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采用电位滴定法、酸碱中和滴定法及分光光度法,对硫酸亚铁、间苯二酚、没食子酸、葡萄糖醛酸以及HCl和NaOH标准溶液浓度进行标定。在恒定离子强度(I=0.1)条件下,利用pH电位法测定了间苯二酚、没食子酸、葡萄糖醛酸3种配体,在不同温度(10、20、30℃)下的加质子常数及与FeSO4的配合物稳定常数。结果显示:没食子酸加质子常数最大;配体加质子常数及配合物稳定常数,均随温度的升高而降低;3种配体与FeSO4的配位能力差别较大,没食子酸(lgK1=10.72,10℃)>间苯二酚(lgK1=7.28,10℃)>葡萄糖醛酸(lgK1=2.43,10℃)。
Potentiometric titration, acid-base neutralization titration and spectrophotometry were used to calibrate the concentration of ferrous sulfate, resorcinol, gallic acid, glucuronic acid and standard solutions of HCl and NaOH. Under the conditions of constant ionic strength (I = 0.1), the potentials of resorcinol, gallic acid and glucuronic acid ligands were determined by pH potentiometry at different temperatures (10, 20 and 30 ℃) And its stability with FeSO4 complex. The results showed that gallic acid plus proton constant was the largest. The ligand plus proton constant and the stability constant of the complex decreased with the increase of temperature. The ligands of the three ligands differed greatly from FeSO4. Gallic acid (lgK1 = 10.72 , 10 ° C)> resorcinol (lgK1 = 7.28, 10 ° C)> glucuronic acid (lgK1 = 2.43, 10 ° C).