摘要
Mg ion-exchanged samples were prepared with acid-washed Shengli lignite.The chemical composition of the ash of the raw sample was determined by X-ray fluorescence.The equilibrium adsorption water contents of samples were determined in a range of relative humidity.The ion-exchange process was characterized by FT-IR,ash content,and p H value.A possible mechanism is proposed for equilibrium adsorption water of ion-exchanged samples at different humidities.The extent of ion-exchange reaction between Mg2+and lignite is controlled by the concentration of Mg2+in Mg SO4solution.The effect of Mg2+on equilibrium adsorption water content varies with relative humidity and content of Mg2+.The factor that controls equilibrium adsorption water content at low relative humidity is water interactions with sorption sites,which are Mg2+–carboxyl group complex.At middle relative humidity capillary force between Mg2+–water clusters Mg+(H2O)nand capillary is more important.At high relative humidity,free water–free water interactions are more significant.
Mg ion-exchanged samples were prepared with acid-washed Shengli lignite.The chemical composition of the ash of the raw sample was determined by X-ray fluorescence.The equilibrium adsorption water contents of samples were determined in a range of relative humidity.The ion-exchange process was characterized by FT-IR,ash content,and p H value.A possible mechanism is proposed for equilibrium adsorption water of ion-exchanged samples at different humidities.The extent of ion-exchange reaction between Mg2＋and lignite is controlled by the concentration of Mg2＋in Mg SO4solution.The effect of Mg2＋on equilibrium adsorption water content varies with relative humidity and content of Mg2＋.The factor that controls equilibrium adsorption water content at low relative humidity is water interactions with sorption sites,which are Mg2＋–carboxyl group complex.At middle relative humidity capillary force between Mg2＋–water clusters Mg＋（H2O）nand capillary is more important.At high relative humidity,free water–free water interactions are more significant.
基金
Supported by the National Basic Research Program of China(2012CB214900)
the National Natural Science Foundation of China(51274197)
the 111 Project(B12030)
the Fundamental Research Funds for the Central Universities(2014XT05)
