Acidic surface functional groups control chemisorption of ammonium onto carbon materials in aqueous media

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dc.contributor.author Sumaraj, Sumaraj en
dc.contributor.author Xiong, Z en
dc.contributor.author Sarmah, AJ en
dc.contributor.author Padhye, Lokesh en
dc.date.accessioned 2020-02-11T23:05:31Z en
dc.date.issued 2020-01-01 en
dc.identifier.issn 0048-9697 en
dc.identifier.uri http://hdl.handle.net/2292/49924 en
dc.description.abstract Elucidation of mechanistic insight into the interaction of carbon materials' physicochemical surface properties and ammonium (NH4+) adsorption in aqueous media was made by conducting a systematic study using a wide range of carbon materials. Three types of biochars (rice husk, poultry litter, and enhanced poultry litter) and activated carbons (fresh and aged coconut shell-based and charcoal-based) were used for investigating the NH4+ adsorption mechanism. Poultry litter biochar, with lowest surface area (3 m2 g−1) and largest pore diameter (29 nm), showed the highest NH4+ adsorption capacity (0.34 mg NH4+g−1), while charcoal-based activated carbon, with the highest surface area (1133 m2 g−1) and small pore diameter (6 nm), had the least NH4+ adsorption capacity (0.09 mg NH4+g−1). The value of Freundlich isotherm constant ‘n’ was >1 for all tested carbon materials indicating chemisorption as the dominant sorption mechanism. Aging of the carbon surface resulted in 30% increase in NH4+ retention. Surface chemical properties that most influenced NH4+ chemisorption on to carbon materials were found to be acidic surface functional groups (ASFGs), elemental composition, ash content, and pH. The optimal conditions for NH4+ adsorption, regardless of type and source of carbon materials, were solution pH of 8, a high amount of ash content, and carboxyl, carbonyl, and phenolic functional groups. Evaluation of CEC and ASFGs indicated that CEC and ASFGs are not equivalent terms. Through this study, conducted on carbon adsorbents derived from different sources, with different surface physical and chemical properties, we established that ASFGs, and not CEC, play a critical role in ammonium chemisorption on carbon materials. The study showed that low cost and eco-friendly biochars, with optimal surface chemistry, can replace expensive activated carbons for NH4+ remediation in aqueous media. en
dc.relation.ispartofseries Science of The Total Environment en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title Acidic surface functional groups control chemisorption of ammonium onto carbon materials in aqueous media en
dc.type Journal Article en
dc.identifier.doi 10.1016/j.scitotenv.2019.134193 en
pubs.volume 698 en
dc.rights.holder Copyright: The author en
dc.rights.accessrights http://purl.org/eprint/accessRights/RestrictedAccess en
pubs.subtype Article en
pubs.elements-id 780037 en
pubs.org-id Engineering en
pubs.org-id Civil and Environmental Eng en
pubs.number 134193 en
pubs.record-created-at-source-date 2019-09-05 en
pubs.online-publication-date 2019-09-04 en
pubs.dimensions-id 31514032 en


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