(1. 中南大學(xué) 冶金與環(huán)境學(xué)院，長沙 410083；
2. 中南大學(xué) 難冶有色金屬資源高效利用國家工程實(shí)驗(yàn)室，長沙 410083)
摘 要: 采用雙極膜電去離子技術(shù)(EDI-BP)處理低濃度模擬含鎳廢水，研究了Ni(OH)2沉淀產(chǎn)生的原因及消除措施。結(jié)果表明：沿膜器高度的電流密度分布不均勻；濃水室靠近產(chǎn)水出水端陰膜面產(chǎn)生的Ni(OH)2 沉淀由于局部Ni2+、OH-離子濃度過高造成。第一脫鹽室進(jìn)水端陽膜面產(chǎn)生的Ni(OH)2沉淀由水解離造成。采用降低原水pH、濃水pH等措施能夠有效地避免沉淀的產(chǎn)生；在原水Ni2+濃度30 mg/L、流速0.317 cm/s、pH值2.77，濃水pH 1.18和電流密度9.5 mA/cm2的條件下進(jìn)行濃縮試驗(yàn)，試驗(yàn)穩(wěn)定運(yùn)行285 h，得到的產(chǎn)水電導(dǎo)率約為1.5 μS/cm，產(chǎn)水中未檢測出Ni2+離子，濃水中Ni2+濃度可達(dá)2.7 g/L，濃縮倍數(shù)達(dá)90倍。
關(guān)鍵字: 電去離子；雙極膜；鎳；廢水；沉淀
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. National Engineering Laboratory for Efficient Utilization of Refractory Non-ferrous Metals Resources,
Central South University, Changsha 410083, China）
Abstract:The generation and avoidance of Ni(OH)2 precipitation during the treatment of the simulated dilute Ni2+-containing wastewater were investigated by electrodeionization with bipolar membrane. The results show that, the current density distribution along the height of EDI-BP stack is uneven. The reason of Ni(OH)2 precipitates on the surface of anion membrane near the outlet of feed in concentrate compartment is high local concentration of Ni2+ and OH-. Ni(OH)2 precipitating on the surface of the cation membrane near the inlet of first dilute compartment due to the splitting of water. By lowering the pH value of concentrate and feed, the generation of Ni(OH)2 precipitate can be avoided. Under the condition of Ni2+ concentration, flowrate, pH value of feed, pH value of concentration and the current density are 30 mg/L, 0.317 cm/s, 2.77, 1.18 and 9.5 mA/cm2, respectively, the concentration experiment carries stably for 285 h. The diluate is Ni2+-free at the conductivity of 1.5 μS/cm, and the concentration of Ni2+ in concentrate reaches 2.7 g/L which is 90 times of that in feed.
Key words: electrodeionization; bipolar membrane; nickel; wastewater; precipitation
