煤化工含盐废液中杂质对硫酸钠溶解行为影响研究

INFLUENCE OF IMPURITIES ON DISSOLUTION BEHAVIOR OF SODIUM SULFATE IN COAL CHEMICAL INDUSTRY SALINE WASTEWATER

研究含盐废液中典型杂质对硫酸钠溶解行为影响机制,有利于优化硫酸钠废盐结晶工艺,促进硫酸钠高值化利用。以煤化工行业硫酸钠杂质体系为研究对象,使用OLI与COSMO-RS研究了温度、典型无机杂质离子和有机杂质对硫酸钠溶解度、溶剂化及相互作用的影响规律。结果表明,硫酸钠溶解行为由杂质极性、Na^(+)与SO_(4)^(2-)溶剂化能力、杂质浓度及同离子效应共同控制,极性影响最强。弱极性Ca^(2+)、NH_(4)^(+)、K^(+)、HCO_(3)^(-)、F^(-)、NO_(3)^(-)促进硫酸钠结晶,其中,阳离子通过同离子效应协同促进硫酸钠结晶,阴离子通过同离子效应及削弱Na^(+)与SO_(4)^(2-)溶剂化作用协同促进硫酸钠结晶;强极性Mg^(2+)、CO_(3)^(2-)抑制硫酸钠结晶,Mg^(2+)通过增强Na^(+)与SO_(4)^(2-)溶剂化协同促进硫酸钠溶解,CO_(3)^(2-)通过强极性特征,促进硫酸钠溶解,在含盐废液中去除Mg^(2+)和CO_(3)^(2-)是促进硫酸钠结晶的必要措施;低浓度有机杂质通过削弱Na^(+)与SO_(4)^(2-)溶剂化作用促进Na_(2)SO_(4)结晶。相关理论研究为硫酸钠废盐资源化提供理论支撑。

The study on the influence of typical impurities in saline wastewater on the crystalline properties of sodium sulfate is beneficial for optimizing the sodium sulfate crystallization process and promoting the value-added utilization of sodium sulfate.Taking the sodium sulfate waste impurities system in the coal chemical industry as the research object,this study used OLI and COSMO-RS to investigate the effects of temperature,typical inorganic impurity ions,and organic impurities on the solubility,solvation,and interactions of sodium sulfate.The results indicate that the solubility behavior of sodium sulfate is controlled by the polarity of impurities,the solvation capacity of Na^(+)and SO_(4)^(2-),the concentration of impurities,and the common ion effect,with polarity exerting the strongest influence.Calcium ions(Ca^(2+)),ammonium ions(NH_(4)^(+)),potassium ions(K^(+)),bicarbonate ions(HCO_(3)^(-)),fluoride ions(F^(-)),and nitrate ions(NO_(3)^(-))are with less polarity than Na^(+)and SO_(4)^(2-),and they promote the crystallization of sodium sulfate.Among these,cations promote the crystallization of sodium sulfate through the common ion effect,while anions promote it through both the common ion effect and weakening the solvation of Na^(+)and SO_(4)^(2-).Magnesium ions(Mg^(2+))and carbonate ions(CO_(3)^(2-))promote the dissolution of sodium sulfate.Magnesium ions enhance the solvation of Na^(+)and SO_(4)^(2-),thus promoting the dissolution of sodium sulfate,while carbonate ions promote the dissolution of sodium sulfate through their strong polarity.Removing Mg^(2+)and CO_(3)^(2-)from saline wastewater is a necessary measure to promote the crystallization of sodium sulfate.At low concentrations,organic impurities promote the crystallization of Na_(2)SO_(4) by weakening the interaction between Na^(+)and SO_(4)^(2-).Calcium ions and fluoride ions not only significantly increase the freezing crystallization time of sodium sulfate,but also generate new substances with sodium sulfate.Related theoretical research provides theoretical support for the utilization of sodium sulfate waste salt.