[Recovery of zinc ion and cadmium ion with hollow fiber membrane extraction].
The efficiency of hollow fiber membrane solvent extraction for the system of Meaq/bis(2-ethylhexyl) phosphate in heptane(Me = Cd2+, Zn2+) was studied for wastewater treatment and hydrometallurgy. It was found that the two phases velocity, the initial concentration and the pH value of the aqueous phase greatly influenced the extraction ratio. For very dilute solution with concentration lower than 500 mg/L, the mass transfer resistance was mainly in aqueous phase. When the aqueous phase concentration was relative higher than that of dilute solution, all the individual mass transfer resistances would not be ignored. For the concentrated solution, the mass transfer in the organic phase and the diffusion in membrane pores controlled the transport process. In the back extraction, the mass transfer resistance lied in the organic phase and the diffusion in membrane pores. The experimental results showed that it was possible that the extraction percentage achieved 90% when the metal ion concentration was lower than 400 mg/L. When the cadmium concentration was lower than 200 mg/L, its concentration can decrease 2 orders by extraction in a single-pass flow mode. The values of (HTU)w were between 15 cm and 30 cm, which was much lower than those of traditional extraction columns. The results indicated that membrane extraction with hollow fiber modules could efficiently remove or recover metal ions in the aqueous phases.
Wang
Y
Y
State Key Laboratory of Solvent Extraction, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Luo
G
G
Wang
Y
Y
Wu
Z
Z
Dai
Y
Y
D002104:Cadmium / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D018508:Water Purification / Q000379:methods*; D015032:Zinc / Q000302:isolation & purification*
D002104:Cadmium; D015032:Zinc