胜利褐煤Ca~(2+)负载量对其平衡复吸水含量的影响

以胜利褐煤为研究对象,利用XRF、FT-IR等手段,采用灰分、pH值、不同相对蒸气压下的复吸水含量等参数,研究了Ca2+的离子效应对褐煤在不同相对蒸气压下复吸水含量的影响。研究结果表明,煤中Ca2+的负载量随用于交换的钙离子溶液浓度的增大而增加。煤中Ca2+的负载量对煤样的平衡复吸水含量影响较大,Ca2+负载量越大,煤样的平衡复吸水含量越大。相对蒸气压高于92%平衡复吸水含量的主要控制因素为游离水分子与游离水分子之间的相互作用力。相对蒸气压在11%~92%平衡复吸水含量的主要控制因素为金属水簇Ca+(H2O)n与毛细管之间的毛细管作用力。

Effect of Ca2+ content loaded in Shengli lignite on its equilibrium re-adsorption water content

Shengli lignite has been acid-washed. The chemical composition of ash from the raw sample was determined by X-ray Fluorescence (XRF). The acid-washed lignite was subsequently exchanged with different concentrations of Ca(CH₂COOH)₂ solution. Ion-exchange process was characterized by FT-IR, the ash content and pH value. The re-adsorption water contents of treated and raw samples were determined across a range of relative vapor pressures. The extend of ion-exchange reaction between Ca(CH₃COO)₂ and -COOH groups was controlled by the concentration of Ca(CH₂COOH)₂ solution. The effects of Ca²⁺ on equilibrium re-adsorption water values varied depending on relative vapor pressures and the amount of loaded Ca²⁺. Furthermore, the factor that controls equilibrium re-adsorption water content at relative vapor pressure of 92% or less is capillary force between Ca²⁺-carboxyl group complex and capillary. However, at higher relative vapor pressure the key factor becomes interactions of free water molecules.