脱硫石膏转化α-半水石膏的特征及机理:实验与模拟  

Characteristics and mechanism of desulfurization gypsum toα-hemihydrate gypsum:Experiments and simulations

作　　者：怀立业 仲兆平[1] 杨宇轩 HUAI Liye;ZHONG Zhaoping;YANG Yuxuan(School of Energy and Environment,Southeast University,Nanjing 210096,Jiangsu,China)

机构地区：[1]东南大学能源与环境学院,江苏南京210096

出　　处：《化工进展》2024年第8期4694-4703,共10页Chemical Industry and Engineering Progress

基　　金：清洁高效燃煤发电与污染控制国家重点实验室开放基金(D20227K076)。

摘　　要：脱硫石膏的高效利用可以有效缓解一系列环境问题,变废为宝。本文利用二水石膏在含有微量无水硫酸钠的乙二醇水溶液中制备α-半水石膏,探究温度(94~98℃)、乙二醇体积分数(25%~35%)、硫酸钠浓度(0.1~0.3mol/L)对二水石膏向α-半水石膏脱水转化过程的α-半水石膏摩尔分数和动力学参数变化。研究发现,在乙二醇水溶液中,二水石膏向α-半水石膏脱水转化过程符合分散动力学模型。随着温度和乙二醇浓度的增加,动力学参数α基本保持不变,而参数β显著增加,导致活化熵△S*增大,进而导致能垒E_(a)降低,促进了二水石膏向α-半水石膏脱水转化。微量无水硫酸钠的添加,显著缩短了α-半水石膏的成核诱导时间。通过分子动力学模拟,增加硫酸钠的浓度,Na^(+)与SO_(4)^(2-)的配位数增加,扩散系数绝对差值∆D降低,从而导致配位能力增加,解耦能力降低。本研究对高效利用脱硫石膏、掌握其向α-半水石膏的转化特征具有重要意义。The efficient utilization of desulfurized gypsum can effectively alleviate a series of environmental problems and turn waste into treasure.This paper used dihydrate gypsum to prepareα-hemihydrate gypsum in ethylene glycol aqueous solution containing trace anhydrous sodium sulfate,and explored the effects of temperature(94—98℃),ethylene glycol volume fraction(25%—35%),sodium sulfate concentration(0.1—0.3mol/L)on the mole fraction ofα-hemihydrate gypsum and kinetic parameters in the dehydration conversion process from dihydrate gypsum toα-hemihydrate gypsum.The results showed that in ethylene glycol aqueous solution,the dehydration conversion process of dihydrate gypsum toα-hemihydrate gypsum conformed to the dispersion kinetic model.With the increase of temperature and ethylene glycol concentration,the kinetic parameterαremained basically unchanged,while the parameterβincreased significantly,leading to an increase in the activation entropy(∆S*),which in turn led to a decrease in the energy barrier(E_(a))and promoted the dehydration of dihydrate gypsum toα-hemihydrate gypsum.The addition of a small amount of anhydrous sodium sulfate significantly shortened the nucleation induction time ofα-hemihydrate gypsum.Through molecular dynamics simulation,with increasing the concentration of sodium sulfate,the coordination number of Na^(+)and SO_(4)^(2-)increased,and the absolute difference of diffusion coefficient∆D decreased,resulting in the increase of coordination ability and the decrease of decoupling ability.This study was of great significance for efficient utilization of desulfurized gypsum and mastering its conversion characteristics toα-hemihydrate gypsum.

关 键 词：二水石膏 Α-半水石膏 乙二醇 结晶 动力学模型 分子模拟 

分 类 号：TQ177.37[化学工程—硅酸盐工业]