Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison

The capacity and underlying mechanism of hydrochars derived from commercial D -glucose and wasted orange peels (designated as pristine-hydrochars) and further modified with nitric acid (designated as oxidized-hydrochars) to adsorb methylene blue were investigated. Both pristine- and oxidized-hydroch...

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Main Authors: Duy H Nguyen, Hai Nguyen Tran, Huan-Ping Chao, Chu-Ching Lin
Format: Article
Language:English
Published: SAGE Publications 2019-10-01
Series:Adsorption Science & Technology
Online Access:https://doi.org/10.1177/0263617419867519
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author Duy H Nguyen
Hai Nguyen Tran
Huan-Ping Chao
Chu-Ching Lin
author_facet Duy H Nguyen
Hai Nguyen Tran
Huan-Ping Chao
Chu-Ching Lin
author_sort Duy H Nguyen
collection DOAJ
description The capacity and underlying mechanism of hydrochars derived from commercial D -glucose and wasted orange peels (designated as pristine-hydrochars) and further modified with nitric acid (designated as oxidized-hydrochars) to adsorb methylene blue were investigated. Both pristine- and oxidized-hydrochars were characterized by scanning electron microscopy, Brunauer–Emmet–Teller-specific surface area, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and mass titration. The maximum methylene blue adsorption capacity at 30°C estimated by the Langmuir model was found to follow the order: mGH (246 mg/g) > mOPH (107 mg/g) > OPH (59.6 mg/g) > GH (54.8 mg/g). Six adsorption mechanisms were elucidated, in which the electrostatic interaction and hydrogen bonding were identified as the primary methylene blue-hydrochar adsorptive interaction; furthermore, because the nitric acid modification process enhanced oxygen- and nitrogen-containing functional groups and unsaturated bonds on the surface of oxidized-hydrochars, the π – π and n – π interaction became minor pathways for methylene blue adsorption onto oxidized-hydrochars. Our results suggest that modified hydrochars could be used as environmentally friendly adsorbents alternative to activated carbon in dealing with methylene blue contamination in aqueous solutions.
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spelling doaj.art-9e0085e93fdb4a6fa4ece2c1d2b01e752024-03-02T01:59:49ZengSAGE PublicationsAdsorption Science & Technology0263-61742048-40382019-10-013710.1177/0263617419867519Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparisonDuy H NguyenHai Nguyen TranHuan-Ping ChaoChu-Ching LinThe capacity and underlying mechanism of hydrochars derived from commercial D -glucose and wasted orange peels (designated as pristine-hydrochars) and further modified with nitric acid (designated as oxidized-hydrochars) to adsorb methylene blue were investigated. Both pristine- and oxidized-hydrochars were characterized by scanning electron microscopy, Brunauer–Emmet–Teller-specific surface area, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and mass titration. The maximum methylene blue adsorption capacity at 30°C estimated by the Langmuir model was found to follow the order: mGH (246 mg/g) > mOPH (107 mg/g) > OPH (59.6 mg/g) > GH (54.8 mg/g). Six adsorption mechanisms were elucidated, in which the electrostatic interaction and hydrogen bonding were identified as the primary methylene blue-hydrochar adsorptive interaction; furthermore, because the nitric acid modification process enhanced oxygen- and nitrogen-containing functional groups and unsaturated bonds on the surface of oxidized-hydrochars, the π – π and n – π interaction became minor pathways for methylene blue adsorption onto oxidized-hydrochars. Our results suggest that modified hydrochars could be used as environmentally friendly adsorbents alternative to activated carbon in dealing with methylene blue contamination in aqueous solutions.https://doi.org/10.1177/0263617419867519
spellingShingle Duy H Nguyen
Hai Nguyen Tran
Huan-Ping Chao
Chu-Ching Lin
Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison
Adsorption Science & Technology
title Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison
title_full Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison
title_fullStr Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison
title_full_unstemmed Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison
title_short Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison
title_sort effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue an adsorption mechanism comparison
url https://doi.org/10.1177/0263617419867519
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