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36. Autohydrolysis treatment of bamboo and potassium oxalate (K2C2O4) activation of bamboo product for CO2 capture utilization.

Author

Viet, Dang Duc, Thao, Doan Thi, Anh, Khuong Duy, and Tsubota, Toshiki

Abstract

Typically, the hydroxide agents, such as sodium hydroxide and potassium hydroxide, which have corrosive properties, are used in the carbon activation process. In this study, potassium oxalate (K2C2O4), a less toxic and non-corrosive activating reagent, was used to synthesize activated carbon from the solid residue after autohydrolysis treatment. The effect of the autohydrolysis treatment and the ratio of the K2C2O4/solid residue are presented in this study. Moreover, the comparison between the activated carbon from bamboo and biochar from the solid residue are also reported. The resulting activated carbon from the solid residue exhibited a high surface area of up to 1432 m2·g−1 and a total pore volume of up to 0.88 cm3·g−1. The autohydrolysis treatment enhanced the microporosity properties compared to those without pretreatment of the activated carbon. The microporosity of the activated carbon from the solid residue was dominated by the pore width at 0.7 nm, which is excellent for CO2 storage. At 25 °C and 1.013 × 105 Pa, the CO2 captured reached up to 4.1 mmol·g−1. On the other hand, the ratio between K2C2O4 and the solid residue has not played a critical role in determining the porosity properties. The ratio of the K2C2O4/solid residue of 2 could help the carbon material reach a highly microporous textural property that produces a high carbon capture capacity. Our finding proved the benefit of using the solid residue from the autohydrolysis treatment as a precursor material and offering a more friendly and sustainable activation carbon process. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Synergistic effect of the heterojunction g-C3N4/Bi2MoO6/clinoptilolite to enhance the photocatalytic degradation of antibiotics in water in the presence of persulfateElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ew00549j

Author

Le, Phuong Thu, Nguyen, Thu Phuong, Do, Thi Hai, Nguyen, Hong Nam, Dinh, Thi Mai Thanh, Phan, Thi Thuy, Tsubota, Toshiki, and Nguyen, Trung Dung

Abstract

A novel and highly efficient photocatalyst, g-C3N4/Bi2MoO6/clinoptilolite nanocomposite (CNBC), was synthesized by a hydrothermal method and acted as a Z-scheme heterojunction for efficient activation of peroxydisulfate (PDS) to degrade oxytetracycline (OTC) under visible light (vis) irradiation. The morphology and structure of the photocatalyst were determined by XRD, FT-IR, FE-SEM, EDX, BET, TGA, UV-vis DRS, PL, and XPS. The results showed that CNBC-30 had the best photocatalytic performance with an OTC removal efficiency of more than 87% within 120 min under the conditions of [OTC] = 20 mg L−1, [catalyst] = 500 mg L−1, [Na2S2O8] = 1.26 mM, and pH = 4 at room temperature, which was much better than those of pure g-C3N4, Bi2MoO6, and CNB composites. This superiority is due to the excellent adsorption ability of clinoptilolite that effectively forms the g-C3N4/Bi2MoO6heterojunctions, thus improving the ability to separate charge carriers while decreasing the recombination rate of electron–hole pairs. Furthermore, the effect of catalyst dosage, oxidant concentration, initial pollutant concentration, solution pH, and coexisting anions on the OTC degradation was comprehensively studied. The results showed that the CNBC-30/PDS system had high reusability and adaptability at different pH levels (3.0–11.0). Quenching tests showed that 1O2, O2−, and h+played the main roles in OTC degradation. In addition, OTC intermediates were identified and degradation pathways were proposed based on the results of MS analysis. DFT calculations successfully predicted the positions on the OTC molecule with high Fukui numbers that are suitable for attack by oxidants. CNBC-30 was stable for OTC degradation after four cycles with a degradation efficiency of above 78%, demonstrating its durability and potential for practical applications. This study provides insight into PDS activation in the visible light region by a clinoptilolite-based Z-scheme heterojunction for organic pollutant degradation.

Published
2024
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