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Determining the degree of the reducing power of multi-walled carbon nanotubes (MWCNTs) and granular activated carbon (GAC) enables their effective application in various fields. In this study, we estimate the reducing power of carbon nanotubes (CNTs) and GAC by measuring the reduction degree of various compounds with different reduction potentials. MWCNTs and GAC materials can reduce Cr(VI), Fe(III) and PMo12O403−, where the reduction potentials range from +1.33 V to +0.65 V. However, no reduced forms of PW12O403− and SiW12O404− compounds were detected, indicating that the reducing power of MWCNTs and GAC is insufficient for reduction potentials in the range +0.218 V to +0.054 V. MWCNTs exhibit a short reduction time (5 min), whereas GAC exhibits a gradually increasing reduction degree of all the compounds assessed until the end of the reaction. This indicates a higher reduction degree than that of MWCNTs systems. Acidic initial pH values favor reduction, and the reduction degree increases as the pH becomes lower than 4.0. Moreover, large quantities of MWCNTs and GAC increase the concentrations of the reduced compounds.
Heesoo Woo; Ilho Kim; Saerom Park. Estimating the Reducing Power of Carbon Nanotubes and Granular Activated Carbon Using Various Compounds. Water 2021, 13, 1959 .
AMA StyleHeesoo Woo, Ilho Kim, Saerom Park. Estimating the Reducing Power of Carbon Nanotubes and Granular Activated Carbon Using Various Compounds. Water. 2021; 13 (14):1959.
Chicago/Turabian StyleHeesoo Woo; Ilho Kim; Saerom Park. 2021. "Estimating the Reducing Power of Carbon Nanotubes and Granular Activated Carbon Using Various Compounds." Water 13, no. 14: 1959.
To investigate the impact of carbon phase conversion on the catalytic activity of nanodiamonds, in this study, we tested nanodiamonds subjected to graphitization at varying temperatures for persulfate activation. Temperatures beyond 1000℃ (where only surface graphitization occurs) steadily enhanced the persulfate activation capability as the inner carbon underwent substantial sp3-to-sp2 transformation. Nanodiamonds annealed at 2000℃ outperformed benchmark nanocarbons in terms of persulfate activation efficiency. Non-radical activation occurred primarily based on the effects of radical quenchers, oxidation product distribution, substrate-dependent reactivity, and electron paramagnetic resonance spectra. Aligned with the density functional theory calculations of the binding energies of peroxydisulfate on the slab models, built via Bernal stacking of graphitic carbon layers on the diamond plane, isothermal titration calorimetry measurements suggested that the binding affinity of peroxydisulfate decreased as the sp2/sp3 ratio increased. Therefore, the enhancing effect of graphitization arose from the electrical conductivity of nanodiamonds, which increased proportionally with graphitization extent.
Bowen Yang; Haisu Kang; Young-Jin Ko; Heesoo Woo; Geondu Gim; Jaemin Choi; Jaesung Kim; Kangwoo Cho; Eun-Ju Kim; Seung-Geol Lee; Hongshin Lee; Jaesang Lee. Persulfate activation by nanodiamond-derived carbon onions: Effect of phase transformation of the inner diamond core on reaction kinetics and mechanisms. Applied Catalysis B: Environmental 2021, 293, 120205 .
AMA StyleBowen Yang, Haisu Kang, Young-Jin Ko, Heesoo Woo, Geondu Gim, Jaemin Choi, Jaesung Kim, Kangwoo Cho, Eun-Ju Kim, Seung-Geol Lee, Hongshin Lee, Jaesang Lee. Persulfate activation by nanodiamond-derived carbon onions: Effect of phase transformation of the inner diamond core on reaction kinetics and mechanisms. Applied Catalysis B: Environmental. 2021; 293 ():120205.
Chicago/Turabian StyleBowen Yang; Haisu Kang; Young-Jin Ko; Heesoo Woo; Geondu Gim; Jaemin Choi; Jaesung Kim; Kangwoo Cho; Eun-Ju Kim; Seung-Geol Lee; Hongshin Lee; Jaesang Lee. 2021. "Persulfate activation by nanodiamond-derived carbon onions: Effect of phase transformation of the inner diamond core on reaction kinetics and mechanisms." Applied Catalysis B: Environmental 293, no. : 120205.
