Confirmation of Pore Formation Mechanisms in Biochars and Activated Carbons by Dual Isotherm Analysis

18 Pages Posted: 20 Oct 2021

See all articles by L. Scott Blankenship

L. Scott Blankenship

University of Nottingham - School of Chemistry

Jacek Jagiello

Micromeritics Instrument Corporation

Robert Mokaya

University of Nottingham

Abstract

In this study biochars and activated carbons were synthesized either directly via the pyrolysis of sodium carboxymethyl cellulose (NC) or via hydrothermal carbonization of sawdust (SD) in an aqueous solution of KOH. The amount of porogen was varied by modulating the degree of sodium carboxymethyl substitution on NC or the amount of KOH mixed in solution with SD. Pore size distributions (PSDs) of these carbons were determined from the dual fit of kernels based on the two-dimensional version of the nonlocal density functional theory (2D-NLDFT) heterogeneous surface models to either N2 and H2 or O2 and H2 isotherms measured at 77 K. By comparing PSDs of carbons from the same starting material at increasing degrees of activation, we show that those derived using O2 and H2 isotherms not only give more detail of variations in pore size but that the results also fit better with current understandings of porosity development in carbons derived through oxidative activation. This is likely a result of superior diffusion of O2 into ultramicropores at low pressure relative to N2.

Keywords: carbon, Adsorption, porosity, activation

Suggested Citation

Blankenship, L. Scott and Jagiello, Jacek and Mokaya, Robert, Confirmation of Pore Formation Mechanisms in Biochars and Activated Carbons by Dual Isotherm Analysis. Available at SSRN: https://ssrn.com/abstract=3946228 or http://dx.doi.org/10.2139/ssrn.3946228

L. Scott Blankenship (Contact Author)

University of Nottingham - School of Chemistry ( email )

Nottingham
United Kingdom

Jacek Jagiello

Micromeritics Instrument Corporation ( email )

United States

Robert Mokaya

University of Nottingham ( email )

University Park
Nottingham, NG8 1BB
United Kingdom

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