(湘潭大學(xué) 化工學(xué)院，湘潭 411105)
摘 要: 采用理論分析與實(shí)驗(yàn)驗(yàn)證相結(jié)合的方法，研究了二苯硫腙萃取分離磷酸鈉溶液中鋅離子的萃取行為，考察了二苯硫腙在甲苯、苯、三氯甲烷及四氯化碳中的溶解度。在此基礎(chǔ)上，研究以苯及三氯甲烷為溶劑的二苯硫腙萃取體系對(duì)磷酸鈉溶液中微量鋅的萃取平衡關(guān)系，探討體系pH值、攪拌速度、萃取劑用量、溫度及相比等因素對(duì)萃取效果的影響。結(jié)果表明：二苯硫腙在三氯甲烷中的溶解度最大，25 ℃時(shí)達(dá)17.55 g/L；在萃取體系pH為7.25、攪拌轉(zhuǎn)速為550 r/min、溫度為25 ℃、相比(A/O)為1:1時(shí)，濃度為1.2 g/L的二苯硫腙-三氯甲烷有機(jī)相對(duì)磷酸鈉溶液中微量鋅的單級(jí)萃取率可達(dá)92.57%；萃取時(shí)，二苯硫腙與溶液中的鋅離子以近似2:1的摩爾比進(jìn)行螯合；該螯合反應(yīng)為吸熱反應(yīng)，反應(yīng)焓變值為26.02 kJ/mol。
關(guān)鍵字: 二苯硫腙；萃取；鋅離子；磷酸鈉溶液；反應(yīng)焓變
（School of Chemical Engineering, Xiangtan University, Xiangtan 411105, China）
Abstract:The extraction behavior of trace zinc(II) in sodium phosphate solution was studied by dithizone extraction. The solubility of dithizone in toluene, benzene, chloroform and carbon tetrachloride was investigated experimentally. On this basis, the extraction equilibrium relationship of trace zinc in sodium phosphate solution was studied by using dithizone as extractant and benzene or chloroform as its solvent, respectively. The effects of the extraction system pH , the stirring speed, the amount of extractant, the temperature and the phase ratio on the extraction efficiency were investigated. The results show that, among the four solvents, the solubility of dithizone in chloroform is the highest, reaching 17.55 g/L at 25 ℃. When the pH of the extraction system is 7.25, the stirring speed is 550 r/min, the temperature is 25 ℃ and the phase ratio is 1:1, the single-stage extraction efficiency of trace zinc can reach 92.57% with a concentration of 1.2 g/L of dithizone in trichloromethane. During the extraction, the molar ratio of dithizone and zinc in the chelate was estimated at approximately 2:1; the chelating reaction was an endothermic reaction with a reaction enthalpy change of 26.02 kJ/mol.
Key words: dithizone; extraction; zinc ion; sodium phosphate solution; reaction enthalpy
