4 years ago

Microwave-induced combustion: Thermal and morphological aspects for understanding the mechanism of ignition process for analytical applications

Microwave-induced combustion: Thermal and morphological aspects for understanding the mechanism of ignition process for analytical applications
In the present work, for the first time a systematic study was performed using an infrared camera and scanning electron microscopy (SEM) coupled to energy dispersive X-ray spectrometry (EDS) to evaluate the mechanisms involved in microwave-induced combustion method, which has been extensively used for sample preparation. Cellulose and glass fiber discs, wetted with the igniter solution (6molL−1 NH4NO3), were evaluated under microwave field in a monomode system. The temperature of the discs surface was recorded during microwave irradiation and the effect of NH4NO3 concentration and irradiation time on cellulose oxidation was evaluated. The morphology of the discs surface was characterized by SEM before and after irradiation in an inert atmosphere. According to the results, the surface temperature of the discs increased near to 100°C and remained in this temperature for few seconds while water evaporate. After that, temperature increased over 200°C due to the thermal decomposition of NH4NO3 salt, releasing a large amount of energy that accelerates cellulose oxidation. The higher the igniter concentration, the shorter was the microwave irradiation time for cellulose oxidation. The SEM images revealed that cellulose disc was more porous after microwave irradiation, enhancing oxygen diffusion within the paper and making easier its ignition. The EDS spectrum of cellulose and glass fiber discs showed that signal intensity for nitrogen decreased after microwave irradiation, showing that NH4NO3 was consumed during this process. Therefore, it was demonstrated that the ignition process is the result of synergic interaction of NH4NO3 thermal decomposition and organic matter oxidation (cellulose) releasing heat and feeding the chain reaction.

Publisher URL: www.sciencedirect.com/science

DOI: S0039914017305969

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.