The efficacy of biomass derived pyrogenic carbons (PyC) as sorbents of cationic/metallic contaminants is largely driven by the deprotonation/protonation behavior of surface carboxylic/phenolic functional groups. Variability in this behavior is largely a function of the effect of formation conditions and feedstock chemistry on the surface heterogeneity of PyC. We combined ion-probe flow microcalorimetry with a modified Henderson-Hasselbalch equation, to determine surface uniformity, pKa and cation exchange envelope of various lignin-rich and cellulose-rich PyCs. PyC’s derived from lignin-rich feedstocks showed increasing heterogeneity and brønsted acidity with increased heat treatment temperature (HTT). Brønsted acidity in cellulose-rich PyCs also increased but heterogeneity decreased with increased HTT. pH limits on the cation exchange envelope were definable by the expression: where u is a quantitative uniformity factor describing the deviation of deprotonation behavior from an ideal “Henderson-Hasselbalch type” acid (with u =1). The presentation will discuss the application of this new technique to the understanding of metal sorption and sorptive behavior of, PyC in engineered and environmental systems.

Ion-probe flow adsorption microcalorimetry: A new approach to the study of surface heterogeneity, acid dissociation and cation exchange behavior at the PyC-water interface

251st National Meeting (2016)

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