Release and Transformation of Sodium in Kitchen Waste during Torrefaction

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• 作者：Shuai Liu ; Yu Qiao ; Zhaoling Lu ; Ben Gui ; Mengmeng Wei ; Yun Yu ; Minghou Xu
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：March 20, 2014
• 年：2014
• 卷：28
• 期：3
• 页码：1911-1917
• 全文大小：398K
• 年卷期：v.28,no.3(March 20, 2014)
• ISSN：1520-5029

文摘

The release and transformation of typical chemical forms of sodium (i.e., H₂O-soluble salts and carboxylates) in kitchen waste during torrefaction at 200鈥?00 掳C was investigated in this study. It was found that sodium release is negligible (<2%) at 200 掳C after torrefaction for 15 min, but the release increases to 10% when the temperature is increased to 300 掳C. Because of the high concentration of water-soluble sodium in raw noodles, the release of sodium during torrefaction is mainly in the form of NaHCO₃ or Na₂CO₃, as NaCl is relatively stable at torrefaction temperatures. The transformation of Na from a water-soluble form to a CH₃COONH₄-soluble form during torrefaction was found to be an important factor in the release of sodium from raw noodles, since sodium release occurs much more readily from a Na-exchanged sample during torrefaction. CH₃COONH₄-soluble sodium is also found to transform back into a water-soluble form during torrefaction. For example, 18% of the sodium in a Na-exchanged sample transforms to a water-soluble form (i.e., Na₂CO₃) at 300 掳C, indicating the existence of an interconversion mechanism between the water-soluble and CH₃COONH₄-soluble forms. A small amount of water-soluble or CH₃COONH₄-soluble sodium could also transform to acid-soluble and stable forms during torrefaction at high temperatures (i.e., 300 掳C).