environment and competition for accessible adsorption domains, although a specific Cu-associated interaction mechanism remains unconfirmed. BP7003 retained most of its adsorption performance after four regeneration cycles, although a greater decline was observed for DR79. Overall, the results highlight the combined roles of surface chemistry, interfacial electrostatics, and pore accessibility in shaping Cu(ii)-DR79 co-adsorption across different loading regimes.
SN - 2046-2069
ER -