0541619 - ÚCHP 2022 RIV NL eng J - Journal Article
Moško, Jaroslav - Pohořelý, Michael - Skoblia, S. - Fajgar, Radek - Straka, Pavel - Soukup, Karel - Beňo, Z. - Farták, J. - Bičáková, Olga - Jeremiáš, Michal - Šyc, Michal - Meers, E.
Structural and chemical changes of sludge derived pyrolysis char prepared under different process temperatures.
Journal of Analytical and Applied Pyrolysis. Roč. 156, JUN 2021 (2021), č. článku 105085. ISSN 0165-2370. E-ISSN 1873-250X
R&D Projects: GA MZe(CZ) QK21020022; GA MŠMT(CZ) EF16_026/0008413
Grant - others:AV ČR(CZ) StrategieAV21/3
Program: StrategieAV
Institutional support: RVO:67985858 ; RVO:67985891 ; RVO:61389021
Keywords : sewage sludge * pyrolysis * sludge-char
OECD category: Energy and fuels; Environmental sciences (social aspects to be 5.7) (USMH-B); Energy and fuels (UFP-V)
Impact factor: 6.437, year: 2021
Method of publishing: Open access with time embargo
DOI: https://doi.org/10.1016/j.jaap.2021.105085

Sewage sludge was pyrolyzed at 400–800 ◦C to study the influence of the pyrolysis temperature on the bulk and structural properties of the resulting sludge-chars. For this purpose, sludge-chars were subjected to proximate and ultimate analyses and the textural and porous properties were examined by the nitrogen adsorptiondesorption isotherm. Raman spectroscopy was employed to correlate the results of the structural changes of the sludge-chars obtained by conventional analysis (textural properties) and together with solid state NMR it was used to characterize the organic part of the sludge-chars. Additionally, an XPS of the chars’ surfaces and inner layers of the char particles was conducted to study the phosphorus, nitrogen and sulfur speciation and its changes with regard to the change in pyrolysis temperature and the depth of the char particles. Raising the pyrolysis temperature increased the relative content of phosphates and metaphosphates and decreased the reduced P species relative content. Sulfur speciation analysis revealed an increase in sulfides content and a decrease in
sulfates and sulfites content as the temperature was raised. The influence of the temperature on N speciation was marginal. The NMR and Raman spectroscopy results showed a significant contribution of graphite and (poly) aromatic hydrocarbons and a negligible contribution of the carbonyl groups to the structure of the organic part of sludge-chars. The increase in the pyrolysis temperature increased the content of (poly)aromatic hydrocarbons over the total carbon content, revealing its contribution to the porosity evolution. This is in good correlation with
the microporosity and surface area analyses. Regarding the sludge-char potential soil application, the results may help to predict and better understand the sludge-char stability and N and P plant availability.

Permanent Link: http://hdl.handle.net/11104/0319409