Work Function Characterization of Potassium-Intercalated, Boron Nitride Doped Graphitic Petals

McCarthy, Patrick T.; Paul, Rajib; Zemlyanov, Dmitry; Reifenberger, R.; Fisher, Timothy S.

doi:10.3389/fmech.2017.00006

Cited by 4 publications

(1 citation statement)

References 31 publications

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“…Measurements were carried out at EMSL-PNNL using a Physical Electronics Quantera scanning X-ray microprobe (Physical Electronics, a division of ULVAC PHI). Spectral deconvolution was based on peak assignments for C, N, and O forms in five standard compounds: ammonium carbonate ((NH 4 ) 2 2+ CO 3 2– ), ammonium bicarbonate (NH 4 + HCO 3 – ), urea, proline, and valine (Figure S2, Tables S5 and S6), along with online and published literature. − Instrument specifications and data analyses are presented in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

Sequential Ammonia and Carbon Dioxide Adsorption on Pyrolyzed Biomass to Recover Waste Stream Nutrients

Krounbi

Enders

Anderton

et al. 2020

ACS Sustainable Chem. Eng.

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The amine-rich surfaces of pyrolyzed human solid waste (py-HSW) can be “primed” or “regenerated” with carbon dioxide (CO2) to enhance their adsorption of ammonia (NH3) for use as a soil amendment. To better understand the mechanism by which CO2 exposure facilitates NH3 adsorption to py-HSW, we artificially enriched a model sorbent, pyrolyzed, oxidized wood (py-ox wood) with amine functional groups through exposure to NH3. We then exposed these N-enriched materials to CO2 and then resorbed NH3. The high heat of CO2 adsorption (Q st) on py-HSW, 49 kJ mol–1, at low surface coverage, 0.4 mmol CO2 g–1, showed that the naturally occurring N compounds in py-HSW have a high affinity for CO2. The Q st of CO2 on py-ox wood also increased after exposure to NH3, reaching 50 kJ mol–1 at 0.7 mmol CO2 g–1, demonstrating that the incorporation of N-rich functional groups by NH3 adsorption is favorable for CO2 uptake. Adsorption kinetics of py-ox wood revealed continued, albeit diminishing NH3 uptake after each CO2 treatment, averaging 5.9 mmol NH3 g–1 for the first NH3 exposure event and 3.5 and 2.9 mmol NH3 g–1 for the second and third; the electrophilic character of CO2 serves as a Lewis acid, enhancing surface affinity for NH3 uptake. Furthermore, penetration of 15NH3 and 13CO2 measured by NanoSIMS reached over 7 μm deep into both materials, explaining the large NH3 capture. We expected similar NH3 uptake in py-HSW sorbed with CO2 and py-ox wood because both materials, py-HSW and py-ox wood sorbed with NH3, had similar N contents and similarly high CO2 uptake. Yet NH3 sorption in py-HSW was unexpectedly low, apparently from potassium (K) bicarbonate precipitation, reducing interactions between NH3 and sorbed CO2; 2-fold greater surface K in py-HSW was detected after exposure to CO2 and NH3 than before gas exposure. We show that amine-rich pyrolyzed waste materials have high CO2 affinity, which facilitates NH3 uptake. However, high ash contents as found in py-HSW hinder this mechanism.

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