Recovery of magnesium from flue gas desulfurization wastewater using thermomorphic hydrophilicity amines

作者：Geng, Wenda; Zou, Juncong; Niu, Qiuya^*; Lin, Yan; Liu, Haiyang; Jing, Yachao; Yang, Chunping^*

来源：SEPARATION AND PURIFICATION TECHNOLOGY, 2023, 316: 123776.

DOI：10.1016/j.seppur.2023.123776

• Hardness
• Magnesium
• Wastewater treatment
• Thermomorphic hydrophilicity amine

The concentrations of hardness ions in saline wastewater from flue gas desulfurization (FGD) are usually very high, which could result in severe membrane fouling in consequent membrane systems. Hence, we investigated the feasibility of recovering Mg2+ from saline wastewater collected from a coal-fired power plant through uti-lizing thermomorphic hydrophilicity amines. Triethylamine (TEA), diisopropylamine (DIPA) and N,N-dimethylisopropylamine (DMIPA) were chosen as thermomorphic hydrophilicity amines. The effects of tem-perature change on solubility of amines in aqueous phase were evaluated, and the influences of molar ratio of amine to Mg2+ were also investigated. Results show that the solubility of amines in aqueous phase decreased substantially when temperature was increased from 25 degrees C to 60 degrees C. Thermomorphic hydrophilicity amines could be regenerated by mild heating, and regenerated TEA could remove up to 95% of Mg2+ in the actual FGD wastewater. Meanwhile, three amines could effectively increase the pH value of the solutions, and the recovery of Mg2+ was more than 98% as Mg(OH)2 at an amine ratio molar ratio of 2.5. This study demonstrated the great potential of using thermoresponsive amines as alkali sources to recover Mg2+ and the synthesis of reactive MgO in FGD wastewater, providing a reference for the recovery of resources such as Mg2+.

• 单位
  南昌航空大学; 茂名学院