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33 results on '"Shin, Jaegwan"'

21. Effects of the Pyrolysis Temperature on Adsorption of Carbamazepine and Ibuprofen by NaOH Pre-treated Pine Sawdust Biochars

Author

Shin Jaegwan, Sangwoo Park, Jinwoo Kwak, and Kangmin Chon

Subjects
021110 strategic, defence & security studies, pyrolysis temperature, Chemistry, 0211 other engineering and technologies, Pine sawdust, 02 engineering and technology, Carbamazepine, pharmaceuticals, 010501 environmental sciences, Ibuprofen, 01 natural sciences, lcsh:Environmental engineering, Adsorption, adsorption, carbamazepine, Biochar, medicine, biochar, lcsh:TA170-171, Pyrolysis, ibuprofen, 0105 earth and related environmental sciences, Nuclear chemistry, medicine.drug
Abstract

Objective: The main purpose of this study was to examine the impacts of the pyrolysis temperature on the removal of pharmaceuticals (i.e., ibuprofen (IBF) and carbamazepine (CBZ)) using NaOH pre-treated biochars produced from pine sawdusts.Methods:Two different types of kinetic and isotherm models were applied to investigate the adsorption mechanisms of IBF and CBZ by the NaOH pre-treated biochars produced at 600℃ (PB-600) and 800℃ (PB-800). In addition, the removal efficiencies of IBF and CBZ by PB-600 and PB-800 were compared under various conditions (adsorbent doses: 5-40 mg/L; 20-160 mg/L; temperature: 15-45℃; ionic strength: 0-0.5 M) to assess their feasibility as an alternative adsorbent for the removal of pharmaceuticals. Results and Discussion:PB-800 could more effectively remove CBZ and IBF than PB-600 because of its larger specific surface area (PB-600 = 408.70 m2/g; PB-800 = 472.92 m2/g), pore volume (PB-600 = 0.336 cm3/g; PB-800 = 0.658 cm3/g), and pore size (PB-600 = 4.63 nm; PB-800 = 6.25 nm). The Langmuir isotherm was more suitable for adsorption of IBF by PB-600 and the Freundlich isotherm was well fitted to the adsorption of CBZ by PB-600 and adsorption of CBZ and IBF by PB-800. The adsorption of CBZ by PB-600 and PB-800 was not affected by temperature while the removal efficiency of IBF was decreased with increasing the temperature due to the increased repulsive interaction between IBF and the biochars. Furthermore, the effects of the ionic strength on the adsorption of IBF were more pronounced than that of CBZ due to the differences in the surface charge properties.Conclusions:The higher pyrolysis temperature can improve the physicochemical properties of the NaOH pre-treated pine sawdust biochars associated with the removal of the pharmaceuticals (i.e., CBZ and IBF). Moreover, the adsorption mechanisms of CBZ and IBF by the biochars were strongly influenced by their specific surface area, pore volume and pore size.

Published
2020

22. Changes in adsorption mechanisms of radioactive barium, cobalt, and strontium ions using spent coffee waste biochars via alkaline chemical activation: Enrichment effects of O-containing functional groups

Author

Shin, Jaegwan, primary, Kwak, Jinwoo, additional, Lee, Yong-Gu, additional, Kim, Sangwon, additional, Son, Changgil, additional, Cho, Kyung Hwa, additional, Lee, Sang-Ho, additional, Park, Yongeun, additional, Ren, Xianghao, additional, and Chon, Kangmin, additional

Published
2021
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33. Effects of physicochemical properties of biochar derived from spent coffee grounds and commercial activated carbon on adsorption behavior and mechanisms of strontium ions (Sr2+).

Author

Shin, Jaegwan, Lee, Sang-Ho, Kim, Sangwon, Ochir, Duuriimaa, Park, Yongeun, Kim, Jihye, Lee, Yong-Gu, and Chon, Kangmin

Subjects
ACTIVATED carbon, COFFEE grounds, STRONTIUM ions, BIOCHAR, STRONTIUM, ADSORPTION (Chemistry)
Abstract

This study examined differences in the adsorption isotherms, kinetic equations, and thermodynamics of Sr2+ by biochar from spent coffee grounds (SCG) and powdered activated carbon (PAC). The specific surface area (957.6 m2/g) and pore volume (0.676 cm3/g) of PAC were much greater than those of SCG biochar (specific surface area = 11.0 m2/g, pore volume = 0.009 cm3/g). However, SCG biochar showed a higher maximum adsorption capacity of Sr2+ (Qmax = 51.81 mg/g) compared with PAC (Qmax = 32.79 mg/g) due to its abundance of O-containing functional groups. The negligible removal efficiencies of Sr2+ by SCG biochar and PAC under acidic conditions (pH = 1.0–3.0) are evidence that the electrostatic repulsion might hinder severely the adsorption of Sr2+ by the carbonaceous adsorbents. The higher R2 values of the pseudo-second-order model (R2 ≥ 0.999) compared with the pseudo-first-order model (R2 ≥ 0.815) suggest that chemisorption governed the removal of Sr2+ using SCG biochar and PAC. Furthermore, the better description of the adsorption behavior of Sr2+ by the Langmuir isotherm model (R2 ≥ 0.994) than the Freundlich isotherm model (R2 ≥ 0.982) supports the assumption that the monolayer adsorption played critical roles in the removal of Sr2+ using SCG biochar and PAC. The thermodynamic studies revealed that adsorption of Sr2+ onto SCG biochar and PAC was endothermic and happened spontaneously. Despite the significant inhibitory effects of DOM, SCG biochar exhibited the higher removal efficiencies of Sr2+ compared with PAC. Hence, SCG biochar could be considered as an alternative to PAC for the removal of Sr2+ from aqueous solutions. [ABSTRACT FROM AUTHOR]

Published
2021
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