Novel use of TGA–FTIR technique to predict the pollution degree in marine sediments

In this work, thermogravimetric analysis (TG) coupled with Fourier transform infrared spectrometry (TG–FTIR) was applied to compare the thermal behavior of sediments from Cadiz port and a pristine zone. The samples were thermally degraded in air atmosphere using a heating rate of 10 °C/min. The Physico-Chemical analyses (organic matter, organic carbon, carbonate, total nitrogen, moisture, granulometric analyses; Cu, Zn, Pb and Hg) of sediments indicate that the pollution in zone coming from Cadiz port is mainly of anthropogenic origin. By means of differential thermogravimetric (DTG) and Gram–Schmidt the curves of sediments coming from Cadiz port, showed four stages with temperatures of maximum decomposition rate approximately at 120 °C, 292 °C, 493 °C and 741 °C. The FTIR spectra corresponding to these temperatures shows the formation of high quantities of gases, as carbon dioxide, carbon monoxide, water vapor, aliphatic hydrocarbons, ether and ammonia, while in sediment coming from pristine zone the thermal degradation occurs in two stages, with temperatures of maximum decomposition rate around 500 °C and 750 °C, producing only little quantities of gases, as carbon dioxide and water vapor. By comparing the TG–FTIR of sediments coming from the port and the no polluted zone, it is possible to identify the volatile organic compounds emitted between 200 and 600 °C. These results suggest that modifications in the structures of sediment from the port are due to different sources of contamination. This study demonstrates that TG–FTIR is capable for screening of contaminated sediments.