離子配位平衡研究
(中南大學(xué) 冶金科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 根據(jù)配位化學(xué)熱力學(xué)平衡原理，繪制4種金屬離子(Zn2+、Cu2+、Cd2+、Pb2+)−水系的pc—pH圖、羥合配離子分率αn—pH圖及4種金屬氫氧化物條件溶度積與pH關(guān)系圖。pc—pH圖描述了4種金屬氫氧化物在溶解平衡時(shí)，總離子平衡濃度與pH關(guān)系。 Zn(OH)2(s)，Cu(OH)2(s)，Cd(OH)2(s)和Pb(OH)2(s)分別在pH為8.35~10.82，7.32~10.68，9.84~13.31和10.096~10.997時(shí)的溶解度最小。αn-pH圖指出了各種羥合配離子分率與pH的關(guān)系，4種金屬羥合配離子都有其最佳的存在pH范圍。pPS—pH圖指出了4種金屬氫氧化物的條件溶度積與pH的關(guān)系，pH分別在8.0~9.0，7.0~9.0，9.5~10.5和10.3~11.2范圍內(nèi)Zn(OH)2(s)，Cu(OH)2(s)，Cd(OH)2(s)和Pb(OH)2(s)的條件溶度積最小。這些熱力學(xué)圖在中和水解法中的應(yīng)用比電位—pH圖更具實(shí)用價(jià)值，能為中和水解法處理各種重金屬?gòu)U水及濕法冶金除雜質(zhì)提供更加嚴(yán)格的理論依據(jù)。
關(guān)鍵字: 重金屬?gòu)U水；pc—pH圖；羥合配離子分率；αn—pH圖；條件溶度積
heavy metals(Cu2+, Pb2+, Zn2+, Cd2+)−H2O system
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Diagrams for the concentration of complex ions pc—pH, the ratio of four kinds of heavy metals(Zn2+, Cu2+, Cd2+, Pb2+) hydroxyl complex ions αn—pH, conditional solubility product of their hydrates to pH in their system were drawn respectively based on the thermodynamic equilibrium principle of complex chemistry. The relationship between the equilibrium concentration of total heavy metal ions and pH is illustrated in Me2+-H2O system, when dissolution of hydrate is in equilibrium. The solubility of Zn(OH)2 is at the minimal level in pH range from 8.35 to 10.82, Cu(OH)2 from 7.32 to 10.68, Cd(OH)2 from 9.84 to 13.31, and Pb(OH)2 from 10.096 to 10.997. The diagram for αn-pH shows that each hydroxyl complex ion existing in the system depends on an optimized pH value. The diagram for the conditional solubility product pPS—pH indicates that pPS reaches the minimum in the pH range from 8.0 to 9.0 in Zn2+-H2O system, from 7.0 to 9.0 in Cu2+-H2O system, from 9.5 to 10.5 in Cd2+-H2O system and from 10.3 to 11.2 in Pb2+-H2O system. It is of greater practical value of these diagrams than that of potential—pH diagram. Moreover, it can offer more strict theoretical foundation for treatment of heavy metals-containing wastewater by neutralization and for purification of hydrometallurgy.
Key words: wastewater containing heavy metal; diagram of pc—pH; ratio of complex ions; diagram of αn—pH; conditional solubility product
