Analysis Of The Binding Effect And The Influence Factors Of Water Adsorption In The Shengli Lignite

This paper,which severs as a basic study for an efficient and clean utilization of lignite,takes lignite as the research object and studies on its characteristic of absorbing moisture easily.Lignite is tested for water absorption in different thermal treatment.The features are analyzed through low field1H-nuclear magnetic resonance technique,thermogravimetric analysis,in situ FTIR and X ray diffraction analysis.Then,the binding mode and the combination between the lignite surface and water are detected in this research.The main research work and achievements are as follows.The result shows that the more the moisture is adsorbed on lignite,the weaker the binding between lignite and water will be.And the less the moisture is adsorbed,the stronger the binding will be.It is also found that most of the water is removed before 80?from the desorption process and in situ FTIR test,which proves that the binding is weak.However,the amount of strong binding water is small,and the temperature of desorption is higher.With the decrease of water content,the relative content of hydrogen bonds increases and then decreases.It is also indicated that the binding effect becomes stronger with the decreasing of water.Until the water is removed completely,the surface of the original hydrogen bonding appears.Secondly,there are various states of lignite water absorption,which is not affected by the heat treatment temperature,and can be divided into stronger binding water,strong combined water and weak binding water.The process of water absorption is mainly affected by the oxygen containing functional groups,When there is more water,there will be a larger amount which can be combined with oxygen functional groups.However,the non oxygen functional groups are mainly related to the carbon crystallite structure of the lignite,which belong to hydrophobic binding sites,and the binding effect is weak.It is found that hydroxyl,carboxyl and ketone groups can form strong hydrogen bonds with water,and the hydroxyl group has the strongest binding effect with water,and the hydroxyl group has the strongest ability to absorb water.It also shows that this relationship between oxygen functional groups in lignite and water is existential.As there will be no carboxyl group or ketone group when lignite is treated above 500?,,the main factor leading to the adsorption of moisture is the presence of hydroxyl.