Liquid products of thermal treatment of organo-mineral sludge: Chemical characterization and fuel properties

Кубашева Раушан Нуртаевна, Ержанова Нургуль Сандибаевна, Raisa Ivanovna Kuzmina, Zaripa Kh. Kunasheva

Izvestiya of Saratov University Chemistry Biology Ecology, 2026

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DOI 10.18500/1816-9775-2026-26-1-4-12
Data confidence 70 medium
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Abstract

This study presents the results of a comprehensive investigation of liquid products obtained during the thermal treatment of organo-mineral sludge. The main focus is placed on determining the chemical composition, establishing fractional distribution, and evaluating the fuel characteristics of the resulting liquid fraction. A set of analytical methods, including gas chromatography, infrared spectroscopy, and elemental analysis, has been employed to provide a detailed characterization of the product. It has been established that the liquid fraction is enriched with isoparaffinic, aromatic, naphthenic, and olefinic hydrocarbons, while paraffins (5,2 wt.%) and oxygenates (4,5 wt.%) are present in smaller amounts. The chemical composition indicates the occurrence of complex thermal degradation processes of the organic part of the sludge, followed by secondary condensation of volatile products. Chromatographic analysis of the light fraction revealed significant contents of toluene (10,96 wt.%), ethylbenzene (3,06 wt.%), o-xylene (3,75 wt.%), and 1,2,4-trimethylbenzene (4,19 wt.%). In addition, isoparaffinic hydrocarbons such as 2,3,5-trimethylhexane (5,20 wt.%) and i-butylcyclopentane (5,77 wt.%) have been identified, along with naphthenic compounds (C7-C17) and arenes (C11-C18), forming a diverse hydrocarbon profile of the liquid fraction. Fractionation of the liquid product showed that the light fraction (up to 100°С ) is characterized by high octane numbers: 76,8 by the motor method and 93,3 by the research method. The main contribution to the octane number comes from isoparaffins (38,1 by the research method) and aromatic compounds (33,5), while the share of paraffins, olefins, and oxygenates is significantly lower. Thus, the liquid fraction obtained from the thermal treatment of organo-mineral sludge exhibits properties comparable to motor fuels and may be considered both as a promising alternative fuel and as a feedstock for chemical synthesis. These findings highlight the potential of utilizing organo-mineral wastes as secondary energy resources within sustainable waste-to-energy technologies.