Yongsung Kim; Xiaoqiang Dong; Heesoo Woo; Junboum Park. Erratum to: A developed soil column test device for measuring the electrical conductivity breakthrough curves. Environmental Earth Sciences 2015, 73, 6725 -6725.
AMA StyleYongsung Kim, Xiaoqiang Dong, Heesoo Woo, Junboum Park. Erratum to: A developed soil column test device for measuring the electrical conductivity breakthrough curves. Environmental Earth Sciences. 2015; 73 (10):6725-6725.
Chicago/Turabian StyleYongsung Kim; Xiaoqiang Dong; Heesoo Woo; Junboum Park. 2015. "Erratum to: A developed soil column test device for measuring the electrical conductivity breakthrough curves." Environmental Earth Sciences 73, no. 10: 6725-6725.
A new material was developed and evaluated for the targeted removal of trichlorophenol (TCP) from among potential interferents which are known to degrade removal activity. To achieve TCP-targeted activity, an alginate bead containing nanoscale palladium/zero-valent iron (Pd/nZVI) was coated with a highly hydrophobic oleic acid layer. The new material (Pd/nZVI-A-O) preferentially sorbed TCP from a mixture of chlorinated phenols into the oleic acid cover layer and subsequently dechlorinated it to phenol. The removal efficacy of TCP by Pd/nZVI-A-O was not affected by co-existing organic substances such as Suwannee River humic acid (SRHA), whereas the material without the oleic acid layer (Pd/nZVI-A) became less effective with increasing SRHA concentration. The inorganic substances nitrate and phosphate significantly reduced the reactivity of Pd/nZVI-A, however, Pd/nZVI-A-O showed similar TCP removal efficacies regardless of the initial inorganic ion concentrations. The influence of bicarbonate on the TCP removal efficacies of both Pd/nZVI-A and Pd/nZVI-A-O was not significant. The findings from this study suggest that Pd/nZVI-A-O, with its targeted, constant reactivity for TCP, would be effective for treating this contaminant in surface water or groundwater containing various competitive substrates.
Jaewon Chang; Heesoo Woo; Myoung-Soo Ko; Jaesang Lee; Seockheon Lee; Seong-Taek Yun; Seunghak Lee. Targeted removal of trichlorophenol in water by oleic acid-coated nanoscale palladium/zero-valent iron alginate beads. Journal of Hazardous Materials 2015, 293, 30 -36.
AMA StyleJaewon Chang, Heesoo Woo, Myoung-Soo Ko, Jaesang Lee, Seockheon Lee, Seong-Taek Yun, Seunghak Lee. Targeted removal of trichlorophenol in water by oleic acid-coated nanoscale palladium/zero-valent iron alginate beads. Journal of Hazardous Materials. 2015; 293 ():30-36.
Chicago/Turabian StyleJaewon Chang; Heesoo Woo; Myoung-Soo Ko; Jaesang Lee; Seockheon Lee; Seong-Taek Yun; Seunghak Lee. 2015. "Targeted removal of trichlorophenol in water by oleic acid-coated nanoscale palladium/zero-valent iron alginate beads." Journal of Hazardous Materials 293, no. : 30-36.
Washing and drying processes are essential when synthesizing nano-scale zero valent irons (nZVIs) by borohydride reduction of iron salts in aqueous phase. However, effects of these processes on nZVI reactivity have not been investigated in detail, although different washing and drying conditions might alter surface characteristics of nZVIs and thus vary their reactivity towards reducible contaminants. In this study, effects of three washing solutions and drying conditions on the reactivity of nZVIs for nitrate were investigated. Washing with volatile solvents and drying under anaerobic condition decreased thickness of Fe-oxide layer on nZVIs and increased content of Fe(2+)-containing oxides in the layer, which enhanced nZVI reactivity toward nitrate. Volatile solvent washing could minimize the decrease in nZVI reactivity according to changing anaerobic drying condition to aerobic. Findings from this study suggest that application of washing with volatile solvents and drying under aerobic condition should be recommended as effective processes to obtain nZVIs with maximum reactivity at reasonable costs and efforts.
