TG–FTIR–MS analysis of the pyrolysis of blended seaweed and rice husk

Abstract

Pyrolysis of seaweed (Enteromorpha clathrata), rice husk, and five kinds of samples of blended Enteromorpha clathrata and rice husk (at different mass ratios as 3:1, 2:1, 1:1, 1:2, and 1:3) was investigated with thermogravimetric–infrared–mass spectrometry analysis. The results indicated that the pyrolysis of seaweed and rice husk can be divided into four stages: evaporation, depolymerization, devolatilization, and carbonization. However, due to the major pyrolysis component differences between seaweed and rice husk, the pyrolysis characteristics between them varied significantly. Through differential scanning calorimetry analysis, seaweed showed a special exothermic reaction during the stage of precipitation of main volatiles, while the rice husk showed mainly an endothermic reaction in that process. But it appeared to be an exothermic process during pyrolysis of the seaweed and rice husk mixture. We can infer that there was mutual promotion between the seaweed and rice husk, and energy coupling was realized. Meanwhile, it can be concluded that the experimental value of thermal mass loss rate turns out to be higher than that of theoretical value in the process of the main stage of pyrolysis through the comparison between the experimental data and the theoretical data for calculated DTG curves in the pyrolysis of blended sample of different proportions of seaweed and rice husk. The FTIR analysis indicated that with the increasing proportion of the rice husk, the volatile gas, sulfurous gas, and nitrogen gas are decreasingly released from the process of pyrolysis. Judging from the thermogravimetric–mass spectrometry, the pyrolysis of the blended mixture of seaweed and rice husk has been affected because of the increasing amount of rice husk. This reduced the emission of NO, NO2, and SO2 gases which are released from the above process of pyrolysis. Therefore, for the pyrolysis of mixed seaweed and rice husk, there was actually a synergistic effect rather than the simple sum of the characteristics of the pyrolysis of different components.