Experimental Research Of Internal Phase Precipitation Extraction Nickel By Emulsion Liquid Membrane

The emulsion liquid membrane method of internal phase precipitation has double advantages of extraction and reverse extraction in treating methods of heavy metal wastewater.Heavy metal contaminations can be selectively transferred from the external water phase to the internal phase by this technology,and these heavy metal ions are removed from the waste water with the form of precipitation or complex.This paper mainly studies the emulsion liquid membrane system with NaOH solution as the precipitant of internal phase for extraction and separation of nickel ion in the wastewater.The Ni?OH?₂ powder and the NiO powder are prepared by this method in the experiment,respectively.The properties of Ni?OH?₂ and NiO powders are also studied in the paper.This paper uses the internal phase precipitation to extract the Ni²⁺ from 300 mg/L simulated wastewater by emulsion liquid membrane for the research.The emulsion liquid membrane of Span85-TBP-NaOH system is used to remove the Ni²⁺ in the experiment,and then determines the composition of emulsion liquid membrane and emulsion preparation conditions.The experiment investigates the extraction efficiency of Ni²⁺ by different influence factors,which are mainly containing the concentrations of surfactant,carrier and internal phase,the emulsification stirring time and emulsification stirring speed and other factors.The results of experiment show that the higher extraction efficiency is obtained at the surfactant Span85 of 5%,carrier TBP of 3%,internal phase NaOH concentration of 0.10 mol/L,emulsification stirring time of 20 min and emulsification stirring speed of 5000 r/min.The extraction efficiency of Span85-TBP-NaOH system for Ni²⁺ is up to 98.89%.In order to investigate the properties of Ni?OH?₂ samples prepared by emulsion liquid membrane method of internal phase precipitation,The experiment uses the internal phase precipitation to extract the Ni²⁺ from 1000 mg/L simulated wastewater and prepares the Ni?OH?₂powder by emulsion liquid membrane.Effects of the internal phase NaOH concentration,emulsification stirring time and emulsification stirring speed and other factors on the photocatalytic activity of Ni?OH?₂ samples are investigated with UV-Vis spectrophotometry,respectively.The phase,particle size,morphology and structure of Ni?OH?₂ samples are analyzed and researched with using XRD,SEM,FT-IR,BET and BJH and other detection means in theexperiment.The results show that the higher photocatalytic activity of Ni?OH?₂ sample is obtained at internal phase NaOH concentration of 0.20 mol/L,emulsification stirring time of 20 min and emulsification stirring speed of 5000 r/min,and its photocatalytic activity is up to 90% for 5 mg/L methylene blue solution.The Ni?OH?₂ samples have certain absorbability for the methylene blue solution,and its photocatalytic activity increases with increasing of photocatalytic time.The obtained powder samples are nanometer ?-Ni?OH?₂,and its particle size are between 8 nm and 26 nm.The pore diameter of sample particle is much larger,and they have apparent reunion phenomenon among the particles.The Ni?OH?₂ powders prepared by emulsion liquid membrane are calcinated under certain temperature in this experiment.Effects of the internal phase NaOH concentration,emulsification stirring time,emulsification stirring speed and calcination temperature and other factors on the photocatalytic activity of NiO samples after calcining are investigated with UV-Vis spectrophotometry,respectively.The surface morphology and physical and chemical properties of NiO samples are analyzed and researched with different detection means in the experiment.The results show that the higher photocatalytic activity of NiO sample is obtained at internal phase NaOH concentration of 0.20 mol/L,emulsification stirring time of 20 min,emulsification stirring speed of 5000 r/min and calcination temperature of 350⁴00 ?,and its photocatalytic activity is up to 94% for 5 mg/L methylene blue solution.The NiO sample has also certain absorbability for the methylene blue solution,and its photocatalytic activity increases with increasing of photocatalytic time.The obtained powder samples are nanometer NiO,and its particle size are between 8 nm and 12 nm.The pore diameter of NiO samples particle is more smaller than Ni?OH?₂ samples,and they have also obvious reunion phenomenon among the particles.