Construction Of Functional Ionic Liquid Extraction System And Experimental Study On Treatment Of Zinc-containing Wastewater

Ionic liquids have replaced organic solvents as new green solvents widely used in fields such as extraction separation,synthesis catalysis,and electrochemistry,due to its unique physical and chemical properties.Among them,because ionic liquids have minimal environmental pollution,they have received extensive attention from environmental workers.Aiming at the problem of selective treatment and recovery of Zn²⁺-containing wastewater in the electroplating industry and membrane treatment concentrates,this reaserch prepared a hydrophobic functional imidazole ionic liquid by microwave-assisted indirect synthesis,and mixed it with traditional imidazole ionic liquid to construct a functional composite extraction system replaces the organic solvents that are harmful to the environment in the solvent extraction method,and realizes the extraction and treatment of Zn²⁺and other heavy metal wastewater.The main contents are as follows:1.Under different microwave intensity synthesis conditions,1-hexyl-3-（3-methylthioureidopropyl）imidazole hexafluorophosphate[HMPSM][PF₆]was prepared,and it was found that it was synthesized under 800W microwave conditions The hydrophobic functional ionic liquid ionic liquid has the highest purity of 96.3%;2.After investigation,25℃,pH 5,initial metal ion concentration of 100mg/L,and water-ionic liquid volume ratio of 50 are selected as the optimal extraction conditions.The research results show that the functional ionic liquid[HMPSM][PF₆]synthesized using alone can increase the extraction rate of Zn²⁺from about 40%to 83%compared with the traditional imidazole-type ionic liquid[HBim][PF6];The promotion mechanism lies in the Lewis acid-base coordination effect between the thiourea group introduced in the functional ionic liquid and Zn²⁺,and additional reaction sites are added on the basis of electrostatic adsorption,which greatly enhances the extraction effect of Zn²⁺.3.Using 90% thioureido imidazole ionic liquid[HMPSM][PF₆]and 10%non-functional imidazole ionic liquid[HBim][PF₆]to form a new composite extraction system,which is more effective than a single functional ionic liquid for Zn²⁺The extraction rate of 83%is increased by an additional 7%,which can reach more than90%,and the ionic liquid system can be used for the selective separation of Zn²⁺under a certain salt（1%-5%Na Cl）concentration.In particular,ultrasound can be used as an auxiliary means,the extraction time of the composite extraction system will be shortened from 60min to about 10min;The composite extraction system’s electrostatic interaction between ionic liquid and metal ions,Lewis acid-base coordination,steric hindrance changes,etc,The multiple extraction promotion mechanism also shows better extraction performance.4.According to the actual water quality of the acid zinc plating wastewater,simulated wastewater was prepared,and the ionic liquid composite extraction system was used to extract and treat it.The effect is small,and the extraction rate is still above85%.In addition,the functional ionic liquid containing zinc ions obtained in the extraction experiment was back-extracted with nitric acid.The results show that only less than 2.5%of the ionic liquid is lost after each stripping,and the extraction performance of the functional ionic liquid after recovery is only reduced by about 1.5%,while the extraction system could be repeatedly recycled and reused.