Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption
Surface oxygen functional groups of biochar were tuned by oxidation and reduction of biochar for establishing Cr(VI) adsorption mechanism. Oxygen functional groups (OFGs) on the surface of leached rice straw biochar (LBC4-6) obtained from pyrolysis at 400, 500 and 600 °C, were oxidized to furnish OB...
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Elsevier
2023-11-01
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| Series: | Heliyon |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2405844023089430 |
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| author | Amarjeet Dahiya Akanksha Bhardwaj Archana Rani Meenu Arora J. Nagendra Babu |
| author_facet | Amarjeet Dahiya Akanksha Bhardwaj Archana Rani Meenu Arora J. Nagendra Babu |
| author_sort | Amarjeet Dahiya |
| collection | DOAJ |
| description | Surface oxygen functional groups of biochar were tuned by oxidation and reduction of biochar for establishing Cr(VI) adsorption mechanism. Oxygen functional groups (OFGs) on the surface of leached rice straw biochar (LBC4-6) obtained from pyrolysis at 400, 500 and 600 °C, were oxidized to furnish OBC4-6 using modified Hummer's method. Reduced biochar RBC4-6 were obtained by esterification and NaBH4/I2 reduction of oxidized biochar (OBC4-6). The modified biochar were characterized by increase in O/C and H/C ratio, respectively, in case of OBC4-6 and RBC4-6. The Cr(VI) adsorption by modified biochar LBC4-6, OBC4-6, and RBC4-6 showed optimum conditions of pH 3 and dose 0.1 g/L with a good non-linear fit for Langmuir & Freundlich isotherm. The maximum adsorption (Qm) followed the trend: OBC4 (17.47 mg/g) > RBC4 (15.23) > OBC5 (13.23) > LBC4 (10.23) > RBC5 (9.83) > OBC6 (9.60) > RBC6 (7.24) > LBC5 (6.32) > LBC6 (5.98). The adsorption kinetics for adsorption of Cr(VI) on to modified biochar fits pseudo second order (PSO), Elovich and intraparticle diffusion kinetics, showing a chemisorptions in case of biochar L/O/RBC4-6. The lower temperature modified biochar O/RBC4 show better Cr(VI) adsorption. X-ray Photoelectron Spectroscopy (XPS) studies establish optimum OFGs for reduction of Cr(VI) and chelation of the reduced Cr(III). Adsorption and stripping cycles show the oxidized and reduced biochar as better adsorbents with excellent stripping of Cr up to >98 % upon desorption with 1 M NaOH. |
| first_indexed | 2024-03-09T09:18:42Z |
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| institution | Directory Open Access Journal |
| issn | 2405-8440 |
| language | English |
| last_indexed | 2024-03-09T09:18:42Z |
| publishDate | 2023-11-01 |
| publisher | Elsevier |
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| series | Heliyon |
| spelling | doaj.art-40a775106099460faf6a4699124ab2bc2023-12-02T07:04:02ZengElsevierHeliyon2405-84402023-11-01911e21735Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorptionAmarjeet Dahiya0Akanksha Bhardwaj1Archana Rani2Meenu Arora3J. Nagendra Babu4Department of Chemistry, School of Basic Sciences, Central University of Punjab, VPO Ghudda, Badal Road, Punjab, 151401, IndiaDepartment of Environmental Science & Technology, Central University of Punjab, VPO Ghudda, Badal Road, Bathinda, Punjab, 151401, IndiaDepartment of Chemistry, School of Basic Sciences, Central University of Punjab, VPO Ghudda, Badal Road, Punjab, 151401, IndiaDepartment of Chemistry, Maharaja Ranjit Singh Punjab Technical University, Badal Road, Bathinda, Punjab, 151001, IndiaDepartment of Chemistry, School of Basic Sciences, Central University of Punjab, VPO Ghudda, Badal Road, Punjab, 151401, India; Corresponding author.Surface oxygen functional groups of biochar were tuned by oxidation and reduction of biochar for establishing Cr(VI) adsorption mechanism. Oxygen functional groups (OFGs) on the surface of leached rice straw biochar (LBC4-6) obtained from pyrolysis at 400, 500 and 600 °C, were oxidized to furnish OBC4-6 using modified Hummer's method. Reduced biochar RBC4-6 were obtained by esterification and NaBH4/I2 reduction of oxidized biochar (OBC4-6). The modified biochar were characterized by increase in O/C and H/C ratio, respectively, in case of OBC4-6 and RBC4-6. The Cr(VI) adsorption by modified biochar LBC4-6, OBC4-6, and RBC4-6 showed optimum conditions of pH 3 and dose 0.1 g/L with a good non-linear fit for Langmuir & Freundlich isotherm. The maximum adsorption (Qm) followed the trend: OBC4 (17.47 mg/g) > RBC4 (15.23) > OBC5 (13.23) > LBC4 (10.23) > RBC5 (9.83) > OBC6 (9.60) > RBC6 (7.24) > LBC5 (6.32) > LBC6 (5.98). The adsorption kinetics for adsorption of Cr(VI) on to modified biochar fits pseudo second order (PSO), Elovich and intraparticle diffusion kinetics, showing a chemisorptions in case of biochar L/O/RBC4-6. The lower temperature modified biochar O/RBC4 show better Cr(VI) adsorption. X-ray Photoelectron Spectroscopy (XPS) studies establish optimum OFGs for reduction of Cr(VI) and chelation of the reduced Cr(III). Adsorption and stripping cycles show the oxidized and reduced biochar as better adsorbents with excellent stripping of Cr up to >98 % upon desorption with 1 M NaOH.http://www.sciencedirect.com/science/article/pii/S2405844023089430BiocharHexavalent chromiumOxidized biocharGrapheneGraphene oxideReduced graphene oxide |
| spellingShingle | Amarjeet Dahiya Akanksha Bhardwaj Archana Rani Meenu Arora J. Nagendra Babu Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption Heliyon Biochar Hexavalent chromium Oxidized biochar Graphene Graphene oxide Reduced graphene oxide |
| title | Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption |
| title_full | Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption |
| title_fullStr | Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption |
| title_full_unstemmed | Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption |
| title_short | Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption |
| title_sort | reduced and oxidized rice straw biochar for hexavalent chromium adsorption revisiting the mechanism of adsorption |
| topic | Biochar Hexavalent chromium Oxidized biochar Graphene Graphene oxide Reduced graphene oxide |
| url | http://www.sciencedirect.com/science/article/pii/S2405844023089430 |
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