Heesoo Woo; Junboum Park; Seockheon Lee; Seunghak Lee. Effects of washing solution and drying condition on reactivity of nano-scale zero valent irons (nZVIs) synthesized by borohydride reduction. Chemosphere 2014, 97, 146 -152.
AMA StyleHeesoo Woo, Junboum Park, Seockheon Lee, Seunghak Lee. Effects of washing solution and drying condition on reactivity of nano-scale zero valent irons (nZVIs) synthesized by borohydride reduction. Chemosphere. 2014; 97 ():146-152.
Chicago/Turabian StyleHeesoo Woo; Junboum Park; Seockheon Lee; Seunghak Lee. 2014. "Effects of washing solution and drying condition on reactivity of nano-scale zero valent irons (nZVIs) synthesized by borohydride reduction." Chemosphere 97, no. : 146-152.
Yubin Zeng; Heesoo Woo; Gwanghun Lee; Junboum Park. Removal of chromate from water using surfactant modified Pohang clinoptilolite and Haruna chabazite. Desalination 2010, 257, 102 -109.
AMA StyleYubin Zeng, Heesoo Woo, Gwanghun Lee, Junboum Park. Removal of chromate from water using surfactant modified Pohang clinoptilolite and Haruna chabazite. Desalination. 2010; 257 (1-3):102-109.
Chicago/Turabian StyleYubin Zeng; Heesoo Woo; Gwanghun Lee; Junboum Park. 2010. "Removal of chromate from water using surfactant modified Pohang clinoptilolite and Haruna chabazite." Desalination 257, no. 1-3: 102-109.
Adsorption of Cr(VI) on Pohang zeolite (PZ) and Haruna zeolite (HZ) modified with surfactant hexadecylpyridinium bromide (HDPB) was investigated by batch studies, X-ray diffraction (XRD), FT-IR spectroscopy and scanning electron microscopy (SEM) analyses. The results show that Cr(VI) adsorption on HDPB-zeolites have quick initial speed and adsorption kinetics follow pseudo-second order kinetic model within the initial adsorption stage. HDPB-zeolites have higher affinities toward chromate than that to natural zeolites, and particularly, HDPB-HZ exhibits the highest adsorption capacity in the all samples studied. Additionally, the adsorption of Cr(VI) on HDPB-PZ is almost constant in a wide pH range 3.0–11.0 of solution. In contrast, the Cr(VI)-uptake for HDPB-HZ strongly depends on the solution pH. The highest Cr(VI) adsorption on HDPB-HZ occurs in acidic solutions (pH 3.0–5.0) and the amount of sorbed Cr(VI) decreases rapidly with increasing pH. High solution ionic strength has a significant effect on chromate adsorption. The chromate adsorptions by HDPB-zeolites are not affected by coexisting chloride, nitrate, sulfate, and calcium as well as magnesium ions but are reduced drastically in the presence of bicarbonate and phosphate ions. Moreover, HDPB-zeolites can achieve high regeneration efficiency after using sodium carbonate extraction and hydrochloric acid. The analyses of XRD, FTIR and SEM reveal that HDPB cations are incorporated into the zeolite’s structure via ion-exchange and Van der Waals forces. It also suggests that anion exchange and electrostatic interaction are probably the main mechanisms that govern the Cr(VI) adsorption.
Yubin Zeng; Heesoo Woo; Gwanghun Lee; Junboum Park. Adsorption of Cr(VI) on hexadecylpyridinium bromide (HDPB) modified natural zeolites. Microporous and Mesoporous Materials 2010, 130, 83 -91.
AMA StyleYubin Zeng, Heesoo Woo, Gwanghun Lee, Junboum Park. Adsorption of Cr(VI) on hexadecylpyridinium bromide (HDPB) modified natural zeolites. Microporous and Mesoporous Materials. 2010; 130 (1-3):83-91.
Chicago/Turabian StyleYubin Zeng; Heesoo Woo; Gwanghun Lee; Junboum Park. 2010. "Adsorption of Cr(VI) on hexadecylpyridinium bromide (HDPB) modified natural zeolites." Microporous and Mesoporous Materials 130, no. 1-3: 83-91.