关键词: 污泥, 热解, 含碳官能团, 含氧官能团, Py-GC/MS, 反应路径

Abstract:

Pyrolysis-gas-chromatography/mass spectrometry (Py-GC/MS) was employed to investigate the thermal cracking evolution and thermochemical conversion pathways of the main carbon and oxygen-containing functional groups contained in sewage sludge under different pyrolysis temperatures. The results show that sewage sludge mainly contain carbon-carbon double bonds (C=C), carboxyl groups (—COOH), hydroxyl groups (—OH), aldehyde groups (—CHO) and benzene (π-π^*). Pyrolysis temperature has an evident influence on the functional groups evolution. At the stage of the pyrolysis with a temperature lower than 350℃, the increased temperature results in the largest decrease of —COOH content, which is approximately 33%. In the mid-temperature thermal cracking stage (350-550℃), the production of C=C, —OH, —CHO, and π-π^* in pyrolysis product increased significantly, while —COOH show a decreasing trend, but its mass ratio is still the highest. The benzene becomes the main functional groups when the pyrolysis temperature higher than 550℃. In the high temperature pyrolysis stage (>550℃), due to aliphatic hydrocarbon molecules. The chemical activity is enhanced, mainly due to aromatization polycondensation reaction such as dehydration, decarboxylation, decarbonylation and aldol condensation. In the range of pyrolysis temperature study, carbon-carbon double bonds, aldehyde groups and hydroxyl groups content are lower, but show obvious pyrolysis rules. Further, combining the pyrolysis rules of each functional group, the possible path of the pyrolysis evolution of carbon and oxygen-containing functional groups in sludge is proposed.

Key words: sewage sludge, pyrolysis, carbon-containing functional, oxygen-containing functional, Py-GC/MS, reaction pathways