Degradation of p-Nitrophenol by Lignin and Cellulose Chars: H2O2

Jul 7, 2017 - Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States. •S Supporting Information...
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Degradation of p-Nitrophenol by Lignin and Cellulose Chars: HO-Mediated Reaction and Direct Reaction with the Char 2

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Jing Yang, Joseph J. Pignatello, Bo Pan, and Baoshan Xing Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b01087 • Publication Date (Web): 07 Jul 2017 Downloaded from http://pubs.acs.org on July 8, 2017

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Environmental Science & Technology

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Degradation of p-Nitrophenol by Lignin and Cellulose Chars: H2O2-Mediated

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Reaction and Direct Reaction with the Char

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Jing Yang#&, Joseph J. Pignatello*^, Bo Pan*#, and Baoshan Xing& #

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Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, P. R. China

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Department of Environmental Sciences, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06504-1106, United States

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Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States

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*Corresponding authors’ contact information: JJP: phone, 203-974-8518; fax, 203-974-8502,

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email, [email protected].

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[email protected].

BP: phone, 86-871-65102829; fax: 86-871-65920530; e-mail,

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ACS Paragon Plus Environment

Environmental Science & Technology

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ABSTRACT

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Chars and other black carbons are reactive towards certain compounds. Such reactivity has been

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attributed to reduction of O2 by persistent free radicals in the solid to H2O2, which then

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back-reacts with the solid to generate reactive oxygen species (ROS; especially HO⋅). We

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studied the decomposition of p-nitrophenol (PNP) by pure lignin and cellulose chars aged in

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moist air or a vacuum at room temperature for up to a month. In air, the chars chemisorbed

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oxygen, a portion of which was liberated as H2O2 when the char was submerged in water. The

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evolved H2O2 was simultaneously decomposed by the char. PNP reacted predominantly in the

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sorbed state and only reduction products (phenol, catechol) were identified. Aging in air sharply

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(within hours) reduced H2O2-producing capacity and free radical concentration, but more

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gradually reduced PNP decay rate over the month-long period. PNP decay was only modestly

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suppressed (12-30%) by H2O2 removal (catalase), and had little effect on the free radical signal

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(