Study Of Ionic Liquid On The Extraction Of Of Pb(?)and Cd(?) In Waste Water

Pb???and Cd???are widely used in electroplating,chemical industry,metallurgy,batteries,mining and other fields.Both of Pb???and Cd???are extremely poisonous.Once discharged into the waste water,they may lead to environmental pollution and health threatening.Solvent extraction is one of the useful technology for wastewater treatment,it has excellent effect on the recycling of heavy metal ions at the same time.In this thesis we focus on the removal of Pb???and Cd???from waste water using ionic liquid as extraction agent.We explore the extraction conditions of heavy metal ions,and meanwhile treat eluent that containing heavy Pb???with the method of precipitation.The precipitation were characterized,and further to explore the mechanism of extraction reaction.At low concentration,The effect of extraction time,initial Pb???or Cd???concentration,the volume ratio of the ionic liquid and water?phase ratio?and acid concentration on extraction rate were investigated.The result show that Omim[PF₆]displays little actual extraction efficiency for both Pb???and Cd???.While using Aliquat336,the extraction rate for two kinds of heavy metal ions can reach to 83%and 97%,respectively.With the increase of the initial concentration of the heavy metals the extraction rate declined.Using Aliquat336 as extraction agent,the optimized extraction conditions are 10 min,phase ratio as 1:5.Acid concentration may affect on heavy metal ions extraction,but the impact is not so obvious.With Aliquat336 as extraction solvent,the soluble lead may exchange into insoluble lead precipitation,and so the lead ions can separate directly from the waste water.It is found that the optimized conditions for Pb???precipitation are 10 min and 40 g/L of initial lead ions concentration.pH value had no obvious effect on deposition rate,but affects the morphology of precipitation.Ionic liquids addition influence the efficient of Pb???precipitation,the volume fraction of ionic liquid as 30%may prompt the settlement of Pb???.Ethanol addition increase the deposition rate of lead,and lead to the size of precipitation decreased at the same time.This investigation provides a convenient approach to the removal and recycling of lead,to solve the problem of lead pollution to the environment.lt is of great significance to solve the problem of lead pollution and lead resources on the brink of exhaustion.