| 摘 要： |
Rare-earth mining in Inner Mongolia has produced wastewater containing neodymium, which has caused certain environmental pollution. Aiming at the low removal efficiency of neodymium in wastewater, we developed microtube ultrafiltration chemical reactor (UFCR). UFCR had organic phosphate system containing wastewater part with buffer solution acetic acid and enrichment part with nitric acid solution and organic phosphate(2-ethylhexyl phosphoric acid-mono-2ethylhexyl-ester) dissolved in fuel oil. Many factors of neodymium(III) removal using UFCR need to explore, including hydrogen ion concentration (or pH), cinit of neodymium(III), different ionic strength of rare-earth mine wastewater, volume ratio of organic phosphate with fuel oil and nitric acid solution (O/W), nitric acid concentration, organic phosphate concentration and different acid solution of enrichment part. The advantages of UFCR compared with the traditional removal methods was investigated. The effects of hydrodynamic properties (stablity and flow rate) and UF system parameters ( inner diameter of microtube, tubule shell thickness, void ratio) etc. on the mass transfer performance of UFCR process for neodymium(III) removal were also studied. The experimental results show that the best removal conditions of neodymium( III) were obtained as that nitric acid concentration was 4.00 mol L-1, organic phosphate concentration was 0.150 mol L-1, and O/W was 0.5 in the enrichment part, and pH value was 4.50 in the wastewater part. Ionic strength of rare-earth mine wastewater had no obvious effect on neodymium(III) removal. When cinit of neodymium(III) concentration was 1.42 x 10(-4) mol L-1, the removal percentage of neodymium(III) was up to 93.5% in 150 min. The results of this study provide theoretical support for the treatment of wastewater containing neodymium in rare-earth mines. |
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