Study of pyrolytic mechanisms of seaweed based on different components (soluble polysaccharides, proteins, and ash)

The pyrolysis mechanisms of the main components of seaweed (soluble polysaccharides, proteins, and ash) were investigated in this study using characterization analysis and thermogravimetric analysis–mass spectrometry. XPS analysis indicated that most of the metal ions existed in the ash, while substituents of Na and K ions were found in polysaccharides. Oxygen-containing functional groups in Enteromorpha were found to exist mainly in the following forms: -OH/C-O in polysaccharides, COO- in proteins, and inorganic oxygen in the ash. Pyrolysis thermogravimetric (TG) curves of the components of Enteromorpha indicated that the thermogravimetric analysis ranges of polysaccharides and proteins were 175–310 °C and 300–350 °C, respectively. During the pyrolysis process, due to the effects of metal ions, the maximum thermal weight loss rate was found to increase, while the pyrolysis temperature also increased. CO2 was generated from the decarboxylation of uronic acids and the decomposition of inorganic carbonates in proteins and polysaccharides.