Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption

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dc.contributor.authorDahiya, Amarjeet
dc.contributor.authorBhardwaj, Akanksha
dc.contributor.authorRani, Archana
dc.contributor.authorArora, Meenu
dc.contributor.authorBabu, J. Nagendra
dc.date.accessioned2024-01-21T10:33:13Z
dc.date.accessioned2024-08-13T11:16:23Z
dc.date.available2024-01-21T10:33:13Z
dc.date.available2024-08-13T11:16:23Z
dc.date.issued2023-11-01T00:00:00
dc.description.abstractSurface 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. � 2023en_US
dc.identifier.doi10.1016/j.heliyon.2023.e21735
dc.identifier.issn24058440
dc.identifier.urihttp://10.2.3.109/handle/32116/3295
dc.identifier.urlhttps://linkinghub.elsevier.com/retrieve/pii/S2405844023089430
dc.language.isoen_USen_US
dc.publisherElsevier Ltden_US
dc.subjectBiocharen_US
dc.subjectGrapheneen_US
dc.subjectGraphene oxideen_US
dc.subjectHexavalent chromiumen_US
dc.subjectOxidized biocharen_US
dc.subjectReduced biocharen_US
dc.subjectReduced graphene oxideen_US
dc.titleReduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorptionen_US
dc.title.journalHeliyonen_US
dc.typeArticleen_US
dc.type.accesstypeClosed Accessen_US

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