(1. 吉首大學(xué) 化學(xué)化工學(xué)院，吉首 416000；
2. 吉首大學(xué) 礦物清潔生產(chǎn)與綠色功能材料開發(fā)湖南省重點實驗室，吉首 416000)
摘 要: 針對酸浸液釩鐵分離的難題，繪制298 K時V(Ⅴ)-Fe(Ⅲ)-S(Ⅵ)-H2O系中存在的各種離子隨pH以及濃度變化的熱力學(xué)平衡圖，全面分析釩、鐵物種隨pH和釩、鐵、硫濃度的變化規(guī)律，在此基礎(chǔ)上提出相應(yīng)的釩鐵分離方法并進行理論分析。結(jié)果表明：強酸條件(-1＜pH＜0.5)時鐵和釩分別以Fe3+和 陽離子的形式存在；弱酸條件(0.5＜pH)時由于硫酸根的配位作用，鐵逐漸由Fe3+轉(zhuǎn)變?yōu)?及 陰離子，而釩由 逐步轉(zhuǎn)變?yōu)?及各種聚合陰離子。定義pH50%為含釩或鐵陰離子的摩爾分?jǐn)?shù)為50%時的pH值。溶液中釩濃度越高，pH50%,V越小；鐵濃度越高，pH50%, Fe越大；硫濃度增高，pH50%, Fe減小。在pH50%, V~pH50%, Fe的酸度范圍內(nèi)，鑒于釩和鐵賦存離子電性的差異，選擇堿性萃取劑或離子交換樹脂優(yōu)先吸附釩聚合陰離子，或選擇酸性萃取劑或離子交換樹脂優(yōu)先吸附鐵，均可達到釩和鐵的有效分離。
關(guān)鍵字: V(Ⅴ)-Fe(Ⅲ)-S(Ⅵ)-H2O系；熱力學(xué)；pH50%；溶劑萃取；離子交換
（1. School of Chemistry and Chemical Engineering, Jishou University, Jishou 416000, China
2. Key Laboratory of Mineral Cleaner Production and Exploit of Green Functional Materials in Hunan Province, Jishou University, Jishou 416000, China）
Abstract:Aiming at the separation of vanadium over iron from acidic leaching solution, the thermodynamic equilibrium diagrams for distribution of species at different pH values and different concentrations of vanadium, iron and sulfur with the systems of V(Ⅴ)-Fe(Ⅲ)-S(Ⅵ)-H2O at 298 K were drawn. The variation regularities were also analyzed. Based on the thermodynamic analysis, the corresponding separation methods of vanadium/iron were put forward. The results show that Fe3+and cations are predominant specials of iron and vanadium in strong acidic solution (-1＜pH＜0.5), respectively. When 0.5＜pH, due to the coordination of sulfate，F(xiàn)e3+transforms to and then progressively, alongside this progressively polymerized to various polyanions. pH50% is defined as the pH value when target metal anions occupy 50% mole fraction of total. It can be seen that the more vanadium in solution the lesser the pH50%,V,the more iron the larger the pH50%, Fe, the more sulfur in solution the smaller the pH50%, Fe. In the pH range of pH50%, V-pH50%, Fe, in view of the difference of ionic electrical properties between vanadium and iron, the effective separation of vanadium over iron can be achieved by ether choosing alkaline extractant or ion exchange resin to preferentially adsorb vanadium polyanions oracid extractant or ion exchange resin to preferentially adsorb iron.
Key words: V(Ⅴ)-Fe(Ⅲ)-S(Ⅵ)-H2O system; thermodynamic; pH50%; solvent extraction; ions exchange
